PREPERATION OF STATUS REPORT OF PERAMBALUR DISTRICT

Sponsored by STATE LAND USE BOARD

CHEPAUK, CHENNAI 600005

Prepared by AGRICULTURAL ENGINEERING DEPARTMENT

NANDANAM, CHENNAI 600035

Contents S. No. Title Page.

1 Introduction 1

2 Study area 6

2.1 Population 7

2.2 Rainfall 7

2.3 Temperature 8

2.4 Drainage 9

2.5 Geo-Morphology 10

2.6 Geology 11

2.7 Lineaments 13

2.8 Hydrogeology 13

2.9 Land Use Pattern 13

2.10 Forest 15

2.11 Irrigation 16

2.12 Soil 18

2.13 Mines 21

3 Methodology 24

3.1 Aim and Objective 25

3.2 Methods follow for obtaining the objectives – 1 & 2 25

3.3 Sequential stage followed to obtain the above

objectives.

27

3.4 Methods followed for obtaining the objectives-3 27

4 Erosion 31

4.1 Slope 32

4.2 Land Use Pattern 34

4.3 Rainfall and run-off 36

4.4 Vegetation 37

4.5 Geology and Structure 41

4.6 Top soil thickness

4.7 USLE

4.8 Preparation of Erosion intensity map. 48

4.9 Interpretation 48

5 Eco-degradation 51

5.1 Eco-degradation due to mine pits 51

5.2 Ecological Restoration 52

5.3 Restoration of mine sites 53

5.4 Conservation of mine sites and storage water tanks. 55

6 Conclusion and recommendation. 57

APPENDIX

(Results of some geophysical surveys conducted)

PLATES

List of Figures

Fig. No.

Title

1. Location map

2. Rainfall Pattern in Perambalur District

3. Drainage Map

4. Geo-morphology

5. Spatial distribution of different Geo-morphological feature.

6. Geology map

7. Land use Pattern

8. Percentage of area covered by different land use classes.

9. Area extent of forest in different taluks.

10. Soil map of the study area.

11. Percentage distribution of soil types.

12. Percentage distribution of Calcereousness in soil of study area.

13. Mine distribution in Perambalur District.

14 Wenner configuration used in the study.

15. Slope map of study area.

16. Gully development in soft easily eroded formations along

ottakovil highway

17. Detailed Land use pattern of Perambalur District.

18. Representation of different Land use classes

19. Spectral reflectance characteristics of common earth surface

materials.

20. NDVI

21. Extent of different Geological formation

22. Top Soil Thickness

23. Flow chart of USLE

24. Soil Erosion

25. Regional extent of soil erosion.

26 Watershed map of the study area

27. Soil erosion map on Micro Watershed basis.

28. Eco-degradation due to mines.

List of Tables

No. Title Page.

1. Area and extent of Panchayat Union as

different taluks, Study Area, Average.

6

2. Rainfall pattern for a period of 70 years in the

study area.

7

3. Monthly Temperature 9

4. Details of River basins in Perambalur District. 10

5. Geographical area of different land use

classes.

14

6. Extent under different crops. 16

7. Cropping Calendar. 17

8. Sources of Irrigation. 18

9. Calcereousness in Soil 19

10. Resistivity ranges for different rocks

11. Area covered by different land use pattern 35

12. K. Values for different soil textures. 46

13. P. Value for different conservation practices. 47

14 P. factor for different land use value 47

15. The attribute values for different factors. 48

16. Percentage of area covered by different zones. 49

PREPARATION OF STATUS REPORT OF PERAMBALUR DISTRICT ON INTEGRATED ECODIVERSIFICATION

INTRODUCTION

Land and water are important natural resources for any form of life sustaining

activity. Their maintenance and improvement lay the foundation of productive,

economically viable, environmentally friendly and socially acceptable system.

Therefore proper conservation and management of these resources yields

long-term protective and productive benefits. Since both of these resources

are in fact limited, these are to be used most optimally and judiciously. Mining

is one of the oldest activities in which man is engaged perhaps after

agriculture, for his subsistence. In fact advancement of civilization has gone

with use of mental and other ore. Hence dependence on mining is increased;

today man is depending on mined materials for industry, energy, agriculture,

construction of buildings and for so many day-to-day requirements for our life.

Vast areas of land all over the world have been rendered unproductive by

human activities. The situation is particularly alarming in tropical areas where

forest loss and degradation, as well as degradation of land that earlier

supported forest, are proceeding at unprecedented rates. Ecosystem

destruction by mining for limestone, quarrying for minerals, and other

processes to meet demands of industries, is an inevitable part of civilization.

The increasing human need for these resources will certainly accelerate

further degradation of natural habitats, as most of the mining areas are on the

land, which was previously occupied by forests. All these will lead to

acceleration of erosion of biological diversity and creation of several other

environmental problems. The mineral extraction process drastically alters the

physical and biological nature of a mined area. Strip-mining, commonly

practiced to recover limestone reserves, destroys vegetation, causes

extensive soil damage and destruction and alters microbial communities. In

the process of removing desired mineral material, the original vegetation is

inevitably destroyed and soil is lost or buried by waste. We are usually

confronted with a complete absence of soil, in either a pedological or a

biological sense, and what is left is just a skeleton full of limiting factors. Strip-

mining can cause compaction, changes in soil texture, loss of soil structure

and reduced water infiltration. In addition, steep-sided soil piles are prone to

erosion.

India is endowed with a wide range of natural resources. Mining industry in

India has been growing at an annual rate of 4 to 5% during last three decades.

With the entry of Indian private sector and foreign equity participation in the

mining sector, the growth is expected to increase further. Presently, both

opencast and underground mining practices are prevalent in India. The extent

of environmental damage caused by mining varies with the scale of operation,

mining technology, nature of topography, etc.

In India, the area rendered waste by mining operation is very small. Even this

relatively microscopic proportion of wasteland is significant for its devastating

effect on environment. Total India’s limestone reserves are estimated about

93623 million tones. Limestone are extensively utilizing for manufacturing of

cement and also building stones.

Tamil Nadu ranks seventh in the country in terms of production of Limestone.

Limestone based Cement and Chemical industries have been flourishing for

the past three decades, as cement grade limestone deposits are abundant in

the State. They occur in the districts of Perambalur, Tirunelveli, Thoothukkudi,

Virudhunagar, Salem, Karur, Namakkal, Dindigul, Coimbatore and Madurai

The total limestone reserves are about 1,473 million tonnes. There are 12

major cement plants functioning in the State. The major players are Tamil

Nadu Cements (TANCEM), Dalmia Cements, Madras Cements, India

Cements, Grasim Industries, Associated Cement Companies and Chettinad

Cements.

These open cast mines result in the extensive removal of overburden. The

excavated overburden is piled up along the mine boundaries inducing soil

erosion, affecting soil profile and fertility. Problems associated with soil

2

erosion, movement and deposition of sediment in rivers, lakes and estuaries

persist through the geologic ages in almost all parts of the earth. But the

situation is aggravated in recent times with man's increasing interventions with

the environment. At present, the quality of available data is extremely uneven.

