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1
Carini, Giovannella, and n/a. "Effects of Contemporary and Historical Processes on Population Genetic Structure of Two Freshwater Species in Dryland River Systems (Western Queensland, Australia)." Griffith University. Australian School of Environmental Studies, 2004. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20050113.081250.
Full textAbstract:
Arid and semiarid river systems in Western Queensland, Australia, are characterized by the unpredictable and highly variable nature of their hydrological regimes as a result of the episodic nature of rain events in the region. These dryland rivers typically experience episodic floods and extremely low or no flow periods. During low or no flow periods, water persists only in relatively wide and deep sections of the river channels, which are called 'waterholes'. These isolated waterholes serve as refugia for aquatic species during protracted intervals between floods. In such discontinuous riverine habitat, dispersal of freshwater species may be achieved only during wet seasons, when water is flowing in rivers and the nearby floodplains. Obligate aquatic species occur in habitats that represent discrete sites surrounded by inhospitable terrestrial landscapes. Thus, movements are very much limited by the physical nature and arrangement of the riverine system. In addition, the distribution of a species may be also largely dependent on historical events. Landscape and river courses continually change over geological time, often leaving distinct phylogenetic 'signatures', useful in reconciling species' biology with population connectivity and earth history. The main aim of this study was to resolve the relative importance of contemporary and historical processes in structuring populations of two freshwater species in Western Queensland river systems. To address this aim, a comparative approach was taken in analysing patterns of genetic variation of two freshwater invertebrates: a snail (Notopala sublineata) and a prawn (Macrobrachium australiense). Mitochondrial sequences were used for both the species. In addition, allozyme and microsatellites markers were employed for N. sublineata. These species have similar distributions in Western Queensland region, although N. sublineata appears to be extinct in some catchments. M. australiense is thought to have good dispersal abilities due to a planktonic larval phase in its life cycle and good swimming capabilities, whereas N. sublineata is thought to have limited dispersal abilities, because of its benthic behaviour and because this species is viviparous. It was hypothesised that these freshwater invertebrates, would display high levels of genetic structure in populations, because physical barriers represented by terrestrial inhospitable habitat, are likely to impede gene flow between populations inhabiting isolated river pools. Genetic data for the two species targeted in this study supported this hypothesis, indicating strong population subdivision at all spatial scales investigated (i.e. between and within catchments). This suggests that contemporary dispersal between isolated waterholes is relatively restricted, despite the potential good dispersal abilities of one of the species. It was hypothesised that levels of gene flow between populations of aquatic species were higher during the Quaternary (likely movements of individuals across catchment boundaries) and that they have been isolated relatively recently. There is evidence that historically gene flow was occurring between populations, suggesting that episodic dispersal across catchment boundaries was likelier in the past. Episodic historical movements of aquatic fauna were facilitated by higher patterns of river connectivity as a result of the climate changes of the Pleistocene. Because the two species targeted in this study exhibit analogous spatial patterns of evolutionary subdivision it is likely that they have a shared biogeographic history. The unpredictable flow regime of rivers in Western Queensland is likely to have considerable effects on the genetic diversity of aquatic populations. First, if populations of obligate freshwater organisms inhabiting less persistent waterholes are more likely to experience periodic bottlenecks than those inhabiting more persistent ones, they would be expected to have lower levels of genetic diversity. Second, if populations inhabiting less persistent waterholes periodically undergo local extinction with subsequent recolonisation, there should be higher levels of genetic differentiation among them, due to the founder effects, than among those populations inhabiting more persistent waterholes. Contrary to the first prediction, the observed levels of genetic diversity in both N. sublineata and M. australiense were high in both more persistent and less persistent waterholes. There was no tendency for genetic diversity to be lower in less persistent than in more persistent waterholes. However, when Cooper waterholes were ranked in order of persistence, positive correlation between water persistence time in waterholes and genetic diversity was detected in N. sublineata but not in M. australiense. Contrary to the second prediction, highly significant genetic differentiation was found among populations from both less persistent and more persistent waterholes. This indicates that not only populations from less persistent but also those from more persistent waterholes were very dissimilar genetically. This study demonstrated the importance of both contemporary and historical processes in shaping the population structure of obligate freshwater species in Western Queensland river systems. It has indicated that contemporary movements of freshwater species generally are extremely limited across the region, whereas episodic dispersal across catchment boundaries was possible during the Pleistocene, due to different patterns of river connectivity.
2
Carini, Giovannella. "Effects of Contemporary and Historical Processes on Population Genetic Structure of Two Freshwater Species in Dryland River Systems (Western Queensland, Australia)." Thesis, Griffith University, 2004. http://hdl.handle.net/10072/367070.
Full textAbstract:
Arid and semiarid river systems in Western Queensland, Australia, are characterized by the unpredictable and highly variable nature of their hydrological regimes as a result of the episodic nature of rain events in the region. These dryland rivers typically experience episodic floods and extremely low or no flow periods. During low or no flow periods, water persists only in relatively wide and deep sections of the river channels, which are called 'waterholes'. These isolated waterholes serve as refugia for aquatic species during protracted intervals between floods. In such discontinuous riverine habitat, dispersal of freshwater species may be achieved only during wet seasons, when water is flowing in rivers and the nearby floodplains. Obligate aquatic species occur in habitats that represent discrete sites surrounded by inhospitable terrestrial landscapes. Thus, movements are very much limited by the physical nature and arrangement of the riverine system. In addition, the distribution of a species may be also largely dependent on historical events. Landscape and river courses continually change over geological time, often leaving distinct phylogenetic 'signatures', useful in reconciling species' biology with population connectivity and earth history. The main aim of this study was to resolve the relative importance of contemporary and historical processes in structuring populations of two freshwater species in Western Queensland river systems. To address this aim, a comparative approach was taken in analysing patterns of genetic variation of two freshwater invertebrates: a snail (Notopala sublineata) and a prawn (Macrobrachium australiense). Mitochondrial sequences were used for both the species. In addition, allozyme and microsatellites markers were employed for N. sublineata. These species have similar distributions in Western Queensland region, although N. sublineata appears to be extinct in some catchments. M. australiense is thought to have good dispersal abilities due to a planktonic larval phase in its life cycle and good swimming capabilities, whereas N. sublineata is thought to have limited dispersal abilities, because of its benthic behaviour and because this species is viviparous. It was hypothesised that these freshwater invertebrates, would display high levels of genetic structure in populations, because physical barriers represented by terrestrial inhospitable habitat, are likely to impede gene flow between populations inhabiting isolated river pools. Genetic data for the two species targeted in this study supported this hypothesis, indicating strong population subdivision at all spatial scales investigated (i.e. between and within catchments). This suggests that contemporary dispersal between isolated waterholes is relatively restricted, despite the potential good dispersal abilities of one of the species. It was hypothesised that levels of gene flow between populations of aquatic species were higher during the Quaternary (likely movements of individuals across catchment boundaries) and that they have been isolated relatively recently. There is evidence that historically gene flow was occurring between populations, suggesting that episodic dispersal across catchment boundaries was likelier in the past. Episodic historical movements of aquatic fauna were facilitated by higher patterns of river connectivity as a result of the climate changes of the Pleistocene. Because the two species targeted in this study exhibit analogous spatial patterns of evolutionary subdivision it is likely that they have a shared biogeographic history. The unpredictable flow regime of rivers in Western Queensland is likely to have considerable effects on the genetic diversity of aquatic populations. First, if populations of obligate freshwater organisms inhabiting less persistent waterholes are more likely to experience periodic bottlenecks than those inhabiting more persistent ones, they would be expected to have lower levels of genetic diversity. Second, if populations inhabiting less persistent waterholes periodically undergo local extinction with subsequent recolonisation, there should be higher levels of genetic differentiation among them, due to the founder effects, than among those populations inhabiting more persistent waterholes. Contrary to the first prediction, the observed levels of genetic diversity in both N. sublineata and M. australiense were high in both more persistent and less persistent waterholes. There was no tendency for genetic diversity to be lower in less persistent than in more persistent waterholes. However, when Cooper waterholes were ranked in order of persistence, positive correlation between water persistence time in waterholes and genetic diversity was detected in N. sublineata but not in M. australiense. Contrary to the second prediction, highly significant genetic differentiation was found among populations from both less persistent and more persistent waterholes. This indicates that not only populations from less persistent but also those from more persistent waterholes were very dissimilar genetically. This study demonstrated the importance of both contemporary and historical processes in shaping the population structure of obligate freshwater species in Western Queensland river systems. It has indicated that contemporary movements of freshwater species generally are extremely limited across the region, whereas episodic dispersal across catchment boundaries was possible during the Pleistocene, due to different patterns of river connectivity.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Australian School of Environmental Studies
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3
Wittenberg, Lea. "Structural patterns and bed stability of humid temperate, Mediterranean and semi-arid gravel bed rivers." Thesis, University of Newcastle Upon Tyne, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391270.
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4
Sarma, Diganta. "Assessment of sustainable groundwater utilization with case studies from semi-arid Namibia." University of the Western Cape, 2016. http://hdl.handle.net/11394/5649.
Full textAbstract:
Philosophiae Doctor - PhDThe thesis addresses sustainability of groundwater utilization in arid and semiarid regions of Namibia. Recharge in this hydrogeological setting occurs as discrete events to aquifers that are bounded in extent. Case studies involving fractured hardrock and alluvial aquifers with aquifer-ephemeral river interaction were considered. The nature of recharge to arid region bounded aquifers was explored. In arid region aquifers, roundwater storage is depleted during extended dry periods due to pumping and natural discharge. Steady state conditions are rarely achieved. With lowering of the water table, evapotranspiration is reduced thus decreasing aquifer discharge. However, depletion of ephemeral river flow is the primary source of water to boreholes. Physical constraints such as river bed and aquifer hydraulic properties set a limit to the degree of natural replenishment possible during flow events. An approach to assessing sustainable yield of a fractured rock aquifer associated with ephemeral river flow is discussed using a case study from rural semi-arid Namibia. Limited data required the simulation results to be verified against geological and hydrogeological constraints. The aquifer’s gain in storage is estimated through numerical simulation. It provides a basis for groundwater scheme management that rely on limited data in semi-arid conditions in sub-Saharan Africa. Aspects related to ephemeral river flow and groundwater recharge to strip alluvial aquifers was addressed in the second case study. The processes controlling infiltration, significance of surface water and groundwater losses, and possible artificial recharge options were investigated through numerical simulation. It was concluded that recharge processes in arid alluvial aquifers differ significantly from those in humid systems. Conjunctive use of surface and groundwater resources require artificial augmentation of aquifer recharge due to constrains in natural infiltration rates. The study provides a reference for sustainable management of alluvial aquifer systems in similar regions. It is seen from the study that high rates of groundwater exploitation deplete surface water resources needed downstream while failure to capture surface flow during flood events cause loss of potential recharge. It is concluded that as water demand in Namibia increases, basin wide combined surface water and groundwater resource evaluation and management have become a necessity.
5
Lindsey, Melanie. "Sampling Frequency for Semi-Arid Streams and Rivers: Implications for National Parks in the Sonoran Desert Network." Thesis, The University of Arizona, 2010. http://hdl.handle.net/10150/193445.
Full textAbstract:
In developing a water quality monitoring program, the sampling frequency chosen should be able to reliably detect changes in water quality trends. Three datasets are evaluated for Minimal Detectable Change in surface water quality to examine the loss of trend detectability as sampling frequency decreases for sites within the National Park Service's Sonoran Desert Network by re-sampling the records as quarterly and annual datasets and by superimposing step and linear trends over the natural data to estimate the time it takes the Seasonal Kendall Test to detect trends of a specific threshold. Wilcoxon Rank Sum analyses found that monthly and quarterly sampling consistently draw from the same distribution of trend detection times; however, annual sampling can take significantly longer. Therefore, even with a loss in power from reduced sampling, quarterly sampling of Park waters adequately detects trends (70%) compared to monthly whereas annual sampling is insufficient in trend detection (30%).
