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Artykuły w czasopismach na temat "Semiarid rivers"
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Strauch, Ayron M. "Seasonal variability in faecal bacteria of semiarid rivers in the Serengeti National Park, Tanzania". Marine and Freshwater Research 62, nr 10 (2011): 1191. http://dx.doi.org/10.1071/mf11075.
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Humans and livestock are known contributors of faecal waste to surface water. However, little is known about natural fluctuations of faecal bacteria, especially where wildlife may contribute substantial amounts of waste. I tested the hypotheses that ecological factors, including seasonal animal impacts, rainfall and physiochemical water quality, influence the abundance of total coliform (TC) and Escherichia coli faecal bacteria in five rivers of the Serengeti National Park, Tanzania. TC and E. coli are indicators commonly used to assess water quality and their abundance can be determined quantitatively by using defined-substrate technology. Results demonstrated substantial variation in faecal bacteria across rivers and seasons. In the southern two rivers, faecal bacteria increased significantly during the wet season, compared with dry-season levels, whereas there were few seasonal differences in the northern rivers, suggesting that large populations of resident wildlife in the north dampen the seasonal influence of migratory wildlife. Faecal bacteria were positively related to rainfall and total ammonia/ammonium, and had a negative quadratic relationship with salinity. The present results demonstrated that wildlife in protected regions can be major contributors of faecal bacteria to surface waters, and as demand for water resources increases, pose a significant threat to human health.
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Wang, J., Y. S. Pei, K. J. Zhang, G. Gao i Z. F. Yang. "Investigating the spatial–temporal variation of nitrogen cycling in an urban river in the North China Plain". Water Science and Technology 63, nr 11 (1.06.2011): 2553–59. http://dx.doi.org/10.2166/wst.2011.537.
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Urban rivers are essential in retaining nutrients, but little is known about nitrogen cycling in these rivers in semiarid areas. We measured chemical and isotopic compositions of ammonium (NH4+-N) and nitrate (NO3−-N) to investigate spatial–temporal variation of nitrogen cycling in the Fuhe River in the North China Plain. Nitrogen pollution in the river was mainly induced by extra NH4+-N inputs which come from the discharges of urban sewage and effluents of wastewater treatment plants in upstream. NH4+-N obtained from decomposing organic matter of sediments can diffuse into the overlying water. Intense nitrification then occurs at the terrestrial–aquatic interface. Due to less vegetation in spring and autumn, loss of NH4+-N is mainly caused by nitrification. In contrast, significant NH4+-N is absorbed by plants in summer. NO3−-N generated from nitrification can be denitrified during the study period. The highest NO3−-N loss (about 86.3%) was observed in summer. The contribution of NO3−-N loss due to denitrification is 44.6%. The remaining 55.4% is due to plant uptake. The results suggested that nitrogen cycling in the river is related to temperature and dry–wet cycles. And vegetation restoration along the river could benefit the incremental improvements to the aquatic ecosystem.
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Oliveira, Regina Célia de, Anádria Stéphanie da Silva, André Rodolfo de Oliveira Ribeiro, José Erivaldo de Araújo, Odaci Fernandes de Oliveira i Ramiro Gustavo Valera Camacho. "List of angiosperm species of the riparian vegetation of the Apodi-Mossoró River, Rio Grande do Norte, Brazil". Check List 9, nr 4 (1.08.2013): 740. http://dx.doi.org/10.15560/9.4.740.
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This article describes the riparian vegetation of a river in the Rio Grande do Norte state for the first time. This is a seasonal river in the semiarid region of the Caatinga biome. The study is based on data from herbarium collections and new expeditions from July 2007 to October 2008. Two hundred and forty seven taxa were recorded and of these, 116 are herbs and three of which are epiphytes, 25 sub-shrubs, 77 shrubs or trees, 26 lianas, one parasite, and two palms. This list of species of riparian vegetation in the river Apodi-Mossoró was compared with only two available lists from rivers in the northeast with similar environmental characteristics and showed a low similarity. This study points to the need for preservation of the species and remnants of riparian vegetation of the river Apodi-Mossoró and to increase efforts in the study of this vegetation type.
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Millares, A., M. J. Polo, A. Moñino, J. Herrero i M. A. Losada. "Bedload dynamics and associated snowmelt influence in mountainous and semiarid alluvial rivers". Geomorphology 206 (luty 2014): 330–42. http://dx.doi.org/10.1016/j.geomorph.2013.09.038.
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Dong, Mingjia, Mingxiao Liu, Lina Yin, Jinjie Zhou i Dongpo Sun. "Concept and Practices Involved in Comprehensive River Control Based on the Synergy among Flood Control, Ecological Restoration, and Urban Development: A Case Study on a Valley Reach of Luanhe River in a Semiarid Region in North China". Water 14, nr 9 (28.04.2022): 1413. http://dx.doi.org/10.3390/w14091413.
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Many rivers in semiarid areas have ecological degradation and flood control problems that need to be addressed urgently. In order to maintain river health and to promote the sustainable development of cities near these rivers, a comprehensive river regulation project must be carried out. In this study, first, the factors influencing river health are discussed, and the principles and main restrictions involved in comprehensive regulations are studied. The scientific regulation mode is proposed, and new financing channels for water conservancy construction are also suggested. Second, a river reach adjacent to a city in the middle part of the Luanhe River in North China is used as a case study. The health status of the river is analyzed, and a comprehensive river regulation plan combined with urban development is put forward on this basis. The plan includes embankment construction, river regulations, multilevel rubber dam storage, ecological restoration, and artificial lake and riverside landscape construction. The influence of the engineering treatment on the river flood discharge capacity is examined, and the treatment effect is verified by a hydraulic scale model. After implementation of the comprehensive river regulations, the flood control safety of the city and river ecological environment are found to be significantly improved, with the hidden danger of dust storms eliminated. The treatment project incurs environmental, social, and economic benefits and preliminarily achieves the coordination and mutual promotion of river regulation and urban development.
