Journal articles: 'Dryland river system'

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Costa, A. C., A. Bronstert, and J. C. de Araújo. "A channel transmission losses model for different dryland rivers." Hydrology and Earth System Sciences 16, no. 4 (April 3, 2012): 1111–35. http://dx.doi.org/10.5194/hess-16-1111-2012.

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Abstract. Channel transmission losses in drylands take place normally in extensive alluvial channels or streambeds underlain by fractured rocks. They can play an important role in streamflow rates, groundwater recharge, freshwater supply and channel-associated ecosystems. We aim to develop a process-oriented, semi-distributed channel transmission losses model, using process formulations which are suitable for data-scarce dryland environments and applicable to both hydraulically disconnected losing streams and hydraulically connected losing(/gaining) streams. This approach should be able to cover a large variation in climate and hydro-geologic controls, which are typically found in dryland regions of the Earth. Our model was first evaluated for a losing/gaining, hydraulically connected 30 km reach of the Middle Jaguaribe River (MJR), Ceará, Brazil, which drains a catchment area of 20 000 km2. Secondly, we applied it to a small losing, hydraulically disconnected 1.5 km channel reach in the Walnut Gulch Experimental Watershed (WGEW), Arizona, USA. The model was able to predict reliably the streamflow volume and peak for both case studies without using any parameter calibration procedure. We have shown that the evaluation of the hypotheses on the dominant hydrological processes was fundamental for reducing structural model uncertainties and improving the streamflow prediction. For instance, in the case of the large river reach (MJR), it was shown that both lateral stream-aquifer water fluxes and groundwater flow in the underlying alluvium parallel to the river course are necessary to predict streamflow volume and channel transmission losses, the former process being more relevant than the latter. Regarding model uncertainty, it was shown that the approaches, which were applied for the unsaturated zone processes (highly nonlinear with elaborate numerical solutions), are much more sensitive to parameter variability than those approaches which were used for the saturated zone (mathematically simple water budgeting in aquifer columns, including backwater effects). In case of the MJR-application, we have seen that structural uncertainties due to the limited knowledge of the subsurface saturated system interactions (i.e. groundwater coupling with channel water; possible groundwater flow parallel to the river) were more relevant than those related to the subsurface parameter variability. In case of the WEGW application we have seen that the non-linearity involved in the unsaturated flow processes in disconnected dryland river systems (controlled by the unsaturated zone) generally contain far more model uncertainties than do connected systems controlled by the saturated flow. Therefore, the degree of aridity of a dryland river may be an indicator of potential model uncertainty and subsequent attainable predictability of the system.

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Burford, M. A., A. T. Revill, D. W. Palmer, L. Clementson, B. J. Robson, and I. T. Webster. "River regulation alters drivers of primary productivity along a tropical river-estuary system." Marine and Freshwater Research 62, no. 2 (2011): 141. http://dx.doi.org/10.1071/mf10224.

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Worldwide, rivers continue to be dammed to supply water for humans. The resulting regulation of downstream flow impacts on biogeochemical and physical processes, potentially affecting river and estuarine productivity. Our study tested the hypothesis that primary production in the downstream freshwater reaches of a dammed river was less limited by light and nutrients relative to downstream estuarine primary production. In a tropical dryland Australian river estuary, we found that water-column primary productivity was highest at freshwater sites that had lowest light attenuation. Nitrogen may also have limited primary productivity. Below the freshwater zone was a region of macrotidal mixing with high concentrations of suspended soil particles, nutrients and chlorophyll a, and lower but variable primary productivity rates. Light controlled productivity, but the algal cells may also have been osmotically stressed due to increasing salinity. Further downstream in the estuary, primary productivity was lower than the freshwater reaches and light and nutrient availability appear to be a factor. Therefore the reduced magnitude of peak-flow events due to flow regulation, and the resulting decrease in nutrient export, is likely to be negatively impacting estuarine primary production. This has implications for future development of dams where rivers have highly seasonal flow.

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Reid, Michael A., Martin C. Thoms, Stephen Chilcott, and Kathryn Fitzsimmons. "Sedimentation in dryland river waterholes: a threat to aquatic refugia?" Marine and Freshwater Research 68, no. 4 (2017): 668. http://dx.doi.org/10.1071/mf15451.

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In dryland river systems subject to prolonged low and no flow periods, waterholes, or sections of river channel that are deep relative to the rest of the channel and that retain water for longer periods of no flow, provide refugia for aquatic biota and hence are critical to the resilience of aquatic ecosystems. This study examined physical, chemical and bio-stratigraphy in refugial waterholes situated along four distributaries of the Lower Balonne River system in semi-arid Australia. In doing so we reconstructed environmental histories for the waterholes, calculated how sedimentation rates have changed in response to land use change over the past two centuries, and assessed whether they are threatened by increased sedimentation through potential effects on waterhole depth and hence persistence times and habitat quality. Our study found that sedimentation rates have increased substantially since European settlement, most likely in response to removal of groundcover by grazers. The increased sediment accumulation rates are estimated to have reduced persistence times during low and no flow periods of the waterholes by 2–4 months. Despite evidence from other similar systems in Australia that increased influx of sediment coincided with loss of submerged macrophytes, stratigraphic records of preserved pollen and diatoms did not provide consistent evidence of biotic or habitat quality changes within the waterholes associated with European settlement.

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Kernich, A. L., C. F. Pain, J. D. A. Clarke, and A. D. Fitzpatrick. "Geomorphology of a dryland fluvial system: the Lower Balonne River, southern Queensland." Australian Journal of Earth Sciences 56, sup1 (July 2009): S139—S153. http://dx.doi.org/10.1080/08120090902871184.

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Goss, Kevin F. "Environmental flows, river salinity and biodiversity conservation: managing trade-offs in the Murray - Darling basin." Australian Journal of Botany 51, no. 6 (2003): 619. http://dx.doi.org/10.1071/bt03003.

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The Murray–Darling basin's river system suffers from over-allocation of water resources to consumptive use and salinity threats to water quality. This paper draws attention to the current state of knowledge and the need for further investigations into the biological effect of river salinity on aquatic biota and ecosystems, the threats of dryland salinity to terrestrial biodiversity, and managing environmental flows and salinity control to limit the trade-offs in water-resource security and river salinity.There is growing evidence that river salt concentrations lower than the normally adopted threshold have sublethal effects on species and ecosystems, over a longer time period. Further knowledge is required.There is no agreed process for incorporating terrestrial biodiversity values at risk into a strategic response for dryland-salinity management. This is a public policy issue to be addressed.Recent studies have quantified the trade-off in surface water flow and river salinity from refforestation and revegetation of upland catchments to control salinity. The potential losses or benefits to environmental values have not been quantified.Such improved knowledge is important to the Murray–Darling basin and relevant to other river basins and catchments in Australia.

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CANDY, I., S. BLACK, and B. SELLWOOD. "Interpreting the response of a dryland river system to Late Quaternary climate change." Quaternary Science Reviews 23, no. 23-24 (December 2004): 2513–23. http://dx.doi.org/10.1016/j.quascirev.2004.06.009.