6
Hussey, Stephen W. "The feasibility of sand-abstraction as a viable method of ground water abstraction." Thesis, Loughborough University, 2003. https://dspace.lboro.ac.uk/2134/14054.
Full textAbstract:
Many rural communities in arid areas of the world make extensive use of perennial water supplies retained within the sediment of a river channel. This naturally filtered water provides for their basic subsistence. A general term applied to the abstraction of water from river sediment is sand-abstraction. Ephemeral and seasonal rivers primarily drain the dryland regions of the world. These arid regions are typically subject to extensive environmental degradation with a consequent high degree of surface erosion. As a result, many of the rivers have become sand rivers, filled with copious amounts of sediment. Most arid areas are subject to occasional rainstorms and flash floods that immediately drain to waterways and saturate the sediment within the river channel. In larger rivers a perennial supply of water is maintained within the sediment. Despite a perceived potential for this water resource there has been little development of any small-scale technology that is suitable for use at a basic rural level. A research and study programme was instigated to assess fully, the potential of such a resource. Field research was undertaken to characterise typical sand rivers and to assess the water storage and water loss and retention factors within river sediment. A check list for identifying possible sand-abstraction sites was devised. In the process of this study the advantages of storing water in sand was fully appreciated and attention given to the development of initially less suitable sites in serious water deficit areas. Systems for efficient abstraction of water were reviewed and designs formulated for the fabrication of equipment to mechanically draw water from river sediment. A series of well-screens, well-points, infiltration galleries and caissons have been designed and initial tests have been conducted under field conditions. Simple technology handpumps that it was considered could be operated, maintained and repaired by rural communities using locally available materials have been developed in conjunction with the abstraction equipment. In consultation with rural people an analysis was made of the technical and sociological requirements that are considered essential for the sustainability of technology suitable for use by disadvantaged rural communities. Both practical and literature research has indicated the latent possibility of this technology. Interaction has been maintained with four communities throughout the research and development period and contributions and indications received are that there is a need to develop such a water source with an upgraded technology. The conclusion from the work undertaken is that development of the technology is worthwhile and that greater efforts should be made to promote it at a small-scale, rural level. In addition the potential to provide clean water in arid regions from such a lowtechnology application should be drawn to the attention of professional water engineers.
7
Capon, Samantha Jane, and n/a. "Flow Variability and Vegetation Dynamics in a Large Arid Floodplain: Cooper Creek, Australia." Griffith University. Australian School of Environmental Studies, 2004. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20040513.110733.
Full textAbstract:
Throughout arid and semi-arid inland Australia, many extensive floodplains occur in association with rivers which are amongst the most hydrologically variable in the world. As rainfall in these areas is characteristically low and patchy, conditions in Australia's 'dryland' floodplains fluctuate unpredictably between extended periods of drought and huge floods that transform vast areas into wetlands, often for months at a time. Vegetation in these floodplains is commonly dominated by short grass and forb associations and patches of open succulent shrubland which are attributed with high ecological and socio-economic values due to their provision of habitat to a diverse array of terrestrial and aquatic fauna and their productive native pasture growth. In temperate and tropical floodplains, a substantial number of studies have shown that plant community composition and structure is determined primarily by flow and alterations to flow in these areas, through water extraction or river regulation, have resulted in many changes to the vegetation including loss of biodiversity and mass invasions of exotic species. Despite increasing pressure for water resource development in 'dryland' regions, relatively little is known regarding the effects of highly variable flows on the vegetation dynamics of arid floodplains, particularly in Australia. This thesis addresses this knowledge gap by examining the role of flow in the vegetation dynamics of a large arid floodplain in central Australia: the Cooper Creek floodplain. The effects of flow on plant community dynamics, from an organism level to that of the landscape, are examined across a range of spatial and temporal scales. Results are presented from a two year temporal vegetation survey during which time two flood pulse events of differing sizes occurred. A large-scale spatial survey was also conducted to determine the effects of flood history on spatial variation in plant community composition and structure. The composition of the soil seed bank and its contribution to vegetation dynamics were additionally investigated through a series of germination trials. Amongst common arid floodplain plants, life history traits that enable persistence under variable hydrological conditions were also considered via several experiments aimed at determining the effects of flow on the outcomes of various life history stages including germination, growth and dispersal. Throughout the study, results are presented for plant groups that were predefined on the basis of life form, life span and taxonomic divisions within these categories. Plant community composition and structure in the Cooper Creek floodplain exhibits significant shifts both temporally, in response to flood pulse wetting and drying, and spatially, in response to flood history. Flood pulse inundation has the potential to influence each life history stage across the range of plant groups present and the outcomes of these appear to be determined by hydrological attributes such as flood pulse timing, duration and rate of drawdown. Vegetation consequently exhibits gradual zonation on a gradient of flood frequency along which plant groups occur at predictable locations depending on their life history traits and recent hydrological conditions. A substantial proportion of species display ruderal life history traits including large, persistent soil seed banks and rapid life cycles which enable escape in time from the stresses associated with flooding and drought. These species, mostly comprising annual monocots and forbs, are widespread throughout the landscape and their presence in the extant vegetation is related primarily to the time since the last flood pulse event and the hydrological attributes of this. Perennial species, particularly shrubs, do not appear to rely similarly on the soil seed bank for recruitment and their distribution in the floodplain vegetation is likely to be determined more by their ability to tolerate either flooding or drought. Overall, this study demonstrates that flow, despite its variability, has an overriding influence on vegetation dynamics in the arid floodplain of the Cooper Creek. The spatial and temporal variability of flow maintains a heterogeneous mosaic of plant communities of differing composition and structure. Given this close relationship between flow and vegetation dynamics, anthropogenic alterations to flow are likely to result in changes to the vegetation including homogenisation of plant communities across the floodplain landscape and eventual loss of biodiversity.
8
Capon, Samantha Jane. "Flow Variability and Vegetation Dynamics in a Large Arid Floodplain: Cooper Creek, Australia." Thesis, Griffith University, 2004. http://hdl.handle.net/10072/366451.
Full textAbstract:
Throughout arid and semi-arid inland Australia, many extensive floodplains occur in association with rivers which are amongst the most hydrologically variable in the world. As rainfall in these areas is characteristically low and patchy, conditions in Australia's 'dryland' floodplains fluctuate unpredictably between extended periods of drought and huge floods that transform vast areas into wetlands, often for months at a time. Vegetation in these floodplains is commonly dominated by short grass and forb associations and patches of open succulent shrubland which are attributed with high ecological and socio-economic values due to their provision of habitat to a diverse array of terrestrial and aquatic fauna and their productive native pasture growth. In temperate and tropical floodplains, a substantial number of studies have shown that plant community composition and structure is determined primarily by flow and alterations to flow in these areas, through water extraction or river regulation, have resulted in many changes to the vegetation including loss of biodiversity and mass invasions of exotic species. Despite increasing pressure for water resource development in 'dryland' regions, relatively little is known regarding the effects of highly variable flows on the vegetation dynamics of arid floodplains, particularly in Australia. This thesis addresses this knowledge gap by examining the role of flow in the vegetation dynamics of a large arid floodplain in central Australia: the Cooper Creek floodplain. The effects of flow on plant community dynamics, from an organism level to that of the landscape, are examined across a range of spatial and temporal scales. Results are presented from a two year temporal vegetation survey during which time two flood pulse events of differing sizes occurred. A large-scale spatial survey was also conducted to determine the effects of flood history on spatial variation in plant community composition and structure. The composition of the soil seed bank and its contribution to vegetation dynamics were additionally investigated through a series of germination trials. Amongst common arid floodplain plants, life history traits that enable persistence under variable hydrological conditions were also considered via several experiments aimed at determining the effects of flow on the outcomes of various life history stages including germination, growth and dispersal. Throughout the study, results are presented for plant groups that were predefined on the basis of life form, life span and taxonomic divisions within these categories. Plant community composition and structure in the Cooper Creek floodplain exhibits significant shifts both temporally, in response to flood pulse wetting and drying, and spatially, in response to flood history. Flood pulse inundation has the potential to influence each life history stage across the range of plant groups present and the outcomes of these appear to be determined by hydrological attributes such as flood pulse timing, duration and rate of drawdown. Vegetation consequently exhibits gradual zonation on a gradient of flood frequency along which plant groups occur at predictable locations depending on their life history traits and recent hydrological conditions. A substantial proportion of species display ruderal life history traits including large, persistent soil seed banks and rapid life cycles which enable escape in time from the stresses associated with flooding and drought. These species, mostly comprising annual monocots and forbs, are widespread throughout the landscape and their presence in the extant vegetation is related primarily to the time since the last flood pulse event and the hydrological attributes of this. Perennial species, particularly shrubs, do not appear to rely similarly on the soil seed bank for recruitment and their distribution in the floodplain vegetation is likely to be determined more by their ability to tolerate either flooding or drought. Overall, this study demonstrates that flow, despite its variability, has an overriding influence on vegetation dynamics in the arid floodplain of the Cooper Creek. The spatial and temporal variability of flow maintains a heterogeneous mosaic of plant communities of differing composition and structure. Given this close relationship between flow and vegetation dynamics, anthropogenic alterations to flow are likely to result in changes to the vegetation including homogenisation of plant communities across the floodplain landscape and eventual loss of biodiversity.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Australian School of Environmental Studies
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9
McIntyre, Rebecca Elise Sinclair. "Soil biogeochemistry and flooding in intermittent streams of the semi-arid Pilbara region." University of Western Australia. School of Plant Biology, 2009. http://theses.library.uwa.edu.au/adt-WU2009.0115.
Full textAbstract:
[Truncated abstract] Most of Australia, and large areas of many other continents, is drained by intermittent rivers and streams, however comparatively few biogeochemical studies have been completed for these systems. Intermittent, dryland streams are highly dynamic environments subject to unpredictable and sporadic flow. Natural disturbance from lengthy drought periods and sudden floods are typical for these systems. Without adequate baselines for natural disturbances, it is difficult to quantify other effects from anthropogenic disturbance such as dewatering, land clearing, and urbanisation, or climate change. This thesis presents work from a four-year study examining the biogeochemistry of nitrogen (N), phosphorus (P) and carbon (C) in soils and sediments of two intermittent streams (Barnett Creek and Pirraburdoo Creek) in the Pilbara region of north-west Australia. The Pilbara is an area of ancient geology and highly weathered environments that is undergoing rapid development yet is poorly understood from an ecological perspective. The principal objectives of this thesis were to determine: i) how flooding affects the spatiotemporal patterns of nutrients in intermittent stream landscapes; ii) the role of flooding in N and C mineralisation and microbial dynamics; and iii) the connections between benthic algae, microbes and nutrient availability in channel sediments. To address these objectives, three field studies and two incubation experiments were conducted. Field studies at Barnett Creek indicated that flooding reduced the spatial heterogeneity of available soil nutrients and microbes in the stream landscape, and that topography (relative elevation) in the stream landscape was of less importance in influencing nutrient and microbial patterns than flooding or landscape position. ... Field studies at Pirraburdoo Creek indicated that microbial biomass and activity increased in benthic algal mats during mat senescent stages, and decreased after flooding when mat biomass peaked. Benthic algae grew rapidly in gravel run environments after flooding, while declining in pools, and demonstrated moderate N limitation and strong P limitation. Pools had two to eight times greater NO3-N, three to five times more total N, and two to three times more labile P, OC and total C than either pools after flooding, or runs before or after flooding. Hence, the pools at Pirraburdoo Creek represented a local, interflood store of nutrients in otherwise nutrient-poor landscape, when connectivity to upstream reaches or upland environments was weak or non-existent. This thesis provides the first detailed analysis of soil and sediment biogeochemical responses to flooding for intermittent streams in the Pilbara region and for semi-arid Australia. Further pressing questions raised by this work include: What is the key pulse size and frequency for maintaining Pilbara riparian communities as well as soil microbial function? How do the spatio-temporal nutrient and microbial patterns observed persist over (i) multi-decadal scales, (ii) mega-spatial (larger landscape to regional) scales, (iii) different flood frequency-magnitude regimes, and (iv) different stream sizes? Stream biogeochemistry is a burgeoning field, and it is therefore reasonable to expect such existing gaps in knowledge may be addressed in the near future.
