ENVIS Hub Manipur
Status of Environment and Related Issues

River and Drainage System of Manipur :

The National Wetland Inventory and Assessment published by the Space Application Centre reported that Manipur has 15 major rivers / streams having 166.77 sq. km. of total area i.e. about 0.75 % of the total geographical area of the state.   About 90% of the drinking water supply in urban area of the state is from the three major rivers namely Imphal River, Nambul River and Iril River. There are four major river basins of Manipur state -

-  the Barak River Basin (Barak Valley) to the west,

-  the Manipur River Basin in central Manipur,

-  the Yu River Basin in the east, and

-  a portion of the Liyai River Basin in the north.

The Manipur River basin in the central Manipur, with a far less discharge capacity of 0.5192 Million ha. meter in a catchment area of 6332 sq. km. on the other hand, is the most important as it passes through thickly populated areas and covers the whole of Manipur valley consisting of the four valley districts. It also covers most of the habitations of Senapati district, the western portion of Ukhrul and Chandel districts and also the more populated eastern one-third of Churachandpur district.  

The Chindwin Drainage System consists of the Imphal River and its tributaries, the lakes and marshes lying in the valley and the hill streams of Ukhrul and Chandel districts which drain into the Chindwin River of Myanmar or into the Yu river, a tributary of Chindwin in Myanmar. The Imphal River, also known as Manipur River originates from the north of Kangpokpi and flows southward to the eastern side of the Loktak lake. The principal tributaries of the river in the valley are the Iril, Thoubal, Nambul and Nambol. The Barak River basin is the largest in terms of the area drained in the state i.e. 9041 sq. km and 68% yield.

Wetlands of Manipur :

The National Wetland Atlas 2010, developed by Space Application Centre has identified 167 wetlands (≥ 2.25 Ha) and 541 wetlands (<2.25 Ha) covering 63,616 ha i.e. 2.85% of total geographic area under different types of wetlands like lake / pond (61.5%), river/steam (26.2%), waterlogged (5.5%) and aquaculture pond. Analysis of wetland status in terms of open water and aquatic vegetation showed (in table 6.1) that around 71 % of wetland area is under open water category during post monsoon and 62% during pre-monsoon respectively. Aquatic vegetation (floating/emergent) occupies around 26 % of wetland area during post monsoon and 37 % during pre-monsoon respectively.

Out of  9 (nine) districts in Manipur, three districts are rich in wetland viz. Bishnupur (30.7 % of total district of total district geographic area under wetland), Thoubal (30.3% of total district geographical area) and Imphal West (2.6 % of total geographical area under wetland). Chandel district has the lowest area under wetland i.e. 0.44 %. Senapati and Thoubal have observed with very high concentration of small wetlands (< 2.25 ha).

Underground Water Resources :

Groundwater in the state is mostly exploited through open wells. As per reported by the Central Ground Water Board (CGWB),  ground water in the deeper aquifers occurs under sub-artesian and artesian conditions. Granular zones are encountered at a depth of about 150 m in Imphal valley and at about 220 m in Jiribam valley. Tube wells have been installed at various places of the valley areas with the yields ranging from 0.6 to 4 cu.m/hr. On the basis of the monitoring of water level in key/dug wells network stations in the area, an annual recharge of 44 M.cu.m has been estimated. Considering the clayey nature of formation in the top aquifer, development of this resource is not considered promising on a large scale either in irrigation of water supply. Hydrological study reports reveal that Manipur valley is underlined by a thin veneer of alluvial deposits, which is largely clayey in nature, underlined by rocks of Tertiary age. Ground water occurs under un-confined and confined conditions. Since the upper formations are mainly silty and clayey, open wells have poor yield prospects. However the deeper zone, consisting of sand stones of Tertiary age, forms good aquifers which are under confined conditions, Auto flow conditions are observed in Imphal where the yield of the tube wells vary from 0.5 to 4 m3/hr.

Hydrology of Ground Water

Source: http://cgwb.gov.in/documents/Country%20Resource.pdf

Water Supply System in Manipur  :

Manipur, though falls under high intensity of rainfall area also faces acute shortage of water particularly during dry / lean season i.e. January - May every year. All the riverine system of the state originates from the hills and their flow depend on the annual monsoon. Deforestation in the hill area of the state also leads to heavy siltation and disturb the water flow of the rivers. The problem is further aggravated due to the climate variability, as a result, the state is also facing erratic monsoon for the past few years resulting to shortage of water supply every year.

Every year, the state is facing acute drought like situation, particularly in the months of February - May, due to depletion of raw water at source and drying up of all the water bodies like Ponds, Lakes, Moats, etc. More over, about 2 % of the domestic water supply in urban area is being supplemented by the private transporting tankers. The present water storage & distribution system of the state in both the urban & rural sectors are reported.

Water Quality in Manipur

The level of pollution and contamination of water bodies in the state is moderate. However in some instances like Nambul river and Kongba river the degree of pollution is very high. With rather denser population in the central valley districts, degradation of water quality is a major concern now-a-days. The wetlands and lakes which are sinks to the water pollution are also deteriorated in an alarming degree. For example, Loktak Lake water quality is a great concern due mainly to inflow of the most polluted drains/rivers like Nambul river. For whatever be the scenario, a regular monitoring is needed. The monitoring work of water quality of the various resources are being carried out by Environment R & D Laboratory, Directorate of Environment, Porompat. Extracts of data are published for dissemination of the environment information, public awareness and responses.