Hydrological Response To Vegetation Change And Climatic Variability In Jing River Basin And The Development Of An Assessment Tool

The hydrological response to vegetation change and climate variability is currently a research hotspot in echohydrology and the most challenging thing is to quantify the impact of vegetation change,climatic variability and other factors on the runoff in the watershed.Numerous studies have shown that the hydrological responses to vegetation change and climatic variability are highly variable among watersheds.In view of the above problems,this study used a combination of modified double mass curve and linear regression model to quantiatively differentiate the effects of vegetation change and climatic variability and other factors on runoff in Dongchuan and Heshuichuan watersheds which are the sub-watersheds in Jing River Basin which located in Gansu province.Based on the MATLAB GUI and.NET framework,an assessment system of hydrological response to vegetation change and climatic variability was developed.The system developed in our study can also be a decision-making-tool for the natural resources management,and facilitate the processing and analysis in hydrological researches.In this paper,Kendall's ? and Sperman's ? tests were used to test the trends on the seasonal/year scales in Dongchuan and Heshuichuan watersheds from 1983 to 2003.And a combination of modified double mass curve and non-parametric test was proposed to calculate the hydrological response to climatic variability and non-climatic events.Next,the impact of vegetation change to runoff can be derived by linear regression and 95% confidence level.Finally,an assessment system of hydrological response to vegetation change and climatic variability was developed under the MATLAB GUI and.NET framework platform.The conclusions are as follows:(1)During the period from 1983 to 2003 in Dongchuan watershed,the annual runoff showed an increasing trend.The climate variability increases the runoff in the wet season,but decreases the dry season and annual runoff.While the vegetation change increases the dry season and annual runoff but reduces the wet season runoff.In this watershed,the grassland was decreased and the forest and was slightly increased as well as the shrubs from 1990 s to 2000 s.The results shows above was mainly due to the evapotranspiration capacity of grassland was lower than that of forest land and shrubs,and the water holding capacity was weaker than that of forest land and shrubs.(2)In Heshuichuan,annual runoff showed a decreasing trend.The climate variability increases the wet season and annual runoff but decreases that in the dry season.While the vegetation change reduce wet season,dry season and annual runoff.From 1990 to 2000 in the watershed,the forestland and grassland was markedly increased but the shrubs were decreased.The evapotranspiration of forestland is greater than that of shrubs and grasslands.Hence,the increase in evapotranspiration in the forestland reduces the yield in the watersheds,which intensifies the drought in the area.Therefore,the large-scale afforestation is inappropriate according to our study.(3)The MATLAB GUI and the.NET framework programs can both achieve quantitative analysis and batch processing.Due to the different programming languages,there are some differences in the two systems.The MATLAB GUI program demonstrates its powerful mathematical computing capabilities while the.NET framework program has expanded its existing functions by developing a scenario prediction module that can predict runoff dynamics under future vegetation and climate change scenarios.Generally,the two programs developed in this paper are functionally uniform and are complement to each other.