| Based on the upper han river basin in shaanxi as the research object, using digital elevation model, meteorology, soil and land/cover raster data and attribute data to construct the ArcSWAT module based on ArcGIS platform build hanjiang upstream hydrological process model, combined with the SWAT attribute database of the database established the han river upstream basin.Related mathematical statistics method is used to spatial and temporal variation analysis of climate factor on this basis, using the Mann-Kendall nonparametric testing method for climate factor to predict the future change tendency. Assumes that the24kinds of climate solutions, using SWAT model assumes that climate solutions under the conditions of runoff. Finally, using the time lag cross-correlation method to analysis of climate factor and the delay of response relationship between runoff. Come to the conclusion as follows:(1) Each parameter’s sensitivity is obtained by SWAT model sensitivity analysis sensitivity, from high to low are:Cn2, Esco, Gwqmn, Alpha_Bf, Canmx, Sol_Awc, Surlag, Revapmn, Ch_K2, Sol_K, Ch_N2. SWAT model of regular rate selected in2003-2006, verification is selected in2007and2010. Rate on a regular basis, Shi Quan station R2=0.87, Ens=0.83; Pike shop standing R2=0.84, Ens=0.80; R2=0.84beach stand high, Ens=0.84; Validation period, Shi Quan station R2=0.85, Ens=0.80; Pike shop standing R2=0.80, Ens=0.79; R2=0.84beach stand high, Ens=0.81. In rate and validation period regularly, R2and Ens were greater than75%, description model of the simulation effect is better.(2) Analysis of climate factor and runoff in time and space change rule, the results are as follows:①Hanjiang river basin from1970to2010annual precipitation change trend is not obvious, four times between41a larger fluctuations, respectively in1972and1979,1990and1990. Flood season and the increase is not obvious, the annual average rainfall flood season41a annual flood season precipitation occurred between two large fluctuations, respectively, from1976to1977and from1981to1982. Between41a, hanjiang upstream watershed of precipitation for five years in a wet year, dry year two years, most of the year at a level period. Uneven distribution of rainfall years, flood season precipitation accounts for65%in the year and season rainfall accounts for only5.8%of annual precipitation and summer precipitation throughout the year, at most, followed by age season, at least for the winter rainfall. After the M-K nonparametric test, in conformity with the trend line, the annual precipitation has a tendency to increase, especially in winter, precipitation increased significantly.②Hanjiang upstream watershed from1970to2010the maximum temperature, minimum temperature, average temperature rising trend, both between41a in1992, there was a large changes from small to large point mutation. Temperature changes during the year for "unimodal", July highest temperature, lowest temperature in January. According to the M-K nonparametric test methods, temperature has a tendency to increase, and obvious increase trend.(3) Based on the24kinds of assumes that the climate situation, study of hydrological factors response to climate change, the results are as follows:①By runoff hydrological response under different climate conditions, the runoff decrease with river basin increased temperature averaged over many years, with the decrease of temperature increase, precipitation and synchronous change, increase or decrease runoff is sensitive to changes in precipitation. When the temperature decrease1℃, precipitation increased by20%, the study area, the largest rise in the average annual runoff, when the climate rise1℃,20%less rainfall, annual average runoff biggest declines in study area. Is a variation of the runoff coefficient of variation analysis, the annual average runoff as temperatures rise, increased modestly,1℃when temperatures rise, precipitation decreased by20%, the biggest annual runoff variation coefficient, the annual runoff of volatile and prone to drought. Through runoff and the time lag cross-correlation analysis of climate factor, monthly rainfall and runoff was a strong synchronization, runoff of the highest temperature lag time for1months.②By evaporation on hydrological response under different climate conditions, the regional evapotranspiration and precipitation in a river basin are synchronous, increase or decrease with the decrease of temperature decrease, but with the increase of temperature, evaporation is increased before they are cut. When the temperature decrease1℃, precipitation decreased by10%, the study area the largest rise in the average annual evaporation; When1℃temperatures, precipitation decreased by20%, the study area of annual mean evaporation biggest declines. Based on evapotranspiration quantity difference coefficient of variation analysis shows that when the temperature rises of1℃,20%less rainfall, annual evapotranspiration quantity fluctuation is bigger. By the time lag cross-correlation analysis shows that evaporation is sensitive to precipitation temperature of reaction, and have strong synchronicity.③The sediment loads for different climate change response shows that when temperature2℃, precipitation increased by20%, the study area, the largest rise in the average annual evaporation, when1℃temperatures, precipitation decreased by20%, average annual evaporation within the study area biggest declines. At the same time, by the coefficient of variation,1℃when temperatures rise, precipitation decreased by20%, the volatile years sediment loads change. By the time lag cross-correlation analysis shows that sediment loads and precipitation temperature of strong synchronicity.(4) based on the four kinds of extreme land use type scenario, analysis study area hydrological processes, we can see that when all the woodland, runoff and sediment reduction, soil and water conservation effect for the best; building land,runoff and sediment volume increased more and more serious soil erosion.(5) Based on100kinds of climate and land use/cover a comprehensive change scenarios, analysis of hydrological processes of the study area shows that most cases, when the temperature rises to2℃and precipitation increase of20%, runoff, evapotranspiration and the amount of sedimentincrease; reduced at a temperature2℃and20%reduced precipitation, runoff, evapotranspiration and the amount of sediment reduction have reached the maximum. |
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