| The past50years, human activities cause global warming as the main feature of climatechange. It directly and indirectly affected water resources and a series of macrodecision-making related to water resource. Northwest China is located in the hinterland ofEurasia, it's ecologically fragile and climate-sensitive area. The ecological environment isgreatly affected by the water. Hexi region is located in the Inland Northwest.Water shortageslimit sustainable socio-economic development, The development of oasis agriculture and therestoration and reconstruction of the ecological environment.Therefore, study on the climatechange trends and response of water resources to climate change in this are is very importantfor regional water resource management decision-making and understanding of the risks ofclimate change. The main contents and conclusions are as follows:(1)Analysis on elements of climate change and reference crop evapotranspiration in thestations in Hexi region with Kendell correlation analysis and the orderly clustering analysismethod.The results are as follows.Temperature rised significantly, most stations had mutationin1996. The average wind speed significantly decreased in most stations. Average relativehumidity and sunshine hours changed complicatedly, increased in some stations anddecreased in others. Most stations had no mutation.(2)Reference crop evapotranspirations in Hexi region are calculated with the Penman-Monteith formula and analysised with correlation analysis method. The laws of variations areobtained. ET0values are larger in the west and smaller in the east. They are significantlyrelated to geographical location. Annual mean ET0values of the stations in the middle and inthe east of Hexi region will decrease by19mm while they will decrease by12.4mm in thewest if altitudes increase by100m. The influence capacity of meteorological factors on ET0are as follows: humidity＞wind speed＞sunlight hours＞precipitation＞temperature. In thenext20years, most stations' annual ET0values will be increasing in the east of Hexi region,while decreasing in the middle and in the west.(3) Irrigation water demand of the main crops in Shiyang River Basin are calculated.With the principal component regression analysis, the paper analyzes the degree of relativeinfluence on irrigation water requirement of the crops in Minqin. In accordance with the orderof magnitude of the impact, the order is temperature, wind speed, humidity, precipitation,sunlight hours.(4) On the basis of the analysis for variations of climate elements and referenceevapotranspiration and according to possible future climate scenarios, this paper researchesthe influence, which caused by climate change, on agricultural irrigation water requirement inShiyang River on the assumption of the temperature, precipitation amplitude. Results showthat, the average total irrigation water would increase19.5824million m~3when thetemperature rise of up to0.5℃, as while as the total irrigation water would respectivelyincrease20.6019million m~3,19.4763million m~3and21.3590million m~3in common flowyear, low flow year and special low flow year. The average total irrigation water woulddecrease25.6624million m~3and the total irrigation water would respectively increase25.7710million m~3,19.8207million m~3and17.4107million m~3in common flow year, lowflow year and special low flow year when the precipitation increased by10%. A2climatescenario and B2climate scenario are similar, they're the possible future climate scenarios.Temperature will increase by0.9℃in2015.Temperature will increase by1.5～1.6℃andprecipitation will increase by2%～3%in2025. Temperature will increase by2.2～2.4℃andprecipitation will increase by6%～7%in2050. The total irrigation water in Shiyang Riverwould respectively increase34.7917million m~3,49.7515～56.3621million m~3and65.8207～76.2719million m~3in the year2015,2025and2050in the possible future climatescenarios.(5) Carrying on the regression analysis of nature runoff with annual average temperature,annual rainfall and annual ET0values in Dajing River, Huangyang River and Zamu River, it isfounded that they has no remarkable pertinence relation, the significant alters inrainfall-runoff process maybe due to the bigger evaporation. By using double cumulativecurve method and time series comparative analysis method, the author comprehensive analyzethe flows in Dajing River, Huangyang River and Zamu River, which with significant trendand mutation, and distinguish the runoff influence degree that caused by precipitationvariation, human activities and air temperature in different stages with double mass curvemethod and time series analysis method. The result shows that: Contribution rates of climatechanges on runoff changes are25.3%—55.8%and contribution rates of human activities are44.2%—74.7%for Dajing River.They are-188.2%—-0.2%and100.2%—288.2%forHuangyang River.And they are-127.8%—-20.9%and120.9%—227.8%for Zamu River.(6) Runoff changes of eight tributaries in Shiyang River Basin are forecasted with double mass curve in diffierent precipitation and temperature scenarios. Changes of water resourcesdemand and supply in Shiyang River Basin of Hexi region are analyzed. The result shows thatin possible future climate scenarios, the annual average runoff would respectively decrease211.9864million m~3while irrigation water demand would increase49.7515million m~3by2015.And the annual average runoff would respectively decrease102.3382million m~3whileirrigation water demand would increase80.2443million m~3by2025. Because of the climatechange, the gap between demand and supply would increase. |
