Responses Of Water Resources To The Climate Change In The Yellow River Basin

With the rapid development of social economy, the demands for water resources is increasing,long-standing contradiction between supply and demand of water resources in the Yellow River basin, and the culture and geographical environment of the Yellow River basin determines its water resources system is very sensitive to climate change. The future of global climate change will have a profound impact on the water resources of the Yellow River Basin, brings to the planning of river basin water resources management and sustainable utilization of the challenge. Therefore, it is necessary to study the response of w ater resources to cl imate change of historical and future periods in the Yellow River basin. In this paper, based on VIC hydrological model, combined with surface meteorological data and climate change scenarios derived from Global Climate Model (GCM),analysis of the response of water resources and the sensitivity of meteorological factors to runoff and evaporation in the Yellow River Basin. The main research contents and results are summarized as follows:(1) This paper constructs the VIC hydrological model in the Yellow River Basin, simulation of hydrological processes in the Yellow River Basin, and verify the applicability of the constructed model. The results show that the VIC hydrological model constructed in this paper can simulate the runoff process of the Yellow River Basin, runoff simulation were basically identical with the process of nature runoff process, which had good applicability in the study area, can meet the requirements of runoff simulation.(2) Based on the hydrological observation data of historical period and the VIC hydrological model, study on hydrological and meteorological factors in the Yellow River basin. The results show that, during the period of 1966-2005 years, the average annual precipitation of the Yellow River basin increased gradually from upstream to downstream. However, the precipitation in the upper reaches of the area decreased from ? to ?. The annual precipitation time series showed a downward trend, except for the increase of winter precipitation, the remaining seasonal precipitation are reduced; From upstream to downstream, the minimum and maximum temperature in the Yellow River basin are gradually increased, and the time series are also rising; The water conditions determine the size of the simulated evaporation, and the spatial distribution of evaporation is consistent with the precipitation distribution. In the time series, the evaporation in the upper reaches of the river increased gradually, the middle reaches gradually decreased. Evaporation decreased in spring and autumn and increased in summer and winter; Runoff is closely related to precipitation,and the highest runoff producing area in the Yellow River basin is I. The contribution rate of climate change and human activities to runoff change was separated in the Yellow River basin, the results are as follows: The contribution of human activities in the source area of the Yellow River is low,the rest of the district, human activity is the main factor of runoff change.(3) Changes of meteorological elements in the future climate. First, we compare the simulation ability of three GCMs to the contemporary climate in the Yellow River Basin. It is found that the climate model is not good for precipitation simulation, but still has a certain amount of precipitation simulation. Compared to precipitation, the climate model is better for air temperature simulation,especially the minimum temperature. The Delta method is used to obtain the characteristics of future climate elements from GCM data, forecast the future climate change of the Yellow River Basin, the results show: Most future climate scenarios of precipitation increased, maximum and minimum temperature showed a warming trend. Different models, different regions and different seasons have different spatial variation of meteorological elements. Compared with the history of the Yellow River basin, the largest change in seasonal precipitation is winter, the largest change in seasonal maximum temperature is autumn,and the largest change in seasonal minimum temperature is winter.(4) Changes of hydrological elements in future climate. The VIC hydrological model was driven by the future climate scenario data, and comparison of contemporary climate and future climate hydrological factors, the results show that the Yellow River basin evaporation will increase in the future, and the increase range decreased gradually from upstream to downstream. Runoff change was affected by precipitation and air temperature. The change of runoff in different control sites in the Yellow River basin was different under different climate models. Maqu average annual runoff decreased under BCC-CSM1.1 model. In addition to RCP8.5 scenarios,Tangnaihai station runoff are reduced under RCP2.6 and RCP4.5 scenarios. The annual average runoff of Lanzhou,Toudaoguai, Sanmenxia and Huayuankou station are increased. The runoff of MIROC-ESM model was the highest, and the runoff of each control station in the Yellow River Basin are increased. In addition to the runoff of Huayuankou station runoff decreases under RCP2.6 scenario, the rest of the runoff are increased under MIROC-ESM model.(5) Sensitivity of meteorological factors to runoff and evaporation. The runoff and evaporation data in the corresponding period were obtained by using the method of assumed climate change scenarios. The climatic elastic coefficient method was used to compare the different time scales to determine the sensitivity of meteorological elements to runoff. The increase of precipitation resulted in a significant increase in runoff of each site in the study area, on the contrary runoff significantly decrease; The effect of the minimum temperature change on runoff is different with the change of the station, the decrease of minimum temperature leads to the increase of runoff. While the minimum temperature increase will lead to decreased in the upper reaches of Maqu,Tangnaihai,Lanzhou and Toudaoguai station runoff, increased in the middle reaches of Sanmenxia and Huayuankou Station runoff; The increase of the maximum temperature will lead to the decrease of runoff in each station,whereas the runoff will increase, and the change is much higher than the minimum temperature;From the point of view of runoff change in four seasons, the change of meteorological factors in winter is most sensitive to runoff. The relative change of meteorological factors on runoff is complex,different seasons and different sites have different promotion or inhibition, with obvious nonlinear change characteristics.The evaporation increases with the increase of precipitation. On the contrary,evaporation is obviously decreased, and the change of evaporation caused by the increase of precipitation is obviously larger than that caused by the decrease of precipitation. The increase of ?and ? minimum temperature leads to the increase of evaporation, on the contrary, evaporation is decreased. While increase of ? and ? minimum temperature leads to the decrease of evaporation.On the contrary, evaporation is increased. The increase of the maximum temperature leads to the increase of evaporation, On the contrary, evaporation is decreased. When the maximum temperature change is the same increment, the change of evaporation at maximum temperature decreases is significantly lower than the change of evaporation at maximum temperature. The relative change of meteorological factors on evaporation and runoff is complex, different seasons and different sites have different promotion or inhibition, with obvious nonlinear change characteristics.