Tian, F; Zhang, Y; Lu, SH (2020). Spatial-temporal dynamics of cropland ecosystem water-use efficiency and the responses to agricultural water management in the Shiyang River Basin, northwestern China. AGRICULTURAL WATER MANAGEMENT, 237, 106176.

To deal with serious water resources crisis, the Shiyang River Basin (SRB) of Hexi Corridor in Northwestern China has been experiencing rehabilitation for water-saving since 2006. Water-use efficiency in cropland (WUEc) is a critical indicator to understand the response of carbon-water interactions. Because we currently lack a clear picture of how WUEc responds to climate and human activities factors in the SRB, here we applied Moderate Resolution Imaging Spectroradiometer (MODIS) satellite images to obtain a regional estimation of gross primary productivity in cropland (GPPc) and actual evapotranspiration in cropland (ETc), and analyzed the variations in WUEc and climate and human activities factors, then we evaluated the annual WUEc responses to climate and human activity factors and discussed major driving factors underlying the interannual variability (IAV) of WUEc from 2000 to 2014 in the SRB. Finally, we clarified the implications of the water saving project (WSP) on the water cycle. Results indicated that increased WUEc covered 97.25 % of the cropland area, with a trend of 0.017 g C kg(-1) H2O yr(-1). ETc decreased at 0.41 mm yr(-1). ETc decreasing pixel mainly occurred in the irrigation districts of WSP completed by 2010. The IAV of WUEc was mainly determined by ETc (68 %) rather than GPPc (6%). The relative contribution of human activities factors in the WSP to ETc was 77.5 %, while that of climate factors was 22.5 %. Which further proved water availability increase was mainly artificially controlled, an effect of the WSP rather than that of climate factors.