Land use planning based on unreliable data can lead to costly and gross

errors. Soil erosion research is a capital-intensive and time-consuming

exercise. Global extrapolation on the basis of few data collected by diverse

and non-standardized methods can lead to gross errors and it can also lead to

costly mistakes and misjudgements on critical policy issues. Remote sensing

provides convenient solution for this problem. Further, voluminous data

gathered with the help of remote sensing techniques are better handled and

utilized with the help of Geographical Information Systems (GIS). In this case

study, GIS functionality were extensively utilized in the preparation of erosion

and natural resources inventory and their analysis for assessing soil erosion

and soil conservation planning. Scientific management of soil, water and

vegetation resources on watershed basis is, very important to arrest erosion

and rapid siltation in rivers, lakes and estuaries. It is, however, realized that

due to financial and organizational constraints, it is not feasible to treat the

entire watershed within a short time. Prioritization of watersheds on the basis

of those sub-watersheds within a watershed which contribute maximum

sediment yield obviously should determine our priority to evolve appropriate

conservation management strategy so that maximum benefit can be derived

out of any such money-time-effort making scheme.

A recent national workshop on "Drought management - space inputs" by the

centre and ISRO, recommended greater use of space inputs at State and

district levels for planning and implementation of watershed projects and

taking up agro-horticulture in drought-prone areas using space inputs. It

suggested the establishment of decision support system using space inputs at

district and taluk levels for effective planning and decision-making it is in this

direction the current work has been in carried out.

3

Twenty-four scientists were analysing the contents of the soil collected from

different districts of Andhra Pradesh for Soil mapping through satellite remote

sensing on techniques on a scale of 1:50,000 (one cm on map is equivalent to

500 metres on the ground) of the entire State would be completed in three

years. Tumkur, Kolar, Bangalore Urban, Bagalkot, Dharwad, Bijapur,

Dakshina Kanada, Udupi and Uttara Kannada districts had been covered. The

database in Geographic Information System (GIS) had been created for those

districts. Hence similar kind of work has been attempted to serve as a ready

reconer for future development in the proposed Perambalur region.

4

2. STUDY AREA

Perambalur district is a centrally located inland district of Tamilnadu, spread

over 3690.07 sq.kms, which was trifurcated from the erstwhile composite

Tiruchirappalli district and was formed on 1 November 1995. The district is

bounded by Cuddalore district in the North, Tiruchirappalli district in the South,

Thanjavur in the East and Namakkal and Tiruchirappalli districts in the West.

Perambalur District lies in the geographical co-ordinates of East longitude

78o36’ and 79o31’ and North latitude 10o51’ and 10o31’.

The district for administrative purpose has been divided into six Taluks

(Perambalur, Kunnam, Veppanthattai, Ariyalur, Sendurai and Jayakondam),

which is further sub-divided into ten blocks viz.

Table 1: Area and Extent of Panchayat unions in different taluks

SI.No. Taluks Panchayat unions Extent of taluks (ha)

No. of revenue villages

1. Ariyalur 1. Ariyalur

2. Thirumanoor 67,650 68

3. Veppur . 2. Kunnam

4. Alathur 84,680 80

3. Perambalur 5. Perambalur 33,684 26

4. Sendurai 6. Sendurai 31,452 28

7. Jeyamkondam 8. T.Pazhur 5. Udaiyarpalaiyam 9. Andimadam

94,269 96

6. Veppanthattai 10.Veppanthattai 57,372 38

Total 3,69,107 336

Perambalur, Veppanthattai, Veppur, Alathur, Ariyalur, Thirumanur, Sendurai,

Jayakondam, Andimadam and T.Palur) comprising of 327 Villages, 322

Village Panchayats and nine Town Panchayats.

5

2.1. POPULATION

The total population of the district as per 2001 census is 11,81,029 of which

5,88,441 are males and 5,92,588 are females. The sex ratio is 1007 with the

birth rate at 21.6 and the death rate at 7.7. The density of population of the

district per sq.km is 281 persons as against the state average of 429 persons.

(Census,2001)

2.2 RAINFALL

The annual distribution of rainfall in all the six taluks of Perambalur district

over a period of 70 years is furnished below:

Table 2: Average Rainfall pattern for a period of 70 years in the study area.

Seasonal rainfall

South West Monsoon

North East Monsoon

Winter Summer Mean annual rainfall

(June - Sep) (Oct - Dee) (Jan - Feb) (Mar - May)

S.No. Taluks

(mm) mm % mm % Mm % mm %

1. Ariyalur 829 328 39.6 381 45.9 23 2.8 97 11.7

2. Kunnam 832 306 36.8 414 49.8 23 2.7 88 10.7

3. Perambalur 952 220 23.2 589 61.8 30 3.2 112 11.8

4. Sendurai 923 324 35.1 503 54.5 22 2.4 74 8.0

5. Udaiyarpalaiyam 1110 418 37.7 570 51.3 43 3.9 79 7.1

6. Veppanthattai 801 284 35.5 394 49.1 26 3.3 97 12.1

The data shows that on an average the amount of rainfall received remains to

be the same. It is also evident rainfall is received in all four periods of which

the maximum rainfall is during Northeast Monsoon, followed by southwest

monsoon and the minimum rainfall was noted in winter.

7

The average rainfall in the district shows a minor increasing trend with less

slope (Fig 2). The increase in rainfall results in accelerated erosion factors

under favourable conditions.

Fig 2. Rainfall pattern in Perambalur District.

2.3 TEMPERATURE

The atmospheric temperature data recorded over a period of 70 years (1927 -

1996) was computed and the mean maximum and mean minimum

temperature were arrived using graph. It is seen that the not months are April,

May and June with the maximum temperature ranging from 38° to 39°C and

the cool months being January and February with the minimum temperature

ranging from 20°C to 21°C.

8

Table 3: Monthly Temperature (oC)

Temperature (oC) SI. No. Months

Maximum Minimum Mean

1. January 31.0 20.0 25.5

2. February 34.0 21.0 27.5

3. March 35.0 23.0 29.0

4. April 38.0 25.0 31.5

5. May 39.0 27.0 33.0

6. June 38.0 26.0 32.0

7. July 36.0 26.0 31.0

8. August 36.0 27.0 31.5

9. September 36.0 24.0 30.0

10. October 35.0 24.0 29.5

11. November 33.0 23.0 28.0

12. December 30.0 21.0 25.5

2.4 DRAINAGE

In this district, Vellar is the important river flowing and substantially benefiting

agricultural activities. The Vellar river rises from Salem district and forms

boundary between Perambalur and Cuddalore district (Fig 3).

The Marudaiyar river traverse through Ariyalur taluk and empties in to the

Coleroon river. Kallar and Chinnar, which are tributaries of Vellar and

Marudaiyar rivers, traversing through Perambalur taluk and Kallar and

Marudaiyar in Udaiyarpalaiyam taluk benefit the agricultural activity (Table 4).

9

Table 4. The details of river basins in Perambalur District

SI. No.

Watershed Code River Basins Taluks

1 4B1A5 Kollidam - Veeranam Perambalur & Udayarpalayam

2 4B1A6 Marudaiyar Perambalur, Ariyalur, Udayarpalayam

3 4B1A7 Nandiyar Perambalur

4 4B1B2 Ayyaru Perambalur

5 4C1A6 Chinnar Perambalur & Udayarpalayam

6 4C1A8 Kallar Perambalur

2.5 GEOMORPHOLOGY

The general Physiographic of this district is versatile with hill ranges, series of

plains, valley bottoms undulating upland area and broken chains of Eastern

Ghats viz., Pachamalai hills. A part of Pachamalai hill is the important hill, in

Perambalur taluk of this district. The average height of Pachamalai hill is 600

me though a few of the peaks rise to about 1020 metres above Mean Sea

Level. But for this hill, Perambalur forms a gentle undulating upland and

having hilly areas, gullied lands and small hillocks. While Udaiyarpalaiyam

taluk is fair1y flat and the southern end is very gently sloping. Ariyalur taluk is

having slightly elevated (Fig 5), undulated area on the north-western portion

and rock out crops in central eastern part.

