Synergistic Effect Of Future Land Use And Climate Change On The Runoff Of Liuyang River Basin Assessed By SWAT Model

Typically,water is considered as an essential natural resource for lives on earth as it helps maintain the growth and development of societies,economics,as well as ecological environment.With this essence,water resource has become an important part of human societies,for instance,water supply in their livelihood,and agricultural activities,economic activities and so forth.Regarding this hugely usage and a rapid growth of cities development and population,the need of water resource has also increased.Water shortage has become a global issue which many countries particularly in the arid and semi-arid regions have been facing for decades.Furthermore,in the context of climate change;extreme weather events,such as heavy rain causing flooding hazard,temperature rises resulting drought occurrence,can be found in many areas around the world.Changsha city,Hunan province,China,which has Liuyang River as a main river,is one of those affected regions which has a rapid growth of population and urbanization,and water scarcity has been problematic to individuals for long time.In order to combat this shortcoming,it requires an appropriate technique and approach to enhance management and utilization of water resource in a sustainable way.To achieve this,it would involve the changes of human activities,and an understanding of a changing of global climate as they play a crucial role in basin hydrological cycle.The result from this current study shows that the runoff of Shuangjiangkou hydrological station in the upper of Liuyang River has been gradually decreasing since 2008,while the runoff of the Alipin hydrological station in the lower of the river has shown a slow increase since the reforming and opening in the 1980.This subsequent increase trend tends to be significant.The change of rainfall at the hydrological station seem not to be able to explain the change of runoff very well which could indicate that the change of runoff is strongly interfered by either human activities or climate change such as rainfall.Historical data establishing and verifying the model of Liuyang River basin yielded from SWAT is used to simulate monthly runoff of the basin.The study is divided this basin into 21 sub-basin and 221 hydrological response units(HRUs).The automatic calibration approach of SUFI-2 in SWAT-CUP is employed in parameter calibration and validation.This indicates a relatively good agreement between monthly simulated values and observed values in the calibration and validation period.Finally,quantitative assessment of land use and climate change effects on runoff in future watersheds is shown in SWAT model and scenario analysis method.Future land use changes are simulated up to the year 2020 and 2050 by applying a Cellular Automata(CA)-Markov chain model.Weather data obtained from WorldClim represents the future climate change in the study area,and SWAT model generated in Liuyang River basin is to simulate the runoff and thus quantitatively evaluate the effects of land use and climate change on runoff in the future.The research result shows that the area of forest,urban constructions and cultivated lands are likely to increase in the future.The future weather in Liuyang River basin tends to be warmer and drier.The runoff of the basin is anticipated to decline to 2.42 m3/s in 2020,and 0.96 m3/s in 2050 under pressure of the changes of land use scenarios.Similarly,the runoff is likely to decline to 3.02 m3/s in 2020 and 1.13 m3/s in 2050 under the climate change scenarios.Under the land use and climate change scenarios,the runoff is predicted to decrease to 8.54 m3/s and 4.27 m3/s in 2020 and 2050 respectively.This reveals that the runoff in this basin tends to be more sensitive to climate change.The synthesized impacts of land use change and climate change to Liuyang River basin is nonlinear.