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CHAPTER 3

A GEOGRAPHICAL PROFILE OF THE STUDY AREA

3.1 GENERAL

Kothagiri is a sub district (tehesil or taluk) in the Nilgiris district, in the

state of Tamil Nadu, Southern India. This taluk has an extensive hilly and rocky area as

well as undulating terrain. The natural boundary of the plateau along much of its

Southern side is the Bhavani River and the Northern frontiers are bounded by Moyar

River. The entire taluk is hilly zones namely the Nilgiris plateau. In this region, the

majority of landslides occur in a loose cover of debris consisting of boulders. Inter hills

basin and valleys are found between the dissected hills and hill rocks. The plain area of

the taluk can found on north eastern side of Taluk. In recent times, casualties and

damages due to landslides have increased in the Kothagiri region during monsoon

season.

3.2 KOTHAGIRI TALUK –LOCATION

Kothagiri is situated at an average elevation of around 1793m above sea

level and it is one of the popular hill stations located in the Nilgiri District. This

picturesque hill station is bounded by verdant green tea estates and offers a number of

trekking options. It is one of the main taluk lies in Nilgiri District, Tamil Nadu,

Southern India. It is a inland taluk bounded in Sathiyamanagalam taluk on the East,

Mettupalayam taluk in South, Udhagamandalam and Coonoor in West, Gundulupet

taluk from Karnataka state on the North (Figure 3.1). The study area covers 396.65 Km2

and lies between latitudes 11° 10' 00"N to 11° 42' 00" N and longitudes 76° 14' 00" E to

76° 02' 00" E and located at 70 km northwest of Coimbatore city in Tamil Nadu which

falls with the Survey of India (SOI) toposheets 58 A/12 (NE, SE, NW, SW), 13(NE, SE,

NW, SW), and 15(NE, SE, NW, SW) at 1:25,000 scale.

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3.3 PHYSIOGRAPHY

Kothagiri Taluk the topography is rolling and steep. About 60% of the

cultivable land falls under the slopes ranging from 16 to 35%. Inter hills basin and

valleys are found between continues hills and hill rocks. The plain area of the taluk can

be found on northwestern side of study area. The topographical elevation values vary

between 242 m and 2630 m in Nilgiri Eastern Ghats reserve forest at rugged terrain with

gentle slopes and deeply incised northeastern part of the study area, relief is moderate

and low. Elevation and relief increases from southeast to northwest. In general two

different types of physiographic landforms have been identified in the region. Many of

the high peaks have steep rocky escarpments with or without soil cover are noted.

3.4 DRAINAGE

The drainage pattern of the Kothagiri Taluk is dendritic to radial at

places with prominent rapids, cascades and waterfalls. The natural boundary of the

plateau along much of its Southern side is the Bhavani River and the Northern frontiers

are bounded by Moyar River. These two rivers Bhavani and Moyar are the main river

streams that drain the Nilgiri hills, Pykara River, Sigur River, Kavithole halla,

Kedirayar halla, Kalavahalla, Madukadu halla and other streamlets originating from

northern parts of the Nilgiri hills flow northward to join Moyar River. The Moyar River

is originated from Bhandipur Reserve forest in Guldelpet district of Karnataka state, and

flows 300 km east thro ugh Tamil Nadu and Karnataka, The river Bhavani flows along

southern part of the study area, many minor streams originate in the hilly terrain.

Among such streams, Kuttaltorai Halla, Tatta Halla, Kothagiri Halla, Gundegal Halla,

Pattikombai stream and Kanduni perennial streams originate in the Nilgiri Eastern

Ghats reserve forest and Rangaswamy peak reserved forest, which flows towards the

north east and join the main river of Moyar. Segur halla, Gudakal halla, Yerkada halla,

Kallar Pallam other streams were originated from Kallur Reserve forest flows in the

South Easterly and Easterly directions to join the Bhavani River, Both the perennial

rivers are finally amalgamated in Bhavanisagar Reservoir which is situated in the

eastern part of the Nilgiri District. The drainage is dendritic to radial at places with

prominent rapids, cascades and waterfalls.

Figure 3.1 Location map of Study area.

