Impacts Of Climate Variability And Land Use Change On Streamflow In Jinqian River Basin

The influence of climate change and human activities change on basin scale to the runoff is the key in the fields of hydrological. Jinqian river basin is located in the south slope of qinling in Shaanxi Province, it belongs to the Hanjiang River system, is the important fountainheads of south-to-north water transfer project. This article took the Jinqian river basin as the research object, using the1960-2009runoff measured data from Jinqian he Nankuanping hydrological station,the precipitation data of1960-2009in study area,1985and2009current land use data and combining with actual investigation, this paper analyzes the runoff change rule of50years of Jinqianhe river basin and forecast the future trend; Combined with the index of runoff and precipitation’s concentration and focus on stage to analysis the lags of runoff to precipitation; Use precipitation and runoff double cumulative curve model to quantitatively evaluate the contribution of climate change (the change of precipitation) and human activities (LUCC) to runoff; Through comparing the data of land use change of study area analyzes the influence of land use/cover change on runoff change. Reveal the runoff change rules under the influence of climate change and human activities and explore the contribution of climate change and human activities on runoff variety of Jinqian river, the research of runoff change law and effect factors of Jinqianhe river provide the theory basis and the support to ensure the sustainable development of the hydrologic water resources utilization and management of river basin and the hydrology of the ecological warning.This paper obtains the research results and progresses are as follows:(1) Jinqian river basin runoff change study of50yearsJinqianhe river basin runoff distribution is not uniform, mainly concentrated in the autumn and spring; The average concentration of runoff is41.6%in50years, concentrated period is August20; Most of the time scale of runoff trend analysis found that Jinqianhe river runoff have a significant decrease in the future for a period of time and there were strong sustainability from1960to2009; In winter and spring,runoff were very significant decrease and perform a strong persistent in a period of time for the future; In summer, runoff is not significant in the decreases and there were strong sustainability in the future for a period of time; Winter is the significant decrease of runoff in the future for a period of time and there were strong sustainability; In August the rest except in the runoff was produced both present significant decline.(2) The influence of the change of precipitation and runoff of Jinqianhe river basinThe precipitation distribution within the year of Jinqianhe river basin also don’t even, In50years the concentration degree of the precipitation is49.02%, and the concentrated period for July25; The trend of runoff coefficient were very significant decrease in the basin state that the part of precipitation change into runoff has fallen while the part of evaporation and rainfall infiltration and fill in the va and the part of the plant intercept were increasing; Compare the concentration of runoff and precipitation found it exists a lagging effect of runoff and precipitation,50years of Runoff lag precipitation average days is23.56d and after days has a rising trend; Use of precipitation and runoff double cumulative curve model quantitative analysis of the precipitation factors and human activities factors on the contribution of runoff reduce, Regard1960-1974as the base period, research the influence of the change of precipitation to runoff variety during1975-2009years, and the results show that the contribution rate of the change of precipitation to runoff reduce53.419%during1975-2009years, the contribution rate of human activities accounted for46.581%, the change of precipitation is the main reason to lead to runoff reduce, human factors is the secondary reasons. But the2003-2009the influence of the artificial factor value is as high as82.956%, It indicates that in recent years, human activities on the influence of the runoff variety are strengthening.(3) the influence of the land use/cover change to the runoffVegetation coverage index NDVI in the valey were very significant rising trend, the results show that the vegetation cover come a long way and restore; In the month scale, month by month NDVI are similar to natural runoff change trend, and has significantly correlation between them, and year average NDVI and years runoff coefficient have no distinct correlation. Woodland、grassland and cultivated land are the three main land use types in Jinqianhe river basin, From1985to2009, land use type change on the whole is not big, forest grassland area increased, and this is conform to the conclusion of basin NDVI has a rising trend, Obviously, returning cultivated land to forestry policy implementation within the basin has positive function of vegetation restoration; On a type rate is concerned, construction land use change rate is the largest. Analysis of the characteristics of land use and combining with the runoff change trends can concluded that the increase of forest areas and the construction land use acreage has the role of weaken runoff, the increase of cultivated land area can enhance the runoff.