Effects of land use/land cover and climate changes on surface runoff in a semi-humid and semi-arid transition zone in northwest China

Abstract

Abstract. Water resources, which are considerably affected by land use/land cover (LULC) and climate changes, are a key limiting factor in highly vulnerable ecosystems in arid and semi-arid regions. The impacts of LULC and climate changes on water resources must be assessed in these areas. However, conflicting results regarding the effects of LULC and climate changes on runoff have been reported in relatively large basins, such as the Jinghe River basin (JRB), which is a typical catchment (> 45 000 km 2 ) located in a semi-humid and arid transition zone on the central Loess Plateau, northwest China. In this study, we focused on quantifying both the combined and isolated impacts of LULC and climate changes on surface runoff. We hypothesized that under climatic warming and drying conditions, LULC changes, which are primarily caused by intensive human activities such as the Grain for Green Program, will considerably alter runoff in the JRB. The Soil and Water Assessment Tool (SWAT) was adopted to perform simulations. The simulated results indicated that although runoff increased very little between the 1970s and the 2000s due to the combined effects of LULC and climate changes, LULC and climate changes affected surface runoff differently in each decade, e.g., runoff increased with increased precipitation between the 1970s and the 1980s (precipitation contributed to 88 % of the runoff increase). Thereafter, runoff decreased and was increasingly influenced by LULC changes, which contributed to 44 % of the runoff changes between the 1980s and 1990s and 71 % of the runoff changes between the 1990s and 2000s. Our findings revealed that large-scale LULC under the Grain for Green Program has had an important effect on the hydrological cycle since the late 1990s. Additionally, the conflicting findings regarding the effects of LULC and climate changes on runoff in relatively large basins are likely caused by uncertainties in hydrological simulations.

Evaluation of land‐use change effects on runoff and soil erosion of a hilly basin — the Yanhe River in the Chinese Loess Plateau

“…Models like the Soil and Water Assessment Tools (SWAT), which have the advantages of flexible scenario settings and the ability to detect spatial variations, can quantify the individual impacts of land‐use changes under otherwise identical conditions (Li, Liu, Zhang, & Zheng, ). SWAT has been applied to and shown to perform well in various regions of the world (Gassman, Reyes, Green, & Arnold, ), including China's Loess Plateau (Xu, Fu, & He, ; Yin, He, Xiong, & Qiu, ).…”

The Impact of Precipitation Deficit and Urbanization on Variations in Water Storage in the Beijing-Tianjin-Hebei Urban Agglomeration

“…In addition, LUCC was found to influence the hydrological cycle including precipitation, evapotranspiration, infiltration and runoff [37]. Evapotranspiration decreased rapidly from 1980 to 1998, and then decreased slightly from 1999 to 2015 ( Figure S9a).…”

Impact of LUCC on streamflow based on the SWAT model over the Wei River basin on the Loess Plateau in China

“…The modeled streamflow represents the impacts of constant LUCC data for 1980 and 2005, whereas the observations are based on dynamic LUCC data, which could explain the discrepancy. Yin et al (2017) studied the impact of LUCC on the streamflow in the Jinghe River basin, which is the largest tributary of the Wei River basin, and found that the streamflow was increasingly influenced by LUCC; it contributed to 44 % of the streamflow changes between the 1980s and the 1990s and 71 % of the streamflow changes between the 1990s and the 2000s. At the same time, different land use types hydrologically respond differently, even to the same meteorological forcings; i.e., rainfall intensity was of great importance in influencing the hydrological process in semi-dry and semi-humid regions (Lacombe et al, 2008;Wang, 2014).…”