Regional Drought Assessment Based On Water Resources System

In the context of rising global temperatures,climate change will change the water cycle rate and accelerate the hydrological cycle,leading to frequent hydrological events such as drought and floods.Since the 21 st century,China has been affected by climate change,and extreme droughts have occurred frequently.This has not only caused huge losses to the national economy,especially agricultural production,but also caused far-reaching adverse effects such as water shortage,increased desertification,and frequent sandstorms.Guizhou Province is located in the southwestern part of China.Due to the influence of monsoon climate and special landform types,the frequency of drought events is high and the impact range is wide.Studying the drought characteristics of Guizhou Province and identifying the future drought evolution trend of the region is a good representative of the drought research in the monsoon region.Guided by the “natural-society” dual water cycle theory,this paper builds regional drought assessment index system and grading standards from the perspective of water resources system based on the regional climate and water use characteristics,and then "municipal administrative unit cutting three-level water resources area" was used as evaluation unit to identify the evolutionary trend of drought events in Guizhou Province in the next 30 years.Taking Guizhou Province as the research object and taking the "natural-society" dual water cycle theory as the guide.A regional drought evaluation index system and grade standard from the perspective of water resources system were constructed in this paper,and then "municipal administrative unit cutting three-level water resources area" was used as evaluation unit to identify the future drought event evolution trend in Guizhou Province.The main results are as follows:(1)Analysis on the Evolution Characteristics of Meteorological Elements in Guizhou Province in the Past 60 Years and the Next 30 Years.Trends of the average annual temperature in the past 60 years was increasing.Trends of the annual precipitation was to decrease.The annual evapotranspiration showed an increasing trend.In the next 30 years in Guizhou Province,the temperature is increasing,and the rate of temperature increase is more than twice the history of the past 60 years.Under the RCP2.6 and RCP4.5 scenarios,precipitation showed an increasing trend.Under the RCP8.5 scenario,precipitation showed a decreasing trend.(2)According to the Palmer drought indicator framework,the regional drought evaluation index system is constructed.The total water supply combined with the effective precipitation and the hydraulic engineering;Identify the agricultural water demand based on accumulated temperature,calculate the agricultural water demand,and combine the water demand characteristics of life,industry and ecology to obtain the total water demand.That is,based on the characteristics of water supply and demand water resources system.The index system is compared with the results of meteorological drought(SPI index)and hydrological drought(SRI index).The results show that the results of general drought assessment are closer to reality.The SPI and SRI indicators do not consider the ability of water conservancy projects to relieve drought.The simulation of spring drought is deviated from the actual situation.And SPI and SRI indicators can can not better identify the spatial difference of drought frequency in the process of calculation.(3)The spatial and temporal evolution characteristics of drought frequency,drought duration and drought intensity in the next 30 years in Guizhou Province are analyzed,indicating that the frequency of drought in the southwestern part of the country is high and lasts for a long time in the next 30 years.The frequency of mild drought is decreasing,and the frequency of local occurrence in the southern and northern parts is high.The mild drought was more severe in the western part of Guizhou,Qiannan and Qianxinan.The frequency of mild drought is increasing.The moderate drought occurred frequently in the western and southern parts of Guizhou,and the moderate drought intensity in the western and southern parts was more severe.The frequency of severe droughts and extreme droughts is increasing.Severe droughts and extreme droughts occur frequently in the western region.Severe droughts and extreme droughts are more severe in the western,southwestern(Qianxinan and Anshun)and northeastern regions of Guizhou.(4)Comparing with that without hydraulic engineering.Under the regulation of hydraulic engineering,the frequency of drought decreased.The drought relief is relatively large in Guiyang City,Zunyi City(excluding Sinanyixia-Zunyi)north of Qiandongnan,southeast of Tongren,north and east of Anshun,north and southeast of Qiannan.The degree of drought relief in Bijie City is smallAiming at Guizhou region with special geomorphological types,this study carries out comprehensive drought assessment based on the analysis of water supply and demand characteristics of regional water resources system,and tries to explore drought research,which can also provide scientific basis for Guizhou Province to adapt to climate change and drought comprehensive response.