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Sanz-Ronda, Bravo-Córdoba, Sánchez-Pérez, García-Vega, Valbuena-Castro, Fernandes-Celestino, Torralva i Oliva-Paterna. "Passage Performance of Technical Pool-Type Fishways for Potamodromous Cyprinids: Novel Experiences in Semiarid Environments". Water 11, nr 11 (11.11.2019): 2362. http://dx.doi.org/10.3390/w11112362.
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Endemic freshwater fish from semiarid environments are among the most threated species in the world due to water overexploitation and habitat fragmentation problems. Stepped or pool-type fishways are used worldwide to reestablish longitudinal connectivity and mitigate fish migration problems. Many of them are being installed or planned in rivers of semiarid environments, however, very few studies about fish passage performance through pool-type fishways has been carried out to date on these regions. The present work focuses on the passage performance of two potamodromous cyprinids endemic of these regions, with different ecological and swimming behavior: southern Iberian barbel (Luciobarbus sclateri) and Iberian straight-mouth nase (Pseudochondrostoma polylepis). These are assessed in two of the most common types of stepped fishways: vertical slot and submerged notch with bottom orifice fishways. Experiments were carried out during the spawning season in the Segura River (southeastern Spain), using a passive integrated transponder (PIT) tag and antenna system. Ascent success was greater than 80%, with a median transit time lower than 17 minutes per meter of height in all trials, and for both species and fishway types. Results show that both types of fishways, if correctly designed and constructed, provide interesting alternatives for the restoration of fish migration pathways in these regions.
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Warrick, Jonathan A., i John D. Milliman. "Hyperpycnal sediment discharge from semiarid southern California rivers: Implications for coastal sediment budgets". Geology 31, nr 9 (2003): 781. http://dx.doi.org/10.1130/g19671.1.
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St-Onge, Denis A., i Frans Gullentops. "Morphodynamics of Cold High Latitude Semiarid Regions: The Example of Ellef Ringnes Island, Nunavut*". Géographie physique et Quaternaire 59, nr 2-3 (4.04.2007): 103–11. http://dx.doi.org/10.7202/014749ar.
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AbstractIn this paper we use the example of Ellef Ringnes Island, Nunavut, to examine active geomorphic processes in a high latitude semiarid region. The spectacular landscape of Ellef Ringnes Island is principally the result of fluvial erosion controlled by geological structure. The nival regime concentrates flow in a brief late-spring period which provides strong erosive capabilities for rivers in spite of low annual precipitation. Other processes related to the cold environment produce a variety of minor landforms such as patterned ground, mud flows associated with ground ice, and solifluction lobes.
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Jia, Xiaopeng, i Haibing Wang. "Element Geochemical Analysis of the Contribution of Aeolian Sand to Suspended Sediment in Desert Stream Flash Floods". Scientific World Journal 2014 (2014): 1–12. http://dx.doi.org/10.1155/2014/620610.
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The interaction of wind and water in semiarid and arid areas usually leads to low-frequency flash flood events in desert rivers, which have adverse effects on river systems and ecology. In arid zones, many aeolian dune-fields terminate in stream channels and deliver aeolian sand to the channels. Although aeolian processes are common to many desert rivers, whether the aeolian processes contribute to fluvial sediment loss is still unknown. Here, we identified the aeolian-fluvial cycling process responsible for the high rate of suspended sediment transport in the Sudalaer desert stream in the Ordos plateau of China. On the basis of element geochemistry data analysis, we found that aeolian sand was similar to suspended sediment in element composition, which suggests that aeolian sand contributes to suspended sediment in flash floods. Scatter plots of some elements further confirm that aeolian sand is the major source of the suspended sediment. Factor analysis and the relation between some elements and suspended sediment concentration prove that the greater the aeolian process, the higher the suspended sediment concentration and the greater the contribution of aeolian sand to suspended sediment yield. We conclude that aeolian sand is the greatest contributor to flash floods in the Sudalaer desert stream.
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Zellman, Kristine L., Piret Plink-Björklund i Henry C. Fricke. "Testing hypotheses on signatures of precipitation variability in the river and floodplain deposits of the Paleogene San Juan Basin, New Mexico, U.S.A." Journal of Sedimentary Research 90, nr 12 (18.02.2021): 1770–801. http://dx.doi.org/10.2110/jsr.2020.75.
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ABSTRACTMuch progress has been made in recent years towards a set of recognition criteria for river discharge variability in river channel deposits, and thus sedimentary proxies for precipitation variability. Despite this progress, there is currently no consensus on how different styles of discharge variability are reflected in river sedimentary records, and whether variable-discharge river records from different climate types can be distinguished. Herein, river discharge and precipitation variability in the Paleogene is investigated using associations between river channel and floodplain deposits across the Paleocene–Eocene boundary from the Paleocene upper Nacimiento Formation and the early Eocene San Jose Formation in the San Juan Basin, New Mexico, USA.The succession is identified as deposits of variable-discharge river systems based on shared channel-deposit characteristics with modern and ancient variable-discharge river systems and the proposed facies models, in addition to alternations of poorly drained and well-drained floodplain deposits and/or slickensides indicating alternating wet–dry cycles. A long-term stratigraphic trend toward increasingly well-drained floodplain deposits is also observed and hypothesized to indicate successively more arid conditions from the Paleocene into the early Eocene. Comparisons with modern rivers from various climate zones suggest a long-term shift from a monsoonal climate in the Paleocene, to a fluctuating subhumid climate, ultimately leading to semiarid to arid conditions in the early Eocene. These observations suggest that floodplain deposits may be a better indicator of ambient climate, whereas channel deposits are records for frequency and magnitude of high-intensity precipitation events. Therefore, the existing facies models for variable-discharge rivers that consider only channel facies may not capture critical information needed to make accurate interpretations of paleoclimatic conditions. This study also adds to a growing body of evidence from geologic records of mid-latitude Paleogene river systems suggesting increases in the magnitude or variability of river discharge coinciding with established climate perturbations.
Rozprawy doktorskie na temat "Semiarid rivers"
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Carini, Giovannella, i 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.
