Temporal and spatial variation characteristics of water conservation function of Upper Danjiang River Basin in Qinling Mountains and its influencing factors

Effective water conservation function can regulate the regional hydrological cycles and ensure the regional ecological security, which are closely related to human production and life. For this reason, the way to accurately evaluate the water conservation function has become a research hot topics in current ecohydrology. Herein, the temporal and spatial variation rules of water conservation in Upper Danjiang River Basin in Qinling Mountains from 2010 to 2020 were analyzed based on the Distributed Hydrology Soil Vegetation Model (DHSVM) and the water balance method, and the effects of changes in climate and land use on the water conservation function of the basin were explored. The results indicate that: (1) The average annual and monthly water conservation of Upper Danjiang River Basin is 61.60 mm and 4.3 mm respectively, showing the characteristics of significant inter-annual and intra-annual variations. (2) In terms of the hydrologic factors, the precipitation, evapotranspiration and runoff all show an increasing trend for 11 year, while the water conservation is in a decreasing trend. Besides, the spatial distribution of water conservation in the basin decreases from southeast to northwest. (3) The primary meteorological factors influencing water conservation vary at different time scales. At the inter-annual scale, precipitation is the main meteorological driving factor affecting water conservation, which is favorable for water conservation. At the intra-annual scale, precipitation and ambient temperature are the main influencing factors of water conservation. Specifically, precipitation is beneficial while ambient temperature is adverse to the water conservation. (4) The main land use types in Upper Danjiang River Basin with the water conservation ranking from high to low are as follows: grassland > woodland > farmland. After the land use types change, the area of grassland increases, while that of woodland and farmland decreases, resulting in the improved water conservation functions within the basin. Generally, this study could provide scientific basis for local water resources management and decision-making on ecological protection.