Using GIS tools and rapid assessment techniques for determining salt intrusion: STREAM, a river basin management instrument

The Ganges, Brahmaputra, Meghna (GBM) catchment covers 1.8 million square kilometers of India, Nepal, Bhutan, Bangladesh and China (Figure 1). It is estimated that by the year 2020 the total population within the basin reaches 1 billion people. The population density varies widely over basin from 850 per km² in Bangladesh to 121 per km² the in Nepal. An important question related to river basin management (RBM) is, given the dense- and the fast growing population, how to maintain the natural resources in the basin in order to satisfy the needs for food and water for the population. One of the key RBM issues is salt intrusion at the coastal areas near the Bay of Bengal. Within this study, a rapid assessment technique developed by Savenije (1992, 1993) has been integrated in the river basin management instrument Stream (van Deursen and Kwadijk, 1994; Aerts, 1997; Aerts et al, 1998). The instrument enables the spatial analysis of the length and concentration of salt intrusion in estuaries. The technique has been applied on the Gorai estuary system in Bangladesh to support estimation of the impacts of salt intrusion on fresh water availability, fish stocks and agricultural production. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.