Study On Ecological Water Requirement Of San Jiang Yuan Region

San Jiang Yuan is the Source area of The Yanntze River, The Yellow River and The Lan Cang-Me Kong international River. It is the largest nature reserve in our Country. In the past few years, with the climate warming and human activities, the environment of San Jiang Yuan region become was deteriorating, it poses a great threat for the safety of water supply, ecology and sustainable development in our Country, thus be aware of the variation of ecological water requirement is important for protecting and restorating ecological environment in San Jiang Yuan region for reference.The remote sensing method based on surface energy equation is used in this research. Using MODIS satellite data, combined with surface weather observation data, calculated 2010-2014 ecological water requirement of vegetation in San Jiang Yuan region, and the distribution of ecological water requirement for further analysis. The main results are as follows:The daily evapotranspiration in San Jiang Yuan region remained a little change for clear day in July for the past 5 years, which mainly distributed in 3mm. 2011 reaches the maximum daily evapotranspiration 3.22 mm, 2010 the minimum 2.85 mm. In 2010 – 2014, the ecological water requirement in San Jiang Yuan did not have obvious yearly changes, it shows Yushu reaches the maximum, Guoluo second and Huangnan minimum. The maximum ecological water requirement 1.1135 billion m3 has reached at 2011, 2010 reaches the minimum 1.0139 billion m3, it corresponding with the variation of evapotranspiration.The grass ecological water requirement on 7.12.2014 at Hai Nan Zhou is verified using the Penman-Monteith method, the deviation between two methods is acceptable in regional scale.The evapotranspiration and the ecological water requirement are closely related with the local ecological environment, vegetation types and meteorological conditions etc., thus the variation tendency for the evapotransparation need further research.