Introduction

Wetlands are areas of land that are covered by water indicating seasonal and perennial variability. Wetlands provides habitat to large varieties of plant and animal species, adapted to seasonal variation of water levels. It meets the essential needs of the human beings such as drinking water, food, energy and stabilizes the climate (Ramachandra andUttam Kumar, 2008). Wetlands are important source of ecosystem that removes the dissolved nutrients and improves the quality of water. In India, 3.2% of the geographic area constitutes the wetlands and supports the aquatic biodiversity (Prasad et al. 2002). However in recent years,increased populations, industrialization, residential and agricultural development, most of these wetlands have discovered to be disappeared and some are degraded in its quality. As a population spikes, the pressure on the wetlands increases (Rahman, and Begum, 2011). The human induced treats and encroachment for infrastructure development have resulted in the destruction of wetlands (Amezaga, et al., 2002).The major causes for the wetland destruction are due to dam construction, soil erosion, intense fertilizer usage, sewage and industrial waste etc.Due to anthropogenic and climatic changes, these wetlands are getting extinct in time.

There is a need for the preservation of wetlands involving sustainable management that guarantees the maintenance of wetlands for future generations (Amezaga and Santamaria, 2000). As a consequence, the sustainable management of wetlands becomes the one of the critical issues for decision makers (Schuyt, 2005). Watershed management is recognized as ideal approach for sustainable and natural resource management in rain fed areas. Watershed is geographical area, in which water becomes concentrated within particular location, to form rivers, streams, and reservoir etc., and also consists of the region drained by these features. The watershed forms the link between the land and wetlands resources which balances the ecosystem by improving the quality of water, controlling flood, stabilizes the climate, reduces soil erosion etc.  Degradation of watershed due to anthropogenic activities as well as natural changes has brought reduction in quantity and quality of water resources. Watershed management aims at providing the sustainable use of natural resources considering both spatial and temporal variability of wetlands (Ramachandra and Uttam Kumar, 2004). Thussustainable management approaches through the optimal resource planning deals with spatial and temporal mapping of wetlandsusing remote sensing and GIS (Deka et al., 2011).The satellite data acquired at various spatial and temporal scales provides the variation in spatial extent of wetlands which further helps in planning and monitoring land and water resources for optimal utilization (Navatha, et al., 2011). Remote sensing and GIS offers cost effective method for delineate the wetlands, drainage networks and to manage precise information on wetland characteristics. In recent years, due to increased urbanized process, wetlands are destructed and encroached by human activities. Thus satellite imagery helps in mapping the temporal changes that occurred in wetlands due tolanduse activities. Remote sensing data plays a vital role in water management and its conservation and mapping of wetlands enables us to study hydrological process (Ramachandra and Uttam Kumar, 2008).