11

Fig 5. Spatial distribution of different Geomorphic features

Spatial distribution of different Geomorphis features

Alluvial Plain

Buried Pediment

Erosional Surface

Low Land Cretaceous

Pediment

Shallow Pediment

Structural Hills

Up Land Tertiary

Valley Fill

2.6 GEOLOGY

Perambalur district is geologically made up of Archaean, cretaceous, tertiary and quaternary formation. Formations of upper Gondwana age are also found in a limited extent. The Archaeans consist of biotite and, hornblende gneisses, charnockites etc., Upper jurassic formations are represented by equivalents of Gondwana in small patches in parts of Perambalur taluk. The sequence of beds of cretaceous age of Thiruchirappali commences with Uttatur stage and ends with Niniyur stage. To the south and north they are covered by alluvial deposits and to the east by the Cuddalore sand stone of Miocene age (Fig 6).

13

In Tertiary, the Miocene and Pliocene members are well developed. The Miocene formation consists of alternate layers of sand and clay. The sand layers are usually found to be more clay bound. They are also ferrugenous in nature. The Pliocene consists of alternating sands and clay beds of limited extent.

Mineral Resources: The district is quite rich in minerals like limestone, clays, clayey sand stones etc., the details are given below: 1. Clays: Upper Gondwana, formation is represented by clays, which are having

economic values. These clays are used locally for superior type of pottery and

also for the manufacture of salt glazed pipes, fine bricks and electrical

insulators. Alluvial clays of Kollidam river and sandy clays occuring over

Cuddalore sand stone, are used locally for bricks making. 2. Lime stone: Sedimentary lime stone occurring as cretaceous formations and is estimated

2,26,000 tonnes of 50% CaO and 17 million tonnes of 42 to 46% CaO also

found in Ariyalur taluk. IKunnam taluk, 3,00,000 tonnes of 50% CaO is also

found.

3. Garnet: Garnet sand concretions occur on the Eastern and Northern sides. Massive

garnet, is reported to occur in crystalline lime stone in Perambalur taluk.

15

2.7 LINEAMENTS

Lineaments are the weaker zones identified from the imageries. There are two

set of lineaments noticed in the study area. First type is NE-SW and the other

is NE-SE of these the first type is more prominent and it is represented in

almost 2/3 of the study area falling prominently in the western part covering

the hard rock and the limestone terrain. The sandstone region is prominently

with the second set of lineament.

2.8 HYDROGEOLOGY

A study conducted by Public Works Department of Tamilnadu (2002) states

that the thickness of the aquifer in the district varies from 15 to 35 MBGL. The

wells in the alluvial formation have good yield of about 300 – 950 lpm,

sandstone 300-350 lpm and the hard rock 80-210lpm.

2.9 LANDUSE PATTERN

In this district, out of the total geographical extent of 3,69,107 hectares only

2,38,814 hectares (64.70%) are used for agricultural purposes. A total of

32,933 hectares (8.92%) are kept as fallow lands. The lands-put to non-

agricultural purposes occupy 43,953 (11.91 %) hectares. The cultivable

wastelands of 7,742 (2.10%) hectares can be brought in to agricultural uses

by suitable measures.

16

Table 5. Geographical area of different land use classes.

S.No Particulars Total (In hectares)

1. Net Area Sown 238814

2. Forests 25347

3. Uncultivable Waste 11384

4. Land put to non Agricultural

uses

43953

5. Cultivable Wastes 7742

6. Permanent Pasture 1515

7. Land under trees not included under net area sown

7419

8. Current Fallows 26952

9. Other Fallows 5981

10. Total Geographical Extent 369107

Fig 8. Percentage of area covered by different landuse classes

Land Use Pattern

Net Area Sow n64.70%

Forests6.87%

Other28.43%

Uncultivable Waste3.08%

Other Fallow s1.62%

Current Fallow s7.30%

Land under trees2.01%

Permanent Pasture0.41%

Cultivable Wastes2.10%

Land put to non Agrl.uses11.91%

18

2.10 FOREST

The total forest wealth of this district is 25,347 hectares, which represent 6.87

percent of the total geographical extent of Perambalur district. The types of

forest include

1. Dry mixed deciduous forest

2. Tropical dry deciduous forest

3. Tropical evergreen forest

4. Sub-tropical hill forest

The vegetative cover of the forest is being destroyed by nearby villagers for

fuel consumption. Afforestation measures must be taken up in all these

forests and in the hill bottom, which in addition to providing a proper

vegetative cover on the hills, helps to prevent the sedimentation in rivers and

to preserve the fertile soils from erosion.

Fig 9. Aerial Extent of Forest in different Taluks

Taluk Wise Distribution of Forest

248

4,904

1,780

7,023

7,114

4,278

0 1000 2000 3000 4000 5000 6000 7000 8000

Ariyalur

Kunnam

Perambalur

Sendurai

Udaiyarpalaiyam

Veppanthattai

Taluks

Extent, Ha

19

2.11 IRRIGATION

Crop Area

The major crops of this district are rice, oilseeds and sugarcane, pulses and

millets are also grown in some area. In uplands, millets like sorghum, pearl

millet, finger millet, and oilseeds such as groundnut and gingelly are grown

both under irrigated and rain fed conditions (Table 6). Cotton is also grown in

both irrigated and rain fed conditions and the cotton area is mainly distributed

in Veppanthattai, Kunnam and Perambalur taluks.

Table 6. Extent under different crops (thousand hectares)

S1.No.

Taluks Rice Pulse

s

Oilseed

s Millets

Sugarcan

e Cotton Other Total

1. Perambalur 3.05 0.07 0.90 0.34 0.30 1.80 2.06 8.52

2. Veppanthattai 4.95 0.10 1.62 0.13 2.28 8.90 0.31 18.29

3. Kunnam 4.49 0.13 0.79 0.28 1.97 2.76 0.72 11.14

4. Ariyalur 7.87 0.01 0.30 0.14 4.13 0.23 0.64 13.32

5. Sendurai 1.28 0.05 0.39 0.01 1.00 0.01 0.10 2.84

6. Udaiyarpalaiyam 6.29 0.03 5.65 0.04 0.69 0.04 0.28 13.02

Total 27.93 0.39 9.65 0.94 10.37 13.74 4.11 67.13

Per cent to total 41.61 0.58 14.37 1.40 15.45 20.47 6.12 100.0

0

Cropping Calander

Rice is grown in three-season viz., Kuruvai, Samba and Thaladi wherever

water resources are available at that particular season. In upland area, rice is

grown as rain fed crop. Oil seeds such as groundnut and gingelly are grown

both under irrigated and rain fed conditions. Pulses like blackgram,

greengram and red gram are grown in rice fallows (Table 7).

20

Table 7. Cropping Calendar in Perambalur District

Crops Irrigated I Rainfed

Seasons Months

Rice Irrigated Kuruvai Thaladi Samba

June to October September to February August to February

Rice Rainfed - September to March

Cotton Irrigated - February to August

Cotton Rainfed - September to March

Sugarcane - - January to December

Sorghum Irrigated - January to May

Sorghum Rainfed - June to October

Groundnut Irrigated - June to December

Groundnut Rainfed - June to November

Gingelly Rainfed - January to March.

Blackgram In rice fallows - January to March

Grengram In rice fallows - January to March

Source Of Irrgation

Vellar is the important river benefiting agricultural activities in Perambalur and

Veppanthattai taluks. Kallar river in Udaiyarpalaiyam benefits the agricultural

activities (Table 8).

Apart from river irrigation, rainfed tanks scattered all over Perambalur district

benefiting considerable extent of lands. Besides rivers and tanks, the other

main source of irrigation is wells.