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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.
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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.
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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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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.
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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.
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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.
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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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Fontenele, SÃvio de Brito. "Water exchanges between river and aquifer in two different lithologies of Brazilian Semiarid". Universidade Federal do CearÃ, 2015. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=15973.
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CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel SuperiorThe interaction between surface water and groundwater is a dynamic process in time and space influenced by factors such as soil moisture, hydrodynamic properties, geomorphology, storage and runoff. The quantification and modeling of the processes related to this dynamic constitute prerequisites for the effective water resources management, given that this interaction affects water availability, especially in semi-arid regions. Before this problem, this study aimed to simulate hydrological processes flow transmission between river and groundwater in basins characterized by distinct lithologies, inserted in the Brazilian semiarid region by generating a semi distributed and flexible hydrological model. Two distinct basins of Cearà semiarid region were monitored and used for application of the model developed. A watershed located in sedimentary structure with large underground water reserves (SÃo Jose watershed in the sedimentary basin of Araripe - South of CearÃ) and the other one inserted into the crystalline environment and characterized by water scarcity (Patos-CariÃs-Iguatu subbasin - Jaguaribe river stretch in the Central-South region of CearÃ). The monitoring of these areas between 2010 and 2014 enabled the generation of data and the choice of 10 events from each watershed monitored to evaluate the dynamic river-aquifer. In the evaluation of the data obtained by the monitoring observed aquifer recharges when large volumes precipitates occur in short periods of time. The high temporal spacing difficult the generation of large flows and the rising water levels of the alluvial aquifer. The proposed model was developed considering the three main processes of river-aquifer interaction: full wave propagation, vertical infiltration and groundwater flow. The simulations of the events showed that conductance of the riverbed and effective porosity are the most sensitive parameters of the model. Variations of these parameters allowed the reduction of flood peaks and consequently increases in the aquifer hydraulic loads. However, the simulations showed an underestimation of the hydraulic loads of the aquifer. For the surface discharges were obtained low efficiency ratios (-16.73 to -3.43) for short-term events and small magnitude. Already for long term events and high magnitude, the Nash and Sutcliffe efficiency coefficient performed between 0 and 1 (0.35 to 0.49), indicating a good behavior of the models used. However, for these events the average absolute error between the measured and the simulated loads remained high. The model needs to be adjusted to better define the dynamics of the river-aquifer interaction. A greater number of simulations in both watersheds, with the available events could indicate better where adjustments must be made. The possibility of application of MIRAS model in different lithological means and different spatial scales of semi-arid regions was not possible due to the inability to simulate the model for MHSJ. Thus, one must understands the failure to formulate an alternative and possibly improve the model. Because the use of this tool is the best option for resolving problems and decision making.
A interaÃÃo entre Ãgua superficial e subterrÃnea à um processo dinÃmico no tempo e no espaÃo influenciado por fatores como umidade do solo, propriedades hidrodinÃmicas, geomorfologia, armazenamento e escoamento superficial. A quantificaÃÃo e a modelagem dos processos relacionados a essa dinÃmica constituem-se prÃ-requisitos para a gestÃo eficiente de bacias hidrogrÃficas, haja vista que essa interaÃÃo afeta a disponibilidade hÃdrica, principalmente em regiÃes semiÃridas. Diante dessa problemÃtica, este estudo objetivou simular processos hidrolÃgicos de transmissÃo de fluxo entre rio e aquÃfero em bacias hidrogrÃficas caracterizadas por litologias distintas, inseridas na regiÃo semiÃrida brasileira, atravÃs da geraÃÃo de um modelo hidrolÃgico semidistribuÃdo e flexÃvel. Duas bacias hidrogrÃficas distintas da regiÃo semiÃrida cearense foram monitoradas e utilizadas para aplicaÃÃo do modelo desenvolvido. Uma microbacia localizada em meio sedimentar com grandes reservas hÃdricas subterrÃneas (microbacia hidrogrÃfica do SÃo Josà na bacia sedimentar do Araripe â Sul do CearÃ) e a outra inserida no meio cristalino e caracterizada por escassez hÃdrica (bacia hidrogrÃfica Patos-CariÃs-Iguatu â trecho do rio Jaguaribe na regiÃo Centro-Sul do CearÃ). O monitoramento dessas Ãreas entre 2010 e 2014 possibilitou a geraÃÃo de dados e a escolha de 10 eventos de cada bacia monitorada para avaliaÃÃo da dinÃmica rio-aquÃfero. Na avaliaÃÃo dos dados obtidos pelo monitoramento observou-se recargas aquÃferas quando grandes volumes precipitados ocorrem em curtos espaÃos de tempo. O elevado espaÃamento temporal dificultaram a geraÃÃo de grandes vazÃes e a elevaÃÃo dos nÃveis freÃticos do aquÃfero aluvionar. O modelo proposto foi elaborado considerando os trÃs principais processos da interaÃÃo rio-aquÃfero: propagaÃÃo de onda de cheia, infiltraÃÃo vertical e fluxo subterrÃneo. As simulaÃÃes dos eventos mostraram que condutÃncia do leito do rio e porosidade efetiva sÃo os parÃmetros mais sensÃveis do modelo. VariaÃÃes desses parÃmetros possibilitaram a reduÃÃo dos picos de cheia e consequentemente acrÃscimos nas cargas hidrÃulicas aquÃferas. No entanto, as simulaÃÃes realizadas apresentaram subestimativas das cargas hidrÃulicas do aquÃfero. Para as descargas superficiais obteve-se baixos coeficientes de eficiÃncia (-16,73 a -3,43) para eventos de curta duraÃÃo e pequena magnitude. Jà para eventos de longa duraÃÃo e elevada magnitude, o coeficiente de eficiÃncia de Nash e Sutcliffe apresentou-se entre 0 e 1 (0,35 a 0,49), indicando um bom comportamento dos modelos utilizados. No entanto, para esses eventos o erro mÃdio absoluto entre as cargas medidas e as simuladas continuaram elevados. O modelo precisa de ajustes para definir melhor a dinÃmica da interaÃÃo rio-aquÃfero. Um nÃmero maior de simulaÃÃes nas duas bacias hidrogrÃficas, com os eventos disponÃveis poderia indicar melhor onde devem ser feitos os ajustes. A possibilidade de aplicaÃÃo do modelo MIRAS em diferentes meios litolÃgicos e escalas espaciais distintas de regiÃes semiÃridas nÃo fora possÃvel devido à impossibilidade de simular o modelo para a MHSJ. Dessa forma, precisa-se entender as falhas para formular uma alternativa e, possivelmente, melhorar o modelo. Pois, o uso dessa ferramenta à a melhor opÃÃo para a resoluÃÃo de problemas e tomada de decisÃo.
