Process And Prediction Of Eco-hydrological Changes In Dawen River Basin

With the gradual economic and social development,the relationship between people and water has become more complicated.The Dawen River Basin,the representative of the small watersheds in South Central Shandong,which is the only river in Tai'an City for flood control and drainage.The Dawen River Basin was selected as the research area.The meteorological and hydrological and land use change characteristics were analyzed by collecting meteorological and hydrological data and land use data,and the future climate and land use changes were simulated by using the SDSM model and CA-Markov model.Meawhile,the SWAT model was used to simulate the ecological hydrological change process of the Dawen River Basin,the future ecological and hydrological changes of the study area was predicted based on the simulated meteorological and land use data.The main conclusions are as follows:?1?By using ENVI?Environment for Visualizing Images?,land use maps of 1985 and1995 and 2005 and 2017 were interpreted from Landsat images.It can be seen that the water body,cultivated land and grassland were slowly expanding,the construction land was obviously expanding,the forest land was significantly decreasing,and the unused land was reversely changing.?2?According to the meteorological and hydrological observation data from 1966 to 2017,the mutation of temperature,rainfall and runoff in the Dawen River Basin were analyzed by using Mann Kendall mutation test.It can be seen that the temperature fluctuated violently during the five years from 1993 to 1997,the rainfall fluctuated violently after 1989,and the annual runoff fluctuated violently during the three years from 2003 to 2005.Using wavelet analysis to analyze the periodicity,it can be seen that the main periods of temperature and rainfall and runoff are 28 and 22 and 23 years,respectively.And the temperature,rainfall,and runoff all have differences on the time scale.?3?After the setting up of SWAT model,the observed streamflow data was used to calibrate and validate by SWAT-CUP.The results showed that SWAT model can perform reasonable streamflow.The periodic E_ns and R² are greater than 0.8 during the rate regularly,and the E_ns and R² are greater than 0.7 during the verification period.The established SWAT model can meet the accuracy requirements of ecological hydrological process simulation in Dawen River Basin.?4?The land use change of Dawen River Basin in 2030 was predict by using CA-Markov model.In 2030,the area of grassland has increased,the area of cultivated land and unused land and water bodies has remained basically unchanged,the area of forest land has decreased significantly,and the construction land has increased.Based on the meteorological data and NCEP reanalysis project and the atmospheric circulation data of RCP2.5 and RCP4.5 and RCP8.5 are output CanESM2,the SDSM model was used to downscale to obtain the future climate data of the Dawen River Basin.?5?Based on future climate data and land use changes,the SWAT model was used to simulate the future ecological hydrological process of the Dawen River Basin.The annual and interannual runoff in the Dawen River Basin gradually increased with time,but rising slightly,and the increase in the three scenarios of RCP2.5,RCP4.5,and RCP8.5 gradually increased.