**3. Land-use/cover change**

236 Ecosystems Biodiversity

Fig. 1. Location of Loktak Lake

Land is used to meet a multiplicity and variety of human needs and to serve numerous and diverse purposes. When the users of land decide to employ its resources towards different purposes, land-use change occurs producing both desirable and undesirable impacts. Landuse is the utilization of all developed and vacant lands on a specific space at a given time. The increasing pressure due to population and human activities of land resources to meet the increasing demands are contributing to significant transformation of land for a variety of land-uses.

Shifting cultivation is the characteristic feature of agriculture in the hilly catchments of the Loktak Lake. This form of land-use practices occupies a distinct position in the tribal economy, with about 74% of the tribal population deriving its sustenance from this traditional mode of agriculture. But due to rapid increase in population, the shifting cycle which until a few decades was more than 20 years has reduced to less than five years. This reduction has led to land degradation and increased soil erosion leading to sedimentation of water bodies consequently reducing its water holding and overall carrying capacity. The analysis of land-use/cover change is essential to formulate the suitable plan for lake conservation.

The data for land-use\cover of Loktak Lake catchment have been derived from secondary sources. The temporal land-use/cover data of Loktak Lake catchment of 1990 and 2004 including structural component data of 2004 have been obtained from Loktak Development Authority and Manipur Remote Sensing Application Centre, Imphal. The land-use/cover map has been prepared by using high resolution data like IKONOS satellite, for some area and merge data of 2.5m resolution using LISS-III (Linear Imaging Self Scanner) and PAN (Panchromatic) data. By comparing the temporal land-use data of 1990 and 2004, major land-use/cover changes that occur between the two periods were obtained. Intensive field investigations were carried out for ground verification.

Ecological Studies of Wetland Ecosystem in Manipur Valley from Management Perspectives 239

During the 15-years period, the major land-use/cover changes are the expansion of built up area, open forest, aqua-ponds/water bodies and wetland (Table 2). There was increased in built up land up by 0.86 % which was the result of rapid urbanization in the Loktak catchment. The urban population in the catchment has grown at an annual rate of 3.5% during 1991-2001. The increased in open forest area by 9.39% in 2004 and decrease in degraded forest area by 5.58% shows that the activities of afforestation program have been taken up by Lake Development Authority (LDA) for catchment treatment that reduces the shifting cultivation area by 1.27% and ultimately led to the process of natural regeneration in the catchment area. However, there was decreased in dense forest area from 1990 to 2004 by 0.89% which was the effect of past deforestation that need some span of years to regenerate again. The evidence of regeneration is very much clear from the open forest area which increased up to 9.39% in 2004. There has been an increase in the water bodies\aquaponds by 1.31%. This is mainly due to conversion of agriculture and marshy/swampy land into aqua-ponds as a result of inundation after the construction of Ithai barrage. This process led to the decreased of agriculture land and Marshy/swampy land by 0.66% and 0.12%, respectively (Table 2). Off the valley's 22 lakes, 9 have silted up and drained for cultivation in the last two or three decades. Loktak Lake itself has shrunk from 495 km2 in 1971 to just 289 km2 (Singh, 1989), whereas increase in the number of athapham in lake resulted in prolific growth of *phumdis*. The *phumdis* cover in the lake has increased significantly from 57% in 1989 to 74% in 2002. *Phumdis* in the central zone have increased at an annual rate of

The Loktak Lake has been the subject of study since 1950s with the primary objective of flood control and optimal use of water resources for accelerated economic development in the region. Water regime of Loktak Lake is determined by the inflow from various streams and direct precipitation on the lake surface. Overall 34 streams from the western hills and the Manipur river via Ungamel and Khordak channels drain into the lake. The hydrological

analysis of the lake is investigated in detail viz., discharge and sediment etc.

Open water 2634 10.19 Dense phum 9176 35.52 Moderate phum 1058 4.09 Sparse phum 1744 6.75 Aqua-ponds 6911 26.75 Agriculture 32 0.12 Island with vegetation 288 1.11 Island without vegetation 66 0.25 Settlement 80 0.30 Phum ring area 3841 14.87 Total 25830 100

(ha) (%)

Habitat type Area

Source: Loktak Lake Development Authority

5.7% (Raleng, 2010).

**4. Hydrological analyses** 

Table 3. Structural components of wetland area, 2004

A detailed land-use/cover inventory was developed to assess the current status of the lake catchment and presented in Table 2. The land-use/cover pattern in the lake catchment as a whole showed about 13.99% and 14.85% area under built-up land in 1990 and 2004, respectively. Agriculture is the main occupation of both the people living in the hill and valley area of Loktak Lake. The total agriculture land in the valley accounts for 36.28% and 35.62% in 1990 and 2004, respectively. On the other hand, shifting cultivation or *Jhum*  cultivation is a very popular practice in the hill catchments. This type of cultivation is also known as slash and burn cultivation and account for 3.01% and 1.74% in 1990 and 2004, respectively. The total forest land in the lake catchment covered about dense forests have more than 40% canopy and accounts for 1.43% and 0.56% of the total area of the catchment in 1990 and 2004, respectively. The area where canopy cover is less than 10% is considered as degraded forest and its area accounts for 8.95% and 3.35% of the total area of the catchment in 1990 and 2004, respectively. Scrub land is observed mostly in the periphery of dense forest. The total areas under this class accounts for 9.35% and 5.80% in 1990 and 2004, respectively. Open forest represents the forest areas which were earlier deforested and presently natural regeneration is going on. The total areas under this class accounts for 0.37% and 9.76% in 1990 and 2004, respectively. The area under marshy/swampy class accounts about 0.60% and 0.84%, whereas hills/hillocks about 0.72% and 0.67% in 1990 and 2004, respectively. Area under water bodies such as ponds, reservoirs, rivers and aquaculture ponds are clubbed together and accounts for 0.93% and 2.24% in 1990 and 2004, respectively. The total area under wetlands accounts for 24.33% and 24.84% in 1990 and 2004, respectively (Table 2). The detailed descriptions of wetlands are presented in Table 3.


