Sub-theme
2. Promoting Water Efficiency, Productivity and Services
Topic
2-2. Water use efficiency and productivity improvement through scientific, technical, economic and educational means
Body
Mountainous areas that experience seasonal freeze/thaw are distributed worldwide, and the impact of freeze/thaw processes on the groundwater cycle is substantial. For these mountainous areas, the rational division of two key parameters, namely, the groundwater resource quantity calculation unit (GCU) and groundwater resource quantity calculation period (GCP), is a prerequisite for the scientific evaluation of groundwater resource quantity. This is especially important for the Changbai Mountains in Jilin Province, China, which have a distinct geology formed by volcanic processes and have experienced soil seasonal freeze/thaw cycle, implying drastic impacts on the spatiotemporal distribution of groundwater resources. Based on the groundwater flow system theory and considering the influences of freeze/thaw cycles on the groundwater resource quantity, we propose a new strategy to deal with the division of GCUs and GCPs. Three first-level GCUs, eight second-level GCUs, and fifty third-level GCUs were delineated within the Changbai Mountains. Five GCPs were then determined, and the spatiotemporal distribution of groundwater resource quantity was calculated for the different GCUs and GCPs. The groundwater resource quantity in the five GCPs (no freezing, unstable freezing, stable freezing, unstable melting, and stable melting periods) accounted for 62.25%, 11.51%, 11.58%, 5.05%, and 9.61% of the total, respectively. Based on the calculation results of total groundwater resource quantity of different GCUs and GCPs and combined with the daily groundwater resource quantity in the different GCUs of the study area, the spatial and temporal distribution map of groundwater resource quantity was developed. The map provides a new basis for planning the exploitation of groundwater resource at different regions and periods of the study area. Considering the Changbai Mountain area of China as an example, this study proposed a new strategy to deal with the calculation of groundwater resource quantity in seasonal freeze/thaw mountainous areas. Our findings can be used as a reference for evaluating groundwater resource quantity in other seasonal freeze/thaw mountainous areas.