Multi-sensor approach for desertification monitoring: case study at coastal area of Vietnam Hoang Viet Anh, Meredith Williams, David Manning School of Civil Engineering and Geosciences University of Newcastle upon Tyne, UK v.a.hoang@ncl.ac.uk Abstract This paper presents the initial findings of an investigation into multi-sensor remote sensing as a cost effective means of monitoring desertification in a semi-arid coastal environment. The project aims to develop a means of providing annually updated information at a range of spatial scales for local government and land use planners. A twin scale approach is employed to facilitate mapping at national and local scale. MODIS and ASAR wide swath data provide a generalized assessment for the whole country, whilst ASTER and ENVISAT ASAR image mode imagery are used to investigate desertification problems at a more detailed level. Three parameters were selected to develop a desertification index: land surface temperature, vegetation index, and soil moisture. The relationship between vegetation density, soil moisture, and surface temperature, and the role of these parameters in the desertification process are under investigation. It has been shown that vegetation index and surface temperature are strongly related to moisture stress and can explain the dynamic of desertification. An index based on relation between vegetation density and surface temperature was tested (Vegetation Temperature Condition Index: VTCI). Soil moisture estimation from delta backscatter ( –  dry ) showed a strong relation with field measurements (r 2 = 0.89) for bare land and sparsely vegetated areas. When the vegetation density is higher (NDVI>0.5), the relation is weak (r 2 = 0.58) therefore soil moisture estimation is not possible. 1 Introduction 1.1 Background Since the International Convention on Desertification of the United Nations that came into force in 1996 (UNCCD, 2004), the need to measure land degradation and desertification processes has substantially increased. While standard ground survey methods for undertaking such measurements are imperfect or expensive it has been demonstrated that satellite-based and airborne remote sensing systems offer a considerable potential. Earth observation satellites provide significant contributions to desertification assessment and monitoring, particularly by providing the spatial information needed for regional-scale analyses of the relationships between climate change, land degradation and desertification processes. Viet Nam is not designated as an arid or semi-arid country. However, some regions within the country are at risk from desertification. It is estimated that 9.34 million hectares of land in Viet Nam are degraded, and a substantial part of that is prone to desertification. Over the past 10 years, drought has caused severe impacts upon the agricultural and forestry production in many areas, especially in the central highland and coastal area of Viet Nam (UNCCD, 2002). In the