Source: Loktak Development Authority (LDA)

Table 2. Area under different land-use/cover in Loktak Lake



Source: Loktak Lake Development Authority

238 Ecosystems Biodiversity

A detailed land-use/cover inventory was developed to assess the current status of the lake catchment and presented in Table 2. The land-use/cover pattern in the lake catchment as a whole showed about 13.99% and 14.85% area under built-up land in 1990 and 2004, respectively. Agriculture is the main occupation of both the people living in the hill and valley area of Loktak Lake. The total agriculture land in the valley accounts for 36.28% and 35.62% in 1990 and 2004, respectively. On the other hand, shifting cultivation or *Jhum*  cultivation is a very popular practice in the hill catchments. This type of cultivation is also known as slash and burn cultivation and account for 3.01% and 1.74% in 1990 and 2004, respectively. The total forest land in the lake catchment covered about dense forests have more than 40% canopy and accounts for 1.43% and 0.56% of the total area of the catchment in 1990 and 2004, respectively. The area where canopy cover is less than 10% is considered as degraded forest and its area accounts for 8.95% and 3.35% of the total area of the catchment in 1990 and 2004, respectively. Scrub land is observed mostly in the periphery of dense forest. The total areas under this class accounts for 9.35% and 5.80% in 1990 and 2004, respectively. Open forest represents the forest areas which were earlier deforested and presently natural regeneration is going on. The total areas under this class accounts for 0.37% and 9.76% in 1990 and 2004, respectively. The area under marshy/swampy class accounts about 0.60% and 0.84%, whereas hills/hillocks about 0.72% and 0.67% in 1990 and 2004, respectively. Area under water bodies such as ponds, reservoirs, rivers and aquaculture ponds are clubbed together and accounts for 0.93% and 2.24% in 1990 and 2004, respectively. The total area under wetlands accounts for 24.33% and 24.84% in 1990 and 2004, respectively (Table 2). The detailed descriptions of wetlands are presented in Table 3.

Land use Classes 1990 2004 Variations (%)

Built-up land 14558 13.99 15448 14.85 0.86 Agricultural land 37735 36.28 37055 35.62 -0.66 Shifting cultivation 3131 3.01 1811 1.74 -1.27 Dense forest 1493 1.43 586 0.56 -0.89 Open forest 391 0.37 10160 9.76 9.39 Degraded forest 9312 8.95 3514 3.35 -5.58 Scrub forest 9732 9.35 6042 5.80 -3.55 Marshy/swampy land 631 0.60 509 0.48 -0.12 Hill / hillocks 755 0.72 705 0.67 -0.05 Aqua-ponds/water bodies 974 0.93 2331 2.24 1.31 Wetland 25312 24.33 25839 24.84 0.51 TOTAL 104000 100 104000 100 -

Source: Loktak Development Authority (LDA)

Table 2. Area under different land-use/cover in Loktak Lake

(ha) (%) (ha) (%)

(1990-2004) Area

Table 3. Structural components of wetland area, 2004

During the 15-years period, the major land-use/cover changes are the expansion of built up area, open forest, aqua-ponds/water bodies and wetland (Table 2). There was increased in built up land up by 0.86 % which was the result of rapid urbanization in the Loktak catchment. The urban population in the catchment has grown at an annual rate of 3.5% during 1991-2001. The increased in open forest area by 9.39% in 2004 and decrease in degraded forest area by 5.58% shows that the activities of afforestation program have been taken up by Lake Development Authority (LDA) for catchment treatment that reduces the shifting cultivation area by 1.27% and ultimately led to the process of natural regeneration in the catchment area. However, there was decreased in dense forest area from 1990 to 2004 by 0.89% which was the effect of past deforestation that need some span of years to regenerate again. The evidence of regeneration is very much clear from the open forest area which increased up to 9.39% in 2004. There has been an increase in the water bodies\aquaponds by 1.31%. This is mainly due to conversion of agriculture and marshy/swampy land into aqua-ponds as a result of inundation after the construction of Ithai barrage. This process led to the decreased of agriculture land and Marshy/swampy land by 0.66% and 0.12%, respectively (Table 2). Off the valley's 22 lakes, 9 have silted up and drained for cultivation in the last two or three decades. Loktak Lake itself has shrunk from 495 km2 in 1971 to just 289 km2 (Singh, 1989), whereas increase in the number of athapham in lake resulted in prolific growth of *phumdis*. The *phumdis* cover in the lake has increased significantly from 57% in 1989 to 74% in 2002. *Phumdis* in the central zone have increased at an annual rate of 5.7% (Raleng, 2010).