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Morino, Kiyomi. "Using False Rings to Reconstruct Local Drought Severity Patterns on a Semiarid River". Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/194123.
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In this research, I describe the use of false rings to reconstruct local histories of seasonal drought in riparian ecosystems in semiarid regions. In tree-ring analysis, false rings are boundary-like features often formed as a response to drought within the growing season. Drought can be a common feature in hydrologic regimes of dryland rivers but in recent decades drought has been intensifying due to climate change and increasing water use by cities, agriculture and industry. Identifying when and where water availability has decreased along the river course is critical for understanding, and therefore managing, these generally endangered ecosystems. The higher density of trees compared to instrumental data make them ideal candidates for reconstructing site-specific drought patterns.The first part of this dissertation is an observational study conducted on the San Pedro River in southeastern Arizona during 2002. I used dendrometer data and local hydrological data to show that a period of negligible radial growth in cottonwood during the middle of the growing season coincided with a channel drying event. Tree-ring core samples confirmed that false-rings had formed in each of the instrumented trees. The second part of this dissertation is an experimental study designed to evaluate the effect of different levels of water stress on false-ring formation in cottonwood and willow. I showed that experimental decreases in water availability for periods as short as ten days were enough to induce false-ring formation in willow. Longer periods of reduced water availability were generally required to induce false-ring formation in cottonwood. In the final part of this dissertation, I reconstructed false-ring occurrence in Fremont cottonwoods at three sites along the San Pedro River. I infer from false-ring frequencies that the severity of summer drought has been increasing over the last four to six decades but that the drought severity varies along a hydrological gradient. Overall, the findings in this body of research confirm that false rings in riparian tree species can be used as indicators of seasonal drought and underscore the importance of identifying site-specific responses to reduced water availability along the riparian corridor.
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Santiago, Cristiane Maria Cordeiro. "Environmental analysis of basin SÃo Nicolau river(semiarid PiauÃ) from physical diagnosis conservacionista - PDC". Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=13201.
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FundaÃÃo de Amparo à Pesquisa do Estado do CearÃThe basin SÃo Nicolau river is located in north Piauà and crosses the territory in EW flowing to Sambito tributary of the Poti. Encompasses five municipalities of the state covering an area of 5.389.8 km2 and has been intensely busy with many uses generating sometimes degradational effects. The area has great importance about maintenance of water resources in this region besides forming ruiniform landscapes in semiarid area. Given the above, the objective was to make the environmental analysis the basin area especially considering the use of this water resource, and verify which state conservationist she presents and how enables the development of wide variety of activities. For this, we used the Physical Conservation Diagnosis (FCD), proceeding to the literature survey and mapping, geoprocessing and analysis of the parameters that make up the end of the DFC descriptive formula such as: Vegetation Cover Index (VCI), in two periods, Climate Index (CI) Rainfall erosivity (R), soil erodibility (K), Average Slope (DM) and drainage density (DD). The diagnostic result was expressed in the descriptive formula which showed the level of degradation/ preservation in the bowl is located. It is observed that there was a decreased risk of physical degradation in sectors A and B in the time interval between 1989 and 2010, in contrast, there was increased risk in C sector, which presented index of 10,54 in 1989 and 10,92 in 2010. However, the basin that showed the highest rate of degradation was the C sector. The lifting of fÃsicoambientais characteristics together with the results of the analysis of the forms of use and cover the basin contributed to the understanding of the results achieved. Thus, it is observed that the levels of degradation of the basin does not have quite pronounced, even because they have been reduced over the years, however it was not what happened in sector C which had major changes in terms of investments, infrastructure and activities at the same time interval. With this, it is necessary to conduct proper planning throughout the basin, especially in the C sector where the level of degradation was considerably increased in recent years. The shift in the use of resources and application of measures of active management on a larger scale would allow more appropriate management and development facing the sustainability of the region.
