The Impacts Of Climate Variability And Land Use/Cover Change On Streamflow In Jiujushui Watershed

Climate change and land use and cover change (LUCC) are the two important factors that affect hydrology of forested watersheds. The relationship between forests and water is also important for designing mitigation of climate change impacts. Thus, how to quantitatively assess the impacts of LUCC and climate change on hydrology is one of the most important priorities. Poyang Lake, the largest fresh water lake in China, is not only as an important regulator in the middle and lower Yangtze River but also provides critical wintering habitat for migratory birds. In this paper, I used Jiu Jushui Watered (the upper reach of Fuhe River in Poyang Lake basin) as an case study to assess how climatic variability and LUCC affect streamflow using long-term historical data. Modified Double Mass Curve or MDMC and Tomer-Schilling Framework (TSF) were used to quantitatively and semi-quantitatively distinguish the contributions of climate change and LUCC to hydrology. The results showed that:(1) Year 1970 is the break point of runoff variation. Analysis from of the MDMC of INTERVENTION analysis in ARIMA model confirms that there is a significant change in streamflow in 1970.(2) Based on the break point, the whole study period was divided into two periods: baseline (1961-1970) and forest change period (1971-2006). The relative contributions of LUCC and climate change to streamflow are -220.23mm and 223.34mm, representing-19.93% and 20.22% of total streamflow, respectively, as compared with that in the baseline period (1104.8mm). the impacts of LUCC and climate change on hydrology account for 49.42% and 50.58% of the runoff gross variation, respectively.(3) TSF analysis showed that climate is the more important factor of runoff variation in the periods of 1965-1974,1979-1987 and 1991-2006, while LUCC plays a more important role in the period of 1974-1979.(4) The results from both MDMC and TSF are consistent, suggesting that our results are robust. The analysis results can provide an important basis for resource managers to respond to the climate change and LUCC impacts in the future.