Evolution Law And Development Law Prediction Of Drought In Haihe River Basin

With the intensification of global climate change and human activities, the global and regional water cycles changed significantly. As extreme events of water cycle process, drought events occurred frequently, widely and seriously, which threatened the water security and ecological security of the basin. And the droughts directly affected the development of regional socio-economic and ecological environment in the Haihe River Basin, which was one of the drought high-incidence areas of China.For these reasons, this thesis analyzed the multi-spatial and temporal evolution of drought based on meteorological data and other basic data in Haihe River Basin during 1961-2010. Assessment of climate simulation for study basin was based on the output data of the global climate models. And the amendment of climate models were analyzed by methods of drought index and statistics. Finally, we made a predict analysis of the evolution characteristics of precipitation and drought of Haihe River Basin under the future climate change scenarios. The following results were carried out:(1) Temporal-spatial evolution of droughts in Haihe River Basin: In Haihe River Basin, multi-year average precipitation decreased from southeast to northwest.The maximum precipitation occurred in 1960 s. The areas where the annual precipitation were ??more than 600 mm reduced significantly, while the areas of other level of annual precipitation showed an increasing tendency. The tendency of annual SPI values was declined in Haihe River Basin. Droughts happened in eight years, among which moderate and severe droughts occurred in five years. The drought areas increased obviously. The occurrence frequency of annual droughts increased from south to north. The occurrence frequency of monthly droughts had large difference during different decades. And the high incidence areas of monthly drought moved northward as the years going on.(2) The applicability evaluation and amendment of global climate models for Haihe River Basin: The thesis used the output data of five global climate models to compare with the experiment data of the Haihe River Basin. The correlation of inter-annual climate change between five climate models and the measured values was bad, which could not reflect the change trend of annual precipitation. And thefluctuation degree of simulated values was weaker than measured values. The proper study area which applied well to the simulate precipitation of Haihe River Basin—secondary area of ??water resources was determined by correlation analysis and multiple linear regression while a modified approach of integration of multi-model and segments was built. The results showed that the simulated precipitation data on the proper study area became more consistently match with the observation.(3) Development forecast of drought under the background of climate change in Haihe River Basin: Based on the monthly precipitation data of five climate models in the context of RCP2.6 emissions scenarios during 2011-2050, the thesis used the method of collection of multi-mode segmentation to calculate the data of monthly precipitation in the future of the secondary area of ??water resources. In the Haihe River Basin, annual precipitation will increase during 2011-2050,particularly in Tuhai Majia Basin. The minimum value of annual precipitation will occur in 2030 s, and the average annual rainfall is 540.7 mm. The spatial trend of average annual rainfall during every decades are basically the same—“southwest-northwest- southeast – northeast”. The SPI values ??in Haihe River Basin shows a slightly upward tendency as well as ??in each secondary zones, and Luan River and Jidong Coastal and Tuhai majia change greatly. The occurrence frequency of annual drought will increase from southwest to northeast. Droughts happened in 84 months,including 14 months of severe drought and 9 months extreme droughts respectively.And in 2020 s the number of monthly droughts will be largest. In the northeast of the basin, annual and monthly droughts will happen frequently, and occurrence frequency of monthly drought shows a declined tendency from north to south during the most decades.Combining the background conditions of water resources and the future temporal and spatial evolution of precipitation and drought of the Haihe River Basin, the paper initially propose some drought coping strategies for the study area.