A Bacia HidrogrÃfica do rio SÃo Nicolau està localizada no Norte do Piauà e cruza o territÃrio no sentido E-W atà desaguar no rio Sambito afluente do Poti. Engloba cinco municÃpios do Estado perfazendo uma Ãrea de 5.389,8 km2 e vem sendo intensamente ocupada com os mais diversos usos gerando, por vezes, efeitos degradacionais. A Ãrea possui grande importÃncia no que tange a manutenÃÃo dos recursos hÃdricos nessa regiÃo alÃm de formar paisagens ruiniformes no domÃnio semiÃrido. Diante do exposto, objetivou-se realizar a anÃlise ambiental na bacia considerando principalmente a Ãrea de aproveitamento desse recurso hÃdrico, verificando o estado conservacionista que ela apresenta e de que maneira possibilita o desenvolvimento de grande variedade de atividades. Para tanto, utilizou-se da metodologia do Diagnostico FÃsico Conservacionista (DFC) procedendo com o levantamento bibliogrÃfico e cartogrÃfico, tÃcnicas de geoprocessamento e anÃlise dos parÃmetros que compÃem a fÃrmula descritiva final do DFC tais como: Ãndice de Cobertura Vegetal (ICV), em dois perÃodos, Ãndice ClimÃtico (IC), Erosividade da Chuva (R), Erodibilidade dos Solos (K), Declividade MÃdia (DM) e Densidade de Drenagem (DD). O resultado do diagnÃstico foi expresso na fÃrmula descritiva a qual mostrou o nÃvel de degradaÃÃo/conservaÃÃo em que se encontra a bacia. Observa-se que houve uma diminuiÃÃo do risco de degradaÃÃo fÃsica nos setores A e B no intervalo de tempo analisado entre 1989 e 2010, em contrapartida, houve aumento do risco no setor C, o qual apresentou Ãndice de 10,54 em 1989 e de 10,92 em 2010. Contudo, a regiÃo da bacia que apresentou o maior Ãndice de degradaÃÃo foi o setor A. O levantamento das caracterÃsticas ambientais juntamente com os resultados da anÃlise das formas de uso e cobertura da bacia contribuÃram para a compreensÃo dos resultados alcanÃados. Assim, observa-se que os nÃveis de degradaÃÃo da bacia nÃo se apresentam bastante acentuados, inclusive pelo fato de terem sofrido uma diminuiÃÃo com o passar dos anos, contudo nÃo foi o que ocorreu no setor C o qual teve maiores modificaÃÃes em termos de investimentos, atividades e infraestrutura no mesmo intervalo de tempo. Com isso, se faz necessÃrio a realizaÃÃo do adequado planejamento em toda a bacia, de modo especial, no setor C onde apresentou aumento do nÃvel de degradaÃÃo nos Ãltimos anos. A reorientaÃÃo na utilizaÃÃo dos recursos e aplicaÃÃo de medidas de gestÃo atuantes numa escala maior possibilitaria um manejo mais apropriado e um desenvolvimento voltado a sustentabilidade da regiÃo.
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Filho, Antonio Alves de Oliveira. "Quality modeling of Poti River water". Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=13435.
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nÃo hÃThe disorderly growth of the capital of PiauÃ, marked mainly by housing occupancy on the banks of river Poti and the existence of clandestine connections of raw sewage in rainwater drainage pipes, has contributed significantly to the pollution of the waters of the river basin of the ParnaÃba River (semiarid region Brazil). This research consists of making water quality measuring campaigns in Poti river and sewage released that, via gallery rainwater, focusing on a river stretch of 36.8 km long, located in the city of Teresina / PI, as well as mathematical modeling of water quality of the river based on WHAT-UFMG platform. The research is presented as the first study involving modeling of water quality in a water body of the state of PiauÃ. Modeled components were: dissolved oxygen (DO), biochemical oxygen demand (BOD) and thermotolerant coliform (TC). The results of field measurements indicated TC parameter discontinuities with respect to CONAMA Resolution n 357/2005. The calibration of the decay coefficients for each parameter resulting in deviations between measured and modeled data of up to 20%, which shows that the QUALUFMG can be used as a basis for predicting the quality of water in rivers located in semiarid regions. The calibrated model was also compared to field data from the literature. Finally, simulations were performed for different flow scenarios (Q10, Q90 and Q7,10), with consistent results and that can be used for the management of water resources in the state of PiauÃ.
O crescimento desordenado da capital piauiense, marcado sobretudo pela ocupaÃÃo habitacional Ãs margens do rio Poti e pela existÃncia de ligaÃÃes clandestinas de esgoto bruto nas tubulaÃÃes de drenagem pluvial, tem contribuÃdo significativamente para a poluiÃÃo das Ãguas da bacia hidrogrÃfica do rio ParnaÃba (regiÃo semiÃrida do Brasil). A presente pesquisa consiste na realizaÃÃo de campanhas de mediÃÃo da qualidade da Ãgua no rio Poti e dos esgotos lanÃados no mesmo, via galeria de Ãguas pluviais, com foco em um trecho do rio de 36,8 km de extensÃo, localizado na cidade de Teresina/PI, bem como na modelagem matemÃtica da qualidade da Ãgua deste rio com base na plataforma QUAL-UFMG. A pesquisa apresenta-se como o primeiro estudo envolvendo modelagem da qualidade da Ãgua em um corpo hÃdrico do estado do PiauÃ. Os componentes modelados foram: oxigÃnio dissolvido (OD), demanda bioquÃmica de oxigÃnio (DBO) e coliformes termotolerantes (CT). Os resultados das mediÃÃes de campo indicaram desconformidades do parÃmetro CT com relaÃÃo à ResoluÃÃo CONAMA n 357/2005. A calibraÃÃo dos coeficientes de decaimento para cada parÃmetro resultou em desvios entre dados medidos e modelados de atà 20%, o que mostra que o QUAL-UFMG pode ser utilizado como base para prediÃÃo da qualidade da Ãgua em rios localizados em regiÃes semiÃridas. O modelo calibrado tambÃm foi comparado a dados de campo obtidos na literatura. Finalmente, foram realizadas simulaÃÃes para diferentes cenÃrios de vazÃo (Q10, Q90 e Q7,10), apresentando resultados coerentes e que podem ser utilizados para a gestÃo dos recursos hÃdricos do estado do PiauÃ.
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Bjørgum, Claudia Pastor Almeida Soares. "Droughts, Morality, State Politics and the Brazilian Semiarid Landscape: A Study of the São Francisco River Integration Project". Thesis, Norwegian University of Science and Technology, Department of Geography, 2008. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-2271.
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The poorest region of Brazil, the Northeast is prone to devastating multi-annual droughts, an inherent part of its geography. The Brazilian state attributes the poverty of the Northeast to the semiarid landscape and a supposed water deficit. The state defends a water diversion project on the biggest river of the region that is rejected by the local population and civil society organizations, as a definitive solution for the water deficit of a section of the semiarid landscape. Based on a large volume of secondary data, primary data collected through open interviews with key informant and participant observation in sections of the semiarid landscape in the state of Ceará, this thesis argues that the problem of the Northeast is not water deficit. Some of the poorest areas of Brazil, in both Northeast and North regions, are abundant in water resources. Droughts have been used as an excuse to intervene in the landscape while drought oriented policies have for a long time divided and sub-divided the region, contributing to the alienation of other structural problems. Poverty and inequality are the most serious problems of the Northeast, inside and outside the limits of the semiarid landscape, just like in the other four regions of Brazil. The São Francisco river integration project (SFIP) reproduces the drought combat discourse and hide the economical intentions of the project. Surrounded by contradictions and certain disregard for Brazil’s Constitution the governmental project benefits from the alienation of the other regions of the Northeastern reality and of the indifference of the National Congress to the conflict. The SFIP analyzed as an example of the historical relationship of interdependence between the central government and the local elite.