10
Cunha, Costa Alexandre. "Analyzing and modelling of flow transmission processes in river-systems with a focus on semi-arid conditions." Phd thesis, Universität Potsdam, 2012. http://opus.kobv.de/ubp/volltexte/2012/5969/.
Full textAbstract:
One of the major problems for the implementation of water resources planning and management in arid and semi-arid environments is the scarcity of hydrological data and, consequently, research studies. In this thesis, the hydrology of dryland river systems was analyzed and a semi-distributed hydrological model and a forecasting approach were developed for flow transmission processes in river-systems with a focus on semi-arid conditions.
Three different sources of hydrological data (streamflow series, groundwater level series and multi-temporal satellite data) were combined in order to analyze the channel transmission losses of a large reach of the Jaguaribe River in NE Brazil. A perceptual model of this reach was derived suggesting that the application of models, which were developed for sub-humid and temperate regions, may be more suitable for this reach than classical models, which were developed for arid and semi-arid regions. Summarily, it was shown that this river reach is hydraulically connected with groundwater and shifts from being a losing river at the dry and beginning of rainy seasons to become a losing/gaining (mostly losing) river at the middle and end of rainy seasons.
A new semi-distributed channel transmission losses model was developed, which was based primarily on the capability of simulation in very different dryland environments and flexible model structures for testing hypotheses on the dominant hydrological processes of rivers. This model was successfully tested in a large reach of the Jaguaribe River in NE Brazil and a small stream in the Walnut Gulch Experimental Watershed in the SW USA. Hypotheses on the dominant processes of the channel transmission losses (different model structures) in the Jaguaribe river were evaluated, showing that both lateral (stream-)aquifer water fluxes and ground-water flow in the underlying alluvium parallel to the river course are necessary to predict streamflow and channel transmission losses, the former process being more relevant than the latter. This procedure not only reduced model structure uncertainties, but also reported modelling failures rejecting model structure hypotheses, namely streamflow without river-aquifer interaction and stream-aquifer flow without groundwater flow parallel to the river course. The application of the model to different dryland environments enabled learning about the model itself from differences in channel reach responses. For example, the parameters related to the unsaturated part of the model, which were active for the small reach in the USA, presented a much greater variation in the sensitivity coefficients than those which drove the saturated part of the model, which were active for the large reach in Brazil.
Moreover, a nonparametric approach, which dealt with both deterministic evolution and inherent fluctuations in river discharge data, was developed based on a qualitative dynamical system-based criterion, which involved a learning process about the structure of the time series, instead of a fitting procedure only. This approach, which was based only on the discharge time series itself, was applied to a headwater catchment in Germany, in which runoff are induced by either convective rainfall during the summer or snow melt in the spring. The application showed the following important features:
• the differences between runoff measurements were more suitable than the actual runoff measurements when using regression models;
• the catchment runoff system shifted from being a possible dynamical system contaminated with noise to a linear random process when the interval time of the discharge time series increased;
• and runoff underestimation can be expected for rising limbs and overestimation for falling limbs.
This nonparametric approach was compared with a distributed hydrological model designed for real-time flood forecasting, with both presenting similar results on average.
Finally, a benchmark for hydrological research using semi-distributed modelling was proposed, based on the aforementioned analysis, modelling and forecasting of flow transmission processes. The aim of this benchmark was not to describe a blue-print for hydrological modelling design, but rather to propose a scientific method to improve hydrological knowledge using semi-distributed hydrological modelling. Following the application of the proposed benchmark to a case study, the actual state of its hydrological knowledge and its predictive uncertainty can be determined, primarily through rejected hypotheses on the dominant hydrological processes and differences in catchment/variables responses.Die Bewirtschaftung von Wasserressourcen in ariden und semiariden Landschaften ist mit einer Reihe besonderer Probleme konfrontiert. Eines der größten Probleme für die Maßnahmenplanung und für das operationelle Management ist der Mangel an hydrologischen Daten und damit zusammenhängend auch die relativ kleine Zahl wissenschaftlicher Arbeiten zu dieser Thematik. In dieser Arbeit wurden 1) die grundlegenden hydrologischen Bedingungen von Trockenflusssystemen analysiert, 2) ein Modellsystem für Flüsse unter semiariden Bedingungen, und 3) ein nichtparametrisches Vorhersage-verfahren für Abflussvorgänge in Flüssen entwickelt. Der Wasserverlust in einem großen Abschnitt des Jaguaribe Flusses im nordöstlichen Brasilien wurde auf Basis von Daten zu Abflussraten, Grundwasserflurabstände und mit Hilfe multitemporaler Satellitendaten analysiert. Dafür wurde zuerst ein konzeptionelles hydrologisches Modell über die Mechanismen der Transferverluste in diesem Abschnitt des Trockenflusses erstellt. Dabei ergab sich, dass der Flussabschnitt mit dem Grundwasser hydraulisch verbunden ist. Der Flussabschnitt weist in der Trockenenzeit und am Anfang der Regenzeit nur Wasserverlust (Sickerung) zum Grundwasser auf. Im Laufe der Regenzeit findet auch ein gegenseitiger Austausch vom Grundwasser mit dem Flusswasser statt. Aufgrund dieser hydraulischen Kopplung zwischen Flusswasser und Grundwasser sind für diesen Flussabschnitt hydrologische Modellansätze anzuwenden, die generell für gekoppelte Fluss-Grundwassersysteme, v.a. in feuchtgemäßigten Klimaten, entwickelt wurden. Es wurde ein neuartiges hydrologisches Simulationsmodell für Transferverluste in Trockenflüssen entwickelt. Dieses Modell ist für unterschiedliche aride und semiaride Landschaften anwendbar und hat eine flexible Modellstruktur, wodurch unterschiedliche Hypothesen zur Relevanz einzelner hydrologische Prozesse getestet werden können. Es wurde für den zuvor genannten großen Abschnitt des Jaguaribe Flusses im nordöstlichen Brasilien und für einen kleinen Flussabschnitt im „Walnut Gulch Experimental Watershed“ (WGEW) in Arizona, Südwest-USA, angewendet. Für die eine prozess-orientierte Simulation von Abflussbedingungen und Transferverlusten im Einzugsgebiet des Jaguaribe hat sich gezeigt, dass die am besten geeignete Modellstruktur sowohl den Austausch zwischen Flusswasser und Grundwasser (senkrecht zur Fließrichtung des Flusses) als auch die parallel zum Fluss verlaufende Grundwasserströmung enthält. Die Simulationsexperimente mit unterschiedlichen Modellstrukturen („Hypothesentest“) reduzierte nicht nur die Modellstrukturunsicherheit, sondern quantifizierte auch die Qualität der Modellergebnisse bei folgenden Varianten der Modellstruktur: a) Abflluss im Fluss ohne Interaktion mit dem Grundwasser (keine Transferverluste) und b) Interaktion zwischen Fluss und Grundwasser ohne parallelen Grundwasserstrom zum Flussstrom. Durch die Anwendung auf die beiden unterschiedlichen Trockenflusssysteme wurden neue Erkenntnisse über die Sensitivität des Modells unter verschiedenen Bedingungen erworben. Beispielsweise waren die Parameter der ungesättigten Zone, die von hoher Relevanz für den kleinen Flussabschnitt im WGEW waren, viel sensitiver als die Parameter der gesättigten Zone, die besonders relevant für den Jaguaribe Flussabschnitt in Brasilien waren. Die Ursache für diese sehr unterschiedliche Sensitivität liegt darin, dass beim WGEW das Flusswasser nur mit der ungesättigten Zone in Kontakt steht, da sich in diesem Gebiet, welche im Vergleich zur Jaguaribe-Region noch deutlich trockener ist, kein Grund-wasserleiter bildet. Letztlich wurde ein nicht-parametrisches Verfahren, zur Simulation der deterministischen Evolution und stochastischen Fluktuation der Abflussdynamik entwickelt. Im Unterschied zu prozessbasiertem Modellsystemen basiert dieses Verfahren nicht auf Modellkalibrierung sondern auf einem Lernprozess, basierend auf Zeitreihendaten. Als Anwendungsbeispiel wurde ein mesoskaliges Einzugsgebiet im Erzgebirge, NO-Deutschland gewählt, in dem starke Abflussereignisse entweder durch konvektive Niederschlagsereignisse oder durch Schneeschmelze generiert werden. Die folgenden wichtigsten Ergebnisse wurden erzielt: • Regressionsmodellansätze basierend auf den zeitlichen Änderungen der Abflüsse liefern bessere Ergebnisse gegenüber Ansätzen basierend auf direkten Abflussdaten; • mit zunehmendem Vorhersagehorizont wandelt sich das hydrologische System von einem mit Zufallsanteilen verrauschten dynamischen System zu einem linearen probabilistischen Zufallsprozess; • Bei zunehmendem Abfluss (ansteigenden Ganglinie) erfolgt meist eine Abflussunterschätzung, bei abnehmendem Abfluss (fallende Ganglinie) erfolgt meist eine Abflussüberschätzung. Dieses nichtparametrische Verfahren ergibt im Vergleich mit einem prozess-orientierten und flächenverteilten hydrologischen Hochwasservorhersagemodell bis zu einem Vorhersagezeitraum von 3 Stunden Ergebnisse von vergleichbar guter Qualität. Letztendlich wurde ein Vorgehen bzgl. künftiger Forschungen zu hydrologischer Modellierung vorgeschlagen. Das Ziel dabei war ein wissenschaftliches Verfahren zur Verbesserung des hydrologischen Wissens über ein Einzugsgebiet. Diese Verfahren basiert auf einem Hypothesentest zu den relevanten hydrologischen Prozessen und der Untersuchung der Sensitivitäten der hydrologischen Variablen bei unterschiedlichen Einzugsgebieten.
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Garófano, Gómez Virginia. "Riparian vegetation patterns according to hydrogeomorphological factors at different spatial and temporal scales in Mediterranean rivers." Doctoral thesis, Universitat Politècnica de València, 2013. http://hdl.handle.net/10251/29395.
Full textAbstract:
Los corredores riparios en ambientes semiáridos mediterráneos son ecosistemas de gran biodiversidad y
complejidad. En ellos confluyen una gran variedad de perturbaciones naturales capaces de crear un mosaico
espacial y temporal con pocos paralelos en otros ecosistemas. Sin embargo, a pesar de su valor, los ecosistemas
riparios están amenazados debido a los altos niveles de intervención humana. La construcción de presas (y la
consecuente manipulación del caudal) está considerada como la perturbación humana más importante que se
cierne sobre ellos. Esta tesis ha tenido como objetivo analizar el ecosistema ripario, abarcando diferentes escalas
espaciales y temporales, y centrándose en los factores que influyen en la distribución, estructura, composición,
calidad y dinámica de su vegetación, tanto en tramos naturales como hidrológicamente alterados de ríos
mediterráneos, concretamente de la Demarcación Hidrográfica del Júcar (Este de España).
