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Title: Impacts of land use and climate variability on hydrology in an agricultural catchment on the Loess Plateau of China

Author
item LI, ZHI - ISWC, YANGLING CHINA
item LIU, WENZHAO - ISWC, YANGLING CHINA
item Zhang, Xunchang

Submitted to: Journal of Hydrology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/2/2009
Publication Date: 9/25/2009
Citation: Li, Z., Liu, W., Zhang, X.J. 2009. Impacts of land use and climate variability on hydrology in an agricultural catchment on the Loess Plateau of China. Journal of Hydrology. 377:35-42.

Interpretive Summary: Land use and climate are the two major factors directly influencing catchment hydrology, and it is difficult to separate the effects of the two. Using a computer model called SWAT (Soil and Water Assessment Tools), we assessed the impacts of land use change and climate variability on surface hydrology including surface runoff, soil water content, and evapotranspiration in an agricultural catchment on the Loess Plateau of China. Results indicated that SWAT was capable of simulating the effect of environmental change on surface runoff. The SWAT model predicted annual stream flow well. During 1981-2000, about 4.5% land use was changed mainly from shrubland and sparse woodland to medium and tall grassland, and climate changed to warmer and drier in the region. The integrated effects of the land use and climate changes all decreased runoff, soil water contents and evapotranspiration. Both land use and climate change decreased runoff by -9.6% and -95.8%, respectively, and decreased soil water contents by -18.8% and -77.1%. Land use change increased evapotranspiration by 8.0% while climate change decreased it by -103.0%. The climate variability influenced surface hydrology more significantly than the land use change in the Heihe catchment during 1981-2000; therefore, the influence of climate fluctuation should be considered and assessed separately when quantifying the hydrological effect of vegetation restoration and conservation practices in the Loess Plateau. This conclusion accentuates the importance of considering climate variation when assessing the conservation effects here in US. This information would be useful to scientists, engineers, and conservationists when evaluating the impacts of conservation practices.

Technical Abstract: Land use and climate are the two major factors directly influencing catchment hydrology; however, it is difficult to separate the effects of the two. Using the SWAT (Soil and Water Assessment Tools) model, we assessed the impacts of land use change and climate variability on surface hydrology (runoff, soil water and evapotranspiration) in an agricultural catchment on the Loess Plateau of China. Results indicated that SWAT was capable of simulating the effect of environmental change on surface runoff. The correlation coefficient and Nash-Sutcliffe model efficiency of annual stream flow in both calibration and validation periods were greater than 0.87. During 1981-2000, about 4.5% land use was changed mainly from shrubland and sparse woodland to medium and tall grassland, and climate changed to warmer and drier. The integrated effects of the land use and climate changes all decreased runoff, soil water contents and evapotranspiration. Both land use and climate change decreased runoff by -9.6% and -95.8%, respectively, and decreased soil water contents by -18.8% and -77.1%. Land use change increased evapotranspiration by 8.0% while climate change decreased it by -103.0%. The climate variability influenced surface hydrology more significantly than the land use change in the Heihe catchment during 1981-2000; therefore, the influence of climate fluctuation should be considered and assessed separately when quantifying the hydrological effect of vegetation restoration in the Loess Plateau.