The Climate Change And Its Hydrological Response Of Jing River Basin

Jing River basin is one of the most serious soil and water erosion regions of the world,which is located in the arid and semi-arid area. The change of runoff will lead to the change ofthe whole hydrological system, so it is of importance to analyze the impact of current andfuture climate change on hydrology and construct the relationship between water resource andclimate change in Jing River watershed. The results can be used to maintain the sustainabledevelopment of social economy and healthy life of Jing River watershed.Jing River watershed was the study area in this research. Statistical downscaling, linearregression, Mann-Kendall and t-test were used to analyze and predict the change of theclimate change during current and future periods in Jing River watershed, includingtemperature, precipitation and potential evapotranspiration. Then the results were adopted tosimulate the runoff to evaluate the impact of climate change on hydrology of the basin withsoil and water assessment tools. The aim of this study was to provide the scientific basis ofwater resource configuration and management to the regional climate change.The results of this study were as follows:(1)The annual mean temperature of Jing River basin from1960to2010was9.2℃。Thespatial distribution of mean temperature, maximum temperature and minimum temperaturewere similar, which decreased from the southeastern part to the northwestern part of the basin.The spatial distribution of precipitation during current period was similar to that oftemperature. Precipitation whose distribution was not uniform though a year decreasedsignificantly with time and its abrupt trend occurred in2003. ET0calculated byPenman-Monteith formula correlated to the pan evaporation well, which means that theestimated ET0was reliable. With annual average of934.6mm for the present period, ET0hada spatial difference decreasing from the eastern to the southwestern part of Jing riverwatershed. An insignificant upward trend of annual ET0was detected for the present periodand an abrupt change occurred in1977. The monthly ET0distributed as a single peak curvewith the greatest and smallest value in June and December, respectively.(2)The precipitation and runoff decreased in the past51years continually. Climatetended to be drier and the control areas of soil conservation measures increased over time.Human activity, whose impact was increasingly obvious, resulted in the runoff reduction from 1970s to2000s, while1990s was an exception. Climate change also led to the reduction of therunoff in the past years; however, the impact of climate change in2000s made a contributionto the increase of the stream flow, which means that the climate condition setoff the reducingeffect of human activity on runoff. The main reason of runoff reduction was human activityfrom1971to2010, except1990s.(3)The future climate scenarios for the Jing River watershed all showed clear upwardtrends in temperature under A2scenario. Temperature in the watershed increased significantlyas time went on. Temperature under A2and B2scenarios both varied significantly amongseasons. The model predicted that daily mean temperature would increase most insummer(A2：1.2，2.5，4.5℃；B2：1.3，2.4，3.2℃). Daily maximum temperature increasedmost in autumn under A2scenario(1.0，2.4，3.8℃) and increased most in winter under B2scenario(1.0，2.0，2.9℃). The daily minimum temperature increased most in summer underA2scenario(1.1，2.4，4.4℃), while increased most in autumn under B2scenario(1.4，2.3，3.3℃). The increases of temperature were largest from southeastern part of Jing Riverwatershed to the northwestern part. The center of temperature increase was in the southeast,whereas the change in the northeastern and the southwestern part were relatively small.(4)Future precipitation of Jing River basin was bound to reduce; however, there was nosignificant difference compared with base period (1961~1990). There were some seasonaldifferences. The decreasing trend of summer precipitation was obvious. A2scenario’s increasewas larger than B2’s, and the change increased gradually with time. Winter precipitationincreased weakly. The precipitation change trends of spring and autumn were similar to thetrend of autumn, and reductive months were more than increased months. There was a spatialdifference of precipitation change in watershed. The increase reduced from the southeast tothe northwest part of the watershed. It was shown that the spatial difference of futureprecipitation would decrease. During21stcentury, ET0would greatly increase by1.9mm/aand1.1mm/a under A2and B2emission scenarios, respectively. ET0appeared to increasedramatically since2049and had an upward abrupt change in2061. Future ET0also variedamong seasons with the greatest increase in summer and the least in winter. The spatialdistribution of future ET0was similar to the current period, but the regional difference wouldincrease over time. The aridity index calculated by the ratio of ET0to precipitation revealedthat Jing river watershed would be threatened by more severe drought during21stcentury, andmost regions would have semiarid climate at the end of21stcentury though now it is atransition region with semiarid and semi-humid climate.(5)The change trends of runoff were similar under A2and B2scenarios in the futureperiods. Runoff fluctuated according to the year from2020s to2050s. The amount of runoff was much littler than the last two periods. Runoff under A2and B2scenarios tended todecrease significantly in the future. Compared to the base period (1961~2000), runoff from2020s to2050s had a big increase, which would decrease in2080s. The hydrological responseto the climate change under B2scenario was stronger than that under A2scenario.