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55

3.5 CLIMATE

The general climatic condition in this region is cool. The study area is

situated at the high elevation, result low temperature, which is further lowered by

excessive moisture content of the atmosphere resulting from the exaltation by the

vegetation. Although situated in the tropical zone, this region enjoys a sub-tropical to

temperate climate by virtue of its altitude. The variation of temperature throughout the

year exhibits a cold climatic condition in study area. Kothagiri enjoys a pleasant climate

throughout the year. Due to the presence of high mountain ranges, southwest monsoon

is not very strong but northeast monsoon causes heavy downpour during the months of

October and November. The region experiences an average maximum and minimum

temperature of 23.1o C and 5.1o C respectively. The coldest month is December and the

hottest month is April during which a dry wind blows from the North - East. Frosty

nights are common during January and February. Thunderstorms are frequent

throughout April and May and the monsoon brings in heavy rainfall. Wind velocity of

this region ranges between 13.4 Km/Hour and 4.4 Km/Hour. Humidity also ranges from

90% (December) to 95% (July). The region has four main seasons

• Cool Months - December to February

• Summer Months - March to May

• Windy Months - June to August and

• Rainy Months - September to November

Kothagiri experiences an average rainfall close to 2000 mm in a year and

its temperature ranges from 19°C in the winter months of December-February to 35°C

in the summer months of April-June. The temperature in November will be between 21-

30°C. Generally the region has a long spell of hot climate with a short spell of rainy

season and winter, which is mild one.

3.5.1 Temperature

Temperature is low during the month of January and the lowest average

mean daily temperature is below 5o C. The mean maximum daily temperature recorded

during the hot season in the month of May is 15o C to 35o C.

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3.5.2 Rainfall

The rainfall distribution is not homogeneous all over the study area, for

this reason an interpolation of annual precipitation data was applied to have a more

representative rainfall distribution. There has been a significant decrease in the number

of rainy days over the years. The first three months of the year are almost without any

rain. February shows no rainfall and the driest month recorded in this region. The

average annual rainfall during the period 1996 to 2013 for the study area was 1227.8

mm. The normal average rainfall in this region varies from place to place and is

somewhere between 1500 mm – 2000 mm. It is observed that storm rainfall values in

excess of 12.5 mm occurring for more than five minutes duration can cause run off and

soil detachment. Normally 70 percent of such storms occur in the months of October,

July, May and November in that order. Erosion intensity is high in May, October and

July. The incidence of drought is also common in the study area. From soil and water

conservation point of view, high incidence of drought during April and December,

excess rainfall noticed during July and October. The southwest monsoon accounts for

38% of the rainfall, while northeast monsoon accounts for 62 % of the rainfall. Figure

3.1 illustrate the average rainfall distribution in the study area.

Figure 3.2 Average rainfall distributions in mm (1996-2013)

3.5.3 Humidity

Mean relative humidity is high throughout the year, and varies from 62%

in May-July to 82% in October – December; June is recorded with lowest relative

humidity.

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3.6 REGIONAL GEOLOGY

Geologically the study area belongs to the Archean continental landmass

of the Indian peninsular region, composed of pre-cambrian metamorphic rocks such as

charnockites, gneisses, and crystalline schist. Due to geotectonic movements in the

southern Deccan resulted in its fragmentation and in vertical dislocations along fault

lines that are oriented in three main directions, namely, W-E, NNW-SSE, and NE-SW

and that recur in the morphological boundaries in the courses of many streams and

rivers of the region. Charnockite group of rocks with the enclaves of Satyamangalam

Schist Complex exposes 70% of the Kothagiri Taluk. This group represented by

chamcokite and pyroxene granulite and covers a southern part of the study area, which

is popularly known as Nilgiri Massif rock [62]. The Satyamangalam Schist Complex is

represented by banded magnetite quartzite, mica schist, and ultramafics. The Nilgiri

massif is capped by aluminous laterite at a number of places indicating the deep zone of

weathering [222]. A major part of study is underlaid by crystalline rocks comprising

Granite and Quartz vein groups of rocks of Archaean age. It is except for recent alluvial

deposits along major drainage courses and patches and Gondwana sediments. Most of

the parts of the district rocks are deeply weathered and the soil thickness is found to be

up to 40m with lithomarge is a common feature in the Taluk [222]. The spatial

distributions of regional geologic features are shown in Figure no 3.3

3.7 GEOMORPHOLOGY

The Geomorphology of Kothagiri taluk is comparatively highly

sensitive. Due to its topological conditions, the earth surface is always prone to

landslides and soil erosion. The geomorphology is created for the study area from the

geology and topographical map obtained from the Geological Survey of India. The

study area is a mountainous region of Nilgiri district with many hill ranges and broad

valleys with slopping towards plain. They are surrounded by the Coimbatore plains in

the southeast, Bhavani plains in the northeast, Moyar valley in the north and Ooty hills

in the Southwest.

