Abstract:
The floating biomass on the lake, locally known as phumdis, are a heterogeneous mass of soil, vegetation and organic matter at various stages of decomposition. Phumdis play an important role in the ecological processes and functions of the lake ecosystem. The presence of phumdis is the characteristic feature of the Loktak lake, the largest freshwater wetland located in the north-eastern part of India about 48 km from Imphal city of Manipur. In this thesis, an attempt has been made to identify the phumdis proliferation from 1989 to 2011 by using the analysis technique of GIS based and pixel based overlay analysis and to examine the changes in phumdi area, analyse its impacts on the agricultural land. The study is based on remotely sensed data of 1989, 2002 and 2011, phumdis thickness and lastly, but at least, bathymetric map. It is found to be spreading the dispersed water of the lake around the lake thereby affecting the agricultural land as well as reducing the water holding capacity of the lake. To examine its impacts on agricultural land, field surveys were conducted and data covered five villages and 10 households. The results showed that the phumdi area has increased from 1989 to 2011. The main causes for phumdi proliferation were the construction of the Ithai Barrage Dam, increase in athaphum fishing, pollution, growth of settlements on phumdis, etc which are listed from the literature review. It was the human pressure that has aided in the growth of phumdis. So, it is concluded by giving the proposal of maintenance of the cleared phumdi areas.
