By Rajkumari Sunita Devi
1. Introduction
Manipur, the eastern most state of India lying 92 o 59’E to 94o45’E longitude and 23o50’N to 25o41’N latitude, straddling the international border between India and Myanmar, has a peculiar situation in the eastern Himalayas and watershed area of the great river basin systems - the Brahma-putra and the Irrawady. It is blessed with an enormously rich heritage of wetlands. Topographically it is surrounded by seven ranges of hills and the valley lies in between. Therefore, wetlands, in Manipur are mostly found in the valley area and are known by the generic name Pat (pronounced as paat). The surrounding hill districts are also replete with many kinds of wetlands, great and small (Wetlands of Manipur, Vol-I- 1999).
The pats of Manipur are known to have their own life-span and hydrologic characteristics related to the evolving geo-physical character of land itself. In the beginning of the 20th century there were nearly 500 pats in the Manipur Valley, covering a large position of its area. Loktak lake after acclaiming Ramsar site is well known internationally but apart from Loktak other well-known pats of Manipur are Ikop pat, Pumlen pat, Waithou pat, Ngakra pat and Loushi pat.
Loktak lake is the largest freshwater wetland in North-eastern region of India and is situated between 240 25’ to 24042’ N latitudes and 930 46’ to 93055’E longitudes. This lake was designated as wetland of International Importance under Ramsar Convention in 1990 because of its biological richness where naturally occurring phumdis (floating vegetation) covers the lake extensively and is a specialized habitat for many biotas besides being useful to the local people in many ways. The Keibul Lamjao National Park in the southern part of the lake is also a unique floating wildlife reserve and the natural home of the endangered Manipur brow antlered deer, Sangai. Deforestation and shifting cultivation in the catchment areas have accelerated the process of soil erosion resulting in the lake’s shrinkage. The nutrients from catchment area and domestic sewage from Imphal city carried by Nambul River are discharged into the lake which is another major problem of the lake (LRIS Report, 2003). All these activities have direct bearing on ecological stability of the lake.
2. Study Area
Loktak has direct catchment of 1040 sq. km and falls under the sub-basin of the Manipur River. The catchment area lies between 24o24’to 24o57’ N latitude to 93o40’ to 93o58’E longitude. The topography is undulating having elevation of 780 m at the foothills adjoining the central valley and about 2068 m at highest peak. There are about 98 villages with a total population of 21,334 (1991 census).
The presence of Ithai Barrage, a multipurpose project for generation of hydel-power and irrigation which was commissioned in 1983 at Ithai at the sou-thern nearest tip of Loktak, has brought about drastic hydrological changes.
Loktak catchment area comprises the elongated hilly terrain of various altitudes along with isolated hillocks, plains and marshy lands. Altitude of elongated hill ranges and isolated hillocks varies between 820 to 2068 metre and 760 to 1100 metre above mean sea level respectively.
The rock formations in the catchment area are cretaceous limestone, the Disang with Serpentinites (Lower to Middle Eocene-Upper cretaceous), the Sumas and the Thipams (Miocene). Surma group occurs in the lower reaches of hills whereas the Disang and Thipam groups occur in high reaches of hills. Disang formation comprises grey sandstone-grit-conglomerate limestone sequences intruded by serpentinites containing minor amounts of enstalite, chromite, amphiboles and magnetite. The Surma and Thipam groups represented by argillaceous and arneceous sequence respectively.
3. Objectives
The present study lays the foundation for developing wetland conservation models using remote sensing and geo-spatial technologies. Some of the detailed objectives of the study area:
* Creation of temporal spatial database using satellite data for catchments (1995, 2000 and 2004-05) and structural components/ habitat types of wetlands
* Generation of Land Capability map for the catchment area for long term and short term management plan such as formulation of soil conservation plan to check soil erosion and subsequent silting up of Loktak Lake.
* Collection, integration and modeling for suggesting sustainable management solution for conservation of Loktak Wetland.
