Low flow hydrology: a review
TL;DR: Low-flow hydrology is a discipline which deals with minimum flow in a river during the dry periods of the year as mentioned in this paper, and it has been extensively studied in the literature.
About: This article is published in Journal of Hydrology.The article was published on 2001-01-10. It has received 1467 citations till now. The article focuses on the topics: Baseflow & Streamflow.
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TL;DR: A global review of the present status of environmental flow methodologies revealed the existence of some 207 individual methodologies, recorded for 44 countries within six world regions, with a further two categories representing combination-type and other approaches as discussed by the authors.
Abstract: Recognition of the escalating hydrological alteration of rivers on a global scale and resultant environmental degradation, has led to the establishment of the science of environmental flow assessment whereby the quantity and quality of water required for ecosystem conservation and resource protection are determined.
A global review of the present status of environmental flow methodologies revealed the existence of some 207 individual methodologies, recorded for 44 countries within six world regions. These could be differentiated into hydrological, hydraulic rating, habitat simulation and holistic methodologies, with a further two categories representing combination-type and other approaches.
Although historically, the United States has been at the forefront of the development and application of methodologies for prescribing environmental flows, using 37% of the global pool of techniques, parallel initiatives in other parts of the world have increasingly provided the impetus for significant advances in the field.
Application of methodologies is typically at two or more levels. (1) Reconnaissance-level initiatives relying on hydrological methodologies are the largest group (30% of the global total), applied in all world regions. Commonly, a modified Tennant method or arbitrary low flow indices is adopted, but efforts to enhance the ecological relevance and transferability of techniques across different regions and river types are underway. (2) At more comprehensive scales of assessment, two avenues of application of methodologies exist. In developed countries of the northern hemisphere, particularly, the instream flow incremental methodology (IFIM) or other similarly structured approaches are used. As a group, these methodologies are the second most widely applied worldwide, with emphasis on complex, hydrodynamic habitat modelling. The establishment of holistic methodologies as 8% of the global total within a decade, marks an alternative route by which environmental flow assessment has advanced. Such methodologies, several of which are scenario-based, address the flow requirements of the entire riverine ecosystem, based on explicit links between changes in flow regime and the consequences for the biophysical environment. Recent advancements include the consideration of ecosystem-dependent livelihoods and a benchmarking process suitable for evaluating alternative water resource developments at basin scale, in relatively poorly known systems. Although centred in Australia and South Africa, holistic methodologies have stimulated considerable interest elsewhere. They may be especially appropriate in developing world regions, where environmental flow research is in its infancy and water allocations for ecosystems must, for the time being at least, be based on scant data, best professional judgement and risk assessment. Copyright © 2003 John Wiley & Sons, Ltd.
1,462 citations
Cites background from "Low flow hydrology: a review"
...Gordon et al. (1992), Stewardson and Gippel (1997) and Smakhtin (2001) review many of the well established hydrological and regionalization techniques used to derive the latter flow indices for gauged and ungauged catchments....
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TL;DR: In this paper, the authors focus on the use of paired catchment studies for determining the changes in water yield at various time scales resulting from permanent changes in vegetation and highlight the potential underestimation of water yield changes if regrowth experiments are used to predict the likely impact of permanent alterations to a catchment's vegetation.
1,384 citations
Cites background from "Low flow hydrology: a review"
...In reviewing paired catchment studies both Stednick (1996) and Sahin and Hall (1996) state that difficulties occur when summarising the result of catchment experiments due to the lack of certain key statistics from the reported results (Sahin and Hall, 1996) or insufficient detail of the site characteristics (Stednick, 1996)....
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...The most widely used definition of low flow is any flow that is exceeded for 70–99% of the time (Smakhtin, 2001), hence this definition has been adopted....
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TL;DR: In this paper, the authors provide an overview of the ecosystem functions responsible for producing terrestrial hydrologic services and use this context to lay out a blueprint for a more general ecosystem service assessment.