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Pitombeira, Sheila Cavalcante. "Basin as a parameter for territorial planning in the semiarid region of the institutional environment: The basin of Jaguaribe river, CearÃ, Brasil". Universidade Federal do CearÃ, 2015. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=14781.
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nÃo hÃThis research highlights the advisability of adopting the Basin as a parameter for territorial planning in the semiarid region, in face of the vicissitudes of climate and regional interest to promote environmental development. It demonstrates the importance of the state since its emergence in modernity and highlights the institutionalization of power since then, contributing to the improvement of the institutional environment throughout its territory. The core idea developed is that the state is endowed with power, being responsible for disciplining of subjects of interest to the community, amongst them water or water resources, it is required to pay attention to regional differences existing Âin its territory, in particular the semiarid, and to promote government actions benefiting everyone equally without distinction. The methodology used was through a literature review of the legal framework devoted to the structure of water and / or water resources and watersheds, comparing that information with historical records around the approach to public policies carried out during periods of drought and with socioeconomic criteria guiding public policy or government policies in these geographic areas. ÂThe informations of the territories citizenship of CearÃ, as to notice the various conceptual dimensions of these geographic areas, watershed territory and citizenship. Finally, the analysis of how the dimensions of the territory of citizenship can (inter) relate to the watershed territorial unit , giving them affinities, similarities and differences aiming to a comparative study of their equivalences in promoting sustainable development, according to indexes from the Brazilian Institute of Geography and Statistics. From this comparison chart, it is possible to show that the basin should be the unit for implementation of territorial planning in the semiarid.
O trabalho pÃe em evidÃncia a conveniÃncia de adotar a Bacia HidrogrÃfica como parÃmetro de planejamento territorial na regiÃo semiÃrida, ante as vicissitudes climÃticas e o interesse regional de promover o desenvolvimento socioambiental. Demonstra a importÃncia do Estado desde seu surgimento na modernidade e realÃa a institucionalizaÃÃo do Poder a partir de entÃo, contribuindo para o aperfeiÃoamento desse ambiente institucional em todo o seu territÃrio. A ideia central desenvolvida à que sendo o Estado dotado de Poder, competindo-lhe o disciplinamento dos assuntos de interesse da coletividade, dentre eles a Ãgua ou recursos hÃdricos, compete-lhe atentar para as diferenÃas regionais existentes em seu territÃrio, em particular o semiÃrido, promovendo aÃÃes governamentais que beneficiem a todos indistintamente. A metodologia utilizada se deu por meio de levantamento bibliogrÃfico sobre o Estado e o ambiente institucional brasileiro, bem como do arcabouÃo jurÃdico devotado ao regime das Ãguas ou recursos hÃdricos e bacias hidrogrÃficas, confrontando essas informaÃÃes com os registros histÃricos em torno da abordagem das polÃticas pÃblicas realizadas nos perÃodos de estiagens e com os critÃrios socioeconÃmicos orientadores dessas polÃticas ou das polÃticas de governo nesses espaÃos geogrÃficos. Tais registros demonstram que, no CearÃ, cujo territÃrio à abrangido pelo semiÃrido em quase totalidade, onde a Ãgua possui significativo valor econÃmico e social, como se observa com o Rio Jaguaribe, e seu percurso permite verificar algumas dimensÃes conceituais desses espaÃos geogrÃficos, dentre eles a territorialidade, a bacia hidrogrÃfica à ignorada como parÃmetro territorial para seu desenvolvimento socioambiental. De sorte que, sendo o Estado do Cearà localizado no semiÃrido e sazonalmente exposto Ãs estiagens, a bacia hidrogrÃfica deveria ser a unidade territorial preponderante para implementaÃÃo do planejamento territorial, conciliando o desiderato legal de ser a unidade territorial para a polÃtica de recursos hÃdricos e inter-relacionando com outras unidades administrativas
Książki na temat "Semiarid rivers"
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Ferrick, M. G. The winter low-flow balance of the semiarid White River, Nebraska and South Dakota. [Hanover, N.H]: US Army Corps of Engineers, Cold Regions Research & Engineering Laboratory, 1995.
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Ferrick, M. G. The winter low-flow balance of the semiarid White River, Nebraska and South Dakota. [Hanover, N.H]: US Army Corps of Engineers, Cold Regions Research & Engineering Laboratory, 1995.
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Ferrick, M. G. The winter low-flow balance of the semiarid White River, Nebraska and South Dakota. [Hanover, N.H]: US Army Corps of Engineers, Cold Regions Research & Engineering Laboratory, 1995.
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Marco, Juan B. "The Segura River Basin Model. Disaggregation in a Semiarid Environment". W Stochastic Hydrology and its Use in Water Resources Systems Simulation and Optimization, 413–23. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-1697-8_25.
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Acuña, V. "Flow regime alteration effects on the organic C dynamics in semiarid stream ecosystems". W Global Change and River Ecosystems—Implications for Structure, Function and Ecosystem Services, 233–42. Dordrecht: Springer Netherlands, 2010. http://dx.doi.org/10.1007/978-94-007-0608-8_16.
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Karienye, David, i Joseph Macharia. "Adaptive Capacity to Mitigate Climate Variability and Food Insecurity of Rural Communities Along River Tana Basin, Kenya". W African Handbook of Climate Change Adaptation, 49–60. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-45106-6_57.
