Estimation of vegetation ecological water requirement using remote sensing in the groundwater-fluctuating belt in lower reaches of Heihe River, Northwest China

Abstract

The Heihe River is the second largest inland river in the arid region of northwestern China. Water resources are the primary limiting factor for the sustainable development of economy and society in the Basin. The water requirement of vegetation is the link of the relationship between the status of natural vegetation and the groundwater level in the study area. With the decrease of water resource, the scientific estimation on ecological water requirement becomes the attention-getting focus and important premise of ecosystem protected. So, The ecological water requirement of vegetation was estimated in the study based on the remote sensing and evapotranspiration process. First, this study simulated the surface flux and the evapotranspiration using the technology of remote sensing and GIS, combining the basic data such as meteorological data, Landsat TM images, current land use maps and the data from field investigate. And then the quantity of ecological water requirement was estimated based on the simulated evapotranspiration and the distributional area of vegetation. By estimation, the quantity of water requirement of dominant species, such as Populus euphratica, Tamarix ramosissima and grassland is 11.37×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sup> m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> , 0.45×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sup> m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> and 3.24×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sup> m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> , respectively. The total ecological water requirement of vegetation is 1.506×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</sup> m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . This method afforded the effectual method for the study of regional ecological water requirement. And this study provide scientific support to banlance the water requirement from human being and natural ecosystem, and confirming the target, measure and project of ecosystem protected.