Abstract
Climate change (CC) and land use/cover change (LUCC) are the main drivers of streamflow change. In this study, the effects of CC and LUCC on streamflow regime as well as their spatial variability were examined by using the Distributed Hydrology Soil Vegetation Model (DHSVM) for the Beichuan River Basin in the northeast Tibetan Plateau. The results showed that CC increased annual and maximum streamflow in the upstream but decreased them in the downstream. CC also enhanced minimum streamflow in the whole river basin and advanced the occurrence of daily minimum streamflow. Temperature change exerted greater influence on streamflow regime than wind speed change did in most situations, but the impact of wind speed on streamflow reflected the characteristics of accumulative effects, which may require more attention in future, especially in large river basins. As for LUCC, cropland expansion and reservoir operation were the primary reasons for streamflow reduction. Cropland expansion contributed more to annual mean streamflow change, whereas reservoir operation greatly altered monthly streamflow pattern and extreme streamflow. Reservoir regulation also postponed the timing of minimum streamflow and extended durations of average, high, and low streamflow. Spatially, CC and LUCC played predominant roles in the upstream and the downstream, respectively.
Highlights
Streamflow is one of the key components of hydrologic cycle, an important water resource for maintaining sustainable social and economic development and an ecosystem with diverse life forms [1,2]
With the increase of atmospheric concentration of radiatively active gases [3], such as carbon dioxide, and continuous development of human society, global natural water balance has been affected [4]. The former, that is, climate change (CC), affects the hydrologic cycle, such as in precipitation and evaporation [5]. The latter primarily refers to land use/cover change (LUCC) caused by human activities, such as deforestation, urbanization, cropland expansion, and reservoir operation, which affect landscape morphological and physiological properties by altering albedo, leaf area index (LAI), surface roughness, soil infiltration rate, and interruption of stream channels, among others [6,7]
To protect the ecosystem and water resources exists in the upper stream (Figure 1, red line outlined), whereas a large area of cropland spreads in the middle reach, and a large reservoir (Heiquan reservoir with 1.82 × 108 m3 water storage capacity) that has operated since 2001 exists in the lower reach
Summary
Streamflow is one of the key components of hydrologic cycle, an important water resource for maintaining sustainable social and economic development and an ecosystem with diverse life forms [1,2]. With the increase of atmospheric concentration of radiatively active gases [3], such as carbon dioxide, and continuous development of human society, global natural water balance has been affected [4]. The former, that is, climate change (CC), affects the hydrologic cycle, such as in precipitation and evaporation [5]. Hydrological response to CC and LUCC at global or large basin scales help us to understand the general condition of the impacts [7,8,9]. Significant spatiotemporal variations of CC and LUCC in different regions indicate that regional or local responses deviate from the general conditions
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