Characteristics and Change Trend of Water Quantity and Quality in Middle and Lower Reaches of Hanjiang River before South-to-North Water Diversion Running

In order to evaluate the characteristics and change trend of the water quantity and quality in the middle and lower reaches of the Hanjiang River before the running of the middle route of the south-to-north water diversion project(MR-SNWDP),6 hydrometry stations and 4 water quality monitoring sections were selected, and mathematical statistics, Mann-Kendall test and Spearman test were used for the analysis. The results are follows:(1) 1999~2013 are in the dry season in the middle and lower reaches of the Hanjiang River based on a comparative analysis of the long term observed flow data;(2) The flow in this area indicate a considerable inter-annual variation with a proportion(maximum/minimum) between 2.7 and 3.3. The variation of annual flow in this area is also noticeable. Runoff during the flood season is accounting for 63 percent to 66 percent of the total runoff of the year, and runoff during the dry season is accounting for 34%~37% of the total runoff in the whole year.(3) The change trend of the flow-time series in this area is not noticeable. However, it experienced two periods: the wet seasons(from 1980 to 1990)and the dry seasons(from 1990 to 2013).(4) The water quality in this area is good according to the analysis of the water quality monitoring data, which can attain the standards of grade III in the most years, and the change trend of water quality in this area is also not noticeable.