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Mueller, E. N., A. Güntner, T. Francke, and G. Mamede. "Modelling sediment export, retention and reservoir sedimentation in drylands with the WASA-SED model." Geoscientific Model Development 3, no. 1 (April 8, 2010): 275–91. http://dx.doi.org/10.5194/gmd-3-275-2010.

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Abstract. Current soil erosion and reservoir sedimentation modelling at the meso-scale is still faced with intrinsic problems with regard to open scaling questions, data demand, computational efficiency and deficient implementations of retention and re-mobilisation processes for the river and reservoir networks. To overcome some limitations of current modelling approaches, the semi-process-based, spatially semi-distributed modelling framework WASA-SED (Vers. 1) was developed for water and sediment transport in large dryland catchments. The WASA-SED model simulates the runoff and erosion processes at the hillslope scale, the transport and retention processes of suspended and bedload fluxes in the river reaches and the retention and remobilisation processes of sediments in reservoirs. The modelling tool enables the evaluation of management options both for sustainable land-use change scenarios to reduce erosion in the headwater catchments as well as adequate reservoir management options to lessen sedimentation in large reservoirs and reservoir networks. The model concept, its spatial discretisation scheme and the numerical components of the hillslope, river and reservoir processes are described and a model application for the meso-scale dryland catchment Isábena in the Spanish Pre-Pyrenees (445 km2) is presented to demonstrate the capabilities, strengths and limits of the model framework. The example application showed that the model was able to reproduce runoff and sediment transport dynamics of highly erodible headwater badlands, the transient storage of sediments in the dryland river system, the bed elevation changes of the 93 hm3 Barasona reservoir due to sedimentation as well as the life expectancy of the reservoir under different management options.

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SOUTHWELL, MARK, and MARTIN THOMS. "Patterns of Nutrient Concentrations across Multiple Floodplain Surfaces in a Large Dryland River System." Geographical Research 49, no. 4 (May 10, 2011): 431–43. http://dx.doi.org/10.1111/j.1745-5871.2011.00699.x.

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Mackay, Alana K., Mark P. Taylor, and Karen A. Hudson-Edwards. "Water and sediment quality of dry season pools in a dryland river system: the upper Leichhardt River, Queensland, Australia." Journal of Environmental Monitoring 13, no. 7 (2011): 2050. http://dx.doi.org/10.1039/c0em00396d.

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Hamilton, Stephen K., Stuart E. Bunn, Martin C. Thoms, and Jonathan C. Marshall. "Persistence of aquatic refugia between flow pulses in a dryland river system (Cooper Creek, Australia)." Limnology and Oceanography 50, no. 3 (May 2005): 743–54. http://dx.doi.org/10.4319/lo.2005.50.3.0743.

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11

Balcombe, S. R., A. H. Arthington, M. C. Thoms, and G. G. Wilson. "Fish assemblage patterns across a gradient of flow regulation in an Australian dryland river system." River Research and Applications 27, no. 2 (February 2011): 168–83. http://dx.doi.org/10.1002/rra.1345.

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HUEY, JOEL A., DANIEL J. SCHMIDT, STEPHEN R. BALCOMBE, JONATHAN C. MARSHALL, and JANE M. HUGHES. "High gene flow and metapopulation dynamics detected for three species in a dryland river system." Freshwater Biology 56, no. 11 (July 27, 2011): 2378–90. http://dx.doi.org/10.1111/j.1365-2427.2011.02666.x.

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13

Lang, S. C., T. H. D. Payenberg, M. R. W. Reilly, T. Hicks, J. Benson, and J. Kassan. "MODERN ANALOGUES FOR DRYLAND SANDY FLUVIAL-LACUSTRINE DELTAS AND TERMINAL SPLAY RESERVOIRS." APPEA Journal 44, no. 1 (2004): 329. http://dx.doi.org/10.1071/aj03012.

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Ephemeral sandy fluvial-lacustrine deltas and terminal splays associated with dryland depositional environments are important reservoirs in many basins around the world, in both pericratonic and intracratonic settings (Triassic of Algeria; Triassic of the North Sea; and Pliocene of the Caspian Sea). Research on modern depositional analogues from dryland basins offers insights into these types of reservoirs. Australia’s modern Lake Eyre Basin, an arid to hyper-arid, low-accommodation intracratonic basin in central Australia, provides an ideal natural laboratory.This paper highlights field observations of modern, sand-prone, reservoir analogues from the Neales River and Umbum Creek, on the western fringe of Lake Eyre, including unique aerial observations of sedimentation from a rare flood event in an ephemeral fluvial system. These rivers flow irregularly in a dryland setting, but are prone to flash flooding and highly variable discharge that moves large volumes of sediment over a few hours or days. Although there are variations in sediment type and discharge, similarities exist with the key reservoir elements common to most modern and ancient dryland fluvial-lacustrine systems.Distinctive elements include fluvial point bar and associated overbank deposits, distributive avulsion channels and down-dip terminal splays, either on the floodplain or onto the playa lake fringe. The terminal splays are formed, where there is not a pre-existing standing body of water, during rapidly decelerating flows with high-flow regime, transitional to low-flow regime conditions. Typical structures include parallel lamination, convex-upward parallel lamination, climbing ripples and small-scale 2D and 3D dunes. Flow interference with in-channel and floodplain vegetation is an important sediment-trapping mechanism with reservoir quality implications. Aeolian deflation is also significant as it causes the removal of fine-grained sediments during dry periods. The main controls on sediment preservation include the overall low-accommodation setting and rare major lake-filling events controlled by flooding out-of-phase with flows down the western rivers. Depositional products are either high-net-to gross fluvial- terminal splay sheet sands or lower net-to-gross fluvial- terminal splay-lacustrine delta sand sheets or stringers.

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14

Li, Jiaguang, Marinus E. Donselaar, Seyed Enayat Hosseini Aria, Roderik Koenders, and Anneleen M. Oyen. "Landsat imagery-based visualization of the geomorphological development at the terminus of a dryland river system." Quaternary International 352 (November 2014): 100–110. http://dx.doi.org/10.1016/j.quaint.2014.06.041.

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15

Yao, Yingying, Yong Tian, Charles Andrews, Xi Li, Yi Zheng, and Chunmiao Zheng. "Role of Groundwater in the Dryland Ecohydrological System: A Case Study of the Heihe River Basin." Journal of Geophysical Research: Atmospheres 123, no. 13 (July 7, 2018): 6760–76. http://dx.doi.org/10.1029/2018jd028432.

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16

Smith, S. F., and K. R. Brye. "Carbon Dioxide Emissions as Affected by Alternative Long-Term Irrigation and Tillage Management Practices in the Lower Mississippi River Valley." Scientific World Journal 2014 (2014): 1–6. http://dx.doi.org/10.1155/2014/626732.