Abstract: Ecosystem services, the benefits that people obtain from ecosystems, are a powerful lens through which to understand human relationships with the environment and to design environmental policy. The explicit inclusion of beneficiaries makes values intrinsic to ecosystem services; whether or not those values are monetized, the ecosystem services framework provides a way to assess trade-offs among alternative scenarios of resource use and land- and seascape change. We provide an overview of the ecosystem functions responsible for producing terrestrial hydrologic services and use this context to lay out a blueprint for a more general ecosystem service assessment. Other ecosystem services are addressed in our discussion of scale and trade-offs. We review valuation and policy tools useful for ecosystem service protection and provide several examples of land management using these tools. Throughout, we highlight avenues for research to advance the ecosystem services framework as an operational basis for policy d...
1,161 citations
TL;DR: The groundwater footprint is the first tool suitable for consistently evaluating the use, renewal and ecosystem requirements of groundwater at an aquifer scale and can be combined with the water footprint and virtual water calculations, and be used to assess the potential for increasing agricultural yields with renewable groundwater.
Abstract: A newly developed concept called ‘groundwater footprint’ is used to reveal the degree of sustainable use of global aquifers by calculating the area relative to the extractive demands; globally, this footprint exceeds aquifer area by a factor of about 3.5, and excess withdrawal is centred on just a few agriculturally important aquifers. In many parts of the world, groundwater is being extracted for agricultural use and human consumption at a greater rate than the Earth's natural systems can replace it. Tom Gleeson and colleagues estimate the true scale of the problem using a newly developed concept called the 'groundwater footprint' — defined as the area required to sustain groundwater use and groundwater-dependent ecosystem services. The authors find that globally, the groundwater footprint exceeds the aquifer area by a factor of about 3.5. Overexploitation centres predominantly on a few agriculturally important aquifers in arid or semiarid climates, especially in Asia and North America. The groundwater footprint could serve as a useful framework for analysing the global groundwater depletion data sets emerging from NASA's GRACE satellites. Groundwater is a life-sustaining resource that supplies water to billions of people, plays a central part in irrigated agriculture and influences the health of many ecosystems1,2. Most assessments of global water resources have focused on surface water3,4,5,6, but unsustainable depletion of groundwater has recently been documented on both regional7,8 and global scales9,10,11. It remains unclear how the rate of global groundwater depletion compares to the rate of natural renewal and the supply needed to support ecosystems. Here we define the groundwater footprint (the area required to sustain groundwater use and groundwater-dependent ecosystem services) and show that humans are overexploiting groundwater in many large aquifers that are critical to agriculture, especially in Asia and North America. We estimate that the size of the global groundwater footprint is currently about 3.5 times the actual area of aquifers and that about 1.7 billion people live in areas where groundwater resources and/or groundwater-dependent ecosystems are under threat. That said, 80 per cent of aquifers have a groundwater footprint that is less than their area, meaning that the net global value is driven by a few heavily overexploited aquifers. The groundwater footprint is the first tool suitable for consistently evaluating the use, renewal and ecosystem requirements of groundwater at an aquifer scale. It can be combined with the water footprint and virtual water calculations12,13,14, and be used to assess the potential for increasing agricultural yields with renewable groundwaterref15. The method could be modified to evaluate other resources with renewal rates that are slow and spatially heterogeneous, such as fisheries, forestry or soil.
1,070 citations
TL;DR: It is shown that pulse size regulates C balance by determining the temporal duration of activity for different components of the biota, and a greater understanding of the complexities of these eco-hydrologic systems may enhance the ability to describe the ecology of desert ecosystems and their sensitivity to global change.
