| Water is the source of life, also is the lifeblood of economic and socialdevelopment. In recent years, influenced by global climate change and humanactivities, many countries and regions have the problems of river flow reduction,water environment deterioration and water pollution, which restrict the sustainabledevelopment of social economy. Weihe River basin is a water-lacking area, andclimate change brings an important impact to water cycle factors such as temperature,precipitation and runoff in season and space, which will increase the occurrenceprobability of flood and drought in the river basin, lead to water security situationmore serious, and result in the imbalance between supply and demand more poignantin the future. With climate warming and water demand increasing, it is especiallyurgent and important to understand and analyze the evolution of dynamic water cycleunder climate change in Weihe River basin.This paper firstly established the distributed hydrological model to carry out thesimulation of water cycle process in Weihe River basin, and then used a variety ofmodern statistical methods to full-scale analyze the variation characteristics ofhydrologic and meteorological elements, and in addition, combining with statisticaldownscaling model, this paper carried out the research on simulation and predictionof water cycle elements under future climate change scenarios, so as to providescientific reference for reasonable development and utilization of basin waterresources and management of water regulation. The main results and conclusions areas follows:(1) According to the geographical conditions and meteorological hydrologicalcharacteristics of weihe river basin, and based on EasyDHM hydrological simulationplatform, this paper established the distributed hydrological model in Weihe Riverbasin, completed calibration and validation of parameters for14parameter subareas,and obtained a good simulation result. The results showed that EasyDHM had goodapplicability in Weihe River basin, and the established model described the innermechanism of hydrologic processes objectively, therefore it could be applied toresearch and solve practical problems.(2) Based on the distributed hydrological model in Weihe River basin, the paperused many kinds of statistical test methods to analyze the temporal-spatial distributionand evolution characteristics of temperature, precipitation and runoff during recent55 years (1954-2008) in the different period of time, such as year, season, flood seasonand dry season. The results showed,①There was an irregular spatial distribution ofannual mean temperature and precipitation. The temperature showed a decreasingtrend from the centre near the Xi’an station to all directions, and precipitationappeared a decreasing trend from the east and south to the northwest as a whole.②Inthe95%confidence interval, the temperature, precipitation and runoff time series ofWeihe River basin existed homogeneity.③As for trend change, mean temperaturedemonstrated a remarkable significant increasing trend, there was no significant trendin precipitation, and runoff showed a significant decreasing trend in annual. Thetrends are still likely to continue in future. Except in winter, when there were asignificant increasing trend in precipitation, the variation trends in the rest of theseasons, flood season and dry season were approximately the same as those in annual.④From sudden change analysis, there were significant mutation phenomenon inmean temperature and runoff time series, and precipitation had no significant suddenchange in annual. Except in winter, when the mutation phenomenon was very obviousin precipitation, the conclusions between in other study periods and in annual wereconsistent.⑤As far as period variation was concerned, temperature, precipitation,and runoff existed multi-time scale change characteristics with different periodcompositions, and the periodical variation characteristics in runoff appeared goodcorrelation with those in temperature and precipitation.(3) Based on statistical downscaling model SDSM, this paper established thedownscaling model for temperature and precipitation respectively in Weihe Riverbasin, and carried out the calibration and validation of the model. It showed that thesimulation results were reliable and the model could be applied to predict thevariation trend of meteorological elements such as temperature and precipitation. Thepaper chose A2and B2climate change scenarios for research, and the resultsindicated that in the next90years (2010-2099), mean temperature demonstrated aremarkable significant increasing trend, and variation trend of precipitation was notobvious as a whole under the two scenarios in Weihe River basin. The statistical downscaling model and the distributed hydrological model were coupled to predict thefuture runoff changes of the whole basin and5control hydrological stations onmainstream and tributary. The results showed that the total runoff would be less thanthe average value of reference period (1961-2009) and the decreasing trends in thefuture were very obvious under A2scenario and not significant under B2scenario. |
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