Application of satellite data for monitoring degradation of tidal wetlands of the Gulf of Kachchh, Western India

Abstract

Tidal wetlands act as feeding, spawning and nursery grounds to marine fisheries. They also help in protecting the coast from the marine erosion. Thus there is a need to monitor the tidal wetlands periodically. Landsat MSS and TM data of period 1975–1986 is analysed for monitoring the tidal wetland areas of the Gulf of Kachchh, Western India. This area was declared as the Marine National Park in 1982. Various wetland categories like beach, mudflats, coral reefs, mangroves, marsh vegetation, algae, coastal dunes, salt pans and salt encrustations were delineated. The classification accuracy of these maps is 83% at 90% confidence level. The coral reefs and mangrove ecosystems in the area are in great danger. The total reef area has reduced from 217 to 123 sq km from 1975 to 1986. The degradation and destruction of the reefs is mainly due to high turbidity in the coastal waters and carbonate sand mining, for manufacture of cement in the area. The mangroves have severely degraded and reduced from 275 to 218 sq km in the part of Gulf of Kachchh and 138 to 33 sq km, in the core area of the Marine National Park, from 1975 to 1986. Near the mouth of the Gulf, the mangroves along with marsh vegetation have drastically reduced from 730 to 180 sq km from 1975 to 1982. The destruction is mainly because of their use as fuel and fodder, and the proliferation of the salt works. The analysis of the satellite data, thus helps in planning proper conservation measures and ultimately to its better management.