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AbstractClimate variability is one of the leading natural threats and a root cause of food insecurity in the developing world, more so in Africa. It is a major impediment to the accomplishment of the global Sustainable Development Goals (SDGs), Vision 2030 and Big Four agenda in the Kenyan context. The rise in occurrence and brutality of extreme events resulting from variability of climate including prolonged flooding and drought has become more pronounced in the relatively drier areas. This chapter presents a synthesis about rural communities in Garissa and Tana River Counties, Kenya. The key environmental conditions that face the rural communities in the two counties are prolonged drought and recurrent flooding events. The two conditions have resulted in various challenges facing the communities in these regions through low agricultural production (food and pastures), poor infrastructure, human displacement, and the resultant extreme poverty, overall food insecurity, and tough livelihoods. The problems have been exacerbated by lack of capacity by most of the community members to cushion themselves against these impacts. However, as the conditions continue to manifest themselves, the community members have also identified adaptive mechanisms that are best suited in the region including planting drought-resistant crop varieties, diversifying their livelihoods, embrace sustainable land use, and made efforts to plant trees. We, therefore, conclude that integrated information sharing including early warning alongside affordable and appropriate technologies and crop insurance could be an entry point in cushioning the local communities in the arid and semiarid lands (ASALs) against the extreme weather conditions experienced in the region.
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Chen, Jian, Yan Li, Wendy Zhou, Chong Xu, Saier Wu i Wen Yue. "AHP-Based Susceptibility Assessment on Debris Flows in Semiarid Mountainous Region: A Case of Benzilan-Changbo Segment in the Upper Jinsha River, China". W Communications in Computer and Information Science, 495–509. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-0893-2_51.
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"The Ecology and Management of Wood in World Rivers". W The Ecology and Management of Wood in World Rivers, redaktorzy MICHAEL M. POLLOCK, MORGAN HEIM i DANIELLE WERNER. American Fisheries Society, 2003. http://dx.doi.org/10.47886/9781888569568.ch11.
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<em>Abstract.</em>—Beaver dams alter the hydrology and geomorphology of stream systems and affect habitat for fishes. Beaver dams measurably affect the rates of groundwater recharge and stream discharge, retain enough sediment to cause measurable changes in valley floor morphology, and generally enhance stream habitat quality for many fishes. Historically, beaver dams were numerous in small streams throughout most of the Northern Hemisphere. The cumulative loss of millions of beaver dams has dramatically affected the hydrology and sediment dynamics of stream systems. Assessing the cumulative hydrologic and geomorphic effects of depleting these millions of wood structures from small and medium-sized streams is urgently needed. This is particularly important in semiarid climates, where the widespread removal of beaver dams may have exacerbated effects of other land use changes, such as livestock grazing, to accelerate incision and the subsequent lowering of groundwater levels and drying of streams.
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"Multispecies and Watershed Approaches to Freshwater Fish Conservation". W Multispecies and Watershed Approaches to Freshwater Fish Conservation, redaktorzy Sarah Robertson, Brad D. Wolaver, Todd G. Caldwell, Timothy W. Birdsong, Ryan Smith, Thomas Hardy, Julie Lewey i Joe Joplin. American Fisheries Society, 2019. http://dx.doi.org/10.47886/9781934874578.ch13.
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<em>Abstract</em>.—The Devils River is a groundwater-dominated, semiarid river in southwest Texas and considered one of the most pristine rivers in the state. It is one of the last strongholds for multiple species of regionally endemic freshwater fishes and mussels. However, groundwater pumping in the watershed poses an imminent threat to the river and its fragile ecosystem. Reductions in groundwater availability have the potential to result in concomitant reductions in spring discharge and thus instream flows. Base flow reductions would negatively impact many already imperiled aquatic species and degrade one of the state’s most remote and scenic paddling and angling destinations. Development of a comprehensive basinwide fish and mussel conservation plan is ideal due to the relatively small size of the watershed. However, challenges include the isolated location of the river and the low proportion of publicly held lands for implementing on-the-ground conservation measures. To best determine science needs, focus resources, and increase informed stewardship of the river, the Texas Parks and Wildlife Department has partnered with governmental agencies, universities, nonprofit organizations, and landowners interested in preserving this unique resource. Through collaborative research aimed at a better understanding of groundwater–surface water interactions and instream flow needs of endemic species, and by building cooperative relationships with landowners and nonprofit conservation organizations, steps are underway to preserve the esthetic, ecological, and recreational values of the Devils River.
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Arriagada, Joselyn, María-Victoria Soto i Pablo Sarricolea. "Morphodynamic Environment in a Semiarid Mouth River Complex Choapa River, Chile". W Advanced Geoscience Remote Sensing. InTech, 2014. http://dx.doi.org/10.5772/57410.
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Unganai, Leonard S. "Monitoring Agricultural Drought in Southern Africa". W Monitoring and Predicting Agricultural Drought. Oxford University Press, 2005. http://dx.doi.org/10.1093/oso/9780195162349.003.0030.
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Southern Africa lies between 0°S to 35°S latitude and 10°E to 41°E longitude. In this region, annual rainfall ranges from below 20 mm along the western coastal areas of Namibia to as high as 3000 mm in some highland areas of Malawi. Rainfall generally increases from south to north in response to topography and the main rain-bearing systems affecting the subregion. In the southwest sections of the sub-region, annual rainfall averages below 400 mm, whereas the high-altitude areas receive up to 3000 mm due to orographic enhancement. Two important features that control the climate of southern Africa are the semipermanent subtropical high-pressure cells centered in the southeast Atlantic and the southwest Indian Ocean. These subtropical high pressure cells are associated with widespread and persistent subsidence (Lockwood, 1979). Part of southern Africa is under the downward leg of the Hadley Cell, superposed on the zonal Walker cell. The complex interaction of these cells, particularly during warm El Niño/Southern Oscillation (ENSO) episodes, is usually associated with drier than normal austral summers over much of southern Africa. Much of southern Africa is therefore semiarid and prone to recurrent droughts. In South Africa, for operational purposes, a drought is broadly defined as occurring when the seasonal rainfall is 70% or less of the long-term average (Bruwer, 1990; Du Pisani, 1990). It becomes a disaster or severe drought when two or more consecutive rainfall seasons experience drought. Drought affects some part of southern Africa virtually every year. Southern Africa has suffered recurrent droughts since record keeping began (Nicholson, 1989; Unganai, 1993). Severe drought periods included 1800– 30, 1840–50, 1870–90, 1910–15, 1921–25, 1930–50, 1965–75, and 1980–95. During some of these drought periods, rivers, swamps, and wells dried up and well-watered plains turned into barren lands. For Zimbabwe, the worst drought years were 1911–12, 1923–24, 1946–47, 1972–73, 1981–82, 1982–83, 1986–87, and 1991–92 (Zimbabwe Department of Meteorological Services, personal communication, 2002). During the severe and recurrent droughts of the 1980s and 1990s, the impact on vulnerable communities and the environment was catastrophic.
