Impacts of land use change and climate variability on green and blue water resources in the Weihe River Basin of northwest China

Background: Land use change and climate variability influence water resources availability and separation of these influences are important for water resources management. Methods: SWAT model and the Mann-Kendall method were used in this study which investigated the spatiotemporal variations of blue and green water resources under different land use change, agricultural irrigation expansion and climate variability scenarios during the 1980s-2000s for the Weihe River Basin. Results: Farmland area decreased by 1.4% and woodland, grassland, and construction land area increased by 0.6%, 0.2%, and 0.6%, respectively. The combined impact of land use change, agricultural irrigation expansion and climate variation decreased the blue water flow, green water flow, and green water storage by 21.62 mm year(-1), 35.01 mm year(-1) and 28.07 mm year(-1), respectively. Climate variability decreased the blue/green water flow and green water storage, land use change decreased the blue water and green water flow while it increased the green water storage, irrigation expansion decreased the blue water flow while it increased the green water flow/storage. The spatial distribution showed an uneven change in the Weihe River Basin. Together, we suggested that the variability of water resources availability in the Weihe River Basin was mainly attributed to climate variability, while land use change plays a key role in the sub-basins which experienced dramatic changes in land use. (C) 2015 Elsevier B.V. All rights reserved.