Para lograr este objetivo, se han hecho los siguientes aportes a la investigación: A) Determinar los patrones de
distribución de especies leñosas riparias en el gradiente transversal de la ribera y definir grupos de especies con
respuesta similar a las condiciones físicas del hábitat; B) Comparar la respuesta de dichas especies en tramos
naturales y alterados hidrológicamente; C) Definir curvas de respuesta y gremios hidrológicos de especies en
tramos con régimen natural; D) Establecer los principales factores que determinan la calidad del hábitat ripario y
fluvial y los patrones longitudinales de la composición florística, así como de las características del hábitat fluvial
en un segmento hidrológicamente alterado; E) Describir los cambios espacio-temporales en la estructura y
complejidad de la vegetación, y los cambios temporales en el régimen de caudales del corredor ripario de un
tramo hidrológicamente alterado.
Los objetivos anteriores fueron abordados con diferentes metodologías que implicaron la combinación de
diversas fuentes de información y un esfuerzo importante en la toma de datos en varios lugares de estudio de los
ríos Cabriel, Mijares y Serpis. Para cumplir con los objetivos A y B, se llevaron a cabo un muestreo de suelos y
un muestreo georreferenciado de vegetación a través de transectos transversales al cauce en dos tramos naturales
y tres regulados. Los datos fueron analizados con estadística robusta y multivariante. Para cumplir el objetivo C,
el muestreo georreferenciado anterior (junto con un muestreo dendrocronológico) fue acoplado con un modelo
hidráulico en los dos tramos naturales, con el fin de obtener la serie temporal de cotas del agua a la que habían
estado expuestas cada una de las plantas durante su vida. La respuesta de las especies y su posible agregación en
gremios hidrológicos fue comparada mediante estadística robusta en relación a la duración de la inundación,
duración de la inundación durante el período de crecimiento, duración continua de la inundación, frecuencia de
inundación y elevación de la planta respecto al caudal base. Para lograr el objetivo D, toda la sección regulada del
río Serpis (desde la presa Beniarrés - hasta la desembocadura; 40 km) se dividió en segmentos. En cada uno de
ellos se llevó a cabo un inventario de flora y se aplicaron índices hidromorfológicos. Los segmentos fueron
agrupados de acuerdo a su composición florística y características del hábitat fluvial utilizando diferentes técnicas
de estadística multivariante. Finalmente se discutieron los factores principales que controlan los patrones
espaciales de la composición florística, las características del hábitat fluvial, la calidad del hábitat ribereño y la
heterogeneidad del hábitat fluvial. Para alcanzar el objetivo E, se combinaron series históricas de caudales y su
manipulación humana con imágenes aéreas históricas (reveladoras de cambios en la cubierta vegetal) y
observaciones de campo de la distribución de edades de la vegetación y morfología del corredor ripario del río
Mijares en los últimos 60 años. De esta información, se extrajeron métricas del paisaje e índices hidrológicos para
identificar y resumir los cambios espacio-temporales en la estructura de la ribera y en el régimen de caudales.
El estudio a escala transversal nos ayudó a comprender en cada uno de los tramos la zonación de las especies
leñosas riparias en función de la morfología y características del suelo, revelando que la alteración del caudal
puede influir en la modificación de los patrones posicionales de las especies. Se definieron tres gremios
hidrológicos: ¿altamente tolerante a la inundación¿, ¿tolerante intermedio¿ y ¿de transición entre ripario y
terrestre¿. El estudio a escala longitudinal sugirió que la respuesta de la vegetación a un cambio hidrológico es
altamente dependiente de la geomorfología local. Se constató que los factores principales que determinan los
patrones hidromorfológicos y florísticos son un régimen de caudales artificial y altamente variable (identificado
en los segmentos con peor calidad del hábitat ripario y fluvial), la presencia de estructuras laterales en el cauce y
las características geomorfológicas. Como efectos importantes de la regulación del caudal a largo plazo, el estudio
a escala espacio-temporal reveló un aumento en la cobertura y densidad de la vegetación leñosa, una deriva en la
composición de especies y una disminución en las áreas de sedimento desnudo (esencial para el reclutamiento de
las especies riparias pioneras), junto con una reducción sincrónica en la complejidad de la ribera. Estos cambios
estarían relacionados con la disminución de la magnitud y variabilidad de los caudales en las últimas seis décadas.
Solo una mejor comprensión de los procesos ecohidrológicos y de las implicaciones de la alteración hidrológica
sobre los ecosistemas riparios mediterráneos podrá apoyar la integración eficaz de estos sistemas en las
decisiones de gestión del agua.Garófano Gómez, V. (2013). Riparian vegetation patterns according to hydrogeomorphological factors at different spatial and temporal scales in Mediterranean rivers [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/29395
TESIS
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Fox, John Tyler. "Spatiotemporal Patterns and Drivers of Surface Water Quality and Landscape Change in a Semi-Arid, Southern African Savanna." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/81462.
Full textAbstract:
The savannas of southern Africa are a highly variable and globally-important biome supporting rapidly-expanding human populations, along with one of the greatest concentrations of wildlife on the continent. Savannas occupy a fifth of the earth's land surface, yet despite their ecological and economic significance, understanding of the complex couplings and feedbacks that drive spatiotemporal patterns of change are lacking. In Chapter 1 of my dissertation, I discuss some of the different theoretical frameworks used to understand complex and dynamic changes in savanna structure and composition. In Chapter 2, I evaluate spatial drivers of water quality declines in the Chobe River using spatiotemporal and geostatistical modeling of time series data collected along a transect spanning a mosaic of protected, urban, and developing urban land use. Chapter 3 explores the complex couplings and feedbacks that drive spatiotemporal patterns of land cover (LC) change across the Chobe District, with a particular focus on climate, fire, herbivory, and anthropogenic disturbance. In Chapter 4, I evaluated the utility of Distance sampling methods to: 1) derive seasonal fecal loading estimates in national park and unprotected land; 2) provide a simple, standardized method to estimate riparian fecal loading for use in distributed hydrological water quality models; 3) answer questions about complex drivers and patterns of water quality variability in a semi-arid southern African river system. Together, these findings have important implications to land use planning and water conservation in southern Africa's dryland savanna ecosystems.Ph. D.
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Yaraghi, N. (Navid). "Assessing the impacts of artificial groundwater recharge structures on river flow regime in arid and semi-arid regions." Master's thesis, University of Oulu, 2017. http://urn.fi/URN:NBN:fi:oulu-201709062799.
Full textAbstract:
In dry and semi-dry climate, Artificial Groundwater Recharge Structures are used for flood control and managed aquifer recharge. These damps basin runoff response decrease the maximum flows and increase the runoff duration through wet seasons. In this study, a framework to quantify the role of AGWRS in headwater tributaries on the total water balance of major basin and alteration of flow pattern in the main river has been presented. The study contains four main subroutines: rainfall-runoff model, reservoir flood routing, river analysis system and seepage analysis. The flood hydrographs with different return periods are estimated based on the climatic data and the characteristics of headwater basin. River flow analysis below the structure is carried out for two unsteady flow scenarios, first with the hydrographs of the natural system (as pre-impact: quick flood with significant peak flow) and second the altered flow hydrographs due to detention process in the reservoir (as post-impact: damped flood lower peak with longer duration time). Two sets of dynamic water surface along the river (from the location of detention structure (x=0) to the confluence point with the main river (x=L) are developed based on two hydrologic conditions as results of river analysis system. The results of framework define the impact of flood detention structure by comparing the timing, magnitude, and variability of flow. The Kamal Abad artificial groundwater recharge in Mahrlou Lake basin in Southern Iran was selected as case study to demonstrate the application of the created framework. Through the probability analysis, the return period for hydrological drought has been compared to the pre-impact and post-impact condition. The results clearly showed how embankments influence floods in tributaries and in some cases the flow reduced significantly and disappear in tributaries.
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Imam, Bisher 1960. "Evaluation of disaggregation model in arid land stream flow generation." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277033.
Full textAbstract:
A Disaggregation model was tested for arid land stream flow generating. The test was performed on data from Black River, near Fort Apache, Arizona. The model was tested in terms of preserving the relevant historical statistics on both monthly and daily levels, the monthly time series were disaggregated to a random observation of their daily components and the daily components were then reaggregated to yield monthly values. A computer model (DSGN) was developed to perform the model implementation. The model was written and executed on the Macintosh plus personal computer Data from two months were studied; the October data represented the low flow season, while the April data represented the high flow season. Twenty five years of data for each month was used. The generated data for the two months was compared with the historical data.
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Bunting, Daniel Paul. "Riparian Restoration and Management of Arid and Semiarid Watersheds." Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/228166.
Full textAbstract:
Riparian ecosystems are valued for ecosystem services which have impacts on the well-being of humans and the environment. Anthropogenic disturbances along rivers in arid and semiarid regions have altered historical flow regimes and compromised their integrity. Many rivers are hydroecologically deteriorated, have diminished native riparian forests, and are pressured for their water supplies. My first study is founded on the premise that river restoration has increased exponentially with little documentation on effectiveness. We designed a conference to discuss lessons learned from past restoration activities to benefit future efforts. Participants, including scientists, managers, and practitioners, agreed that creating measureable objectives with subsequent monitoring is essential for quantifying success and employing adaptive management. Attendees stated that current projects are local and have limited funding and time, whereas future efforts must have longer funding cycles, larger timeframes, should contribute to regional goals, and address factors responsible for ecological decline. Bridging gaps among science, management, and policy in the 21st century is a key component to success. My second study focused on the benefits of long-term monitoring of local riparian restoration. Many efforts include revegetation components to re-establish native cottonwood-willow communities, but do not address how high-density establishment impacts vegetation dynamics and sustainability. Over five years, we documented significantly higher growth rates, lower mortality, and higher cover in cottonwood compared to non-native tamarisk. Cottonwood height, diameter at breast height, growth rates, and foliar volumes were reduced at higher densities. Herbaceous species decreased every year but native shrubs volunteered after two years resulting in a reduction of overall plant diversity from 2007-2009 with a slight increase from 2009-2011.My third study focused on improving basin-scale evapotranspiration (ET), a large component of the water budget, to better inform water resource allocation. My research suggests that multiple models are required for basin-scale ET estimates due to vegetation variability across water-limitation gradients. We created two empirical models using remote sensing, a multiplicative riparian ET model (r²=0.92) using MODIS nighttime land surface temperature (LST(n)) and enhanced vegetation index, and an upland ET model (r²=0.77) using multiple linear regression replacing LST(n) with a precipitation input.
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Fossati, Jacques. "Caractéristiques du système oued en milieu hyperaride, végétation des oueds du désert oriental septentrional (Egypte) et phytoécologique d'un secteur de l'oued Sannur." Université Joseph Fourier (Grenoble), 1995. http://www.theses.fr/1995GRE10138.
Full textAbstract:
La vegetation des oueds est etudiee a deux echelles spatiale: la region du desert oriental septentrional d'egypte (3010'n a 2610'n et 3050'e a 3230'e) et un secteur de l'oued sannur (29104n ; 3128'e). A l'echelle regionale, quatre groupements s'individualisent au sein des gradients climatiques nord/sud (precipitations et temperature moyenne annuelle) et nord-ouest/sud-est (evapotranspiration). Un gradient biogeographique se surimpose a cette description, avec des especes mediterranneennes au nord et des especes soudano-angolanes au sud, le fond commun etant saharo-arabique. A l'echelle d'un secteur de l'oued sannur ou la frequence des crues est estimee a sept ans, les especes perennes s'organisent en cinq groupes. La geomorphologie et la granulometrie de surface expliquent une partie de la structure de la vegetation: les especes sont liees au chenal ou aux rives et terrasses d'une part, a une granulometrie de surface fine ou a des zones plus grossieres d'autre part. Les especes annuelles ephemerophytes constituent une synusie ombrique en relation avec les precipitations hivernales et atteignent un maximum de recouvrement au mois de mars. Leur repartition depend essentiellement de la granulometrie dominee par des particules fines. D'une echelle spatiale a l'autre, le poids des facteurs expliquant la structure de la communaute vegetale peut etre different. A l'emboitement des echelles spatiales peut correspondre un emboitement des facteurs mesologiques explicatifs, parmi eux, certains seront pertinents a une echelle donnee et d'autres a plusieurs niveaux
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Potts, Daniel Lawrence. "Rainfall Variability and Carbon Cycling in Semi-Arid Ecosystems." Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1338%5F1%5Fm.pdf&type=application/pdf.
