Loktak lake: How does the "Floating lake" actually float?

Loktak Lake is the largest freshwater lake in northeastern India. It is also called the only in the world due to the floating Phundies on it. It is located near Moirang in Manipur state. It was designated as a wetland of international importance under the Ramsar Convention on March 23, 1990. It is an ancient lake and plays an important role in the economy of Manipur. It serves as a source of water for hydropower generation, irrigation and drinking water supply. The lake is also a source of livelihood for the rural fishermen who live in the surrounding areas and on Phumdis - floating islands, which are actually heterogeneous mass of vegetation, soil, and organic matters at various stages of decomposition. Loktak lake is considered to be the lifeline of the State of Manipur due to its importance in the socio-economic and cultural life of the people. It is the largest natural freshwater lake in the north - eastern region of India and plays an important role in the ecological and economic security of the region. A large population living in and around the lake depends upon the lake resources for sustenance. The staple food of Manipur is directly linked to Loktak lake. The lake is rich in biodiversity and was des ig nated as a Wetland of International Importance under Ramsar Convention in 1990.It is covered extensively by naturally - occuring phoomdis (mass of floating vegetation) which are a specialized habitat for many biota, besides being useful to the local people in many ways. The Keibul Lamjao National Park, in the southern part of the lake, is a unique floating wildlife reserve and the only home of the endangered Manipur brow - antlered deer or sangai, with an estimated population of 106 (in 1991). It has been the breeding ground of a number of riverine migratory fishes from the Irrawady - Chindwin river system and continues to be vital as a fish habitat.The Keibul Lamjao National Park, which is the last natural refuge of the Manipur brow-antlered deer (Cervus eldi eldi), is situated in the southeastern region of this lake. It is also the home of other endangered species including a species of python (Python molurus molurus).Human activities have led to severe pressure on the lake ecosystem.The Loktak lake with its numerous floating lands covers a variety of habitats which sustains rich biological diversity. The aquatic macrophytes comprising 233 species belonging to emergent, submergent, free - floating and rooted floating leaf types have been reported in the lake.A total of 425 species of animals (249 vertebrates and 176 invertebrates) have been recorded from the lake, which includes some rare animals such as Indian python, sambhar and barking deer..Loktak lake has been considered to be the lifeline for the people of Manipur due to its importance in their socio-economic and cultural life, besides influencing the climate of the State. The socio - economic values of the lake include hydropower generation (Loktak Hydel National Project), irrigation of 24,000 ha of agricultural land, fisheries, control of floods, supply of drinking water, production of aquatic organisms of food and of commercial importance, and the many uses of phoomdi and water transport. More than 100,000 people, on and around the lake, depend for their livelihood to a great extent on the lakefishery, which is now a mix of capture and culture systems. The lake yields about 1,500 tonnes offish per year..

People angling in Loktak Lake at the main chanel of Loktak Hydro Electrict Power Project.Bamboo net seen here is a device to protect the phumdis in the main chanel of the Loktak Hydro Electrict Power project. The root-cause problems can be traced to loss of vegetal cover in the catchment area and construction of Ithai barrage. The degradation of the catchment area has led to the problems of siltation and increased flow of nutrients. The construction of Ithai barrage has led to: Changes in hydrological regimes thereby affecting ecological processes and functions of the wetland; Inundation of agricultural lands and displacement of people from flooded lands; and. Loss of fish population and diversity; and decrease in the thickenss of phoomdis in the Keibul Lamjao Naitonal Park thereby threatening the survival of Sangai deer. State Government of Manipur constituted Loktak Development Authority (LDA) in 1986 "to check deterioration of the lake and to bring improvement in the areas of power generation, fisheries,tourism and siltation control." The main activities carried out by LDA include survey and demarcation, removal of silt, removal of phoomdis, control of water hyacinth through release of weevils, construction of silt detention structures, afforestation of critical catchment area by plantation of appropriate species of plants and fruit-bearing trees and soil conservation through engineering measures.