Assessing rainwater harvesting potential in a humid and semi-humid region based on a hydrological model

Study region: The upper regions of the Yangtze River in China. Study focus: Evaluating the rainwater harvesting potential (RWHP) is essential for alleviating regional drought and water shortage and solving water shortage and water crisis globally. However, previous studies have mainly focused on arid and semi-arid zones, whereas the assessment of RWHP in humid and sub-humid zones during the dry season is lacking. To fill this gap, a soil and water assessment tool based on meteorology, digital elevation model data, soil, land use, and observed streamflow, was constructed for a selected site. Additionally, a method of assessing RWHP in humid and semi-humid zones was proposed. New hydrological insights for the region: The results indicate that the average annual RWHP throughout the dry season (March-August) in the upper regions of the Yangtze River is 5657.02 x 10(5) m(3), and that for spring and summer are 1766.21 x 10(5) and 3890.95 x 10(5) m(3), respectively. Regarding the RWHP structure, it was observed that surface runoff (42.59 %) > groundwater recharge (29.53 %) > base-flow (19.43 %) > soil water content (7.16 %) > lateral flow (1.29). The analysis indicated that the spatial distribution of RWHP is consistent with that of drought, and can alleviate agricultural drought. The inter-annual variation of RWHP was relatively stable, exhibiting a weak increasing trend at the seasonal (dry, spring, and summer) and monthly (March-August) scales during 1999-2018. RWHP trends are primarily regulated by rainfall with the trend for a small part of the region being influenced by evapotranspiration. Our study provides a reference for the evaluation of RWHP in dry seasons in humid and semi-humid zones.

Automated summary

This study evaluated the rainwater harvesting potential in the upper regions of the Yangtze River in China during the dry season, providing insights into the structure and spatial distribution of the potential. It was found that the rainwater harvesting potential has a relatively stable inter-annual variation with a weak increasing trend, primarily regulated by rainfall. Overall, the rainwater harvesting potential can help alleviate agricultural drought in the region, offering a reference for evaluating potential in humid and semi-humid zones during dry seasons.