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Ensuring the sustainability of cultivated soils is an ever-increasing priority for producers in the Lower Mississippi River Valley (LMRV). As groundwater sources become depleted and environmental regulations become more strict, producers will look to alternative management practices that will ensure the sustainability and cost-effectiveness of their production systems. This study was conducted to assess the long-term (>7 years) effects of irrigation (i.e., irrigated and dryland production) and tillage (conventional and no-tillage) on estimated carbon dioxide (CO2) emissions from soil respiration during two soybean (Glycine maxL.) growing seasons from a wheat- (Triticum aestivumL.-) soybean, double-cropped production system in the LMRV region of eastern Arkansas. Soil surface CO2fluxes were measured approximately every two weeks during two soybean growing seasons. Estimated season-long CO2emissions were unaffected by irrigation in 2011 (P>0.05); however, during the unusually dry 2012 growing season, season-long CO2emissions were 87.6% greater (P=0.044) under irrigated (21.9 Mg CO2ha−1) than under dryland management (11.7 Mg CO2ha−1). Contrary to what was expected, there was no interactive effect of irrigation and tillage on estimated season-long CO2emissions. Understanding how long-term agricultural management practices affect soil respiration can help improve policies for soil and environmental sustainability.

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Webb, Munique, Martin Thoms, and Michael Reid. "Determining the ecohydrological character of aquatic refugia in a dryland river system: the importance of temporal scale." Ecohydrology & Hydrobiology 12, no. 1 (January 2012): 21–33. http://dx.doi.org/10.2478/v10104-011-0005-8.

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Xie, Zunyi, Alfredo Huete, Xuanlong Ma, Natalia Restrepo-Coupe, Rakhesh Devadas, Kenneth Clarke, and Megan Lewis. "Landsat and GRACE observations of arid wetland dynamics in a dryland river system under multi-decadal hydroclimatic extremes." Journal of Hydrology 543 (December 2016): 818–31. http://dx.doi.org/10.1016/j.jhydrol.2016.11.001.

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Matheson, Adrian, Martin Thoms, Mark Southwell, and Michael Reid. "Does the reintroduction of large wood in a large dryland river system benefit fish assemblages at the reach scale?" Marine and Freshwater Research 69, no. 2 (2018): 232. http://dx.doi.org/10.1071/mf16290.

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Benefits of reintroduced large wood in river channels are largely based on studies at site scales in high-energy systems. By comparison, relatively little is known of the benefit of reintroduced large wood in low-energy systems at larger, reach scales. The present study assessed the effects of reintroducing large wood on fish assemblages along the Barwon–Darling River, Australia. Fish were sampled in replicated reaches subject to three treatments: six reference (wooded), six control (unwooded) and six managed (wood reintroduced) reaches. Sampling was conducted before and several months after wood addition, and then during a period following several large floods. Results demonstrate that reintroducing large wood had limited effects on fish. There were significant differences between treatments in fish length, but not in total abundance or species composition between treatments. Significant differences were detected in total abundance, species composition and fish length over time. There was an interaction recorded between treatments and time for fish length, but not total abundance or species composition. It is suggested that the lack of response by fish was because the physical character and position of the reintroduced wood pieces did not replicate ‘natural’ reference conditions. However, high variability in fish assemblages through time, likely in response to hydrological variation, reduced the power of the study to detect differences between fish over the shorter time period of the study (<5 years).

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Das, Archana, Falguni Bhattacharya, B. K. Rastogi, Gaurav Chauhan, Mamata Ngangom, and M. G. Thakkar. "Response of a dryland fluvial system to climate–tectonic perturbations during the Late Quaternary: Evidence from Rukmawati River basin, Kachchh, western India." Journal of Earth System Science 125, no. 6 (August 2016): 1119–38. http://dx.doi.org/10.1007/s12040-016-0733-7.

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Khan, Shahbaz, Muhammad Nadeem Asghar, Shahbaz Mushtaq, and Aftab Ahmad. "On-farm options for managing stream salinity in irrigation areas: an example from the Murray Darling Basin, Australia." Hydrology Research 39, no. 2 (April 1, 2008): 157–70. http://dx.doi.org/10.2166/nh.2008.036.

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Increasing salt concentration in tributaries from catchments and rising water tables are the prime contributor to environmental degradation of rivers, creeks, streams or other water bodies. This is especially true during periods of mid- and low stream flows in arid and semi-arid regions around the globe. Catchment scale studies suggest that management of stream salinity requires greater land use change than is economically viable. Therefore, rather than focusing on the opportunity cost of catchment scale interventions, exploring interventions that are potentially viable at farm scale could be an appropriate strategy for stream salinity management. This paper presents an analysis of alternative on-farm strategies, such as evaporation ponds and serial biological concentration of salts, aimed at developing an economically self-sustainable stream salinity management system for the Box Creek stormwater escape channel located in the Murray–Darling Basin (MDB), Australia. It is concluded that irrigation areas, with careful management of flows in tributary streams, may be able to play a role in safeguarding the Murray River against further salinisation from irrigation and dryland areas. The outcomes of this paper will be helpful, but not limited to, the MDB in addressing environmental, economic and social issues associated with management of salt concentration in tributaries.

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du Toit, Raoul F. "Soil Loss, Hydrological Changes, and Conservation Attitudes, in the Sabi Catchment of Zimbabwe." Environmental Conservation 12, no. 2 (1985): 157–66. http://dx.doi.org/10.1017/s0376892900015575.

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The Communal Lands—occupied by peasant farmers—of the upper catchment of the Sabi River (which drains the southeastern portion of Zimbabwe) are severely deforested, overgrazed, and eroded. Siltation of the river channel has increased the risk of overbank flooding at a downstream irrigation scheme, and a rise in annual outflow from the catchment over the last three decades has additional implications for irrigation development, as well as for the availability of ground-water reserves in the areas of dryland peasant farming.In a study area within one of the Communal Lands, the average rate of soil loss from fields of gentle slope is estimated to be such that the next generation of peasant farmers will be unable to achieve crop-yields above a very low ‘subsistence’ level. The degraded environment is the inevitable consequence of the expansion of a primitive system of cultivation—in a region of low inherent potential for crop production—under the pressure of rapid population growth. While the peasants are aware of many of the consequences of their exploitative methods of land-use, and recognize the importance of basic conservation measures such as erosion-control terraces, they generally feel that remedial action is beyond their means.The effective implementation of available technical solutions to the deterioration of the land resources, will depend upon the provision of greater financial incentives for intensified production, as well as upon more positive political influences, than exist at present. The eventual stabilization of the situation is achievable only if population growth is reduced; but much might be done to improve production, and promote conservation, through field research into appropriate farming systems for peasant agriculture in the Sabi catchment and similar environments.

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Balcombe, Stephen R., Fran Sheldon, Samantha J. Capon, Nick R. Bond, Wade L. Hadwen, Nick Marsh, and Sofie J. Bernays. "Climate-change threats to native fish in degraded rivers and floodplains of the Murray–Darling Basin, Australia." Marine and Freshwater Research 62, no. 9 (2011): 1099. http://dx.doi.org/10.1071/mf11059.