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Alcantara-Ayala, Irasema. "Modelling mass movement risk under semi-arid mountainous conditions : the Alpujarride complex, Spain." Thesis, King's College London (University of London), 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267249.
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Wirth, Timo Matti. "Water, Agriculture + settlement design in the arid lower Colorado River Basin : 3 new models." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/65750.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Architecture, June 2011."June 2011." Cataloged from PDF version of thesis.
Includes bibliographical references (p. 108-109).
This thesis investigates possible conversions of an increasingly unviable type of irrigated agricultural landscape, seen under the influences of three simultaneous processes: urban growth, change of cropping practice and return to the desert. Three new prototypical models are designed and tested: an urban-rural oasis, an adapted rural settlement and an inhabited desert park. An analysis of historical hydrological alteration and agrarian/urban settlement processes in the Colorado River Lower Basin focuses on a region in a pivotal situation: Central Arizona and its agricultural irrigation districts. Here, the three models are tested on a hypothetical site of one square mile and simultaneously investigated in an abstract matrix of regionally applicable principles. In an increasing order, the urbanrural oasis, the adapted rural settlement, and the inhabited desert park reduce water needs by rainwater harvesting/-storage and greywater re-use. They are resilient towards droughts by allowing farmers to temporarily fallow agricultural elements, or, in the case of the desert park, by hosting partially seasonal uses and importing drinking water as necessary. The urban-rural oasis relies on a localized form of agriculture that allows selling all produce directly on site, mainly to its inhabitants, with a large recreational emphasis. The adapted rural settlement targets the emerging new food markets in the urban region with high-value crops, and diversifies production to include native agroforestry for energy production and woodcraft. The desert park contains a low input-output dryland agriculture and sporadic recreational desert harvesters. All three models rely on phased forms of settlement growth, increased income opportunities on site by the (re-)combination of land uses and the creation of microclimates by a strategic arrangement of vegetated land cover in proximity to settlement. Residential options span from medium- to low-density detached courtyard types; different sizes of garden homes, haciendas and farm communities to desert villas, and even RV campgrounds; with the urban-rural oasis having the largest range of choices among the options. Each model may attract broad concentrations and ranges of regional lifestyle groups between urban/suburban, agrarian and nature-oriented communities, of a permanent or an ephemeral nature. A single overarching condition is the realistic acknowledgment of both the obvious challenges and plentiful qualities of the desert. Various cultures could unfold together with the idea of saving water. There seems to be an enormous potential in converting the agricultural landscape into a more resilient and diversified one, along pathways proposed by the three models. Moreover, attempts to free up volumes of water on large sites would be one of the fundamental necessary steps to more permanently embrace both human and natural life in an arid and unique environment like the Lower Colorado River Basin.
by Timo Matti Wirth.
S.M.
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Treese, Samantha. "Stream/Aquifer Interactions in a Semi-Arid Effluent Dependent River: A Clogging Conceptual Model." Thesis, The University of Arizona, 2008. http://hdl.handle.net/10150/193317.
Full textAbstract:
Treated wastewater (effluent) has been used as a water source for aquifer recharge and sustaining perennial surface water flow. Artificial recharge basins allow effluent to seep into the ground relieving stressed aquifers. However, these basins frequently become clogged due to physical, chemical, and biological processes. Effluent is also used to replace baseflow for dry streambeds. However, little is known about the effect of effluent on stream-aquifer interactions. Effluent from the Nogales International Waste Water Treatment Plant sustains perennial flow in the Upper Santa Cruz River, Arizona. A series of monthly field campaigns were undertaken to understand the impact of effluent on the streambed at 16 different sites along a 30 km river reach. The field campaigns had two foci: physical transformations in the streambed and water source identification using chemical composition. Historic data sets including USGS stream gauging records, NIWTP outfall data, ADWR well transducer data and USGS well chemistry data were also analyzed to provide a larger context for the work. Results indicate that localized clogging forms in the Upper Santa Cruz River. The clogging layers perch the stream and shallow streambed causing a desaturation below the streambed. A clogging cycle is established in the context of a semi-arid hydrologic cycle: formation during dry and hot pre-monsoon months, and removal by a set of large flood flows (10+ m3/sec) during the monsoon season. However, if the intensity of flooding during the semi-arid hydrologic cycle is lessened, the dependent riparian area can experience a die off.
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Dlikilili, Sinethemba. "Variability of vegetation in the Touws river and catchment using remote sensing." University of the Western Cape, 2019. http://hdl.handle.net/11394/6955.
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Magister Artium - MAChanges in climate patterns have raised concerns for environmentalists globally and across southern Africa. The changes greatly affect the growth dynamics of vegetation to such an extent that climate elements such as rainfall have become the most important determinant of vegetation growth. In arid and semi-arid environments, vegetation relies on near-surface groundwater as the main source of water. Changes in the environment due to climate can be examined by using remotely sensed data. This approach offers an affordable and easy means of monitoring the impact of climate variability on vegetation growth. This study examined the response of vegetation to rainfall and temperature, and assessed the dependence thereof on groundwater in a climatically variable region of the semi-arid Karoo. The methodology used included sampling plant species in the riparian and non-riparian areas over two plant communities in seven vegetation plots. The Normalised Difference Vegetation Index (NDVI) derived from the Landsat OLI and TM was used to measure vegetation productivity. This was compared with rainfall totals derived from the Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS) and the mean monthly temperature totals. A drought index, (Standardised Precipitation Index – SPI) was an additional analysis to investigate rainfall variability. Object-based Image Analysis (OBIA) and Maximum Likelihood supervised classification approaches together with indicators of groundwater discharge areas (Topographic Wetness Index – TWI, and profile curvature) were used to map vegetation and surface water that depend on groundwater.
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Whittemore, Aaron Maitland. "Analysis of Human Influence on Drought Conditions in the Upper Colorado River Basin (Texas)." Thesis, Virginia Tech, 2020. http://hdl.handle.net/10919/99053.
Full textAbstract:
Globally, it is expected that arid and semi-arid areas will face increasing frequency of drought through the 21st century. Drought is normally attributed to climatic factors. However, humans constantly alter hydrologic systems through manipulating and consuming water, which can also cause drought. However, human influence on drought, outside of influences on warming-driven climate change, is rarely studied. Here, the upper Colorado River Basin (Texas) is studied to assess the human influence on drought conditions in a semi-arid basin. An observation-modeling framework is used to simulate naturalized runoff conditions which are compared to observed data in an undisturbed (little human influence) and disturbed (much human influence) period to elucidate human influences on drought. Further, public water storage and supply data are incorporated to analyze how human water management may be specifically affecting downstream hydrologic drought in the upper Colorado River Basin. Results show that according to observed data, drought occurred more often, persisted longer on average, and had a higher maximum duration during the disturbed period. Naturalized model output did not predict such increases, indicating that human influence is responsible. Water deliveries in the study area were found to significantly affect downstream flow and are connected to instances of human-influenced drought. Results suggest that in order to reduce downstream drought conditions, deliveries will likely have to be reduced and that reducing deliveries during periods of low rainfall, or during months in which deliveries constitute a large portion of human influenced drought severity could be especially helpful in alleviating downstream drought.Master of Science
It is expected that many arid climates around the globe will become even experience more frequent drought during the 21st century. Drought is a lack of water relative to normal levels and has important implications for agriculture, industry, fisheries, water managers, and the broader public. Drought is normally attributed to natural factors such as lack of rain or increases in temperature. Humans have affected these factors through global climate change, and many researchers have focused their efforts on understanding how global warming impacts drought conditions. However, humans can also affect drought conditions through water consumption. Despite the impact of human water consumption, it is rarely a topic of specific study in relation to the occurrence of drought. Here, conditions lacking human influence (i.e. no water consumption, land-use change, etc.) are simulated and compared to observed data from a stream gage downstream from human intervention, allowing for examination of human influences on drought. Public water usage and management data from the Colorado River Municipal Water District are also incorporated to allow for more specific understanding of how human influence affects drought conditions downstream of reservoir operation and groundwater pumping. Results show that drought occurred more often, persisted longer on average, and had a higher maximum duration due to human influence. Water usage and management by the Colorado River Municipal Water District are connected to and have a role in causing decreases in downstream flow and occurrence of drought. Results indicate that demand reductions will likely be needed to ensure sustainable water availability and that reducing demand during periods of low rainfall or during times of the year in which human water use accounts for larger portions of drought severity could be most helpful in lessening downstream drought.
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Fuller, Jonathan Edward. "Paleoflood hydrology of the alluvial Salt River, Tempe, Arizona." Thesis, The University of Arizona, 1987. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_etd_hy0163_sip1_w.pdf&type=application/pdf.
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Ahmed, Mohamed Saber Mohamed Sayed. "Hydrological Approaches of Wadi System Considering Flash Floods in Arid Regions." 京都大学 (Kyoto University), 2010. http://hdl.handle.net/2433/126791.
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Fish, Suzanne K. "Agriculture and society in arid lands a Hohokam case study /." Diss., The University of Arizona, 1993. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_1993_589_sip1_w.pdf&type=application/pdf.
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Thesis (Ph. D.)--University of Arizona, 1993."In addition to chapters [leaves 20-57] unique to the dissertation, ten papers are included that were published during the period of doctoral enrollment"--Leaf 19. Includes bibliographical references.
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Nelson, Gregory A. "Optimal well field design for reducing phreatophyte uptake losses." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277142.
Full textAbstract:
A two-dimensional, finite difference model was used to simulate the lowering of the water table below a floodplain in order to affect water conservation by reducing phreatophyte transpiration. Evapotranspiration capture percentages and unit water costs associated with alternative well network designs were calculated in order to determine those factors which are most important in designing an evapotranspiration capture project.
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Henshel, Judy 1958. "Copper, manganese, and zinc in Puerco River sediments." Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276725.
Full textAbstract:
A study was conducted to test for the presence of heavy metals (Cu, Mn, and Zn) in surface sediments of the Puerco River channel in the aftermath of a toxic spill in 1979 near Church Rock, New Mexico. Analysis of samples from five sites downstream from the spill showed that these substances were not present in unusually large amounts, though an increasing gradient of metal concentration with distance downstream was revealed. Statistical analysis revealed the Cu, Mn, and Zn were associated with clay and silt, soil organic matter, organic carbon, and carbonates, all of which existed as extraneous, uncontrolled variables. Adjusted metal concentrations, obtained with covariate analyses, confirmed the increasing gradient downstream. Clay and silt also increased downstream. Some toxic substances may have leached into the riverbed; possible mechanisms for this process are also discussed and further study to substantiate or disprove this hypothesis is recommended.
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Guber, Albert L. "Channel changes of the San Xavier Reach of the Santa Cruz River, Tucson, Arizona 1971-1988." Thesis, The University of Arizona, 1988. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_1988_608_sip1_w.pdf&type=application/pdf.
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Najmaddin, Peshawa Mustafa. "Simulating river runoff and terrestrial water storage variability in data-scarce semi-arid catchments using remote sensing." Thesis, University of Leicester, 2017. http://hdl.handle.net/2381/40771.
