Study On Climate Change Impact On Runoff Of Typical Watershed In Tajikistan

Xinjiang and Central Asia are located on Eurasia's main arid region. They are far from ocean and climate presents drought. And they occupy 90% area of temperate desert on the earth. It forms the hudrothermal system which is obviously different from other continents because of the influence comes from west wind circulation, the high-latitude air mass in the Arctic Ocean and the warm and wet airflow in Indian Ocean. And it makes that the process of ecosystem response to global climate change seems unique and complicated. The five countries in Central As ia, and also Xin Jiang, there are many transnational r ivers cross distribution among each other, ecosystem and natural areas have connectivity, which can bring out international ecological problem by the changes in partial ecosystem. Therefore, we carry the research of drive mechanism and influence factor about regional climate change, w hich plays a guidance role in predicting the problem of ecological change about climate in the study area, and helps us generate coping strategy earlier. This paper simulates runoff process of Zeravshan River and Pyandj River Bas in in Tajikistan based on Xin'anjiang Hydrological Model with snowmelt structure. Then it makes use of method of hypothesis scence to analyse the response of the two river basins to climate change.This paper analyses the spatial and temporal distribution of temperature and precipitation in Tajikistan, which is based on the data of Tajikistan from 1980 to 2010. It studys the runoff distribution characteristic during an year and its correlation with temperature and precipitation as well. The results showes that: The temperature of Tajikistan kept rising from 1980 to 2010. And it has greater difference either in space or in latitudes. The rainfall presents generally stable, then it has a relatively signif icant fluctuation among years. The precipitation increases from east to west in the country roughly. The annual distribution of runoff is changeful. The runoff in the two basins reachs to peak during June to August. The runoff increases with temperature rising, while it has no distinct correlation with precipitation.This paper constructs the Snowmelt Xin'anjiang Model in Zeravshan River and Pyandj River respectively. By simulat ing the monthly flow process in 1981-1990, It comes to reasonable results. Simulation results revealed that it fits with the observed flow processes both in Zeravshan River basin and Pyandj River. And the amplitude of annual runoff error is small, and it keeps under reasonable limits. The model's structure keeps stable, and its parameters are reasonable generally which can reflects the main physical mechanism of the runoff generation and confluence in Zeravshan River and Pyandj River.Using the method of Hypothetical Scenario to set the climate change scenarioes, It can carry the study that the runoff how to response to climate change in Zeravshan River and Pyandj River. The results indicate: In Zeravshan River Bas in, when precipitation keeps constant and temperature rises 1?, the runoff increases 4.2%. When the temperature keeps constant, the precipitation increases by 20%, the runoff increases 8.0%, while it will be reduced by 7.4% when the precipitation reduced by 20%. The study proves that the runoff 's change has a positive correlation with the precipitation's change. In Pyanj river basin, while the precipitation remains constant, the temperature rises 1?, the runoff increases 16.0%. When the temperature keeps constant, precipitation increases by 20%, then the runoff increases 6.5%, while precipitation reduces by 20%, the runoff in Pyanj River reduces by 5.5%. In summary, the change of runoff keeps a completely positive correlation with precipitation.