Remote Sensing Monitoring And Driving Force Analysis In Gansu Province Section Of Heihe River Basin

Wetland is one of the ecosystems blessed with the most abundant biodiversity on the earth.Apart from plentiful wetland resources,it also boasts huge capability to regulate environment and ecology,creating a good environment for the sustainable development of mankind.Over the past decade,an increasing number of wetlands in the Gansu province section of Heihe River Basin(HRB)have been reclaimed or appropriated,resulting in a rapid decrease of wetland area and remarkable deterioration of wetland functions.Against this background,the research on wetland as well as the protection and proper utilization of wetland resources have become one of the most significant issues confronting the local people and government.This paper focuses on the Gansu province section of HRB.A systemic research on the types,total area,composition,distribution,etc.of the wetland resources in this section is made by utilizing data sources of TM,ETM remote sensing image,geographical conditions census data,water conservancy census data acquired in 2000,2008,and 2013,as well as statistical data of many years.Remote sensing and GIS technologies are employed,and field survey is conducted during the research.A further exploration is made from the perspective of both natural factors and human activities.The main research results are as follows:(1)The wetland area in this section is decreasing.Specifically,the deceasing speed is fast before 2008,while it is obviously lowered after 2008.(2)The transformation of wetland resources in this section mainly take place in marsh wetlands and riverine wetlands.Riverine wetlands account for the largest area of the transformations,followed by marsh wetlands.The transformation area of other types of wetlands is relatively small and stable.(3)An analysis of principal components demonstrates that both the first and the second components,namely the transformation of marsh wetlands and riverine wetlands are caused by human factors,while the third component,namely the transformation of other types of wetlands is due to natural factors.Therefore,the main forces driving the transformation of wetland resources in the Gansu province section of HRB are social-economic factors,industrial structure factors and natural factors,among which social-economic development is the leading factor.(4)The transformation of wetland resources is a result of both natural factors and human activities.Major natural factors affecting the transformation in this section include precipitation,temperature,the inflow amount from the upper reaches,runoff amount,etc.Externally,human factors are playing an increasingly significant role in such transformation.The most active and director factors are population growth and human's intense transformation and utilization of lands,while government policies and wetland protection and rejuvenation projects are positively driving the evolution of wetland resources.