Keithelmanbi, Gopibung and Parsai are the villages located about 39 km north of Imphal on the western side of National Highway. They are located on both side of Twineh stream (in Kuki 'Twi' means water and 'neh' means dirty) on the piedmont slope within 1 to 2 km from the National Highway. The actual spot of landslide, roughly half a sq km area, is nearly seven kilometers up in the upper course of Twineh stream. The steep slope begins from an altitude of 1800m above the sea level and goes up towards the ridge. The immediate up-slope hill of the landslide spot is steep slope with little vegetation but further up the terrain is covered with vegetation and remains cloudy most of the time during summer, which increases the water seepage activity. As reported by the villagers there are continuous rainfall and very heavy rain for about a week before the 10th July 2004. The saturated rock mass of the steep slopes fell down with big sounds late in the evening. A huge amount of rock fell and viscous fluid flew down along the channel of Twineh stream.

The devastation took place in the lower reach spreading the mudflow with huge deposition. The NH-39 was closed for some days because of it. The mudflow fanned out and extended upto the Imphal River.

So, far 11 houses of Keithelmanbi Kuki, 15 of Gopibung Kuki and five of Gopibung Nepali villages have been damaged. Besides, the violent current of mudflow also smashed two school building and one HT electric tower post. More than 180 persons were dislocated and have been staying in the Keithelmanbi relief camp and relatives's houses.

b) Landslide - II

Chandramal-Pukhri and Makuli are Nepali villages located on the upper Kalapahar area at the altitude of 1500 m above the sea level. The spots of landslides are on the southern side of Kali stream where one small branch of it traverses through.

Scarp face of above 450 slopes is the terrain feature. Up-slope terrain up to the top of hill is covered with vegetation and remains cloudy during the rainy season which gives a good amount of rain. Interestingly, there are small ponds (pukhris) just below the steep slope of escarpment, which increase the seepage of water. Along the channel, debris of the rocks composed of shale, mudstone, clay etc. are brought down. In and around ponds, landslides took place and the debris-flow joined the Kali stream that runs through the northern side of Kalapahar village. Here, the debris flow was not like that of Twineh stream, as those landslide spots scattered at this place are relatively small. However, the Kali stream is a mud-laden stream even today as it carries down a large amount of earth materials.

In this case, affected villages are near the landslides. The upper portion of Chandramal-pukhri village was seen with tension cracks. Nearly 32 houses of Chandramal-Pukhri and 21 houses of Makuli village were damaged. Two jersey cows lost their lives. Other household properties could be evacuated as the landslide impact took some hours. The affected family members of about 250 are still either in their relative houses or relief camp of lower Kalapahar village.

c) Landslide- III

Toribari is a Nepali village spread on both side of IT road, just one kilometer from Kangpokpi and 45 km from Imphal in the north. The landslide spots are 1600m above the sea level and extend for about one-fourth a kilometer in the NS direction at the middle of Toribari village. The steep slopes of between 300 and 600 and weakened rock masses of the area caused landslide when heavy rainfall took place.

Above the spot, Songpekjang, a Kuki village, is located. Wherever possible, the Nepalis do terrace farming. The location of two permanent small ponds at 1700m above the sea level, made for the supply of water for agriculture, however caused greater seepage of water situation during heavy rain at the place. It was on the afternoon 10th of July 2004 when the tragedy took place and a heap of rock mass started moving followed by the debris flow. As reported by the villagers, landslides occurred earlier also around two years back damaging some houses.

The small streams flowing downwards acted as channel for the movement of debris. The gravity force on semi-fluid debris was so strong that vast areas were damaged and tension cracks appeared. The high intensity of landslide continued for five days, and then the downward movement retarded. Even after two months the movement has not stopped as the soggy mass is well saturated. Nearly 40 houses have been damaged and 25 hectares of standing paddy crops got spoil. The affected families are still in four relief camps opened near the village.

Causes of landslides:

The following factors probably synchronized to have landslide along the fault line. Among them, factors (i) and (ii) are very important.

i) There is fault line on the border of the Disang and the Barail Groups and landslides occurred along the weak zone where sedimentary rocks such as sandstone, mudstone, shale, clay etc. dominate. The affected villages are along the piedmont region of the Koubru hills. Landslides occurred on the steep hill slopes exceeding 500 inclinations.

ii) During the months of June, July and August, high amount of rain occurred in Manipur. The moisture-laden wind of South West Monsoon by that time, met the stagnant moisture above the 2000m height of the Kourbru hills which caused heavy rainfall.

When the rainfall continued for several days the hill escarpments led to landslide and subsequently formed mudflow/earth flow/debris flow particularly in areas dominated by shale, clay and mudstone. The existing streams or small channels often guided the flows, sometimes with violent current depending on the terrain, slope, volume of water and loaded debris.

iii) All along the fracture zone, earth tremor is common. So there might be tremor upto 2-3 Richter scale. This minor jolt in combination with other factors could lead to landslides, especially during the rainy season. So, there was simultaneous occurrence of landslide on the above-mentioned spots and Tadubi area (landslide), which is also located along the fault line.

iv) The degradation of forests and removal of vegetation cover for agricultural activities on the steeper hill slopes is another factor created by man. There is increasing scale of degradation of forests with population increasing every year.

The exposed rocks and soils of steep slopes could not resist longer and lead to the occurrence of landslide or mass wasting. All the landslide spot of Koubru hill are characterized with deforested surface.

v) Creation of small ponds below the steep hill slopes for agricultural purpose is another factor. When heavy rainfall takes places, the collected water percolate to increase the soil moisture content of the surrounding land. This naturally link with small channels. In such a situation, the seepage and gravity cause landslide. Toribari, Chandramal and Makuli villages are examples.

Therefore, it is obvious that these areas are prone to landslide especially during the rainy season and so necessary precautionary measures are required.

The Landslide Survey team is grateful to the authority of TBA Church, Keithelmanbi village for providing free accommodation of 20 persons and also to the local people, for extending their full cooperation during the survey.

(Courtesy: The Sangai Express)