Full textAbstract:
Remotely sensed data can be used as an alternative to ground based observations to predict river discharge and water storage variability. The latter dataset used consists of meteorological records from four stations (2003-2014) and daily river discharge records from one stations (2010-2014). A model was developed named ‘Leicester Model for Semi-Arid Region’ (LEMSAR). It was applied in the semi-arid Kurdistan region of Northern Iraq. TRMM Multi-satellite Precipitation Analysis (TMPA) data products (TMPA 3B42 and 3B42RT) were used with and without a bias correction. The uncorrected TMPA underestimated observed mean catchment rainfall by 10% compared to corrected data with 0.7%. Four methods of computing reference evapotranspiration (ETₒ) were applied which include Hargreaves-Samani (HS), Jensen-Haise (JH), McGuinness-Bordne(MB) and FAO Penman Monteith(PM). The variables utilised are air temperature, relative humidity and cloud cover fraction from the Atmospheric Infrared Sounder / Advanced Microwave Sounding (AIRS/AMSU), and wind speed at 10 m height from MERRA (Modern-Era Retrospective Analysis for Research and Application). Compared to ETₒ-G (PM), ETₒ-RS (HS) underestimated ETₒ-G (PM) by 3% while JH and MB overestimated by 8% to 40% at different stations. Nash-Sutcliffe Efficiency (NSE) for the LEMSAR fit with the observed hydrograph was 0.75, for a calibration period (2010-2011) using gauged rainfall data with ETₒ-G (PM). Model validation performance (2012–2014) was best (NSE =0.61) using the corrected 3B42 data with ETₒ-RS HS and poorest when driven by uncorrected 3B42RT data with ETₒ-RS JH (NSE =0.07). Data from the Gravity Recovery and Climate Experiment (GRACE: 2003-2014) were used to evaluate total water storage variability and compared with that of well observations data and LEMSAR. Trends in GRACE_TWSA were approximately -33.72 mm y-1 for the Lesser Zab catchment and -35.4 mm y-1 for the Hawler well monitoring zone while LEMSAR predicted 15 mm y-1 for the Lesser Zab Catchment. This suggest that reduction in recharge (modelled by LEMSAR) may only be responsible for about 50% of the reduction in groundwater storage. The rest could be the result of increased abstraction in response to the drought. Overall, results suggest that RS data can be usefully employed to simulate river discharge and to evaluate terrestrial water storage variability in semi-arid areas. It has the potential to help decision-makers improve water resources management.
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Neenan, Johnathan. "Evaluation of Stream Bank Restoration to Improve Water Quality in a Semi-Arid Stream." DigitalCommons@USU, 2019. https://digitalcommons.usu.edu/etd/7687.
Full textAbstract:
Human watershed activities such as converting land cover to agriculture and livestock grazing have negatively impacted stream water quality worldwide. One such case is Utah’s Upper Sevier River where a loss of woody bank vegetation (reduced shading) and accelerated bank erosion (increased fine sediment inputs) has led to increased stream temperature and water turbidity. As a result, the state of Utah sought to improve water quality conditions using streambank restoration. While commonly recommended and performed, the effectiveness of this sort of restoration has rarely been quantified. Here, I evaluated a restored reach of the Upper Sevier River near Hatch, UT using continuous monitoring data and a historical photo analysis. As Utah wishes to continue performing this type of restoration in additional locations on the Upper Sevier River, I applied a simple sediment budget model to test its value in informing future streambank restoration decisions.
Continuous monitoring data at the upstream and downstream extent of restoration showed that both stream temperature and turbidity increased downstream along the restored reach. In addition, I found that stream temperature violated Utah’s cold-water stream threshold at both sites but did not violate thresholds for rainbow trout. Turbidity violated state and biological thresholds at both sites. I was unable to conclude whether the streambank restoration directly altered water quality because I lacked monitoring data before restoration occurred. Results of the historical aerial photo analysis showed that restoration practitioners were successful in reducing cut bank erosion. My use of SIAM as a simple sediment budget model proved insufficient due to poor data quality and quantity. Overall, streambank restoration was successful at reducing cut bank erosion, and I recommended monitoring future restoration before and after project completion, identifying and monitoring upstream sources of fine sediment, and pursuing more comprehensive sediment models to inform future streambank restoration.
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Parker, John Travis Chesluk 1947. "Geomorphology and hydrology of the Santa Cruz River, Southeastern Arizona." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/191201.
Full textAbstract:
The Santa Cruz River in southeastern Arizona is typical of large rivers of the semiarid southwestern United States. The 390-kilometer long river displays great variability in morphology, hydraulics, hydrologic, conditions, and bank stability, reflecting incomplete integration of the drainage system and the disequilibrium that is often characteristic of desert channels. Spatial variability is paralleled by temporal variability at all scales, from instantaneous conditions to millenia of geologic history. The alluvial history of the Santa Cruz River drainage basin suggests that transverse sediment transport toward the valley across alluvial fans has dominated fluvial processes for most of the history of the basin. No evidence is apparent for external drainage of the basin before the beginning of Fort Lowell Formation deposition, about 2.0 to 2.5 million years ago. The mid to late Pleistocene history of the system is poorly understood because of the paucity of the geologic record for this period. Several episodes of terrace formation apparently represent climatically induced sediment pulses and subsequent incision. The Holocene record of the Santa Cruz River suggests a major change in hydrologic regimen about 5,000 years ago when deposits indicate a substantial decrease in stream power. The last 2,500 years are marked by a sequence of channel cut and fill episodes similar to the historic episode of channel entrenchment that began in the 19th century. The hydrologic regimen of the Santa Cruz River is dominated by the occurrence of floods in direct response to precipitation. Three major storm types—monsoonal, frontal, and dissipating tropical—account for most streamflow. The storms cause floods with distinctly different characteristics. Monsoonal storm-caused floods may have quite high peak discharges, but are local and of short duration. Frontal and tropical storms cause floods of longer duration and flood volume and are more efficient agents of sediment transport and geomorphic change than are those caused by monsoonal storms. Geologic controls are the major factor governing the spatial variability of channel morphology and change. Hydrologic factors control the temporal variability of channel processes. Frontal and tropical storms are more likely to produce floods capable of causing and maintaining a continuously entrenched main channel. Floods caused by monsoonal storms do not appear capable of maintaining such a system.
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Sekese, Siviwe Pamela. "Geomorphic analysis of river character and behaviour in three semi-arid, mountainous catchments in the Eastern Cape, South Africa." University of Western Cape, 2019. http://hdl.handle.net/11394/7412.
Full textAbstract:
>Magister Scientiae - MScThe analysis of what controls why rivers are the way they are, and how and why they change is crucial in predicting river dynamics and deriving classification systems that can assist management. A variety of factors control the pattern of fluvial styles in a river system across spatial scales. The geomorphic response of a river to an individual control, such as stream power for example, will vary due to a combination of other contributing factors such as geology and climate.
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Mendes, Wagner Josà da Silva. "Adaptation of streeter model - Phelps for water quality modeling in a large semi-arid basin." Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=13522.
Full textAbstract:
This paper presents an adaptation of the classical model of Streeter-Phelps modeling of Dissolved Oxygen (DO) and Biochemical Oxygen Demand (BOD) in the basin of the Upper Jaguaribe (25,000 km2), State of Ceara, Brazil. The adaptation of the model consisted of the numerical solution of differential equations Streeter-Phelps, considering the effect of incremental flows and sewage releases over the sections, as well as the variability of the sections of rivers and tributaries. For model calibration, including the adjustment of reaeration coefficients (K2) and removal of BOD (Kd), we used the data of the Plan of Management of Waters of the Rio Jaguaribe Basin. Calibration results showed that this simplified model represented well the balance between DO and BOD in a large semi-arid basin, with a good fit for both parameters. For OD, the average deviation was 8.44% and 6.04% by the end and beginning of the rainy season, respectively. As for BOD, the deviations were 18.51% and 30.43% for the two seasons, respectively. In both periods, the OD remained within the standards for Class 2 of Resolution CONAMA 357/2005 throughout the stretch and the BOD breached this limit on a short stretch near the city of Taua. With the already calibrated model were simulated three scenarios: a large full, using as reference flow Q10 of a historical series of Jaguaribe; drought, using the Q50 of the series; and implementation of a WWTP with 80% removal of BOD in all seats. The simulations showed consistent results and that serve as a basis for management of water resources of the study area.Este trabalho apresenta uma adaptaÃÃo do modelo clÃssico de Streeter-Phelps para modelagem de OxigÃnio Dissolvido (OD) e Demanda BioquÃmica de OxigÃnio (DBO) na bacia do Alto Jaguaribe (Ãrea de 25.000 km2), Estado do CearÃ, Brasil. A adaptaÃÃo do modelo consistiu na resoluÃÃo numÃrica das equaÃÃes diferenciais de Streeter-Phelps, considerando o efeito de vazÃes incrementais e lanÃamentos de esgoto ao longo dos trechos, assim como a variabilidade das seÃÃes dos rios e tributÃrios. Para calibraÃÃo do modelo, incluindo o ajuste dos coeficientes de reaeraÃÃo (K2) e remoÃÃo de DBO (Kd), foram utilizados os dados do Plano de Gerenciamento das Ãguas da Bacia do Rio Jaguaribe. Os resultados da calibraÃÃo mostraram que esse modelo simplificado representou bem o balanÃo entre OD e DBO em uma grande bacia semiÃrida, apresentando um bom ajuste para os dois parÃmetros. Para OD, o desvio mÃdio foi de 8,44% e 6,04% para o fim e inÃcio da estaÃÃo chuvosa, respectivamente. Jà para DBO, os desvios foram de 18,51% e 30,43% para as duas estaÃÃes, respectivamente. Nos dois perÃodos, o OD manteve-se dentro dos padrÃes para Classe 2 da resoluÃÃo CONAMA 357/2005 em todo o trecho e a DBO infringiu este limite em um pequeno trecho prÃximo à cidade de TauÃ. Com o modelo jà calibrado, foram simulados trÃs cenÃrios: uma grande cheia, utilizando como vazÃo de referÃncia o Q10 de uma sÃrie histÃrica do Jaguaribe; estiagem, utilizando o Q50 da sÃrie histÃrica; e, implantaÃÃo de uma ETE com remoÃÃo de 80% de DBO em todas as sedes. As simulaÃÃes apresentaram resultados coerentes e que servem como base para o gerenciamento dos recursos hÃdricos da bacia estudada.
34
Baillie, Matthew Nelson. "Quantifying baseflow inputs to the San Pedro River a geochemical approach /." Thesis, The University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_2005_019_sip1_w.pdf&type=application/pdf.
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Hirschboeck, Katherine K. "Hydroclimatology of flow events in the Gila River basin, central and southern Arizona." Diss., The University of Arizona, 1985. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_1985_68_sip1_w.pdf&type=application/pdf.
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Roth, Frances Ann. "Implications of stratigraphic completeness analysis for magnetic polarity stratigraphic studies." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/558017.
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Betancourt, Julio L. "Tucson's Santa Cruz River and the arroyo legacy." Diss., The University of Arizona, 1990. http://hdl.handle.net/10150/191157.
