Spatial and Temporal Patterns of Water Retention and Its Influencing Factors in Chengde City from 1990 to 2017

Chengde City is an important ecological barrier in the Jing-Jin-Ji region and a key water retention area. Quantitative assessment of the water retention function of this region has important ecological and research implications. InVEST model and center of gravity migration model were used to quantify temporal and spatial changes in the water retention function of Chengde City from 1990 to 2017; scenario analysis method was used to evaluate the effects of the changes of climate and land use/cover on water retention function. The results show as follows: The annual average water retention was 33.12×10⁸ m³·a^-1, and the average water retention depth was 83.9 mm. Over the past 28 years, the water retention function in Chengde City first decreased and then increased. The center of gravity of the water retention function migrated from the northwestern to the southeastern part of the city over a distance of 14.28 km. The water retention function was significantly and positively correlated with precipitation and the normalized difference vegetation index (NDVI) and significantly and negatively correlated with the comprehensive land-use index. The relative contributions of climate and land-use changes to the migration of the water retention function in Chengde City were 94.49% and 5.51%, respectively. Climate change was the most important factor affecting the migration of the water retention function, and the effect of land-use change on the migration of the water retention function gradually increased over the study period. Our findings provide new insights that could aid future researches on ecosystem services in Chengde City.