Loktak Lake - Topography and Geography

Topography and Geography

Of the two river systems which drain the Manipur state—the Barak river and the Manipur River—the Manipur River flows through the Manipur Valley. The river rises in the north at Karong, flows south of Imphal and hence is also known as the Imphal River. Along its course through the valley, downstream of Imphal, the bed slope of the river is gentle. Drainage pattern, typical of hilly terrain, is sub-dendritic, sub-parallel and sub-radial, which is dictated by the structure and lithology of the area. Imphal, Iril and Thoubal River valleys also exhibit a meandering river course.

At the Ithai barrage outlet of the Lake, the direct catchment area draining into the lake is 980 km2 (380 sq mi) out of which 430 km2 (170 sq mi) is under paddy cultivation, 150 km2 (58 sq mi) under habitation and 400 km2 (150 sq mi) under forest cover. The area of the lake is 236.21 km2 (91.20 sq mi), comprising large pockets of open water and marshy land formed at the southern part of the Imphal valley up to the confluence of Manipur River and Khuga River in the district of Imphal West. The Lake is divided into two zones, namely, the “Core Zone” which is the no-development zone or totally protected zone comprising 70.3 km2 (27.1 sq mi) and the balance area is called the "Buffer Zone". Within the lake and on its periphery, there are 14 hills of varying size and elevation; in the southern part of the lake are the Sendra, Ithing and Thanga islands.

Lake Zonation

Geographically, in terms of biodiversity and pressure of human activities, the lake is broadly divided into northern, central and southern zones as elaborated below.

The Northern Zone, extending from eastern side of Nambol River near Ngaikhong Khunou to Phabakchao including Maibam Phumlak, has five main streams/rivers namely, the Nambol, Merakhong, Ishok, Waishel and Nambul flowing into the lake. The zone is separated from the central zone by large phumdis (varying thickness of 0.4 to 4.5 m or 1.3 to 15 ft) that stretches from the northwest to the southeast. During January to March, phumdis in this area are usually burnt for construction of fish cum paddy farms; many large fish farms with raised levees have been built.

The Central Zone, extending from Awang Laisoi pat (western side of Nambol River near Ngaikhong Khunou) to Laphu pat (between Khordak channel and Imphal River) encloses prominent islands of Thanga, Karang and Ithing. It is the main open water zone of the lake, which was relatively free from phumdis in the past, but over the years 'athaphums' (artificially created phumdis for fishing) constructed by villagers for fishing have proliferated choking the entire lake. The State Fisheries Department has established a fisheries centre within this zone at Takmu pat for fisheries development

The Southern Zone encompasses the Keibul Lamjao National Park, Ungamel and Kumbi pats at the southern part of the lake and the zone is linked with Khuga River by the Ungamel channel. The Imphal River is also linked with this zone by the Khordak channel. The western catchment drained by the Kangshoibi River flows into this zone. Proliferation of phumdis has been observed near the mouth of Ungamel channel, Kumbi pat, Nongmaikhong and Khordak area.