Figure 3.3 Geology Map Figure 3.4 Geomorphology Map 58

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The prominent geomorphic units identified in the area through interpretation of Satellite

imagery are 1) Barren valley, 2) Dissected plateau, 3) Dissected Uplands, 4) Fracture

Valley fills, 5) Valley fills. The Kothagiri Hills rise abruptly from the plains 400 m

above Mean Sea Level (MSL) to an average elevation of 2500 m above MSL. Kothagiri

Taluk covers with prominent peaks like, Kolari (2625 m), Bhavani Betta (2456m) and

Deva Betta (2552 m), the conical grass covered Der Betta and Bear hill (2531 m) and

Nilgiri peak. Moyar is a prominent river in the district and flows in an easterly direction,

along the northern boundary of the region. The spatial distributions of geomorphologic

features are shown in Figure no 3.4

3.8 SOIL

In the study area, the soil is the charnockite group of bedrocks, covered

by the ubiquitous red laterite or lateritic soil. This is taken as a common factor for the

whole area. Because of its uniform nature, it is not taken into account for this study. The

soil of Kothagiri Taluk can broadly be classified into four major soil types viz., lateritic

soil, skeletal soil, lateritic soil with top humic layer and alluvial soil. Major part of the

Taluk was covered by lateritic soil and lateritic soil with top humic layer, red skeletal

soil and alluvial loams are occurring as small patches. Alluvial soil is developed in the

valleys; where the water logging is also common during the monsoon period. The

alluvial soils are seen along the valleys and major river courses respectively.

The Kothagiri falls in the tropical zone of weathering. Most part of the

study area is deeply weathered and at some places thick soil cover of up to 40 m was

found. The exposed area reveals a humus zone of 0.50 to 1.0 m followed by red or

brown or yellow silt and clay. The weathered zone between the clay and the fresh rock

is normally about a meter thick. The soils are derived from rocks, having an admixture

of organic matter and capable of supporting vegetation. Intense rainstorm followed by

dry period has helped formation of considerable depth of weathering and at some places

extended up to 45 m. Rocks seen along gentle slopes in few road cuttings are only

boulders derived from bluffs [223].

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3.9 DEMOGRAPHIC DETAILS

3.9.1 Settlement

The taluk is located over an elevation range of 242 -2,636 m above sea

level, comprising hilly peaks, plateau and lower plateau regions - most of the

settlements are located in the Kodandu and Kothagiri regions. This taluk is home to a

number of indigenous communities and they include the Kurumbas, Jenukurumbas,

Bettu Kurumbas, Mullu Kurumbas, Todas, Badagas, Kotas,, Irulas, Paniyas and

Mandadan Chettis. Spatial-temporal taluk exist, where cultures converge like the Kotas

– Todas –Badagas in the upper areas (Kodanadu), the Irulas-Kurumbas (in the lower

areas), the urban and migrant population in the middle elevations. According to the

2011 census, the Kothagiri taluk total population had a population of 108,684. Of this

about 66,094 people are living in the urban (towns and cities) area and about 42,590 are

living in villages (rural areas). There are 31,168 households in this taluk. There are

52,668 males (48%); There are 56,016 females (52%) in the study area.

Total Scheduled Caste population is 29816, representing nearly 27.43%

of the population. The Scheduled Tribe population is 6,312 representing nearly 5.8 % of

the total taluk population. The Scheduled Caste population is distributed equally in rural

and semiurban areas, whereas three fourth of the Scheduled Tribes are living in rural

areas. Todas, Kothas, Kurumbas, Paniyas and Irulas are the important tribes in the study

area.

3.9.2 Sex Ratio

While the population is 108,684, there are 52,668 males and 56,016

females. Further the children below 6 years of age are 9,125 of which 4,666 are males

and 4,459 are females [224]. Workers in the State of Kothagiri are calculated as 57,588

of which 32,274 are males and 25,314 are females. Further 54,139 are regular and 3,449

are irregular i.e. get jobs only few days in a month. There are 51,096 Non Workers

include students, house wives, and children above 6 years also [224].The following

table show demographic details of the study area Population in 2011 Table 3.1.

