Watershed Drought and Ecosystem Services: Spatiotemporal Characteristics and Gray Relational Analysis

This study explored the spatiotemporal characteristics of drought and ecosystem services (using soil conservation as an example) in YanHe Watershed, which is a typical water basin Loess Plateau China, experiencing erosion. Herein, was simulated using Soil Water Assessment Tool (SWAT), relationship between drought, services, meteorological, vegetation, other factors since implementation ‘Grain for Green’ Project (GFGP) 1999, were analyzed gray relational analysis (GRA) method. The results showed that: (1) vegetation cover Watershed has increased significantly, evapotranspiration (ET) by 14.35 mm·a?1, thereby increasing consumption 8.997 × 108 m3·a?1 (compared to 2000). (2) Drought affected 63.86% watershed area, gradually worsening from south north; it decreased certain middle areas but humid on southern edge. (3) measured modulus (SCM), steadily 116.87 t·ha?1·a?1 2000 412.58 2015, at multi-year average 235.69 t·ha?1·a?1, indicated great spatial variations, with large variation downstream small variations upstream midstream areas. (4) Integrating normalized difference index (NDVI) data into SWAT model improved simulation accuracy; during calibration period, coefficient determination (R2) 0.63 0.76 Nash–Sutcliffe efficiency (NSE) 0.46 0.51; validation R2 0.82 0.93 NSE 0.57 0.61. (5) GRA can be applied control systems, such ecosystem; herein, primarily ET services. that restoration enhanced aggravated extent. coverage response verify significant role restraining erosion evaluate extent resource due semi-arid semi-humid Loess-area GFGP period. Thus, this approach may effectively provide scientific basis evaluating ecological effects formulating policies identify impact human