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Many aquatic ecosystems have been severely degraded by water-resource development affecting flow regimes and biological connectivity. Freshwater fish have been particularly affected by these changes and climate change will place further stress on them. The Murray–Darling Basin (MDB), Australia, represents a highly affected aquatic system with dramatically modified flow regimes. This has impaired the health of its rivers, and potentially limited the adaptive capacity of its biota to respond to a changing climate. Here, we present our predictions of the potential impacts of climate change on 18 native fish species across their distributional ranges against the back-drop of past and continuing water-resource development (WRD). Because most of these species are found across a wide range of geographical and hydrological settings, we classified the MDB into 10 regions to account for likely variation in climate-change effects, on the basis of latitude, elevation and WRD. Cold water-tolerant species will be under greater stress than are warm water-tolerant species. In some regions, the negative impacts on exotic fish such as trout are likely to improve current conditions for native species. Because the impacts of climate change on any given species are likely to vary from region to region, regional fish assemblages will also be differentially affected. The most affected region is likely to occur in the highly disturbed Lower Murray River region, whereas the dryland rivers that are less affected in the northern MDB are likely to remain largely unchanged. Although climate change is a current and future threat to the MDB fish fauna, the continued over-regulation of water resources will place as much, if not more, stress on the remnant fish species.

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Hart, Barry, Glen Walker, Asitha Katupitiya, and Jane Doolan. "Salinity Management in the Murray–Darling Basin, Australia." Water 12, no. 6 (June 26, 2020): 1829. http://dx.doi.org/10.3390/w12061829.

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The southern Murray–Darling Basin (MDB) is particularly vulnerable to salinity problems. Much of the Basin’s landscape and underlying groundwater is naturally saline with groundwater not being suitable for human or irrigation use. Since European settlement in the early 1800s, two actions—the clearance of deep-rooted native vegetation for dryland agriculture and the development of irrigation systems on the Riverine Plains and Mallee region—have resulted in more water now entering the groundwater systems, resulting in mobilization of the salt to the land surface and to rivers. While salinity has been a known issue since the 1960s, it was only in the mid-1980s that was recognized as one of the most significant environmental and economic challenges facing the MDB. Concerted and cooperative action since 1988 by the Commonwealth and Basin state governments under a salinity management approach implemented over the past 30 years has resulted in salinity now being largely under control, but still requiring on-going active management into the future. The approach has involved the development of three consecutive salinity strategies governing actions from 1988 to 2000, from 2001 to 2015, and the most recent from 2016 to 2030. The basis of the approach and all three strategies is an innovative, world-leading salinity management framework consisting of: An agreed salinity target; joint works and measures to reduce salt entering the rivers; and an agreed accountability and governance system consisting of a system of salinity credits to offset debits, a robust and agreed method to quantify the credits and debits, and a salinity register to keep track of credits and debits. This paper first provides background to the salinity issue in the MDB, then reviews the three salinity management strategies, the various actions that have been implemented through these strategies to control salinity, and the role of the recent Basin Plan in salinity management. We then discuss the future of salinity in the MDB given that climate change is forecast to lead to a hotter, drier and more variable climate (particularly more frequent droughts), and that increased salt loads to the River Murray are predicted to come from the lower reaches of the Mallee region. Finally, we identify the key success factors of the program.

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Jarihani, Abdollah A., Joshua R. Larsen, John N. Callow, Tim R. McVicar, and Kasper Johansen. "Where does all the water go? Partitioning water transmission losses in a data-sparse, multi-channel and low-gradient dryland river system using modelling and remote sensing." Journal of Hydrology 529 (October 2015): 1511–29. http://dx.doi.org/10.1016/j.jhydrol.2015.08.030.

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Khosravichenar, Azra, Morteza Fattahi, Hamideh Amini, and Hans von Suchodoletz. "The Potential of Small Mountain River Systems for Paleoenvironmental Reconstructions in Drylands—An Example from the Binaloud Mountains in Northeastern Iran." Geosciences 10, no. 11 (November 9, 2020): 448. http://dx.doi.org/10.3390/geosciences10110448.

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Fluvial sediments are valuable paleoenvironmental archives of the Quaternary. Since besides environmental factors they are also affected by local tectonics or intrinsic processes, large instead of small catchments should be studied. In drylands covering ca. 45% of the global terrestrial surface large river systems are generally missing, and most river systems are small rivers originating from mountain ranges. Their sediments are potentially interesting paleoenvironmental archives, but are often affected by intensive tectonics. During this study, to obtain a robust regional paleoenvironmental signal a small river system in the southwestern Binaloud Mountains in semi-arid NE Iran was exemplarily studied with a combined approach that encompassed both alluvial fan and catchment. By using geomorphological mapping and numerical dating, fluvial aggradation followed by incision was independently identified in larger areas or in different parts of the river system ca. 95–88 ka, 40 ka, 20 ka, around/after the Pleistocene/Holocene transition and possibly ca. 2.6 ka. These could be linked with regional and over-regional paleoenvironmental data. Furthermore, large boulders on the alluvial fan suggest anthropogenic destabilisation of the catchment during the last decades. Despite strong local tectonics the fluvial dynamics was mostly controlled by paleoenvironmental changes and human activity. This indicates that despite their small size, such river systems form valuable paleoenvironmental archives in drylands where other archive types are largely missing.

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Malek, Keyvan, Claudio Stöckle, Kiran Chinnayakanahalli, Roger Nelson, Mingliang Liu, Kirti Rajagopalan, Muhammad Barik, and Jennifer C. Adam. "VIC–CropSyst-v2: A regional-scale modeling platform to simulate the nexus of climate, hydrology, cropping systems, and human decisions." Geoscientific Model Development 10, no. 8 (August 17, 2017): 3059–84. http://dx.doi.org/10.5194/gmd-10-3059-2017.

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Abstract. Food supply is affected by a complex nexus of land, atmosphere, and human processes, including short- and long-term stressors (e.g., drought and climate change, respectively). A simulation platform that captures these complex elements can be used to inform policy and best management practices to promote sustainable agriculture. We have developed a tightly coupled framework using the macroscale variable infiltration capacity (VIC) hydrologic model and the CropSyst agricultural model. A mechanistic irrigation module was also developed for inclusion in this framework. Because VIC–CropSyst combines two widely used and mechanistic models (for crop phenology, growth, management, and macroscale hydrology), it can provide realistic and hydrologically consistent simulations of water availability, crop water requirements for irrigation, and agricultural productivity for both irrigated and dryland systems. This allows VIC–CropSyst to provide managers and decision makers with reliable information on regional water stresses and their impacts on food production. Additionally, VIC–CropSyst is being used in conjunction with socioeconomic models, river system models, and atmospheric models to simulate feedback processes between regional water availability, agricultural water management decisions, and land–atmosphere interactions. The performance of VIC–CropSyst was evaluated on both regional (over the US Pacific Northwest) and point scales. Point-scale evaluation involved using two flux tower sites located in agricultural fields in the US (Nebraska and Illinois). The agreement between recorded and simulated evapotranspiration (ET), applied irrigation water, soil moisture, leaf area index (LAI), and yield indicated that, although the model is intended to work on regional scales, it also captures field-scale processes in agricultural areas.

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Amos, Kathryn, Carley Goodwin, and Angel Soria. "Incised valleys in marginal-lacustrine depositional environments: a new reservoir analogue from Lake Eyre, central Australia." APPEA Journal 52, no. 1 (2012): 513. http://dx.doi.org/10.1071/aj11040.

