Theory and methodology for evaluation of carrying capacity of regional groundwater resources in China

It is of great significance to evaluate the carrying capacity of groundwater resources for understanding the basic situation of regional groundwater resource availability and utilization, establishing a national and provincial level monitoring and warning mechanism for resources and environment carrying capacity, and supporting the research oriented to national spatial planning. The current theory and method for evaluation of carrying capacity of groundwater resources are still in an exploratory status, and there is no unified basis in practice. In this paper, the carrying capacity of groundwater resources is defined based on carrying coordination theory between natural resources system and socioeconomic system. After the analyses of quantity, quality and ecologial feature of groundwater resources in China, an evaluation index system is established respectively from the background and status of carrying capacity. Thus, an index grading method and evaluation process of carrying capacity of groundwater resources is put forward. This index system takes the module of exploitable groundwater resources and degree of groundwater exploitation as the basic indexes. The background and status of carrying capacity are firstly judged by the class of basic indexes. Secondly, level of groundwater background quality is used to modify the background of carrying capacity. As revising indexes of the status, degree of groundwater pollution, land subsidence, salinization and seawater intrusion should be used according to actual condition and the modified status of carrying capacity. Integrated carrying capacity of groundwater resources is determined by the above mentioned background and status. This method is used to evaluate the carrying capacity of groundwater resources in the Beijing-Tianjin-Hebei region, and the results show that the integrated carrying capacity is relatively weak in this region. The number of counties with strong, medium-strong, medium, medium-weak, and weak integrated carrying capacity are 18, 72, 19, 36, and 57, respectively. Counties with strong and medium-strong integrated carrying capacity are mainly located in the hilly and mountain areas of the southern part and piedmont alluvial plain of the central part. Counties with medium-weak and weak integrated carrying capacity are mainly located in hilly and mountain areas of the northern part and coastal alluvial plain of the eastern area. This case study of evaluation of carrying capacity of groundwater resources in the Beijing-Tianjin-Hebei region shows that the evaluation method is feasible, and the result is reasonable.