Full textAbstract:
Between 1865 and 1915, arroyos developed in the southwestern United States across diverse hydrological, ecological and cultural settings. That they developed simultaneously has encouraged the search for a common cause-- some phenomenon that was equally widespread and synchronous. There are few southwestern streams for which we have even a qualitative understanding of timelines and processes involved in initiation and extension of historic arroyos. Tucson's Santa Cruz River, often cited in the arroyo literature, offers a unique opportunity to chronicle the arroyo legacy and evaluate its causes. The present study reconstructs both the physical and cultural circumstances of channel entrenchment along the Santa Cruz River. Primary data include newspaper accounts, notes and plants of General Land Office surveys, eyewitness accounts, legal depositions, and repeat photography. On the Santa Cruz River, arroyo initiation and extension happened during relatively wet decades associated with frequent warm episodes in the tropical Pacific (El Niño conditions). Intensified El Niño activity during the period 1864-1891 may be symptomatic of long-term climatic change, perhaps indicative of global warming and destabilization of Pacific climate at the end of the Little Ice Age. During this period all but one of the years registering more than three days with rain exceeding 2.54 cm (1 in) in Tucson were El Niño events. The one exception was the summer of 1890, when the central equatorial Pacific was relatively cold but when prevailing low-surface pressures and low-level winds nevertheless steered tropical moisture from the west coast of Mexico into southern Arizona. In the twentieth century, catastrophic channel widening was caused by floods during El Niño events in 1905, 1915, 1977 and 1983. The Santa Cruz River arroyo formed when climatic conditions heightened the probabilities for occurrence of large floods in southern Arizona. Inadequate engineering of ditches that resulted in abrupt changes in the longitudinal profile of the stream further augmented probabilities that any one of these floods would initiate an arroyo. In the future, changing flood probabilities with low-frequency climatic fluctuations and improved flow conveyance due to intensified land use and channel stabilization will further complicate management of the arroyo in an increasingly urbanized floodplain.
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Moursi, Hossam. "A Risk-Based Assessment of Agricultural Water Scarcity Under Climate Change in a Semi-Arid and Snowmelt-Dominated River Basin." DigitalCommons@USU, 2016. https://digitalcommons.usu.edu/etd/4999.
Full textAbstract:
Water scarcity is the major challenge that water managers face in semi-arid areas, especially in regions that depend on agriculture for rural livelihood. Climate change is one of the major stresses that is expected to exacerbate water scarcity problems in semi-arid regions. In this study, a risk-based approach was used to assess the climate change impacts on the risk of agricultural water scarcity in semi-arid and snowmelt-dominated river basins that are dependent on agriculture. The Sevier River Basin, located in south central Utah, was used as the case study for this work. An agricultural water deficit index was proposed to represent the basin performance in terms of water supply and agricultural water demand. The basin's natural water supply was estimated using a semi-distributed tank model. FAO AquaCrop model was used to estimate the crop water requirements for major crops in the basin. The risk-based methodology begins using a vulnerability analysis to identify the system sensitivity to climate change. Sensitivity of system response to climatic variability was identified by establishing the climate response function, which is the relationship between basin agricultural water shortage and climate variables (i.e., precipitation and temperatures). The climate response function was then used to predict the basin agricultural water shortage in this century across four time slices using the projections of precipitation and temperature from downscaled and bias corrected GCMs outputs from the Coupled Model Intercomparison Project Phase 5 (CMIP5) for RCP4.5 and RCP8.5 scenarios.
The results of this study suggested that more natural water supply is expected in the Sevier River Basin due to the expected increase in precipitation during the future off seasons. However, projected temperature increases in the future may increase crop water requirements. It is also found that there is a high risk of unacceptable climate change impacts on agricultural water scarcity in the basin in the period 2025-2049 under RCP4.5 and for 2075-2099 under the RCP8.5 scenario, indicating climate change adaptation actions may be needed.
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MacLeod, Andrew Harris. "Characterization of Sediment Yield Variation, Little Colorado River Basin Near Saint Johns Arizona." Thesis, The University of Arizona, 2001. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_2001_222_sip1_w.pdf&type=application/pdf.
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McGinness, Heather M., and n/a. "SPATIAL HETEROGENEITY AND HYDROLOGICAL CONNECTIVITY IN A DRYLAND, ANABRANCHING FLOODPLAIN RIVER SYSTEM." University of Canberra. Resource, Environmental & Heritage Sciences, 2007. http://erl.canberra.edu.au./public/adt-AUC20070731.094606.
Full textAbstract:
Riverine landscapes are complex. More than just a single channel, they comprise a
shifting mosaic of hydrogeomorphic patches with varying physical and biological
characteristics. These patches are connected by water during flows of varying magnitude
and frequency, at a range of spatial and temporal scales. Combined, landscape
complexity and hydrological connectivity create biological diversity that in turn
maintains the productivity, ecological function, and resilience of these systems. This
thesis investigates the ecological importance of spatial heterogeneity and temporal
hydrological connectivity in a dryland floodplain river landscape. It focuses on
anabranch channels, and uses major carbon sources in these and adjacent landscape
patches as indicators of ecological pattern and process.
A conceptual model was proposed, describing the potential effects upon the distribution
and availability of major carbon sources of: a) a spatial mosaic of hydrogeomorphic
patches in the landscape (e.g. anabranches, river channel, and wider floodplain); and b)
four primary temporal phases of hydrological connection during flow pulses
(disconnection, partial connection, complete connection, and draining). This was then
tested by data collected over a three year period from a 16 km reach of the lower
Macintyre River (NSW/QLD Australia). Results were examined at multiple spatial
scales (patch scale � river channel vs. anabranches vs. floodplain; between individual
anabranches; and within anabranches � entry, middle and exit sites).
The data indicate that spatial heterogeneity in the lower Macintyre River landscape
significantly influences ecological pattern. Carbon quantity was greater in anabranch
channels compared to adjacent river channel patches, but not compared to the floodplain;
while carbon quality was greater in anabranch channels compared to both adjacent river
channel and floodplain patches. Stable isotope analysis indicated that carbon sources that
were predominantly found in anabranch channels supported both anabranch and river
organisms during a winter disconnection phase. Other carbon sources found in the main
river channel and the wider floodplain appeared to play a comparatively minimal role in
the food web.
Different phases of hydrological connection between anabranch channels and the main
river channel were associated with differences in the availability of carbon sources. In the
river channel, draining of water from anabranches (the draining phase) was associated
with relatively high concentrations of dissolved organic carbon (DOC) and low
concentrations of phytoplankton. Conversely, the disconnection phase was associated
with relatively low concentrations of DOC and high concentrations of phytoplankton in
the river channel. In anabranch channels and their waterbodies, the disconnection and
draining phases were associated with high concentrations of both DOC and
phytoplankton. Concentrations of these carbon sources were lowest in anabranches
during the partial and complete connection phases.
Different hydrological connection phases were also associated with changes in trophic
status in the aquatic components of the landscape. On the riverbanks, relatively low rates
of benthic production and respiration during the complete connection phase were
associated with heterotrophy. The remaining phases appeared to be autotrophic. Benthic
production on riverbanks was greatest during the disconnection phase, and respiration
was greatest during the partial connection phase. In the anabranch channels, rates of
production and respiration were similar during the disconnection phase, and were
associated with heterotrophy in the anabranch waterbodies. The remaining phases
appeared to be autotrophic. Respiration was greatest in anabranches during the
disconnection phase, and production was greatest during the draining phase. Both
production and respiration were lowest during complete connection. These differences
and changes varied according to the landscape patch examined.
At a landscape scale, anabranch channels act as both sinks and suppliers of carbon. High
rates of sediment deposition facilitate their role as sinks for sediment-associated carbon
and other particulate, refractory carbon sources. Simultaneously, anabranch channels
supply aquatic carbon sources from their waterbodies, as well as via processes such as
inundation-stimulated release of DOC from surface sediments. Modelled data indicated
that water resource development reduces the frequency and duration of connection
between anabranch channels and the main river channel. This loss of landscape
complexity via loss of connectivity with anabranches has the potential to reduce the total
availability of carbon sources to the ecosystem, as demonstrated by a modelled 13%
reduction in potential dissolved organic carbon release from anabranch sediments.
This thesis has demonstrated the importance of spatial heterogeneity in riverine
landscapes, by documenting its association with variability in the distribution and quality
of primary energy sources for the ecosystem. It has shown that this variability is
augmented by different phases of hydrological connectivity over time. Spatial
heterogeneity and hydrological connectivity interact to increase the diversity and
availability of ecological energy sources across the riverine landscape, at multiple spatial
and temporal scales. This has positive implications for the resilience and sustainability of
the system. Anabranch channels are particularly important facilitators of these effects in
this dryland floodplain river system. Anabranch channels are �intermediate� in terms of
spatial placement, temporal hydrological connection, and availability of carbon sources;
of high value in terms of high-quality carbon sources; and relatively easy to target for
management because of their defined commence-to-flow levels. Further research should
be directed toward evaluating other ecological roles of anabranch channels in dryland
rivers, thereby providing a more complete understanding of the importance of
connectivity between these features and other patches. This knowledge would assist
management of floodplain river landscapes at larger regional scales, including
amelioration of the effects of water resource development.
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Douglas, John Elmer. "Regional interaction in the Northern Sierra: An analysis based on the late prehistoric occupation of the San Bernardino Valley, southeastern Arizona." Diss., The University of Arizona, 1990. http://hdl.handle.net/10150/185011.
Full textAbstract:
The terms "core" and "periphery" have a long history of use for describing regional variability in the archaeological record. Contemporary theories for the late prehistoric in the Greater Southwest often follow this tradition, postulating underlying social processes that created this division. This dissertation examines the assumptions and the evidence for theories of long-distance social interaction by considering the prehistory of the Northern Sierra, a region in the south-central Greater Southwest located in northwestern Chihuahua, northeastern Sonora, southwestern New Mexico, and southeastern Arizona. Paquime (sometimes called Casas Grandes) in Chihuahua is widely considered to be the core of late prehistoric developments in the Northern Sierra. The history of research and interpretation of the region are carefully considered, an analysis that demonstrates the inadequacies of current data and theory. New frameworks will be needed to resolve disputed issues. Towards this end, evidence of interaction at Paquime is examined by analyzing the quantity and distribution of nonlocal ceramics within the site. These probable exchange items are found to be relatively rare and their distribution diffuse, indicating acquisition was largely casual and infrequent. Attention is then focused on the postulated periphery by examining the upper San Bernardino Valley in the extreme southeastern corner of Arizona. Data collected for this examination includes survey within the Valley and excavation of the late prehistoric Boss Ranch Site (AZ FF:7:10 (ASM)). The interpretive concerns that are addressed include (1) population movements, (2) external influences on settlement systems, (3) trade and interaction, and (4) the influences of subsistence systems. The analysis revealed no evidence of population intrusion from the "core" and few aspects of local material culture that could be ascribed to Paquime. Exchange items are rare, and the probable sources include many areas besides the zone around Paquime. Furthermore, excavation data suggest that settlements may have been occupied repeatedly for short periods. This undermines notions of stable core and periphery interaction by indicating the absence of surplus crops, stable social alliances, and hierarchical settlement systems in the region.
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Lacher, Laurel Jane 1964. "Recharge characteristics of an effluent dominated stream near Tucson, Arizona." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/191199.
Full textAbstract:
Almost 90% of the treated sewage effluent processed by the two treatment plants serving the greater Tucson area is available for passive recharge through the Santa Cruz River streambed north of Tucson. In the absence of any major disturbance of the effluent channel, the recharge capacity of the streambed materials decreases over time as microbial activity, and possibly suspended sediments settling out of solution, act to clog the surficial sediments under the effluent stream. Effluent stream transmission-loss measurements made over the period from November 1994 to August 1995 provided data used to determine the average vertical hydraulic conductivity of the low-flow channel in the study reach through simulations using the computer model known as KINEROS2. Saturated hydraulic conductivity (KSAT) served as the calibration parameter in the model. The appropriate KSAT value was chosen for each set of field data by matching the observed and simulated downstream hydrographs for the study reach. KSAT values were corrected for viscosity changes resulting from changing average daily surface water temperatures over the study period. Saturated hydraulic conductivity values for the effluent stream channel ranged from a maximum of 37 mm/hr in January, 1995, following several major winter storms, to a minimum of 11 mm/hr in August, 1995, after a nearly six-month interstorm period. The saturated hydraulic conductivity values decay exponentially with time after the last major winter storm. The mathematical model describing this decay may be used to estimate effluent recharge rates under similar future meteorological and climatological conditions.