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Incised-valley fill deposits can form important hydrocarbon reservoirs and provide pathways for hydrocarbon migration. Incised-valleys formed in marginal-marine environments are well described, however, marginal-lacustrine incised-valleys have been the focus of extremely few investigations and are poorly understood. This paper provides a new description of incised-fluvial systems that are presently constructing terminal deposits in embayments around the shoreline of Lake Eyre, central Australia. It is anticipated that better awareness of such deposits will assist in the recognition of these depositional environments in the rock record, which should be useful for exploration purposes and for the generation of improved models for continental dryland fluvial-lacustrine reservoir deposits. A classification of all significant river mouth deposits around Lake Eyre (width >300 m; n = 104), from topographic map and satellite image data, found that 54% are incised-valleys presently accreting a terminal deposit in a shoreline embayment (playa lake estuary). The depositional elements of three incised-valley systems have been mapped using satellite imagery in a GIS platform, from which element geometries are described. Controls on incised-valley formation are investigated by comparing these observations with evidence for past lake highstands and neotectonics and observations from satellite images, geological map data, and digital elevation model data. The terminal splay deposits of rivers around Lake Eyre are well-used analogues for dryland reservoirs; however, the focus has been on deposits accreting directly onto the playa. It is likely the incised-valleys and terminal deposits in the embayments described here will be of interest to companies exploring in, and producing from, ancient drylands and other lacustrine depositional environments.

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Sheldon, Fran, Stuart E. Bunn, Jane M. Hughes, Angela H. Arthington, Stephen R. Balcombe, and Christine S. Fellows. "Ecological roles and threats to aquatic refugia in arid landscapes: dryland river waterholes." Marine and Freshwater Research 61, no. 8 (2010): 885. http://dx.doi.org/10.1071/mf09239.

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Dryland rivers are renowned for their periods of ‘boom’ related to the episodic floods that extend over vast floodplains and fuel incredible production, and periods of ‘bust’ where the extensive channel network is restricted to the permanent refugial waterholes. Many of these river systems are unregulated by dams but are under increasing pressure, especially from water abstraction and overland flow interception for agriculture and mining. Although some aquatic organisms with desiccation-resistant life stages can utilise ephemeral floodplain habitats, the larger river waterholes represent the only permanent aquatic habitat during extended periods of low or no flow. These waterholes act as aquatic refugia in an otherwise terrestrial landscape. Variable patterns of connection and disconnection in space and time are a fundamental driver of diversity and function in these dryland river systems, and are vital for dispersal and the maintenance of diverse populations, generate the spatial and temporal variability in assemblage structure for a range of different organisms and fuel the productivity that sustains higher trophic levels. Changes to natural patterns of connection and disconnection of refugial waterholes, owing to water-resource development or climate change, will threaten their persistence and diminish their functional capacity to act as aquatic refugia.

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Balcombe, Stephen R., Angela H. Arthington, Neal D. Foster, Martin C. Thoms, Glenn G. Wilson, and Stuart E. Bunn. "Fish assemblages of an Australian dryland river: abundance, assemblage structure and recruitment patterns in the Warrego River, Murray - Darling Basin." Marine and Freshwater Research 57, no. 6 (2006): 619. http://dx.doi.org/10.1071/mf06025.

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Fish in dryland rivers must cope with extreme variability in hydrology, temperature and other environmental factors that ultimately have a major influence on their patterns of distribution and abundance at the landscape scale. Given that fish persist in these systems under conditions of high environmental variability, dryland rivers represent ideal systems to investigate the processes contributing to and sustaining fish biodiversity and recruitment in variable environments. Hence, spatial and temporal variation in fish assemblage structure was examined in 15 waterholes of the Warrego River between October 2001 and May 2003. Fish assemblages in isolated waterholes were differentiated at the end of the dry 2001 winter but were relatively similar following high summer flows in January 2002 as a consequence of high hydrological connectivity among waterholes. Small, shallow waterholes supported more species and higher abundances than large-deep waterholes. Large, deep waterholes provided important refuge for large-bodied fish species such as adult yellowbelly, Macquaria ambigua, and the eel-tailed catfish, Tandanus tandanus. Recruitment patterns of bony bream (Nematalosa erebi), Hyrtl’s tandan (Neosilurus hyrtlii) and yellowbelly were associated with high flow events and backwater inundation; however recruitment of yellowbelly and bony bream was also evident following a zero-flow period. Departures from typical flood-induced seasonal spawning patterns may reflect opportunistic spawning behaviours appropriate to the erratic patterns of flooding and dry spells in dryland rivers.

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Leigh, Catherine, Fran Sheldon, Richard T. Kingsford, and Angela H. Arthington. "Sequential floods drive 'booms' and wetland persistence in dryland rivers: a synthesis." Marine and Freshwater Research 61, no. 8 (2010): 896. http://dx.doi.org/10.1071/mf10106.

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Flow is a key driver regulating processes and diversity in river systems across a range of temporal and spatial scales. In dryland rivers, variability in the timing and scale of floods has specific ecological significance, playing a major role in sustaining biotic diversity across the river-floodplain mosaic. However, longitudinal effects of floods are equally important, delivering water downstream through channels and wetland complexes. Interaction among spatially distributed wetlands, their connecting channel and floodplain geomorphology and the temporally variable flow events not only creates the spatial complexity in dryland rivers but also determines temporal persistence of wetlands. These act as hydrological ‘sponges’, absorbing water from upstream and needing to fill before releasing water downstream. Sequential high flow events are essential for the ecological persistence of riverine wetlands and the transmission of flows further downstream through the channel network. These flood sequences maintain aquatic refugia and drive booms in productivity sustaining aquatic and terrestrial biota over large spatial and temporal scales. Disrupting the sequence, with modified flow regimes and water removal for diversion (e.g. irrigation), significantly reduces the opportunity for wetland replenishment. As a result, the benefits of sequential flooding to the wetland ‘sponges’ and their biotic communities will be lost.

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Bao, Wen. "Drought Prevention and Mitigation of Agricultural Development in the Dry Upper Valley of Minjiang River." Applied Mechanics and Materials 195-196 (August 2012): 1243–48. http://dx.doi.org/10.4028/www.scientific.net/amm.195-196.1243.

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The distinct characteristics in the dry upper valley of Minjiang River were the complication of natural environment, the frangibility of ecosystem, dryland farming systems, and the transition of culture. Drought is a many faceted natural disaster that leads to serious socio-economic impacts particularly affecting agricultural production of the dry valley. The basic objective of drought prevention and mitigation is to minimize possible adverse outcomes within the constraints of the costs involved. The paper elaborates the specific vulnerability contexts and situation of dryland mountain agricultural systems, highlights the importance of stabilizing dryland agriculture by evolving contingent crop production strategies, economies diversify to include agro-industry or various tertiary products, agricultural extension etc. in dry valley area of upper Minjiang River.

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Sheldon, Fran, and Christine S. Fellows. "Water quality in two Australian dryland rivers: spatial and temporal variability and the role of flow." Marine and Freshwater Research 61, no. 8 (2010): 864. http://dx.doi.org/10.1071/mf09289.