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Table 3.1 Distribution of Population in Kothagiri Taluk (Village wise)

( Source : Population Statistics Census, 2011) [224]

3.9.3 Literacy

The total literates are 82,681 of which males are 43,947 and females are

38,734. There are 26,003 Illiterates like population; here also the ratio of literate male to

female is in favor of male only 53.15 % versus 46.85%

3.10 AGRICULTURE AND HORTICULTURE

The Kothagiri Taluk is basically a Horticulture taluk, and its economy

depends largely upon the success or failure of horticulture crops like Potato, Cabbage,

Carrot, Tea, Coffee, Spices and Fruits. The main cultivation is plantation crops, viz., tea

Village

Name

Total

Population

Total

Male

Total

Female

Total

literacy

Male

literacy

Female

literacy

Illiter

acy

Aracode 781 386 395 484 270 297 297

Denad 8,284 4,061 4,223 6,338 3,408 2,930 1,946

Hallimoyar 225 113 112 165 80 85 60

Jagathala (TP ) 4,602 2,276 2,326 3,286 1,794 1,492 1,316

Kadinamala 407 198 209 268 147 121 139

Kallampalayam 1,691 851 840 1,004 571 433 687

Kengarai 6,820 3,348 3,472 5,090 2,810 2,280 1,730

Kodanad 4,153 2,022 2,131 2,874 1,626 1,248 1,279

Kokkode 147 74 73 80 49 31 67

Konakarai 7,511 3,676 3,835 5,760 3,081 2,679 1,751

Kothagiri 7,952 3,755 4,197 6,110 3,215 2,895 1,842

Naduhatty 10,278 4,946 5,332 7,660 4,106 3,554 2,618

Nandipuram 172 77 95 113 60 52 59

Nedugula 13,071 6,374 6,697 9,421 5,190 4,231 3,650

Kothagiri (TP) 42,590 27,271 25,050 39,118 17,540 16,406 12,931

Total 108,684 52,668 56,016 82,681 43,947 38,734 26,003

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and coffee, but with some cardamom, pepper and rubber too. Tea grows at elevations

from 1,000 to over 2,400 meters [225]. The area also produces Eucalyptus oil and

temperate-zone vegetables. Potato and other vegetables are raised throughout southern

part Taluks. Paddy is also grown in the Thengumarahada area in Kothagiri Taluk.

Besides these crops, millets, wheat, fruit and vegetables, etc., are also found throughout

the Taluk. There are no irrigation schemes here. The crops are mainly rain-fed. Check

dams have been constructed wherever possible to exploit natural springs.

3.11 LAND USE PATTERN

The study area was brought under cultivation more than one hundred

years ago by British people. Earlier to the arrival of British settlers, they introduced

potato, tea, temperate fruit trees, eucalyptus, and acacia. It was a well preserved tribal

tract with small scattered pockets of cultivated areas and did not harm to the tract. The

major consequence of this region recognized rapid land use change is the ecosystem

functioning and loss of biodiversity. The rate of biodiversity loss has been accelerating

rapidly throughout the industrial era. Major changes in this region are human activities,

particularly through large scale construction identified as the major cause of the

dramatic changes in landuse patterns.

3.12 NATURAL VEGETATION

The vegetation types of this region are several like the montane shola

forests & grasslands, evergreen, moist deciduous in the middle escarpments and dry

deciduous towards the lower slopes and finally scrub jungle towards the extreme eastern

slopes. All these forests are classified under the reserve forests and have special

protection status. The forest cover of this taluk is nearly 32 % compared to the other

taluks of the district. The major land holdings are with the private estates and the small

farmers mainly cultivating mono crops like the tea & coffee with horticulture species

like fruits etc. Few valleys are known for vegetable cultivation in this taluk like the

Nedugula, Kodanad valley etc.

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3.13 TRANSPORTATION

Kothagiri is linked by road to Mettupalayam and Ooty. The road which

continues on to Ooty (27 km from Kothagiri to Ooty) is one of the Nilgiri Ghat Roads

and is now one of the five access routes for the entire study area. Coonoor is 23 km

from Kothagiri and connected by a road that branch off the Ooty road. Buses to

Kothagiri are available from Mettupalayam near Coimbatore in the foothills and also

from Ooty and other places. Kothagiri is well-connected with all the major cities of

Tamil Nadu by road. There are regular bus services from Ooty, Mettupalayam and

Coonoor. The nearest railhead is in Coonoor. There is no railway station near to

Kothagiri Taluk in less than 10 km. However, Mettupalayam junction railway station is

major railway station 35 KM near to Kothagiri. The nearest airport is in Coimbatore

International Airport (65 km) which is well-linked to cities like to all the major cities in

India.

