Long-term assessment of groundwater resources carrying capacity using GRACE data and Budyko model

Groundwater is crucial for the economic development in arid and semi-arid areas. However, groundwater resources have been over-exploited for meeting the increasing demands in agriculture, industry and domestic use. Therefore, the capacity of groundwater resources for supporting the economic development has been indeed reduced, which made a challenge for the assessment of the groundwater resources carrying capacity (GRCC). The present study constructed a new GRCC index (D) for assessing the long-term GRCC variation in Zhangjiakou of Hebei Province, China (ZJK) using Budyko equation, Gravity Recovery and Climate Experiment data (GRACE), Global Land Data Assimilation System data (GLDAS), sector water consumption data and GDP data. Our results shows that the short-term (2002-2017) annual and monthly anomalies in terrestrial water storage (TWSA) and groundwater storage appeared to be decreased, the anomalies in soil moisture storage tend to be zero while anomalies in snow water tend to be increased with annual rate of 2 cm year^-1. The Budyko-derived long-term (1948-2018) groundwater storage changes (GWC) has declined from -310.9 to -455.6 cm and the large number of constructed wells for irrigation has accelerated the decline of groundwater resources in ZJK. Our results also shows the time series of D in ZJK were < 30%, 30% < D < 50% and D ≥ 50% during 1948-1988, 1990-1993 and 1994-2018, indicating that the degree of groundwater resources exploitation were in the state of no overload, overload and heavy overload, respectively. The contribution of groundwater resources for the economic development has exceeded 50%, which indicated that the economic development of ZJK depend much more on groundwater resources. Improving the water use efficiency cannot improve groundwater resources carrying capacity, however, reducing the absolute use of groundwater resources should be the effective way to alleviate the shortage of groundwater resources and improve groundwater resources carrying capacity.