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Water quality, along with hydrology, plays an important role in the spatial and temporal dynamics of a range of ecological patterns and processes in large rivers and is also often a key component of river health assessments. Geology and land use are significant drivers of water quality during flow periods while during periods of no-flow, local-scale factors such as evaporation, groundwater influence and the concentration and precipitation of compounds are important. This study explored the water quality changes in two Australian dryland rivers, the Cooper Creek (Lake Eyre Basin) and the Warrego River (Murray–Darling Basin), across different hydrological phases over several years. Water quality varied both spatially and temporally; the greatest spatial variability occurred during the no-flow phase, with temporal changes driven by flow. Concentrations of major anions and cations also varied spatially and temporally, with an overall cation dominance of calcium and magnesium and an anion dominance of bicarbonate. This bicarbonate dominance contrasts with previous data from inland lentic systems where sodium chloride was found to dominate. Such extreme spatial and temporal variability hampers successful derivation of water quality guidelines for these variable rivers and suggests such guidelines would need to be developed with respect to ‘flow phase’.

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Fellows, C. S., M. L. Wos, P. C. Pollard, and S. E. Bunn. "Ecosystem metabolism in a dryland river waterhole." Marine and Freshwater Research 58, no. 3 (2007): 250. http://dx.doi.org/10.1071/mf06142.

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Little is known about ecosystem processes in dryland rivers, despite the global distribution of these systems. Those in Australia are characterised by long periods of no flow in which they persist for many months as series of isolated, often turbid, waterholes. We assessed benthic and pelagic primary production, respiration, and bacterial production in one of these waterholes to determine the metabolic balance of the waterhole and resolve the relative importance of autochthonous and allochthonous sources of organic carbon. Despite a photic zone depth of only 0.25 m, three lines of evidence suggested that autochthonous sources of organic carbon were important for fuelling bacterial production under no-flow conditions: the metabolic balance of the waterhole was not indicative of large allochthonous inputs; rates of gross primary production were great enough to meet a substantial fraction of estimated bacterial carbon demand; and pathways for allochthonous carbon to enter the waterhole were limited. These results suggest that models of lake metabolism based on temperate ecosystems can be expanded to include dryland river waterholes, which group with eutrophic lakes owing to their high levels of inorganic nutrients, low allochthonous inputs and autotrophic metabolic balance.

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Morón, Sara, Kathryn Amos, and Sandra Mann. "Fluvial reservoirs in dryland endorheic basins: the Lake Eyre Basin as a world-class modern analogue." APPEA Journal 54, no. 1 (2014): 119. http://dx.doi.org/10.1071/aj13014.

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Intracratonic dryland basins have been common throughout geological time and significant hydrocarbon reservoirs are contained in these basins. Based on a literature compilation of fluvial dryland reservoirs, the authors demonstrate the need for new modern analogue data from dryland fluvial systems, and present new field data from the Neales River, in the Lake Eyre catchment. The selected study reach has a complex planform, with a downstream transition from single channel to anabranching. Results of the observations of the channel bed grain size, the geomorphology and the channel geometry (width and depth) allow the authors to infer that the channel bed grain size is more strongly related to planform geomorphology than the channel geometry (width to depth ratios). Based on the grain size and channel geometry data the authors present, the authors conclude that the planform geomorphology exerts a greater control on channel bed material size than channel geometry. This interpretation is based on the analysis of satellite imagery, topographic survey data and grain size descriptions. In this paper, the authors provide channel geometry data and grain size data that will improve understanding of dryland fluvial sedimentology. The authors hope this contributes to enhancing hydrocarbon exploration and production in petroleum reservoirs developed in dryland fluvial settings.

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Vélez-Agudelo, Camilo, and Marcela A. Espinosa. "Benthic diatoms in relation to environmental factors in an allochthonous river from Patagonia, Argentina." Marine and Freshwater Research 72, no. 9 (2021): 1340. http://dx.doi.org/10.1071/mf20249.

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Natural and human pressures increasingly threatening the biodiversity and water resources of dryland rivers. Fluvial environments of Patagonia harbour high diatom diversity, but their management value is overlooked. The aim of this study is to explore the diatom distribution in surface sediments of the Chubut River and evaluate their relationship with environmental variables. In total, 243 diatom taxa were identified in 16 littoral zone sites. The physical and chemical variables independently explained the variance in diatom data, whereas sediment texture had a low influence. Conductivity, major ions (HCO3–, Cl–, SO42–, Na+, K+, Ca2+ and Mg2+) and pH were the main environmental drivers explaining the diatom composition. As the highlighted variables increased near the mouth, so did the relative abundances of marine–brackish taxa such as Amphora copulatoides, Sarcophagodes alfred-wegeneri, Nitzschia fonticola and Tryblionella apiculata. Meanwhile, the presence of high pollution-tolerant diatoms can be put forward to explain the river health deterioration towards downstream areas. The marine–brackish taxa found at freshwater sites reflect a weak tidal influence in the estuary compared with other coastal systems of Patagonia. This study provides valuable information to test the hypothesis on the ecological status of aquatic resources and the potential effects of climatic and hydrological changes in the area.

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Bateman, Heather L., Sidney B. Riddle, and Erin S. Cubley. "Using Bioacoustics to Examine Vocal Phenology of Neotropical Migratory Birds on a Wild and Scenic River in Arizona." Birds 2, no. 3 (August 2, 2021): 261–74. http://dx.doi.org/10.3390/birds2030019.

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Passive acoustic recorders have been used successfully as automated survey tools to detect terrestrial wildlife. However, few studies have monitored Neotropical migratory bird use of riparian forest habitat using this technology. Within dryland ecosystems, the forests along rivers support high bird diversity. Many bird species of conservation concern require these floodplain forest habitats for foraging, migration stop-overs, and breeding. Few studies have explored the use of acoustic records in riverine systems designated for conservation for their natural resource value via the Wild and Scenic Rivers Act in the USA. Using acoustic recorders, we document vocal activity of four riparian-obligate species (Bell’s Vireo, Vireo bellii; Summer Tanager, Piranga rubra; Yellow Warbler, Setophaga petechial; and Yellow-billed Cuckoo, Coccyzus americanus) to determine species occurrence along a Wild and Scenic River. We established three study reaches along the perennial Lower Verde River, in the Sonoran Desert of central Arizona, USA. Nine acoustic recorders were used over the period of 80–120 days during the summer of 2018. We measured vegetation composition and structure in 100 m2 plots paired with acoustic recorders. Visualizing vocal activity showed that three species were calling and singing at each reach; whereas, one species, the cuckoo, had fewer recordings and occurred later in the summer. We demonstrate the utility of acoustic monitoring even when applied to rare birds in complex riparian habitats. This information is important for land management and conservation efforts concerning these species of interest and identifying important habitat features in Southwestern US riparian woodlands.