Abstract: In the arid and semiarid regions of North America, discrete precipitation pulses are important triggers for biological activity. The timing and magnitude of these pulses may differentially affect the activity of plants and microbes, combining to influence the C balance of desert ecosystems. Here, we evaluate how a “pulse” of water influences physiological activity in plants, soils and ecosystems, and how characteristics, such as precipitation pulse size and frequency are important controllers of biological and physical processes in arid land ecosystems. We show that pulse size regulates C balance by determining the temporal duration of activity for different components of the biota. Microbial respiration responds to very small events, but the relationship between pulse size and duration of activity likely saturates at moderate event sizes. Photosynthetic activity of vascular plants generally increases following relatively larger pulses or a series of small pulses. In this case, the duration of physiological activity is an increasing function of pulse size up to events that are infrequent in these hydroclimatological regions. This differential responsiveness of photosynthesis and respiration results in arid ecosystems acting as immediate C sources to the atmosphere following rainfall, with subsequent periods of C accumulation should pulse size be sufficient to initiate vascular plant activity. Using the average pulse size distributions in the North American deserts, a simple modeling exercise shows that net ecosystem exchange of CO2 is sensitive to changes in the event size distribution representative of wet and dry years. An important regulator of the pulse response is initial soil and canopy conditions and the physical structuring of bare soil and beneath canopy patches on the landscape. Initial condition influences responses to pulses of varying magnitude, while bare soil/beneath canopy patches interact to introduce nonlinearity in the relationship between pulse size and soil water response. Building on this conceptual framework and developing a greater understanding of the complexities of these eco-hydrologic systems may enhance our ability to describe the ecology of desert ecosystems and their sensitivity to global change.
966 citations
Cites background from "Low flow hydrology: a review"
...…classify ecosystem flux duration curves as “pulsed-dominated” and “steady-state” similarly to the way hydrograph-derived flow duration curves can be described and classified by the physical, biotic and anthropogenic factors controlling stream flow (e.g., Vogel and Fennessey 1995; Smakhtin 2001)....
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References
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TL;DR: In this paper, a summary and review of 94 catchment experiments shows that accumulated information on the effect of vegetation changes on water yield can be used for practical purposes, since no experiments, with the exception of perhaps one, have resulted in reductions in water yield with reductions in cover, or increases in yield, with increases in cover.
2,455 citations
"Low flow hydrology: a review" refers background in this paper
...It has been demonstrated (e.g. Bosch and Hewlett, 1982), that clearfelling and timber harvesting increase annual water yield, and that in many cases this is due to increase in seasonal low flows (Harr et al., 1982; Hetherington, 1982; Keppeler and Ziemer, 1990; Hicks et al., 1991; Smith, 1991)....
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...Bosch and Hewlett (1982), in their review of 94 catchment experiments, illustrated that afforestation may cause a significant reduction in total flow....
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Book•
29 Oct 1997
TL;DR: In this paper, the authors introduce the medium for studying a stream and propose a set of guidelines for studying and managing a stream, including: "Water at Rest and in Motion", "Shifting Sands", and "Stream Classification and Management".
Abstract: Introducing the Medium. How to Study a Stream. Potential Sources of Data (How to Avoid Reinventing the Weir). Getting to Know Your Stream. How to Have a Field Day and Still Collect Some Useful Information. Water at Rest and in Motion. Patterns in Shifting Sands. Dissecting Data with a Statistical Scope. "Putting It All Together": Stream Classification and Management. Appendices. References. Index.
1,636 citations
01 Jan 1993
1,004 citations
"Low flow hydrology: a review" refers methods in this paper
...The use of conditional probability adjustment has been illustrated in Gordon et al., 1992; Stedinger et al., 1993)....
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Book•
01 Jan 1977
TL;DR: In this paper, the authors present many statistical tools helpful to engineers and hydrologists, then demonstrate their uses in solving hydrologic problems, and provide examples and problems with which they can be used.
Abstract: Presents many statistical tools helpful to engineers and hydrologists, then demonstrates their uses in solving hydrologic problems. Numerous examples and problems are provided.
993 citations