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Impacts of Climate Variability on Streamflow in the Upper and Middle Reaches of the Taoer River Based on the Budyko Hypothesis

2011; Chinese Academy of Sciences Geography; Linguagem: Inglês

1007-7588

Bin Li,

Environmental Changes in China

The upper and middle reaches of the Taoer River, representing an ecologically sensitive area in northeastern China, has undergone a combined impact of climate change and human activities (e.g., rapid agricultural and industrial development) since 1961. A series of environmental problems are becoming prominent and a great alteration of the streamflow was reported. There is therefore an urgent need to evaluate the impacts of climate variability and human activities on streamflow to facilitate water resources management in this region. Streamflows during the period 1961-2000 from several gauged stations of three selected sub-catchments and the entire upper and middle reaches of the Taoer River, including Charlson, Gaojiatun, Dashizhai and Taonan, were used. Ten precipitation stations and nine meteorological stations located in or around the basin were selected. The potential evapotranspiration of the study river basin was calculated with mean monthly minimum and maximum temperatures, relative humidity, sunshine hour, and wind speed for the study period in conjunction with the FAO56 Penman Monteith equation. The precipitation observations and calculated potential evapotranspiration were spatially averaged across the study area. A digital elevation model (DEM) with a grid resolution 100m × 100m was used. Land use maps in the early 1970s, 1986 and 2000 with a spatial scale of 1:100,000 were obtained. The nonparametric Mann-Kendall test and moving t-test were jointly used to identify trends and point mutations contained in the streamflow, precipitation, and potential evapotranspiration time series. Results show a marked upward trend for annual streamflows, and that an abrupt change was identified in year 1985 at the Taonan station, the outlet of the entire river basin. In general, the streamflows show agreement with changing patterns in precipitation and potential evapotranspiration, although a discrepancy of about two years was observed. The streamflow time series were then divided into the baseline period and changed period. Six Budyko functions were employed to quantify the impacts of climate variability and human activities on mean annual streamflows on the basis of precipitation and potential evapotranspiration. Analysis of the increment in the mean annual streamflows between the baseline and the changed period indicates that climate variability and human activities accounted for about 45% (15.09 mm) and 55% (18.44 mm) of the change in streamflow, respectively. This study provides an improved understanding of the water balance over this region and creates an opportunity to further apply these approaches and techniques to address climate change impact on streamflows over other river basins.