Abstract
With changes in weather patterns and intensifying anthropogenic water use, there is an increasing need for spatio-temporal information on water fluxes and stocks in river basins. The assortment of satellite-derived open-access information sources on rainfall (P) and land use/land cover (LULC) is currently being expanded with the application of actual evapotranspiration (ETact) algorithms on the global scale. We demonstrate how global remotely sensed P and ETact datasets can be merged to examine hydrological processes such as storage changes and streamflow prior to applying a numerical simulation model. The study area is the Red River Basin in China in Vietnam, a generally challenging basin for remotely sensed information due to frequent cloud cover. Over this region, several satellite-based P and ETact products are compared, and performance is evaluated using rain gauge records and longer-term averaged streamflow. A method is presented for fusing multiple satellite-derived ETact estimates to generate an ensemble product that may be less susceptible, on a global basis, to errors in individual modeling approaches. Subsequently, monthly satellite-derived rainfall and ETact are combined to assess the water balance for individual subcatchments and types of land use, defined using a global land use classification improved based on auxiliary satellite data. It was found that a combination of TRMM rainfall and the ensemble ETact product is consistent with streamflow records in both space and time. It is concluded that monthly storage changes, multi-annual streamflow and water yield per LULC type in the Red River Basin can be successfully assessed based on currently available global satellite-derived products.
Highlights
Global surface and ground water resources are under increasing pressure from human water use and climate change [1,2,3]
The Red River Basin (Figure 1) can be roughly divided in an upstream half situated in the province province of Yunnan in southern China and a downstream half in northern Vietnam, with a minor of Yunnan in southern China and a downstream half in northern Vietnam, with a minor portion of less portion of less than 1% located in Lao PDR
Monthly water runoff patterns are investigated for each subcatchment and storage changes are expressed as a function of rainfall surplus
Summary
Global surface and ground water resources are under increasing pressure from human water use and climate change [1,2,3]. 2016, 8, 279 with tensions between water availability and water demand. This requires a feasible methodology for quantifying the current state of water resources in terms of hydrological flows and connectivity, as well as indicators of water use and reuse [4]. Relating precipitation and/or withdrawals to consumptive use through evapotranspiration provides a basis for an assessment of weekly or monthly surplus (i.e., groundwater recharge, drainage, surface runoff dynamics) or deficit (i.e., irrigation, inundation, return flows and their reuse). The role of soil water storage changes is essential at smaller time scales and should get sufficient attention [9]
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