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Broich, M., A. Huete, M. G. Tulbure, X. Ma, Q. Xin, M. Paget, N. Restrepo-Coupe, K. Davies, R. Devadas, and A. Held. "Land surface phenological response to decadal climate variability across Australia using satellite remote sensing." Biogeosciences Discussions 11, no. 5 (May 28, 2014): 7685–719. http://dx.doi.org/10.5194/bgd-11-7685-2014.

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Abstract. Land surface phenological cycles of vegetation greening and browning are influenced by variability in climatic forcing. Quantitative information on phenological cycles and their variability is important for agricultural applications, wildfire fuel accumulation, land management, land surface modeling, and climate change studies. Most phenology studies have focused on temperature-driven Northern Hemisphere systems, where phenology shows annually reoccurring patterns. Yet, precipitation-driven non-annual phenology of arid and semi-arid systems (i.e. drylands) received much less attention, despite the fact that they cover more than 30% of the global land surface. Here we focused on Australia, the driest inhabited continent with one of the most variable rainfall climates in the world and vast areas of dryland systems. Detailed and internally consistent studies investigating phenological cycles and their response to climate variability across the entire continent designed specifically for Australian dryland conditions are missing. To fill this knowledge gap and to advance phenological research, we used existing methods more effectively to study geographic and climate-driven variability in phenology over Australia. We linked derived phenological metrics with rainfall and the Southern Oscillation Index (SOI). We based our analysis on Enhanced Vegetation Index (EVI) data from the MODerate Resolution Imaging Spectroradiometer (MODIS) from 2000 to 2013, which included extreme drought and wet years. We conducted a continent-wide investigation of the link between phenology and climate variability and a more detailed investigation over the Murray–Darling Basin (MDB), the primary agricultural area and largest river catchment of Australia. Results showed high inter- and intra-annual variability in phenological cycles. Phenological cycle peaks occurred not only during the austral summer but at any time of the year, and their timing varied by more than a month in the interior of the continent. The phenological cycle peak magnitude and integrated greenness were most significantly correlated with monthly SOI within the preceding 12 months. Correlation patterns occurred primarily over north-eastern Australia and within the MDB predominantly over natural land cover and particularly in floodplain and wetland areas. Integrated greenness of the phenological cycles (surrogate of productivity) showed positive anomalies of more than two standard deviations over most of eastern Australia in 2009–2010, which coincided with the transition between the El Niño induced decadal droughts to flooding caused by La Niña. The quantified spatial-temporal variability in phenology across Australia in response to climate variability presented here provides important information for land management and climate change studies and applications.

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Doody, Tanya M., Pamela L. Nagler, Edward P. Glenn, Georgianne W. Moore, Kiyomi Morino, Kevin R. Hultine, and Richard G. Benyon. "Potential for water salvage by removal of non-native woody vegetation from dryland river systems." Hydrological Processes 25, no. 26 (December 14, 2011): 4117–31. http://dx.doi.org/10.1002/hyp.8395.

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40

Hallo Dabasso, Bulle, Oliver Vivian Wasonga, Patrick Irungu, and Brigitte Kaufmann. "Emerging pastoralist practices for fulfilling market requirements under stratified cattle production systems in Kenya's drylands." Animal Production Science 61, no. 12 (2021): 1224. http://dx.doi.org/10.1071/an20042.

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Context Stratified cattle production (SCP) systems, which involve buying lean animals from pastoral areas and fattening them in locations that have better production conditions, are re-emerging in Kenya’s drylands. Aims This study investigated how pastoralists in the drylands of Kenya endeavour to fulfil cattle marketing requirements under the SCP systems. Methods Purposefully identified cattle fattening entrepreneurs in Tana River (n = 10) and Narok (n = 12) counties were interviewed on the requirements they demand in buying animals from pastoralists. Using the information generated from the entrepreneurs, pastoralists (Tana River, n = 10; Narok, n = 12) were interviewed on how they respond to the entrepreneurs’ requirements and make sales. The information was triangulated with a focus group discussion in each county whose members were knowledgeable traders and pastoralists. Using a semi-structured questionnaire, randomly selected pastoral households (Tana River, n = 86; Narok, n = 69) were interviewed on cattle sales made through SCP systems. Key results The results showed that under the SCP systems, pastoralists in the two counties were required to sell cattle of particular qualities, comply with unpredictable supply orders, sell in secondary markets or near urban centres, use sale agents and undertake high commercial off-take rates if the demand arose. To meet these requirements, the pastoralists devised several strategies and practices, including changes in the animal husbandry practices, keeping ‘emergency’ animals in the home-based herds to comply with unpredictable demands, arrangements with market intermediaries to sell in secondary markets and building buyer–seller trust to facilitate sales through agents. In adopting these practices, pastoralists in both counties managed to sell approximately one or two animals per household through the SCP systems over a period of 12 months, which accounted for ~28% of the annual commercial cattle off-take from the households. Conclusion Pastoralists change their management practices in response to livestock marketing requirements and challenges, enhancing their integration into the market economy. Implication The information could guide stakeholders to formulate strategies for improving pastoralists’ involvement in cattle marketing through SCP systems.

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Martínez, Judith, Yasmín S. Cajas, Juan D. León, and Nelson W. Osorio. "Silvopastoral Systems Enhance Soil Quality in Grasslands of Colombia." Applied and Environmental Soil Science 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/359736.

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In the tropical drylands of Colombia, the soils subjected to traditional systems of livestock production are severely degraded and depleted of plant nutrients. Multistrata silvopastoral systems are viable alternatives to improve livestock production; however, it is unknown whether these systems can reduce the negative environmental impacts of traditional systems on soil quality. The objective of this study was to evaluate the effects of 13-year-old multistrata silvopastoral systems on soil quality parameters in degraded soils of the Sinu River Valley, Colombia. The results show that the trees in the silvopastoral systems increased or maintained soil pH values and nutrient availability (phosphorus, potassium, and calcium) with respect to the pastures with only grasses. The effects were significantly controlled by the types of plant species, particularlyGuazuma ulmifoliaandCassia grandis.

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Thoms, M. C., and F. Sheldon. "An ecosystem approach for determining environmental water allocations in Australian dryland river systems: the role of geomorphology." Geomorphology 47, no. 2-4 (October 2002): 153–68. http://dx.doi.org/10.1016/s0169-555x(02)00085-5.

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43

Broich, M., A. Huete, M. G. Tulbure, X. Ma, Q. Xin, M. Paget, N. Restrepo-Coupe, K. Davies, R. Devadas, and A. Held. "Land surface phenological response to decadal climate variability across Australia using satellite remote sensing." Biogeosciences 11, no. 18 (September 29, 2014): 5181–98. http://dx.doi.org/10.5194/bg-11-5181-2014.