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Bermúdez, M., A. Millares, A. Lira-Loarca i A. Baquerizo. "Towards sustainable sediment management strategies in Mediterranean reservoirs: Insights from the Guadalfeo semiarid river basin". W River Flow 2020, 2294–99. CRC Press, 2020. http://dx.doi.org/10.1201/b22619-319.
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Mollenhauer, Robert, Shannon K. Brewer, Desiree Moore, Dusty Swedberg i Maeghen Wedgeworth. "A Hierarchical Approach to Fish Conservation in Semiarid Landscapes: A Need to Understand Multiscale Environmental Relationships". W River Basin Management - Under a Changing Climate [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.105602.
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A multiscale perspective is essential for conservation planning of riverine fishes. Coarse-scale habitat (e.g., basis) can influence both finer-scale habitat characteristics (e.g., reaches and microhabitat) and associated species distributions. Finer-scale management and habitat rehabilitation efforts can fail without the consideration of coarser-scale constraints. We provide a conceptual hierarchical framework for multiscale fish conservation strategies in the semiarid Great Plains. The Great Plains stream network is highly fragmented due to dam construction, water withdrawals, and increased drought severity. Our framework uses relationships with basin-scale connectivity and streamflow and reach-scale physicochemical characteristics in the context of aiding species reintroduction and stream habitat improvements.
Streszczenia konferencji na temat "Semiarid rivers"
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Castillo, L., M. Marín i J. Carrillo. "Hydrological and hydraulic characterization in semiarid regions: Comparison of sediment transport formulae". W The International Conference On Fluvial Hydraulics (River Flow 2016). Taylor & Francis Group, 6000 Broken Sound Parkway NW, Suite 300, Boca Raton, FL 33487-2742: CRC Press, 2016. http://dx.doi.org/10.1201/9781315644479-161.
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Gil Samaniego Ramos, Margarita, Héctor Enrique Campbell Ramírez i Juan Carlos Tapia Olivas. "Water Supply Sustainability Indicators for the Southern California-Baja California Area". W ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-64540.
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Southern California and Baja California share, besides a dynamic social and economic exchange and 226 kilometers of borderline, an important natural resource: water from the Colorado River. Both areas have arid and semiarid climate in large zones and local fresh water sources are scarce, so water imports from the Colorado are strategic for their continued social and economic growth. Southern California’s water supply comes from the State Water Project, the Colorado River Aqueduct and local sources; in turn, Baja California depends mostly on the water supplied by the Colorado River, with an aqueduct that serves the Pacific coastline cities of the state. Both water supply systems are considered high energy consumers, affecting the quality of life in the region. The sustainable development of both communities is a challenge to Mexican and American public policy planners who must recognize that, to meet the future water demands to support sustainable development in this area it will require improved utilization and management of water resources. In this paper, water supply sustainable indicators were calculated for southern California and Baja California to evaluate and compare their performance towards sustainability. Findings show big differences in the indicators like water use per person, percentage of the cost of water relative to household income, cost of electricity to convey water, etc. High contrast in both economies makes up for these differences, but as water stakeholders of an only source, that is, the Colorado River, Mexico and the United States should avoid those imbalances in water use and management efficiencies, as it might affect its availability and cost, bringing potential conflicts and disturbing the traditional friendly coexistence and growth of both communities.
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Gil Samaniego Ramos, Margarita, i He´ctor Enrique Campbell Rami´rez. "Energy and Emissions Assessment in Pumping Water Distribution Systems: Case Study—Colorado River–Tijuana Aqueduct". W ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-63278.
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The northwestern portion of the Mexican territory has a semiarid climate with scarce rains and no reliable water supply sources. The cities of Tijuana, Tecate and Rosarito, Baja California, Mexico, are located within this zone and depend on the Ri´o Colorado–Tijuana Aqueduct to fulfill approximately 90% of its water demand. This large hydraulic facility is 147 km long and elevates 4.0 m3/s of water at a height of 1,060 m. It is composed of 6 pumping stations with a total installed motor capacity of 79,500 hp. At this time the capacity of the aqueduct is being increased to 5.33 m3/s by means of installing an additional pump to each pumping station and a 54″ parallel line. The motor capacity increase will be of 26,500 hp. In 2009, its electricity consumption was of 433,589 MWh at a cost of $29,494,630 USD. Emissions to the atmosphere associated to this electricity consumption were calculated to be: 73 tonnes of SO2, 73 tonnes of NOx and 116,467 tonnes of CO2. This paper presents the methodology used to evaluate the potential savings of electricity and emissions and recommends alternatives to decrease its current energy consumption. Results obtained show that 35,949 MWH at a cost of $2,762,300 USD can be saved annually if the equipment performance were at its optimal efficiency. Emissions to the atmosphere avoided would be of 9,656 tonnes of CO2, 6 tonnes of SO2 and 17 tonnes of NOx.
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Xiuqin Fang, Liliang Ren, Qiongfang Li i Fei Yuan. "Hydrological responses of a semiarid catchment to land use change in North China: case study the Laohahe River Basin". W 2007 IEEE International Geoscience and Remote Sensing Symposium. IEEE, 2007. http://dx.doi.org/10.1109/igarss.2007.4423595.
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