University of California

Presentations 2016

Sood, Aditya

Presentation Title
Global Scale Study for Determining Groundwater Contribution to Environmental Flows and Sustainable Groundwater Abstraction Limits for SDGs
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Goal 6 of the Sustainable Development Goals (SDGs) has at least three targets that explicitly or implicitly cover issues of sustainability of water resources development and freshwater ecosystem maintenance. To incorporate sustainability, environmental flows (EFs) and sustainable groundwater abstraction have to be an integral part of the SDG discourse, but there is a lack of awareness and application of EFs at multiple levels. If countries are to accept and implement EFs over the next 15 years in the context of achieving the SDG targets, some initial EF information is in high demand. In this work, the first global EF assessment carried out by International Water Management Institute from 2004 is modified, specifically to provide initial EF information useful for the calculation of SDG target indicators. The spatial resolution of the analysis has been improved from 0.5 to 0.1 degrees and enables assessment at any larger aggregated scale. Importantly, the EFs are also split into the surface runoff contributed EFs and groundwater contributed EF. The groundwater-contributed EFs help in defining sustainable groundwater abstraction from renewable sources. The desired conditions of rivers are defined by four environmental flow management classes (EMCs). The EF (as percentage of flow required relative to the pristine conditions) and volume of groundwater abstractable without impacting the EFs are calculated for each EMC. The EFs are determined based on modifying synthetic pre-development natural flows (derived from the global hydrological model PCR-GLOBWB). In reality, the current flow and environmental condition of the rivers vary globally. A modified Index for Global Threat to River Biodiversity determined globally by other researchers were used to link the current condition of the rivers to the desired EMC. The results suggest that total accumulated global EFs vary from 80% to 42% of natural flows, from the highest to lowest EMC, and the groundwater contribution ranges from 77% to 39% of natural base flows. Globally, 149 to 376 km3 yr-1 of groundwater can be abstracted sustainably, depending upon the EMC. An online interactive tool was developed, where the user, based on selected area and EMC, can determine the acceptable EF requirements, base flow contribution and sustainable groundwater abstraction. This can then be compared either directly with the information on water withdrawals in the selected area or can be fed into the SDG target equations to determine the sustainability indicators.

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