21

Table 8. Source of irrigation

Sources of Irrigation SI. No.

Taluks Tanks (Nos)

Wells (Nos)

Canal length (Km)

1. Ariyalur 236 4256 34

2. Kurnam 131 14270 3

3. Perambalur 20 9687 -

4. Sendurai 51 1526 -

5. Udaiyarpalaiyam 255 4420 10

6. Veppanthattai 101 12915 -

Total 794 47074 47

The net area under irrigation is 71624 ha. Cauvery is the major river flowing in

the region and the composite district has a canal system covering just 47 Kms

stretch and ayacut of 11610 ha. The Ground water resource through

tubewells and wells contribute nearly 68% of irrigated area command. The

major crops grown in the district are paddy, groundnut, sugarcane and millets.

Cashew is the major plantation crop.

2.12 SOIL

There are three types of soil being noticed in the study area Red soil,

Alluvium and Black soil (Fig 10). The red soil is found in the hard rock terrains

and the black soil in the limestone regions and the alluvial nature in the

sandstone regions. The percent distribution of soil types are shown in

figure 11.

22

Fig 11. Percentage distribution of soil types

Percentage of soil distribution

0

500

1000

1500

2000

2500

3000

3500

4000

Alluvium Black Soil Red Loamy Soil

Area in Sq.Km.

A high carbonate level either due to under ground water or soil solution may

cause calcium deficiency by calcium precipitation as calcium carbonate. The

insoluble calcium carbonate is present in the soil surface or sub surface or

both is referred as calcareousness. The insoluble calcium carbonate is

present in the form of concretions, powder, beds etc.,

A detailed survey on the soil (Soil Survey and Landuse Organisation, 1998)

shows that nearly, 1,52,441 (41.30%) hectares of land are free from

calcareousness (Table 9). Pilamedu and Alangudi soil series which occupy

62,766 (17.00%) hectares are strongly affected by calcareousness (Fig 12)

24

Table 9. Calcareousness of the soil in the study area.

Sl.No.

Calcareousness Class Soil series Extent (ha) Percent to

total

1. Non - Calcareous

Anganur, Madukkur, Pattukkottai, Vallam, Mudukulam, Padalur, Kallagam, Kurumbalur and Padugai

1,52,441 41.30

2. Mild

Kallakkudi, Kalathur, Ariyalur, Palathurai, AYlchavadi, Thevaiyur and Nayakkanpalayam

64,696 17.53

3. Strong Pilamedu and Alangudi 62,766 17.0 Others 63,857 17.30 Forest 25,347 6.87 Total 3,69,107 100.00

Fig 12. Percentage distribution of calcareousness in soil type of study area

Severity of Calcariousness

Non-Calcarious

41.30%

Mild17.53%

Strong41.17%

25

2.13 MINES

The total limestone reserves are about 1,473 million tonnes. There are 12

major cement plants functioning in the State. The major players are Tamil

Nadu Cements (TANCEM), Dalmia Cements, Madras Cements, India

Cements, Grasim Industries, Associated Cement Companies and Chettinad

Cements.

Perambalur district is geologically made up of Archean, Cretaceous, Tertiary

and Quaternary formations. Among sequence of beds of cretaceous age,

Limestone occur as sedimentary formation and is estimated 2,26,000 tonnes

of 50% Calcium Oxide (Ca O) and 17 million tones of 42% to 46% Calcium

Oxide are found in Ariyalur - Sendurai Taluks. 3,00,000 tonnes of 50%

Calcium Oxide also found in Kunnam Taluk. The exploited mineral limestone

is being utilized in the cement plants of Ariyalur, Trichirappalli and Perambalur.

Superior grade fireclay, used for manufacturing flooring tiles, stoneware pipes,

firebricks etc., is available in parts of Kunnam Taluk. Sixteen mining leases

have been granted to private individuals and companies for mining the

mineral in Perambalur District.

Gypsum is the supporting raw material for manufacturing cement and it is also

used in manufacturing "Plaster of Paris". Celestite and Phosphatic Nodules

are used in manufacturing fertilizers. The above said minerals are associated

minerals and are occurring in various parts of Kunnam Taluk. In this category

three leases are in operation.

As for as Minor Minerals are concerned the District has good quality

charnokite rocks for quarrying Blue Metal, Jelly, Aralai stones, Rough Stones

etc., on account of which 53 stone crushing units are functioning in this district.

River sand is available for quarrying in Vellar river of this district.

The Mining department of the district functions under Assistant Director of

mining. The department has following functions and responsibilities. Issue of

26

bulk permits and transport permits to the leaseholders for the transportation of

minerals, and other office activities regarding the mineral administration.

Exploration for the detection of new mineral deposits of the District are also

undertaken.

In Perambalur the following cement factories are available

1.The India Cements Limited Dalavoi Village, Sendurai Taluk, Perambalur

District

2.Grasim Industries Limited situated at Reddipalayam, Perambalur District.

3.Dalmia Cement (Bharat) Limited.

4.Tamilnadu Cements Corporation Limited Ariyalur Cement Factory

5.Madras Cement Limited (Ramco Cement), Alathiyur, Perambalur District

Madras Cement Limited have purchased limestone mineral bearing lands in

Alathiyur sector which belongs to Niniyur formations of Creatceous age , over

an extent of 463.91.0 Hectares covering he villages of Alathiyur,

Adanakurichi , Manakudayan and Tular villages. The mineral inventory of

Alathiyur sector deposit is 78.93. million tons including the existing mining

leases and to be applied for mining lease.

Madras Cement Limited have purchased limestone mineral bearing lands in

Ariyalur sector which belongs to Kallankurichi formations of middle Ariyalur

stage of Cretaceous age, over an extent of 390.690 Hectares covering the

villages of Reddipalayam , Pudupalayam , Periyanagalur Kadugur,

Kailralabad and Kallankurichi. The mineral inventory of Alathiyur sector

deposit is 73.72. million tons including the existing mining leases and to be

applied for mining lease. The life of opencast mine varies between 4 to 30

years and during the entire period of operation as well as the period after

completion of such operation the land degradation is a major problem. The

mine areas are generally located in the boundary between cretaceous and the

cuddalore sandstone. These regions are near the Ariyalur and the sendurai

block of the district.

28

3. METHODOLOGY

Many attempts have been made to use different models to estimate the

volume of soils eroded every year. Models such as SEIM, USLE, EPM,

PSIAC, MPSIAC and FAO are among the most widely used models. The soil

erosion index model (SEIM) was used by Su-Chin Chen 2002 to assess and

predict the potential areas of erosion in Taiwan. The SEIM model uses

different factors such as rainfall, soil characteristics, slope, and cover above

soil surface and land use. PSIAC (Pacific southwest Inter-agency Committee)

model with its 9 possible parameters, among other model, is the most suitable

model for arid and semi-arid regions. Soil erosion in different parts of Iran, as

an arid and semiarid region, has been studied by several researchers.

Heydarian 1996 and Tajbakhsh et. Al, 2003 used PASIC and Modified PSIAC

(MPSIAC) to estimate erosion yield and erosion intensity map.

The district of Perambalur has diversified lithology and has been utilised for

different economic mineral resources. It has been studied by GSI (Geological

Survey of India) for the mineral prospects, and different other academic

institutions for the economic grade of minerals and the type of mining

operations adopted. The region has been extensively studied for the different

aquifer parameters and the groundwater potential of the district by PWD

(Public Works Department), of Tamilnadu and TWAD (Tamilnadu Water

Supply and Drainage Board) board. Still the impact of mining in the district,

soil erosion and the ecodegradation due to the human impact has to be

studies in detail. The present study address the above said problem.