3.14 TOURISM

Kothagiri is situated at an elevation of around 1793m above sea level and

is one of the popular hill stations located in the Nilgiris. This picturesque hill station is

bounded by verdant green tea estates and offers a number of trekking options. This old

hill station has been developed around innumerable knolls and valleys. The Doddabetta

Range is 22 km away. Catherine Falls, Elk Falls and Rangaswami Pillar are the major

attractions in Kothagiri taluk. Kodanad View Point offers a spectacular view of the

gentle sloping hills and blue hills. There is another jungle trekking trail that leads you to

a small stream of water. The three popular trekking trails are Kothagiri - Kodanad;

Kothagiri - St. Catherine Falls and Kothagiri - Longwood Shola. The Kothagiri to

Kodanad trail leads to through splendid views of lush-green tea estates and the

magnificent Moyar River. One has to cross through meadows to reach Kodanad.

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3.15 HISTORY OF LANDSLIDES IN KOTHAGIRI REGION The Kothagiri, Conoor and Ooty regions in Nilgiri district have a long

history of disastrous landslide events. Generally in the monsoon season (October to

December) in Indian subcontinent, landslides are triggered by the heavy intense rainfall

in the region. In 1881, Kothagiri to Mettupalayam road was damaged by a heavy

rainstorm. In that same year landslips smothered the Kothagiri Ghat road at many

places. After 10 years, a record rainfall of 74cm within few days at Kotagiri brought

traffic to a standstill for about three weeks due to many landslips on the Mettupalayam

to Kothagiri highway. There was a heavy thunder storm with 53cm of rain in Kothagiri

in 1891, brought major destruction on the road side. A rainfall of 129 cm was recorded

in a short period causing disastrous floods during year December 1902 [165]. The

continuous weaker zone near Kattambettu to Ooty highways was identified in the

1920’s when the locality was affected by debris falling over the road straggling with its

side. Many people were killed in Kothagiri and Ooty region on account of houses

collapses, landslides and drowning in November 1978. After the next year there was

heavy rain of 105.2mm at Coonoor and Kothagiri hills and a heavy landslide at Coonoor

to Kothagiri region in which a house was completely buried in the debris flow. There

was another 'cloud burst' on 1993 in the upper reach of Yedappalli of Kothagiri Taluk,

about 12 huts situated below the road and washing away Kothagiri to Coonoor

Roadway. More than 60 landslips were reported in the early hours on 14 November

2009 killing one and injuring three persons and disrupting traffic in Ooty. In 2010 there

were 92 landslips reported in Kothagiri region out of these landslides about 78% are

major slips.

3.16 REASONS FOR LANDSLIDE IN KOTHAGIRI REGION

There is human interaction by means of unplanned constructional

activities like excavations, mining and undercutting of roadside, exploitation of forest

resource, and irregular cropping pattern, it causes substantial changes in the geo

environmental of the Kothagiri regions. Many of the environmental problems observed

during the field visits which are described as follows

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3.16.1 Exploitation of Forest Resources

The variety and dense growth of vegetation is an important characteristic

feature of the study area. Due to result of climatic, physiographic factors this region till

now contains a very rich variety of vegetation. The impact of strong moisture-laden

monsoon winds greatly influences the growth of vegetation. The evergreen forest areas

are heterogeneous but mainly intercepted by terraced cultivation land. Most of the

plants in Kothagiri forest used for ethno-medicinal purpose and forest or biodiversity

management of local people that indirectly helps in protection and reduces the scope of

landslide. Illegal logging and establishment of plantations are responsible for

deforestation and subsequent soil erosion turning into severe landslide in this region.

3.16.2 Construction Activities

3.16.2.1 Roads

There is a rapid flow of road construction, all over the region. This is

being done because the economy of this taluk by many ways is tourism based. The

construction of a hill road involves felling existing vegetation, cutting and blasting

stable slopes, and rolling down of resultant debris that in turn destroys vegetation and

causes severe erosion resulting landslides in this taluk. Every year landslides take place

along the roads and block communications. Here, road construction could not be held

responsible for landslide. Due to population growth in the city centre, the human

settlements are relocated to remote areas, so the existing roads of the taluk are laid in

such a way to connects even remote forest areas to the nearest urban centre.

3.16.2.2 Buildings

Landslides due to the construction of buildings and other infrastructures

have been cleared the large area of the forest in the urban and semi-urban areas of hilly

region. Many buildings and infrastructures especially those located on steep high slopes

usually fail due to landslides causing the loss of property and lives in Kothagiri and its

surrounding regions.