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Abstract. Land surface phenological cycles of vegetation greening and browning are influenced by variability in climatic forcing. Quantitative spatial information on phenological cycles and their variability is important for agricultural applications, wildfire fuel accumulation, land management, land surface modeling, and climate change studies. Most phenology studies have focused on temperature-driven Northern Hemisphere systems, where phenology shows annually recurring patterns. However, precipitation-driven non-annual phenology of arid and semi-arid systems (i.e., drylands) received much less attention, despite the fact that they cover more than 30% of the global land surface. Here, we focused on Australia, a continent with one of the most variable rainfall climates in the world and vast areas of dryland systems, where a detailed phenological investigation and a characterization of the relationship between phenology and climate variability are missing. To fill this knowledge gap, we developed an algorithm to characterize phenological cycles, and analyzed geographic and climate-driven variability in phenology from 2000 to 2013, which included extreme drought and wet years. We linked derived phenological metrics to rainfall and the Southern Oscillation Index (SOI). We conducted a continent-wide investigation and a more detailed investigation over the Murray–Darling Basin (MDB), the primary agricultural area and largest river catchment of Australia. Results showed high inter- and intra-annual variability in phenological cycles across Australia. The peak of phenological cycles occurred not only during the austral summer, but also at any time of the year, and their timing varied by more than a month in the interior of the continent. The magnitude of the phenological cycle peak and the integrated greenness were most significantly correlated with monthly SOI within the preceding 12 months. Correlation patterns occurred primarily over northeastern Australia and within the MDB, predominantly over natural land cover and particularly in floodplain and wetland areas. Integrated greenness of the phenological cycles (surrogate of vegetation productivity) showed positive anomalies of more than 2 standard deviations over most of eastern Australia in 2009–2010, which coincided with the transition from the El Niño-induced decadal droughts to flooding caused by La Niña.

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Wang, Can, Houyuan Lu, Wanfa Gu, Naiqin Wu, Jianping Zhang, Xinxin Zuo, Fengjiang Li, et al. "The development of Yangshao agriculture and its interaction with social dynamics in the middle Yellow River region, China." Holocene 29, no. 1 (October 5, 2018): 173–80. http://dx.doi.org/10.1177/0959683618804640.

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This study presents new archaeobotanical evidence for agricultural production in the middle Yellow River region during the Yangshao culture period. Phytolith analyses, together with radiocarbon dating of samples from 10 sites in Zhengzhou, showed that common millet and foxtail millet were cultivated with rice in the region around 4000–3000 cal BC. The ratio of crop remains revealed that common millet was dominant in the crop structure. Rice cultivation was no longer confined to large sites situated in the lowlands and began to spread into the hilly lands and small sites. Furthermore, both dryland and wetland systems may have been used for rice cultivation. This pattern of crop production may have been mainly influenced by social background and artificial selection, which overcame the limitation of environmental factors. Such development of Yangshao agriculture facilitated the establishment of an agricultural society during the fourth millennium BC. It also has implications for understanding the reason why the middle Yellow River region (Central Plain) became known as ‘the cradle of Chinese civilization’.

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Karthe, Daniel. "Environmental Changes in Central and East Asian Drylands and their Effects on Major River-Lake Systems." Quaternary International 475 (May 2018): 91–100. http://dx.doi.org/10.1016/j.quaint.2017.01.041.

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Wright, V. Paul, and Susan B. Marriott. "The dangers of taking mud for granted: Lessons from Lower Old Red Sandstone dryland river systems of South Wales." Sedimentary Geology 195, no. 1-2 (February 2007): 91–100. http://dx.doi.org/10.1016/j.sedgeo.2006.03.028.

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Chuluun, T., B. Tserenchunt, M. Altanbagana, S. Davaanyam, and M. Stafford-Smith. "Dryland development paradigm application for the study of the Tuin and Baidrag river basin social-ecological systems in Mongolia." APN Science Bulletin 2, no. 1 (2012): 49–54. http://dx.doi.org/10.30852/sb.2012.49.

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Muller, R., J. P. Nystuen, and V. P. Wright. "Pedogenic Mud Aggregates and Paleosol Development in Ancient Dryland River Systems: Criteria for Interpreting Alluvial Mudrock Origin and Floodplain Dynamics." Journal of Sedimentary Research 74, no. 4 (July 1, 2004): 537–51. http://dx.doi.org/10.1306/010704740537.

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Khan, Naeem, Shahid Ali, Haleema Tariq, Sadia Latif, Humaira Yasmin, Asif Mehmood, and Muhammad Adnan Shahid. "Water Conservation and Plant Survival Strategies of Rhizobacteria under Drought Stress." Agronomy 10, no. 11 (October 30, 2020): 1683. http://dx.doi.org/10.3390/agronomy10111683.

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Drylands are stressful environment for plants growth and production. Plant growth-promoting rhizobacteria (PGPR) acts as a rampart against the adverse impacts of drought stress in drylands and enhances plant growth and is helpful in agricultural sustainability. PGPR improves drought tolerance by implicating physio-chemical modifications called rhizobacterial-induced drought endurance and resilience (RIDER). The RIDER response includes; alterations of phytohormonal levels, metabolic adjustments, production of bacterial exopolysaccharides (EPS), biofilm formation, and antioxidant resistance, including the accumulation of many suitable organic solutes such as carbohydrates, amino acids, and polyamines. Modulation of moisture status by these PGPRs is one of the primary mechanisms regulating plant growth, but studies on their effect on plant survival are scarce in sandy/desert soil. It was found that inoculated plants showed high tolerance to water-deficient conditions by delaying dehydration and maintaining the plant’s water status at an optimal level. PGPR inoculated plants had a high recovery rate after rewatering interms of similar biomass at flowering compared to non-stressed plants. These rhizobacteria enhance plant tolerance and also elicit induced systemic resistance of plants to water scarcity. PGPR also improves the root growth and root architecture, thereby improving nutrient and water uptake. PGPR promoted accumulation of stress-responsive plant metabolites such as amino acids, sugars, and sugar alcohols. These metabolites play a substantial role in regulating plant growth and development and strengthen the plant’s defensive system against various biotic and abiotic stresses, in particular drought stress.

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Jlassi, W., E. Nadal-Romero, and J. M. García-Ruiz. "Modernization of new irrigated lands in a scenario of increasing water scarcity: from large reservoirs to small ponds." Cuadernos de Investigación Geográfica 42, no. 1 (June 27, 2016): 233. http://dx.doi.org/10.18172/cig.2918.

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Large rainfed, dryland areas were transformed into irrigated land in northeast Spain, where rivers from the Pyrenees Range ensure the availability of abundant water resources. The transformation of the Riegos del Alto Aragón area (RAA), mainly during the second half of the 20th century, was subject to major problems during the 1960s and 1970s, including monoculture of poorly productive winter cereals, water wastage, and soil degradation. Since the 1990s the RAA has been affected by modernization involving: (i) a change in the mode of irrigation, from gravity to sprinkler systems; (ii) the concentration of plots to enlarge the size of irrigated fields; and (iii) the introduction of more productive and highly water-consuming crops (corn, lucerne, vegetables). These changes coincided with enlargement of the irrigated area, increasing water demand at a time of increasing water scarcity because of restriction on the construction of new large reservoirs and declining water resources, because of climate and land use changes. Addressing this major problem has required new strategies, specifically the construction of small reservoirs and water ponds within the irrigated area. The ponds increase water reserves and facilitate sprinkling irrigation by adding pressure to the system. However, this has involved a huge rise in electricity consumption, which has increased the cost of production.

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Journal articles on the topic 'Dryland river system'

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