3.1 Aim and Objective

The study was formulated to obtain the following objectives:

1. to obtain the status of soil erosion problem in the micro watershed

basis

2. Ecological degradation taken place as the areas are being used for

mining purpose for cement industry

29

3. to identify the areas for conversion of mine pits as surface storage

tanks as ponds so that water can be harvested.

3.2 Methods followed for obtaining the objective 1 and 2

Following are the list of data and materials used in this study

1. Digital topographic maps of in the scale of 1: 50000. The digital data of

the SOI (Survey of India) was purchased and the study area was

demarcated and information like drainage, slope etc, were used.

2. Hardcopy topographic maps in the scale of 1: 50000.

Nearly 11 topo sheets of the pertaining study area were used to determine

the Physiographic and the topographic informations.

3. IRS LISS III digital data pertaining to the study area.

Imageries were purchased from NRSA (National Remote Sensing

Agency), Hyderabad for the study area for preparation of land use/ land

cover maps, vegetation, slope maps, and lineaments.

4. Rainfall data for different stations. Rainfall data from the six different

stations were collected to find out the variation in the intensity of

rainfall in the district.

5. Hardcopy soil map of the study area in the scale of 1:50000.

The soil map prepared by Soil survey and land use organisation 1998

was used.

6. Hardcopy Geology map of the study area in the scale of 1 :50000.

The geology map of the study area was obtained from the Profile of

Permabalur district, Tamilnadu in a ground water perspective, published

by state ground and surface water resources data centre, PWD, Chennai.

7. An A0 colour scanner The A0 size scanner was used to incorporate the bigger maps obtained

from different organisation in GIS (Geographical Information System)

environment

30

7. Image processing package (ERDAS )

To create a Digital Elevation Model (DEM) of Bata river basin, contour

segment map and spot-height point map were prepared by digitizing contour

lines and spot-heights from the SOI topo-sheets No 53 F/6, 7, 10 and 11

(1965, 1:50,000 scale). Interpolation of this combined contour map and point

map was done in ERDAS software.

3.3 Sequential stages followed to obtain the above objectives.

The general steps followed in this study are as follows.

A) Preliminary studies to define the objectives and methodology.

B) Preparation of different materials and the selection of software package

C) Registration of all the available maps on each other.

D) Production of digital maps from different data.

E) Assignment of weights to different factors of model.

F) Calculation of R (sum of the effective factors) and Q values for each

location

G) Categorizing different erosion levels.

This study was undertaken with the objective to assess and map soil erosion

using satellite remote sensing derived physiography- soil and land cover and

DEM derived slope maps and ancillary data of soil characteristics and rainfall

as inputs.

3.4 Methods Followed For Obtaining the Objective 3

The properties of the sub surface may be explored by two main procedures

often called as electrical sounding (or drilling) and electrical mapping (or

trenching). The object of sounding is to determine the variation of electrical

conductivity with depth. It's meaningful in areas where conductivity merely

varies with depth and without lateral variation. Good to excellent

approximations to this situation are commonly found in sedimentary areas

with gently dipping or flat lying beds and vertical electrical sounding has been

31

the most important geophysical method of water prospecting in many such

areas (Parasins, 1997). It is assumed that the conductivity varies with depth

only, due to this fact the distance between current and potential electrode is

increased; the current filaments passing across the potential electrodes carry

the current fractions that returns to the surface after reaching increasingly

deeper levels.

Estimation of groundwater potential through geophysical prospecting in

recent years has been lime lightened due to undesirable problems like

unscientific management and use of resources for various purposes. It

requires proper targeting, assessment and management of groundwater

sources. The earlier phases on the groundwater investigation were attributed

to the unconsolidated alluvial and semi-consolidated sedimentary tracts. In

recent years, greater importance is given to the exploration of groundwater in

hard rock areas in which the study area falls. The main aim for a geophysical

investigation in hard rock area is the demarcation of weathered zone, its

thickness and to estimate the groundwater potential, which requires

techniques of both natural and artificial, the latter is more widely accepted

and applied. Different techniques in electrical methods are used for solving

different hydro geological problems. The electrical methods of geophysical

survey give details regarding depth of water table, depth of basement rock,

thickness of the weathered zone/formation, existence of fissures, fractures

and fault zones, depth, thickness and lateral variation in structural and

stratigraphic conditions relevant to the groundwater conditions,

characteristics of formation, quality of groundwater in terms of dissolved

solids/groundwater contamination, location of fresh water and salt water

interface in coastal areas and determination of permeability of the aquifers.

TWAD has conducted geophysical resistivity survey in many parts of the

32

district and identified groundwater potential zones for public utility.

The survey was conducted to find out the top soil thickness and the

subsurface properties in order to identify their suitability for artificial recharge

and the depth of aquifer. The method adopted was Wenner configuration with

uniform spacing between the electrodes. CI and C2 are outer current

electrodes and PI and P2 are inner potential electrodes.

Fig 14. Wenner configuration used in the study

33

The general resistivity ranges for different geological formations (table

10) are given in the table below:

Table 10: Resistivity ranges for different rock types

Rock Type Resistivity range in ohm-m

Granite 3x102 - 6

Granite Porphyry 4.5x103 (Wet) -1.3 x106 (dry)

Syenite 102 - 5x104

Andesite 4.5 x104(wet) - 1.3 x106 (Dry)

Lavas 102- 5 x104

Basalt 10 -1.3 x 107 (Dry)

Schists 20 - 104

Slates 6x102 - 4x107

Gneiss 6.8xl04 (wet) - 3xl06 (dry)

Quartzite 10 - 2 xl08

Consolidated Shale 20 - 2 x l03

Sandstone 1 - 6.4 x lOj

Limestone 50 - 107

Dolomite 3.5x102 - 5x103

Clays 1-100

Alluvium (sand) 10 - 300.

34

4. EROSION

Soil erodibility is an estimate of the ability of soils to resist erosion, based on

the physical characteristics of each soil. Generally, soils with faster infiltration

rates, higher levels of organic matter and improved soil structure have a

greater resistance to erosion. Sand, sandy loam and loam-textured soils tend

to be less erodible than silt, very fine sand, and certain clay textured soils.

Tillage and cropping practices which lower soil organic matter levels, cause

poor soil structure, and result of compacted contribute to increases in soil

erodibility. Decreased infiltration and increased runoff can be a result of

compacted subsurface soil layers. A decrease in infiltration can also be

caused by a formation of a soil crust, which tends to "seal" the surface. On

some sites, a soil crust might decrease the amount of soil loss from sheet or

rain splash erosion, however, a corresponding increase in the amount of

runoff water can contribute to greater rill erosion problems.

Past erosion has an effect on soils erodibility for a number of reasons. Many

exposed subsurface soils on eroded sites tend to be more erodible than the

original soils were, because of their poorer structure and lower organic matter.

The lower nutrient levels often associated with subsoils contribute to lower

crop yields and generally poorer crop cover, which in turn provides less crop

protection for the soil.

Erosion is the detachment and movement of soil material. The process may

be natural or accelerated by human activity. Natural erosion has sculptured

landforms on the uplands and built landforms on the low lands. This type of

removal of soil is by water or wind. Accelerated erosion is the consequence

of human activity. The primary causes are tillage, grazing and- cutting of

timber. Light texture of the surface soil, unchecked surface water flow,

35

topography, and low water holding capacity are the prime reasons for erosion.

Erosion causes depletion of fertility through removal of valuable surface soil

and lead to reduction in the effective arable soil depth and hence it is one of

the limiting factors for crop production. Erosion reduces soil depth and

anchorage will be a problem in these soils.

