Analysis of satellite-based and in situ hydro-climatic data depicts water storage depletion in North China Region

Water storage depletion is an increasing hydrological threat to agricultural production and social stability across the globe. It is fast approaching threshold levels especially in arid/semiarid regions with low precipitation and excessive evapotranspiration (ET). This study analyses water storage dynamics in the North China Region (NCR) an important grain-production base in China. It uses monthly Gravity Recovery and Climate Experiment (GRACE), Global Land Data Assimilation System (GLDAS) and field-measured precipitation data products for 20022009. The datasets are analysed in a basin-scale water balance equation to determine the state of storage in the NCR study area. Based on the validated satellite-based data products with field-measured values, average error/bias in the datasets is <10%. The analysis also shows favourable agreements among the GRACE-derived and flux-based storage changes at various temporal scales. Whereas the amplitudes and phases of the precipitation and ET fluxes are largely stable for 20022009, those of GLDAS runoff and GRACE total water storage anomaly apparently narrow out. The linear trends in the monthly, seasonal and annual storage changes are negative for the study period, suggesting storage loss. There is an apparent seasonality of storage change in the study area; with summer storage gain, winter storage loss and an overall storage loss that is on the average of 16.8mm/yr. Storage loss is most severe in the central floodplain region (the main irrigated production zone) of the study area. Storage depletion in this important agro-based semi-arid region could have negative implications for the millions of people in the region and beyond in terms of water supply, crop production, food security and social stability. Copyright (c) 2012 John Wiley & Sons, Ltd.