43
Ronayne, Michael James, and Thomas III Maddock. "Flow model for the Bingham cienega area, San Pedro river basin, Arizona: a management and restoration tool." Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ), 1996. http://hdl.handle.net/10150/615701.
Full textAbstract:
A finite element groundwater flow model was used to support a hydrologic
assessment for a study area in the Lower San Pedro River Basin which contains the
Bingham Cienega. Consolidated sedimentary rocks associated with an extension of the
Catalina Core Complex truncate the floodplain aquifer system in the study area. The
elevated water table produced by this "hardrock" results in spring discharge at the cienega
and a locally gaining reach of the San Pedro River. The steady -state model suggests that
recharge (and discharge) components for the floodplain aquifer sum to 3.10 cfs. Mountain
front recharge, underflow, and stream leakage are the primary recharge mechanisms, while
stream leakage, evapotranspiration, spring flow, and underflow out are sources for
groundwater discharge. A steady -oscillatory model was used to account for seasonal
periodicity in the system's boundary conditions. Monthly variation in the
evapotranspiration rate was offset primarily by storage changes in the aquifer. Due to a
lack of measured hydrologic data within the study area, results from the model simulations
are only preliminary.
Model development and the subsequent sensitivity analyses have provided insight
into what type of data needs to be collected. Head measurements are most needed in the
area just downstream from Bingham Cienega. The mountain front recharge and
evapotranspiration rates are shown to be highly sensitive parameters in the model;
improved estimation of these values would be helpful. Spring discharge would be a
valuable calibration tool if it could be accurately measured. A more extensive record of
stream baseflow in the San Pedro River should be established. After more hydrologic data
is collected, the model could be recalibrated so as to better represent the system.
Eventually, this tool may be used in direct support of management and/or restoration
decisions.
44
Baird, Kathryn J., Michael J. Ronayne, and Thomas III Maddock. "PRELIMINARY VEGETATION AND HYDROLOGIC ANALYSES FOR BINGHAM CIENEGA." Department of Hydrology and Water Resources, University of Arizona (Tucson, AZ), 1997. http://hdl.handle.net/10150/615776.
Full textAbstract:
This report is in two parts. The first part covers the ecological processes pertinent
to the restoration of Bingham Cienega. The second part presents a subregional groundwater
flow model for analyzing the water budget, stream and spring behavior, and water
table configuration. Because of the sparsity of ecological and hydrologic data, both parts
must be considered as preliminary studies.
45
Sobczak, Robert Valentine. "Confusion where ground and surface waters meet : Gila River General Adjudication, Arizona, and the search for subflow." Thesis, The University of Arizona, 1994. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_etd_hy0325_sip1_w.pdf&type=application/pdf.
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Morehouse, Barbara Jo. "Landscape as text a sociogeographic study of the Santa Cruz River within the vicinity of Tucson, Arizona /." Thesis, The University of Arizona, 1990. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_1990_204_sip1_w.pdf&type=application/pdf.
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Cunha, Costa Alexandre Verfasser], and Axel [Akademischer Betreuer] [Bronstert. "Analyzing and modelling of flow transmission processes in river-systems with a focus on semi-arid conditions / Alexandre Cunha Costa. Betreuer: Axel Bronstert." Potsdam : Universitätsbibliothek der Universität Potsdam, 2012. http://d-nb.info/1022746278/34.
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Grow, David Earl. "Effects of substrate on dendrochronologic streamflow reconstruction: Paria River, Utah with fractal application to dendrochronology." Diss., The University of Arizona, 2002. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_2002_312_sip1_w.pdf&type=application/pdf.
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Lima, Ernane Cortez. "Planejamento ambiental como subsÃdio para gestÃo ambiental da bacia de drenagem do aÃude Paulo Sarasate Varjota-CearÃ." Universidade Federal do CearÃ, 2012. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=10322.
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FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgicoO trabalho tem como objetivo oferecer propostas de planejamento como subsÃdio para gestÃo ambiental da bacia de drenagem do AÃude Paulo Sarasate, localizado no municÃpio de Varjota â CE, regiÃo oeste do estado do CearÃ, com uma Ãrea de 3.501 kmÂ. Neste estudo, procurou-se contextualizar a Ãrea da pesquisa, atravÃs da anÃlise dos atributos do sistema geoambiental (geologia, geomorfologia, clima, recursos hÃdricos, solos, vegetaÃÃo e fauna) e as formas de uso e ocupaÃÃo da terra. A base metodolÃgica utilizada foi a anÃlise geossistÃmica e foram feitos levantamentos bibliogrÃficos, cartogrÃficos e trabalhos de campo. A partir dessa metodologia, foram identificadas quatro unidades geoambientais: a DepressÃo Sertaneja, a PlanÃcie Fluvial do Rio Acaraà os MaciÃos Residuais, e parte do Planalto da Ibiapaba. Utilizou-se como ferramenta bÃsica o sensoriamento remoto, atravÃs de processo digital de imagens de satÃlite Landsat 7; elaborou-se mapas temÃticos tendo como apoio as folhas da SUDENE/DSG SB.24-V-B-I (Santa QuitÃria) e a folha SB.24-V-A-III (IpÃ) (1:100.000), sendo a porÃÃo da unidade geoambiental estudada representada com base em escala de 1:50.000. A montante do AÃude Paulo Sarasate estÃo os municÃpios de HidrolÃndia, Ipueiras, Nova Russas, Catunda, ArarendÃ, Tamboril e Monsenhor Tabosa, e quatro importantes reservatÃrios da bacia do rio Acaraà com capacidade de acumulaÃÃo de Ãgua semelhante à do aÃude em estudo, sÃo eles: Farias de Sousa (Nova Russas), CarÃo (Tamboril), Aroeiras (Nova Russas), Bonito (IpÃ). Grande parte das Ãreas, a montante do AÃude Paulo Sarasate, encontra-se em processo de desmatamento bastante acentuado, como à o caso da Ãrea de nascentes do rio AcaraÃ. Com isso hà ocorrÃncia de processos de assoreamento, vossorocas e ravinamentos nas vertentes, tendo como consequÃncia a diminuiÃÃo do fluxo hÃdrico nas calhas fluviais. Outro fator relevante constitui o crescimento demogrÃfico dos pequenos centros urbanos dos municÃpios, alÃm da criaÃÃo ou mudanÃa de hÃbitos, da âmelhoria do nÃvel de vidaâ, do desenvolvimento industrial (microempresas) e de uma sÃrie de outros fatores. O diagnÃstico elaborado permitiu a definiÃÃo de propostas de estratÃgias de planejamento e gestÃo ambiental no sentido de recuperaÃÃo, conservaÃÃo e preservaÃÃo ambiental, por meio de um zoneamento nas escalas de 1:100.000 (regional), acompanhado por um plano de gestÃo em nÃvel municipal, 1:100.000. Palavras-chave: Planejamento Ambiental. GestÃo Ambiental. SemiÃrido. Bacia HidrogrÃfica.
The work aims at planning and management environmental catchment AÃude Paulo Sarasate, located in the municipality of Varjota â EC, in western state of CearÃ, with an area of 3,501square kilometers. In this study, tried to contextualize the research area by analysis of geoenvironmental system attributes (geology, geomorphology, climate, water resources, soils, vegetation and (fauna) and ways to use and occupy the land. The base design was used to analyze geo were made bibliographic, cartographic and fieldwork. Based on this methodology were identified three environmental units: Depression Hinterland, the river plain of the river and the Solid Acaraà Residuals. Was used as the basic tool remote sensing, through a process of digital Landsat 7 satellite images, thematic maps have been prepared having as support the leaves SUDENE / DSG SB.24-VB- I (Clover St.) and the leaf SB.24-V-B-I (IPU) (1:100,000), the portion of the unit Geoenvironmental studied represented based on a scale of 1:50,000. Upstream of the dam are the Paulo Sarasate HidrolÃndia municipalities, Ipueiras, New Russia, Catunda ArarendÃ, Monkfish and Monsignor Tabosa, and four important reservoirs of the river basin with Acaraà accumulation capacity similar to water in the reservoir study, they were: Farias de Sousa (Nova Russas), CarÃo (Tamboril), Aroeiras (Nova Russas), Bonito (IpÃ). Great of the areas upstream of the dam Paulo Sarasate, is in the process of deforestation rather pronounced as in the case of area sources of the river AcaraÃ. Thus there is an occurrence of processes siltation, solifluxion, Gullies and ravines in strands, resulting in the decreased flow river water in the gutters. Another relevant factor is the population growth of small centers urban municipalities, and the creation or change of habits, âimprovement of living standardsâ, the industrial development (micro enterprises) and a number of other factors. The diagnosis made possible the definition of proposals for planning strategies and environmental management in order to restore, maintain and environmental preservation through zoning in scales of 1:100,000 (regional), accompanied by a plan management at municipal level, 1:100,000. Keywords: Planning. Management Environmental. Semi-Arid. River Basin.
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Carver, Scott Stevenson. "Dryland salinity, mosquitoes, mammals and the ecology of Ross River virus." University of Western Australia. School of Animal Biology, 2008. http://theses.library.uwa.edu.au/adt-WU2009.0100.
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[Truncated abstract] In an era of emerging and resurging infectious diseases, understanding the ecological processes that influence pathogen activity and the influences of anthropogenic change to those are critical. Ross River virus (RRV, Togoviridae: Alphavirus) is a mosquito-borne zoonosis occurring in Australia with a significant human disease burden. In the southwest of Western Australia (WA) RRV is principally vectored by Aedes camptorhynchus Thomson (Diptera: Culicidae), which is halophilic. The inland southwest, the Wheatbelt region, of WA is substantially affected by an anthropogenic salinisation of agricultural land called dryland salinity, which threatens to influence transmission of this arbovirus. This study assessed the ecological impacts of dryland salinity on mosquitoes, mammalian hosts and their interactions to influence the potential for RRV transmission. Many aquatic insect taxa colonise ephemeral water bodies directly as adults or by oviposition. Using a manipulative experiment and sampling from ephemeral water bodies in the Wheatbelt, I demonstrated that salinity of water bodies can modify colonisation behaviour and the distribution of some organisms across the landscape. Halosensitive fauna selected less saline mesocosms for oviposition and colonisation. In particular, Culex australicus Dobrotworksy and Drummond and Anopheles annulipes Giles (Diptera: Culicidae), potential competitors with Ae. camptorhynchus, avoided ovipostion in saline mesocosms and water bodies in the field. This finding suggests salinity influences behaviour and may reduce interspecific interactions between these taxa and Ae. camptorhynchus at higher salinities. Using extensive field surveys of ephemeral water bodies in the Wheatbelt I found mosquitoes frequently colonised ephemeral water bodies, responded positively to rainfall, and populated smaller water bodies more densely than larger water bodies. The habitat characteristics of ephemeral water bodies changed in association with salinity. Consequently there were both direct and indirect associations between salinity and colonising mosquitoes. Ultimately the structure of mosquito assemblages changed with increasing salinity, favouring an increased regional distribution and abundance of Ae. camptorhynchus. The direct implication of this result is secondary salinisation has enhanced the vectorial potential for RRV transmission in the WA Wheatbelt. ... This thesis contributes to an emerging body of research aimed at delineating important ecological processes which determine transmission of infections disease. Collectively the findings in this study suggest dryland salinity enhances the potential for RRV activity in the Wheatbelt. Currently, human RRV notifications in the Wheatbelt do not reflect the salinity-RRV transmission potential in that area, but appear to be associated with dispersal of RRV from the enzootic coastal zone of southwest WA. I speculate dryland salinity is a determinant of potential for RRV transmission, but not activity. Dryland salinity is predicted to undergo a two to four fold expansion by 2050, which will increase the regional potential for RRV activity. Preservation and restoration of freshwater ecosystems may ameliorate the potential for transmission of RRV and, possibly, human disease incidence.