To prevent soil erosion is an important aspect of resource-protection. It is

necessary to estimate the actual (real) soil erosion for efficient precaution.

The presented processes estimate the soil erosion by water. using the

particular geo factors concerning the soil erosion as a continuum prevents the

blurs by cutting of classified vector data. The example "Soil Erosion" shows

the different products "Climate/rainfall", "Slope", "Vegetation" "Drainage

intensity", ''top soil thickness", "erodability of the material (lithology)" and

“Soil" being base data for practical use. 4.1 SLOPE

When a raindrop falls it is usually absorbed into the pore spaces of the soil.

However, when these pore spaces become saturated (full) the raindrops will

either stand on the surface as a puddle or flow downhill. As the water flows

downhill it will carry with it soil particles and other material. This is the start of

erosion. The heavier the rainfall, the more water will run off and the more

force it will have to move material. The steeper the slope, the faster the runoff

flow and the more force it will have to move material. The less vegetative

(plant) cover and leaf material on the ground, the more open the soil will be to

the flowing runoff water. Four things cause slope erosion: the amount and rate

of rainfall, the steepness or gradient of the slope, the amount and nature of

plant cover, and the type of soil and bedrock underneath.

36

Naturally, the steeper the slope of a field, the greater the amount of soil loss

from erosion by water. Soil erosion by water also increases as the slope

length increases due to the greater accumulation of runoff. Consolidation of

small fields into larger ones often results in longer slope lengths with

increased erosion potential, due to increased velocity of water which permits a

greater degree of scouring (carrying capacity for sediment).

Humans cause most soil erosion when we strip the natural vegetation from

the steeper slopes and don't put back a cover of healthy grass or other

vegetation. That causes the worst erosion. When a slope must be cleared it is

very important to replant some vegetative cover. It's important also to make

the slope into terraces. This will give the runoff water a longer and slower

route to the bottom of the hill. The slower the runoff flow, the less force the

water will have to erode the hillside.

Heavy rain on a fairly even slope creates "sheet runoff." The water flows

downslope as an even sheet. Any dips in the slope will collect more runoff

water, which will be able to erode more strongly. If the force of this water is

not stopped it will produce a gully (Figure 16). The gully will collect more and

more water and cause even more erosion. In time it will remove the soil down

to solid bedrock.

The slope of the study area (Fig 15) has been classed in to 8 divisions in

percentages as 0-1, 1-2,2-3,3-5,5-10, 10-15, 15-30 and >30. The greater

percentages (>15%) are noted in the western part of the study area, which is

covered by hilly slopes and major portion of the study area is covered by 1 %

- 2% and 3% - 4% slope-. 5 -10%_slopes are noted along the gullies and the

river courses.

38

FIGURE 16 Gully development in soft, easily eroded along Highway.

Gullies often come together down slope to form even larger gullies. Larger

gullies can carry even larger volumes of water resulting in even greater

erosion. These larger gullies may become "intermittent stream" valleys. An

intermittent stream is one that flows only during and after heavy rainfall.

The chief difference between gullies and small stream valleys is time. Gullies

can and do develop over a short time, even in a single heavy rainstorm. They

can only go as far as solid bedrock. Then it will take time for erosion to dig

deeper. If bedrock becomes exposed to the air through erosion it will begin

slowly to begin weathering.

4.2 LANDUSE PATTERN

In this district, out of the total geographical extent of 3.69107 hectares only

2,38,814 hectares (64.70%) are used for agricultural purposes. A total of

32,933 hectares (8.92%) are kept as fallow lands. The lands-put to non-

agricultural purposes occupy 43,953 (11.91 %) hectares. The cultivable

wastelands of 7,742 (2.10%) hectares can be brought in to agricultural uses

by suitable measures.

39

Fig 18. Representation of different landuse classes

4.3 RAINFALL AND RUNOFF

Both rainfall and runoff factors must be considered in assessing a water

erosion problem. The impact of raindrops on the soil surface can break down

soil aggregates and disperse the aggregate material. Lighter aggregate

materials such as very fine sand, silt, clay and organic matter can be easily

removed by the raindrop splash and runoff water; greater raindrop energy or

runoff amounts might be required to move the larger sand and gravel particles.

Soil movement by rainfall (raindrop splash) is usually greatest and most

noticeable during short-duration, high-intensity thunderstorms. Although the

erosion caused by long-lasting and less-intense storms is not as spectacular

or noticeable as that produced during thunderstorms, the amount of soil loss

can be significant, especially when compounded over time. Runoff can occur

0

200

400

600

800

1000

1200

1400

1600

1800

Area in Sq.Km.

Series2 1586.678028 1677.224301 6.982866035 181.2011424 239.2546088

Water bodies Wasteland Forest Builtup Agriculture

41

whenever there is excess water on a slope that cannot be absorbed into the

soil or trapped on the surface. The amount of runoff can be increased if

infiltration is reduced due to soil compaction, crusting or freezing. Runoff from

the agricultural land may be greatest during spring months when the soils are

usually saturated and vegetative cover is minimal.

4.4 VEGETATION

Soil erosion potential is increased if the soil has no or very little vegetative

cover of plants and/or crop residues. Plant and residue cover protects the soil

from raindrop impact and splash, tends to slow down the movement of

surface runoff and allows excess surface water to infiltrate.

The erosion-reducing effectiveness of plant and/or residue covers depends on

the type, extent and quantity of cover. Vegetation and residue combinations

that completely cover the soil, and which intercept all falling raindrops at and

close to the surface and the most efficient in controlling soil erosion (e.g.

forests, permanent grasses ). Partially incorporated residues and residual

roots are also important as these provide channels that allow surface water to

move into the soil.

The effectiveness of any crop, management system or protective cover also

depends on how much protection is available at various periods during the

year, relative to the amount of erosive rainfall that falls during these periods.

In this respect, crops which provide a food, protective cover for a major

portion of the year (for example, alfalfa or winter cover crops) can reduce

erosion much more than can crops which leave the soil bare for a longer

period of time (e.g. row crops) and particularly during periods of high erosive

rainfall (spring and summer). However, most of the erosion on annual row

crop land can be reduced by leaving a residue cover greater than 30% after

harvest and over the winter months, or by inter-seeding a forage crop (e.g.

red clover).

42

Soil erosion potential is affected by tillage operations, depending on the depth,

direction and timing of ploughing, the type of tillage equipment and the

number of passes. Generally, the less the disturbance of vegetation or

residue cover at or near the surface, the more effective the tillage practice in

reducing erosion.

NDVI

Normalised Difference Vegetation Index (NDVI) products are produced by the

Bureau of Meteorology for the Australian region using measurements from the

Advanced Very High Resolution Radiometer (AVHRR) on board the USA's

NOAA polar orbiting meteorological satellites. Live green plants absorb solar

radiation in the photosynthetically active radiation (PAR) spectral region,

which they use as a source of energy in the process of photosynthesis. Leaf

cells have also evolved to scatter (i.e., reflect and transmit) solar radiation in

the near-infrared spectral region (which carries approximately half of the total

incoming solar energy), because the energy level per photon in that domain

(wavelength longer than about 700 nanometers) is not sufficient to be useful

to synthesize organic molecules: a strong absorption here would only result in

over-heating the plant and possibly damaging the tissues. Hence, live green

plants appear relatively dark in the PAR and relatively bright in the near-

infrared (Gates 1980). By contrast, clouds and snow tend to be rather bright in

the red (as well as other visible wavelengths) and quite dark in the near-

infrared.

