Regional groundwater cycle patterns and renewal capacity assessment at the south edge of the Junggar Basin, China

The groundwater cycle pattern in the arid and semi-arid regions is drastically affected by both natural condition changes and human activities, resulting in serious eco-geological environmental problems. This paper selected the south edge of the Junggar basin as a pilot area for the basin-scale assessment of groundwater renewal capacity. Assessment indicator system was first established, assessment units were then constructed, and the Analytic Hierarchy Process method was used to identify the weights of the assessment indicators. The first three indicators are natural recharge ratio, groundwater residence time, and balance ratio between groundwater recharge and exploration, respectively. Two types of environmental assessment models, including the comprehensive index model and the fuzzy comprehensive model, were used and the results determine that low-lying intermountain areas and alluvial–proluvial piedmont plains have stronger groundwater renewal capacity, whereas that of the alluvial plain is much weaker. Second, at the typical watershed scale, the Manasi watershed was adopted as the study area, and numerical simulation method was used to assess the groundwater renewal capacities of intermountain low-lying land and the pediment alluvial–proluvial plain. They are found to have renewal periods of about 66.95 years and 25.05 years, respectively. These values are favorably compared to the results of isotopic analysis, which is corresponding to 46 years and 30 years, respectively. At last, four schemes were put forward to improve the regulation and storage capacity in different segment of Manasi River watershed. The results not only provide key guidance for reasonable groundwater resource exploitation and eco-environmental protection, but also offer a model for sustainable groundwater utilization for similar northwestern districts in China or other world similar districts.