Linkages between GRACE water storage, hydrologic extremes, and climate teleconnections in major African aquifers
Bridget R. ScanlonAshraf RatebAssaf AnyambaSeifu KebedeAlan MacDonaldMohammad ShamsudduhaJennifer SmallAlexander Y. SunRichard G. TaylorHua Xie
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Abstract Water resources management is a critical issue in Africa where many regions are subjected to sequential droughts and floods. The objective of our work was to assess spatiotemporal variability in water storage and related controls (climate, human intervention) in major African aquifers and consider approaches toward more sustainable development. Different approaches were used to track water storage, including GRACE/GRACE Follow On satellites for Total Water Storage (TWS); satellite altimetry for reservoir storage, MODIS satellites for vegetation indices, and limited ground-based monitoring. Results show that declining trends in TWS (60–73 km 3 over the 18 yr GRACE record) were restricted to aquifers in northern Africa, controlled primarily by irrigation water use in the Nubian and NW Saharan aquifers. Rising TWS trends were found in aquifers in western Africa (23–49 km 3 ), attributed to increased recharge from land use change and cropland expansion. Interannual variability dominated TWS variability in eastern and southern Africa, controlled primarily by climate extremes. Climate teleconnections, particularly El Nino Southern Oscillation and Indian Ocean Dipole, strongly controlled droughts and floods in eastern and southern Africa. Huge aquifer storage in northern Africa suggests that the recent decadal storage declines should not impact the regional aquifers but may affect local conditions. Increasing groundwater levels in western Africa will need to be managed because of locally rising groundwater flooding. More climate resilient water management can be accomplished in eastern and southern Africa by storing water from wet to dry climate cycles. Accessing the natural water storage provided by aquifers in Africa is the obvious way to manage the variability between droughts and floods.Keywords:
Teleconnection
Water storage
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Changes in the pattern of the development and utilization of water resources will lead to the changes in the recharge and discharge properties of groundwater.This article analyses the data interaction between water resources optimal allocation model and groundwater mathematical simulation model,and these models are combined to calculate the exploitable quantity of groundwater,applied in Shanshan County,Xinjiang Uygur Autonomous Region.With the changes of planning optimized allocation,development and utilization of water resources,the calculation results show that exploitation and overexploitation of groundwater can be respectively decreased from 235 million m3 and 186 million m3 in present to 137 million m3 and 0 million m3 in 2030 year.This article solves the problem of accurate quantification for the amount of available groundwater successfully,and it also can be used as the basis for the utilization and protection of groundwater resources.
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