Since early instruments of Earth Observation, such as NASA's ERTS and

NOAA's AVHRR, acquired data in the red and near-infrared, it was natural to

exploit the strong differences in plant reflectance to determine their spatial

distribution in these satellite images. The NDVI is calculated from these

individual measurements as follows:

where RED and NIR stand for the spectral reflectance measurements

acquired in the red and near-infrared regions, respectively. These spectral

43

reflectances are themselves ratios of the reflected over the incoming radiation

in each spectral band individually, hence they take on values between 0.0 and

1.0. By design, the NDVI itself thus varies between -1.0 and +1.0. Subsequent

work has shown that the NDVI is directly related to the photosynthetic

capacity and hence energy absorption of plant canopies (Sellers 1985 and

Myneni et al. 1995).

Figure 19 below shows the spectral reflectance response characteristic for

green vegetation, soil and water compared with the bandwidth of the AVHRR

Channels 1 and 2 used to create the index.

Figure 19: Spectral reflectance characteristics of common earth surface materials [Source: Remote Sensing Digital Image Analysis, J.Richards,1986 ]

44

The differential reflectance in these bands provide a means of monitoring

density and vigour of green vegetation growth using the spectral reflectivity of

solar radiation. Green leaves commonly have larger reflectances in the near

infrared than in the visible range. As the leaves come under water stress,

become diseased or die back, they become more yellow and reflect

significantly less in the near infrared range. Clouds, water, and snow have

larger reflectance in the visible than in the near infrared while the difference

is almost zero for rock and bare soil. Vegetation NDVI typically ranges from

0.1 up to 0.6, with higher values associated with greater density and

greenness of the plant canopy. Surrounding soil and rock values are close to

zero while the differential for water bodies such as rivers and dams have the

opposite trend to vegetation and the index is negative. A range of errors such

as scattering by dust and aerosols, Rayleigh scattering, subpixel-sized

clouds, plus large solar zenith angles and large scan angles all act to

increase Ch1 with respect to Ch2 and reduce the computed NDVI. Each pixel

is an average of the differential reflectance over the range of vegetation, soil

types, water bodies and other surfaces within the pixel footprint. The

vegetative cover in the study area is noted to be higher in the sandstone

region and in the hard rocks (fig 20). There are few representations of

vegetation and agricultural lands in the limestone region.

Geology and structure

In general the hard rocks are believed to be more massive and are more

resisitant towards erosion. Unless in the steep regions erosion takes place

due to the removal of the weathered mantle. In the sedimentary terrain the

erosion is very significant that too in the steeper region. Generally lineaments

are the weaker zones which have been formed due to crustal movement of

the earth. Lineaments may be in the form of fault o geological contact or

shear or major joints. The root cause of the erosion the resistance of the

material subjected to erosion. The hard rock terrains are massive and only

weathered matrix is subjected to erosion in the sedimentary formation there

are rock types of two different nature 1) chemically more active (Lime stone)

and 2) Less active (Sandstone). It the lithology favours predominantly

45

physical weathering in sandstone and hard rock formation; predominantly

chemical weathering in the limestone areas. The lineaments noted in the

study area also forms a region of wetness with loose weathered matrix which

inturn help in erosion

Fig 21. Extent of different geological formations

4.6 Top soil thickness

Soil erosion is a naturally occurring process on all land. Soil erosion may be

a slow process that continues relatively unnoticed, or it may occur at an

alarming rate causing serious loss of topsoil. The loss of soil from farmland

may be reflected in reduced crop production potential, lower surface water

quality and damaged drainage networks. (Fig 22). it is noted that the top soil

thickness ranges from 0.5 to 2.25m lesser thickness is noted in intensive

eroded areas and in the upstream side of rivers. In general the thickness is

more in the sandstone region and less in the hard rock region. Thickness of

topsoil is lesser in the central part of the study area indicating limestone

regions with intensive erosion.

Charnockite33.10%

Tertiary27.21%

Alluvium10.00%

Cretaceous22.95%

Gondwana0.42%

Gneissic Rocks6.33%

47

4.7 Universal Soil Loss Equation (USLE)

Each of the USLE factors with associated attribute data are digitally encoded

in a GIS database to eventually produce five thematic layers. These are then

spatially overlaid to produce a resultant polygonal layer. Application of the

USLE model to the resultant layer yields a soil erosion map with 8 classes of

soil-loss. Schematic chart of the spatial overlay showing spatial data and

associated attribute data is illustrated in figure . Fig 23: Flow chart of USLE

Determination of factors of Modified USLE

Revised USLE - RUSLE uses the same empirical principles as USLE, however it includes numerous improvements, such as monthly factors,

Soil Erosion.

GIS Environment.

Digital Topo-

sheets Field

Check

LISS III & Field Check.

drainage

Slope

Geology

Physiography

Soil

49

incorporation of the influence of profile convexity/concavity using segmentation of irregular slopes. For this study improved empirical equations

were used for the computation of rainfall erosivity (R) (Fournier, 1960), topographic (LS) factor (Foster & Wischmeier, 1974) and crop management (C) factor (Lal, 1994). R= rainfall erosivity factor

K= soil erodibility factor

LS = slope and slope length

factor

c= yegetative cover factor p=

P=conservation practice factor

Modified R factor

Fournnier (1960) developed an erosivity index for river basins. The index

described as climate index C is defined as follows

C = r2/P

where, r is the rainfall amount in the wettest month and P is the annual rainfall

amount.

Modified LS factor

For slope < 21 %,

LS = (L/72.6)*(65.41*sin(S)+4.56*sin(S)+0.065)

For slope ³ 21 %,

LS = (L/22.1)0.7*(6.432*sin(S)0.79*cos(S))

where, LS = Slope length and slope steepness factor

L = Slope length (m) 50

S = Slope steepness (radians)

The LS factor map was created from the slope and aspect map derived from

the DEM.

C Factor

For cropland, below and above ground conditions vary considerably over time.

As a crop grows, increasing amounts of soil surface are protected from rainfall

by canopy, while surface residue cover may decrease because of residue

decomposition and tillage operations. It is important to predict Soil Loss

Ratio's (SLR) frequently for the rapidly changing soil and cropping conditions

common to most cropland. Incorporating the impact of time into the model

requires defining some time step over which the other effects can be assumed

to remain relatively constant. Following the lead of Wischmeier and Smith

(1978), this basic time unit is set at 15 days for agricultural lands.

In MUSLE, a sub-factor method is used to compute soil loss ratios as a

function of five sub-factors (Laflen et. al., 1985) given as:

C = PLU*CC*SC*SR*SM

where, PLU is prior land use factor, CC is crop canopy factor, SC is surface or

ground cover factor (including erosion pavement), SM is soil moisture factor

and SR is surface roughness factor. The estimation of sub factor values for

our conditions requires a long term experiments and considerable resource

base, the crop factor values were computed by giving the weights for different

cropping seasons and fallow period. C factor map was prepared from Land

use/ cover map, which was prepared from supervised classification of FCC of

LISS III images.

