The Impact Of Climate Change On Runoff In Luanhe River Basin

The Luanhe River is the northernmost subbasin in the Haihe River basin, as well as the second largest river that independently flows into the ocean in North China. In addition, the Luanhe River was the water supply resource and is still an important standby water resource for the surrounding area of the Bohai Sea, including Tianjin and Tangshan. Besides, the Panjiakou and Daheiting reservoirs along the Luanhe River are major power-generating centers and flood storage and regulating facilities. By analyzing the meteorological and hydrological data measured, this paper analyzes the climate change, and the runoff change trend of the mainstream of the Luanhe River in the past50years and makes researches on the dry-wet evolution of the Luanhe River basin by using the standardized precipitation evapotranspiration index (SPEI). Then the paper forcasts the climate change and drought evolution of the Luanhe River basin in the next30years using the regional climate model CCLM with a resolution of0.5°×0.5°and finally exports the data-driven HBV hydrological model by climate model and predicts the runoff change trend in the future. The major results are summarized as follows:1. During1961-2010, the annual temperature in the Luanhe River basin is8.59℃, which has a significant upward trend for0.28℃/10a, with the significance level of0.05, and the average precipitation is567mm, which has a slight downward trend for-18mm/10a. The temperature and precipitation progressively increase from the northwest to the southeast and the whole basic becomes warmer and drier, especially the downstream of the river.2. During1961and2010, the Luanhe River basin tends to be drier. Aridity becomes more frequently and seriously since1995. The interannual precipitation had a14years change cycle. In the spatial distribution, the downstream area is drier than the upstream area in the past50years and has a more significant aridity trend (with the0.01 significance level).3. The regional climate model CCLM was selected to simulate the temporal and spatial change rules of the climate change along the Luanhe River. Using the prediction data exported by the CCLM, this paper predicts that the Luanhe River basin will be warmer and drier from2011to2030in RCP4.5and a significant change will happen in the middle reaches. In the spatial distribution, most areas in the Luanhe River basin will change from wet to dry. From the middle2030s, the Luanhe River may face a serious aridity challenge, with more frequent and serious aridity events.4. The calibration and verification result indicates that the data-driven HBV hydrological model exported by the CCLM can be well used to simulate the runoff of the mainstream, in which the simulation result in the wet period is better than that in the dry period. In RCP4.5, the mainstream of the Luanhe River will be in a slightly downward trend from2011to2040. In the year2037, a sudden change will occur in the runoff of the mainstream (tested by the significance test of the0.05significance level) and the downward trend is more significant. The analysis of the annual precipitation, annual temperature, annual SPEI, and annual runoff indicates that the climate change in the Luanhe River basin significantly impacts the dry-wet evolution, and the annual precipitation, annual temperature, and annual SPEI are positively or negatively correlated to the annual runoff (slightly significantly correlated).