Fluctuation and Trends in Precipitation and Runoff in the Dongjiang River Basin over 50 years
Runoff in the Dongjiang River basin is mainly influenced by regional climatic factors such as precipitation, but is being modified by recently-accelerated human activities. To test the impacts of human activities on runoff, this paper analyzed trends in regional precipitation, surface runoff and the coupling relationship between them, through observed long-term rainfall and runoff data as well as evidences of human activities. Kriging interpolation was used to delineate precipitation isobars in upstream watershed beyond Boluo - a main flow gauging station near the final outlet of the basin. The moving average, linear regression, Mann - Kendall rank statistic test, and correlation analysis were used to examine trends and relationships between regional precipitation and runoff in Dongjiang River. We found that the runoff in the Dongjiang River Basin comes mainly from precipitation. Average annual precipitation and the quantity of runoff did not show a significant change in the past 50-year period. However, a trend of increasing runoff in the dry season (November to February) was found and thus the distribution of annual runoff within a year is growing. This was probably because of the construction of a number of dams and reservoirs in the upper-streams of the Dongjiang River basin from 1958 - 1985. Those reservoirs for irrigation, water supply and flood-control evened downstream runoff by filling in at the flood season while draining out at the dry season. At a monthly scale, the response of runoff to seasonal precipitation was more obvious than ever before in the monsoon rainy season, whereas the impacts of human activities on runoff are more prominent in the dry season. In summary, runoff in the Dongjiang River basin has undergone a rapid evolution propelled by increasing regional economic development, and is now regulated by artificial reservoirs, sluices, dams and other water supply systems.
Dongjiang River BasinPrecipitationRunoffRunoff coefficientTrends
NETL
NSTL
万方数据
维普