4. Data used/sources
The database of this catchment study consists of primary, secondary and integrated database of spatial and non-spatial data on different components of the catchment. Census data of 1991 & 2001 is used for socio-economic studies of the hill and valley region. Table 1.2 gives the list of satellite data use.
5. Methodology/Thematic Maps
Visual and digital image interpretation techniques were used to prepared thematic maps on 1:50,000 for 1990, 1995, 2000 using 23.5 meter resolution data of IRS-1C, 1D and 1:25,000 for 2004 -05 using high resolution data like IKONOS , for some area and merge data of 2.5 meter resolution using LISS-III and PAN data . Secondary data for socio-economic etc are also incorporated. The thematic maps are :
* Land use/cover
* Hydrogeomorphology
* Slope
* Drainage
* Road network
* Settlements.
A. Land Use/Cover :
Information on Land use/cover pattern, especially the extent and spatial distribution is a pre-requisite to derive information on temporal changes. The land use /cover information helps to identify areas where immediate attention has to be taken for reviving various landscape elements. The present status of land use (Table 5.1) in the catchment is useful for identifying locations for taking up soil conservation measures by involving village communities, for minimizing land degradation. Land use classification for 2004-05 is base on guideline of ‘Biodiversity Conservation in Wetland Project’ by Space Applications Centre, ISRO, Ahmedabad.
The land use class of wetland is further classified by preparing a structural components map of Loktak wetland area which shows various classes of phums, agriculture land, islands, aquaponds etc. In the present study SOI topography map of 1970 was use as a base to delineate water spread and demarcate wetland boundary. IKONOS data was use for preparation of the structural component map of 2004-05 (Table 5.2).
B. Hydrogeo-morphology: Information on landforms is an important input for land management and soil mapping. The aspects of morphology, morphogenesis, morpho chronology and morphometry are vital inputs in preparation of geomorphologic maps. —
The geomorphic units are delineated based on image characteristics like tone, texture, shape, colour, associations etc. (Fig.5.2 A).
C. Slope:
Information on slope is vital for suggesting actions related to restoration plans of landscape. This information is useful for suggesting checking of soil erosion and drainage related measures. The slope map has been prepared as per IMSD guidelines. Using this information Digital elevation model has been generated using 20 metre contour interval.
D. Drainage/Watershed:
A drainage map of the study area was prepared using satellite data in conjunction with SOI topography maps. Most of the streams originate from the hill ranges to the west of the lake and discharge water directly into Loktak Lake. Some of the major streams include Nambul, Nambol, Thongjaorok, Awang Kujairok, Awang Kharok, Ningthoukhong, Potsangba, Oinam, Keinau and Irulok contributing significant silt during rainy season to the lake. In all 12 micro-watershed were demarcated and they have been given nomenclature according to the standard of All India Soil and Land Use Surveys (AIS & LUS) of the Ministry of Agriculture. ( Fig. 5.2 B)
E. Road Network & Settlements:
The road transport network is one of the major criteria for studying and analyzing the socio-economic problem of a certain area and for assessment of impact on the wetland.
In the present study, there are three types of roads classified as National highway, Village road and other which may include footpaths etc. The total length of National Highway is 59.652, village road is 723.243 km and others are 234.5 km. (Fig. 5.2.C)
6. Results and analysis
i. Spatial Analysis: Land Use Change detection
Multi-temporal satellite data have been used for studying land use practices over a period of fifteen years in the catchment of Loktak Lake. It has been found that there is an increase in the built up area and also decrease in scrub forest. There was increase in dense forest from 1990 to 2002. This may be due to some of the activities of afforestation program taken up by LDA for catchment treatment but again this has decline in 2004-05 (Table5.1). There is an increase in open forest area in 2004 and decrease in degraded forest which again shows that deforestation activities have become less and natural regeneration is going on in the catchment area.
