The Runoff Change Characteistics And Their Responses To Climate Change In The Jialing River Basin

The Jialiang River is one of the major tributaries in the upper reach of the Yangtze River. Its drainage areas are located in Gansu, Shanxi, Sichuan provinces and Chongqing City. Its discharge has decreased gradually due to the global climate change, which threatening the domestic and industrial water usages in its drainage basin. In order for the sustainable development and usage of water resources and the protection of our environment it is extremely important to study the change of discharge in the river and its response to climate change.The historic annual flow data from 1940 to 2007 from the Beibei gaging station on the Jialing River and the temperature and precipitation data from 1951 to 2007 for 12 stations within the drainage basin were collected for this study. The correlation analysis, grey correlation degree analysis, the multiple linear regression method, and the wavelet analysis were used to analyze the change of flow in the Jialing River over the entire data period and correlation of flow with climate change. The findings from this study can be summarized as following:(1) The analysis to the flow time series data show there are great inter-annual variations and the high flow period is from June to September. The annual variations are significant as well with 1980s being the wet period and 1990s and 2000s the dry periods. The Mann-Kendall analysis showed the flow in the Jialing River had a decreasing trend and there was an abrupt change in flow in 1944.The wavelet analysis showed that the annual flow in the river had an about 29-year time scale oscillation, which is the major flow change period.(2) The analysis on the temperature and precipitation data from 12 stations show that annual average temperature had increased by about 0.058℃every ten years, the increase was more obvious in the fall and winter. The Mann-Kendall analysis showed that there was an abrupt change in temperature in 1992 in the river basin. The wavelet analysis showed that the temperature change period is about every 42 years and the annual average precipitation decreased by 8.8mm per a ten-year period, with more obvious decrease in the fall seasons. Precipitation continues to decrease after 1994.This study also showed that precipitation has a 10-year change period.(3) The correlation analysis, grey correlation degree analysis, and the multiple linear regression methods were applied to analyze the correlation between some climatic factors and the flow in the Jialing River. The results showed that the flow is negatively correlated to the temperature but positively to the precipitation. The impact of precipitation to flow change is greater that the temperature.