The Hydro-Climate Service Framework in China in drought detection and water resources evaluation

Hydro-Climate Service (HCS) is an important measure and technique to effectively utilize water resources, predict the extreme climatic events and reduce the loss of disasters. Along with global climate change, accelerated water cycle become serious problems in current China which can lead to more severe drought and water shortages. Also, intense human activities have profoundly changed the spatial-temporal characteristics of land surface and water storage. These facts will put forward new requirements for HCS in present and future. In this study, we construct a new HCS framework based on multi-source datasets and advanced numerical models to improve the HCS level in 2 major basins in China. For Yellow River Basins in north China, we detected the historical drought events by introducing comprehensive drought indices in the main irrigated areas of the basin, and over 88% of the drought months in the upper-mid reach can be detected by the Standardized Precipitation Evapotranspiration Index (SPEI) and self-calibrated Palmer Drought Severity Index (scPDSI) during 1991 to 2012. In the lower reach, the detection ratios were lower than the upper-mid reach, and scPDSI performed better than SPEI with higher detection ratios. We also used advanced coupled regional model to evaluate the terrestrial water storage (TWS) in Yangtze River Basin in south China. The results show well agreement between simulated TWS and Gravity Recovery And Climate Experiment (GRACE) products with high Pearson Coefficient (R=0.81) and Nash-Sutcliffe efficiency coefficient (NE=0.61) over the whole basins, especially in upper reach (R=0.96, NE=0.88). In middle reach, due to the regulation of the Three Gorges Dam, the TWS evaluated results need to be optimized by the observed streamflow. The results can provide basic scientific supporting for further HCS related mapping, prediction and evaluation in Yellow and Yangtze River Basins, and this HCS framework need to play a more positive role in climate change adaptation in the future.