to be contd
Source: http://www.thesangaiexpress.com/Others/Articles.htm
1. Introduction
Manipur, the eastern most state of India lying 92 o 59’E to 94o45’E longitude and 23o50’N to 25o41’N latitude, straddling the international border between India and Myanmar, has a peculiar situation in the eastern Himalayas and watershed area of the great river basin systems - the Brahma-putra and the Irrawady. It is blessed with an enormously rich heritage of wetlands. Topographically it is surrounded by seven ranges of hills and the valley lies in between. Therefore, wetlands, in Manipur are mostly found in the valley area and are known by the generic name Pat (pronounced as paat). The surrounding hill districts are also replete with many kinds of wetlands, great and small (Wetlands of Manipur, Vol-I- 1999).
The pats of Manipur are known to have their own life-span and hydrologic characteristics related to the evolving geo-physical character of land itself. In the beginning of the 20th century there were nearly 500 pats in the Manipur Valley, covering a large position of its area. Loktak lake after acclaiming Ramsar site is well known internationally but apart from Loktak other well-known pats of Manipur are Ikop pat, Pumlen pat, Waithou pat, Ngakra pat and Loushi pat.
Loktak lake is the largest freshwater wetland in North-eastern region of India and is situated between 240 25’ to 24042’ N latitudes and 930 46’ to 93055’E longitudes. This lake was designated as wetland of International Importance under Ramsar Convention in 1990 because of its biological richness where naturally occurring phumdis (floating vegetation) covers the lake extensively and is a specialized habitat for many biotas besides being useful to the local people in many ways. The Keibul Lamjao National Park in the southern part of the lake is also a unique floating wildlife reserve and the natural home of the endangered Manipur brow antlered deer, Sangai. Deforestation and shifting cultivation in the catchment areas have accelerated the process of soil erosion resulting in the lake’s shrinkage. The nutrients from catchment area and domestic sewage from Imphal city carried by Nambul River are discharged into the lake which is another major problem of the lake (LRIS Report, 2003). All these activities have direct bearing on ecological stability of the lake.
2. Study Area
Loktak has direct catchment of 1040 sq. km and falls under the sub-basin of the Manipur River. The catchment area lies between 24o24’to 24o57’ N latitude to 93o40’ to 93o58’E longitude. The topography is undulating having elevation of 780 m at the foothills adjoining the central valley and about 2068 m at highest peak. There are about 98 villages with a total population of 21,334 (1991 census).
The presence of Ithai Barrage, a multipurpose project for generation of hydel-power and irrigation which was commissioned in 1983 at Ithai at the sou-thern nearest tip of Loktak, has brought about drastic hydrological changes.
Loktak catchment area comprises the elongated hilly terrain of various altitudes along with isolated hillocks, plains and marshy lands. Altitude of elongated hill ranges and isolated hillocks varies between 820 to 2068 metre and 760 to 1100 metre above mean sea level respectively.
The rock formations in the catchment area are cretaceous limestone, the Disang with Serpentinites (Lower to Middle Eocene-Upper cretaceous), the Sumas and the Thipams (Miocene). Surma group occurs in the lower reaches of hills whereas the Disang and Thipam groups occur in high reaches of hills. Disang formation comprises grey sandstone-grit-conglomerate limestone sequences intruded by serpentinites containing minor amounts of enstalite, chromite, amphiboles and magnetite. The Surma and Thipam groups represented by argillaceous and arneceous sequence respectively.
3. Objectives
The present study lays the foundation for developing wetland conservation models using remote sensing and geo-spatial technologies. Some of the detailed objectives of the study area:
* Creation of temporal spatial database using satellite data for catchments (1995, 2000 and 2004-05) and structural components/ habitat types of wetlands
* Generation of Land Capability map for the catchment area for long term and short term management plan such as formulation of soil conservation plan to check soil erosion and subsequent silting up of Loktak Lake.
* Collection, integration and modeling for suggesting sustainable management solution for conservation of Loktak Wetland.
4. Data used/sources
The database of this catchment study consists of primary, secondary and integrated database of spatial and non-spatial data on different components of the catchment. Census data of 1991 & 2001 is used for socio-economic studies of the hill and valley region. Table 1.2 gives the list of satellite data use.
5. Methodology/Thematic Maps
Visual and digital image interpretation techniques were used to prepared thematic maps on 1:50,000 for 1990, 1995, 2000 using 23.5 meter resolution data of IRS-1C, 1D and 1:25,000 for 2004 -05 using high resolution data like IKONOS , for some area and merge data of 2.5 meter resolution using LISS-III and PAN data . Secondary data for socio-economic etc are also incorporated. The thematic maps are :
* Land use/cover
* Hydrogeomorphology
* Slope
* Drainage
* Road network
* Settlements.
A. Land Use/Cover :
Information on Land use/cover pattern, especially the extent and spatial distribution is a pre-requisite to derive information on temporal changes. The land use /cover information helps to identify areas where immediate attention has to be taken for reviving various landscape elements. The present status of land use (Table 5.1) in the catchment is useful for identifying locations for taking up soil conservation measures by involving village communities, for minimizing land degradation. Land use classification for 2004-05 is base on guideline of ‘Biodiversity Conservation in Wetland Project’ by Space Applications Centre, ISRO, Ahmedabad.
The land use class of wetland is further classified by preparing a structural components map of Loktak wetland area which shows various classes of phums, agriculture land, islands, aquaponds etc. In the present study SOI topography map of 1970 was use as a base to delineate water spread and demarcate wetland boundary. IKONOS data was use for preparation of the structural component map of 2004-05 (Table 5.2).
B. Hydrogeo-morphology: Information on landforms is an important input for land management and soil mapping. The aspects of morphology, morphogenesis, morpho chronology and morphometry are vital inputs in preparation of geomorphologic maps. —
The geomorphic units are delineated based on image characteristics like tone, texture, shape, colour, associations etc. (Fig.5.2 A).
C. Slope:
Information on slope is vital for suggesting actions related to restoration plans of landscape. This information is useful for suggesting checking of soil erosion and drainage related measures. The slope map has been prepared as per IMSD guidelines. Using this information Digital elevation model has been generated using 20 metre contour interval.
D. Drainage/Watershed:
A drainage map of the study area was prepared using satellite data in conjunction with SOI topography maps. Most of the streams originate from the hill ranges to the west of the lake and discharge water directly into Loktak Lake. Some of the major streams include Nambul, Nambol, Thongjaorok, Awang Kujairok, Awang Kharok, Ningthoukhong, Potsangba, Oinam, Keinau and Irulok contributing significant silt during rainy season to the lake. In all 12 micro-watershed were demarcated and they have been given nomenclature according to the standard of All India Soil and Land Use Surveys (AIS & LUS) of the Ministry of Agriculture. ( Fig. 5.2 B)
E. Road Network & Settlements:
The road transport network is one of the major criteria for studying and analyzing the socio-economic problem of a certain area and for assessment of impact on the wetland.
In the present study, there are three types of roads classified as National highway, Village road and other which may include footpaths etc. The total length of National Highway is 59.652, village road is 723.243 km and others are 234.5 km. (Fig. 5.2.C)
6. Results and analysis
i. Spatial Analysis: Land Use Change detection
Multi-temporal satellite data have been used for studying land use practices over a period of fifteen years in the catchment of Loktak Lake. It has been found that there is an increase in the built up area and also decrease in scrub forest. There was increase in dense forest from 1990 to 2002. This may be due to some of the activities of afforestation program taken up by LDA for catchment treatment but again this has decline in 2004-05 (Table5.1). There is an increase in open forest area in 2004 and decrease in degraded forest which again shows that deforestation activities have become less and natural regeneration is going on in the catchment area.
to be contd
Source: http://www.thesangaiexpress.com/Others/Articles.htm
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