51

K Factor Due to the USLE the K-factor is calculate as follows:

K = 2.77 * 10**-6 * M**1.14 * (12 - OS) + 0.043 * (A - 2) + 0.033 * (4 - D)

Whereas:

M = (% silt and fine sand) * (% silt + % sand)

OS = % of organic material (with as > 4%: as = 4)

A = aggregate class

D = permeability class

Only the laboratory can supply exact values of OS, A, D and fine sand. But it

is possible to approximate these values by suitable regression functions. The

regionalisation (Table 11) of the K-factor is based on regionalised silt and

sand content

Table 11. K values for different soil textures

Organic matter content (%) Textural class 0.5 2.0 4.0

Fine sand 0.16 0.14 0.10

Very fine sand 0.42 0.36 0.28

Loamy sand 0.12 0.10 0.08

Very fine sand 0.44 0.38 0.30

Sandy loam 0.27 0.24 0.19

Very fine sandy loam 0.47 0.41 0.33

Silt loam 0.48 0.42 0.33

Clayey loam 0.28 0.25 0.21

Silty clay 0.37 0.32 0.26

Loamy Clay 0.25 0.23 0.19

52

Conservation Practice (P) Factor

P factor map was prepared from Landuse/landcover map, which was

prepared from supervised classification of FCC of LISS III images, using the

values given in Tables 11 and 12 . The P factor values (Table 13) were

chosen based on the research findings of Central Soil and Water

Conservation Research and Training Institute, Dehradun.

Table 12. P values for different conservation practices

Slope (%) Contour Strip Terrace

0-1 0.80 - -

1-2 0.60 0.30 -

12-18 0.80 0.40 0.16

18-24 0.90 0.45 0.16

2-7 0.50 0.25 0.10

7-12 0.60 0.30 0.12

Table 13. P factor values for different landuse/landcover

Landuse/landcover P factor

Barren land 1.00

Sugar caner 0.12

Wheat 0.10

Dense forest 0.80

fallow land 1.00

Moderately dense forest 0.80

Open forest 0.80

River bed 1.00

53

4.8 Preparation of Erosion Intensity Map

All the factor maps of R, K, LS, C and P were integrated to generate a

composite map of erosion intensity. This intensity map was classified into five

priority classes. Study area was further subdevided into subwatersheds to

find out the priority in terms of soil erosion intensity. Each subwatershed was

analyzed individually in terms of soil type, average slope, drainage density,

land use/ cover and average NDVI with soil erosion to find out the dominant

factor leads to higher erosion.

Table 14. The attribute values for different factors

LS-factor R-factor K-factor

% Slope LS-factor C-Factor P-Factor

364.412 0.16 0-1 0.288 0.32 0.0027

0.44 1-2 0.896 0.6 1

0.27 2-3 1.067 0.45 1

0.28 3-5 2.51 0.04 1

0.24 5-10 7.863 0.30 0

0.33 10 - 15 12.482 0.02 0

0.12 15 - 30 15.624 0.048 0.56

>30 28.714 0.088 0.73

4.9 Interpretation

The entire district is divided into three classes with regard to soil erosion (Fig 24) as poor, moderate and high. the regional extent of erosion (Table I5, Fig25) shows that moderate and severe region are more in the study area.

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Table15: Percentage of area covered by different zones

Class

Area covered (Sq.Km.)

Percent

Low 924.77 25

Moderate 1465.46 39.7

High 1301.11 35.3

3691.34

In total the entire study are is divided into 6 major watersheds (Fig 26) and in

total there are about 417 micro watersheds. The western portion of the study

area show high soil erosion which are represented by nearly about 189

watersheds. The eastern part of the study are in the sandstone region show

moderate soil erosion. 158 watersheds fall in low soil erosion category and

70 in low category (Fig 27)~ All three categories are represented in the

limestone regions, which indicate that erosion takes place in certain regions

by topsoil thickness of the weathered mantle and in certain region by solution

of limestone, as it is susceptible to chemical weathering easily.

The major water sheds 4CIA7, 4CIA8 AND 4BIA7 fall in the high soil erosion

zone, 4BIA5 in the moderate erosion zone, the micro water shed of the other

two watersheds 4BIA6 arid 4CIA6 consist of all three categories with high on

the upstream side low near the mid stream and places where it joins the

main streams Coleroon and Velar respectively. Other regions moderate

erosion is noted the regions with high erosion are recommended for

prevention structures on an extensive scale.

56

Fig 25: Regional extent of soil erosion

Regional Extent of soil erosion

LowModerateHigh

57

5. ECODEGRADATION Limestone mining can have a dramatic effect on the landscape during the

actual removal of the resource. However, properly managed quarry

operations strive to isolate impacts from surrounding properties and may

even improve the environment on a long-term basis. Modern technology,

environmental regulations, permitting requirements and sound and safe

operational practices effectively minimize a mine's influence on air quality,

water quality and the physical landscape.

Modern quarry operations develop comprehensive operation and closure

plans. Quarries are required to control storm water discharge, control fugitive

dust emissions and implement site stabilization and reclamation at the end of

the quarry life.

In some cases, when mining is complete, the site may be converted into

other uses. Open pit mines have been converted into recreation facilities,

home sites, wildlife refuges and wetlands. A few even become solid waste

disposal areas. 5.1 Eco degradation due to mine pits

Apart from the mining area the overburden removed from the mines are

deposited in the surrounding region and the intensive field investigation

reveals that on an average about 500m around the mine pit (fig 28) the

overburden has been accumulated. This accumulated region has been

degraded the soil profile has been changes and unless this region is

vegetated, it enhances the rate of erosion in this areas. In many location it is

witnessed that vegetation has been developed along the mine site

overburden. Still the buffer analysis reveals that nearly about 19.39 Sq.Km

has been found out to be ecologically degraded, due to the mining activity.

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5.2 Ecological Restoration

Widespread loss of production and conservation values of natural habitats

due to mining operations makes large-scale ecosystem restoration an

increasingly urgent task. Ecological restoration is the process of repairing

damage caused by humans to the diversity and dynamics of indigenous

ecosystems. There has been a tremendous upsurge in restoration as a

technique for reversing habitat degradation worldwide. Ecological restoration

implies that we wish to restore organisms and their interactions with one

another and with the physical environment. Ecological restoration

concentrates on processes such as persistence of species through natural

recruitment and survival, functioning food webs, system-wide nutrient

conservation via relationships among plants, animals and the detrivore

community. The goal of restoration is usually to develop a long-term

sustainable ecosystem native to the area where mining occurred.

Restoration (= rehabilitation) aims to return the degraded system to some

form of cover that is protective, productive, aesthetically pleasing, or valuable

in the sense of conservation.

Key processes in restoration include identifying and dealing with the

processes leading to degradation in the first place, determining realistic

goals and measures of success, developing methods for implementing the

goals and incorporating them into land management and planning strategies,

and monitoring the restoration and assessing its success. There are many

approaches to land and vegetation rehabilitation. These depend on severity

of damage to the land resource, the goals of rehabilitation and the availability

of resources for repairing the damage. The most intensive rehabilitation is

sometimes termed reclamation, because the damage to sites is so severe

that soils have to be replaced and landscapes may have to be reshaped.

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Reclamation is the process by which derelict or highly degraded lands are

returned to productivity, and by which some measure of biotic function and

productivity is restored. Long-term mine spoil reclamation requires the

establishment of stable nutrient cycles from plant growth and microbial

processes. However, the reclamation process often becomes arrested

because of severe limitations in the site or the biota. In summary,

rehabilitation, reclamation and restoration can be thought of as a continuum

of outcomes from the least to the most similar to the pre disturbance

ecosystem.

5.3 Restoration of mine sites

The large-scale land disturbances associated with mining operations and

related concerns about the environmental effects have triggered an

increasing number of rehabilitation programmes, which aim for the

restoration of natural ecosystems disturbed by mining. Restoration of mine

sites often entails amelioration of physical and chemical characteristics of

substrate and ensuring the return of vegetation cover. If specific problems

hindering ecosystem redevelopment can be identified, a cure can be

designed using or mimicking natural processes. The most common response

to land degradation has been abandonment or reliance on natural

succession to restore lost soil fertility, species richness and biomass

productivity. However, the process of natural succession on surface-mined

soils is slow due to the removal of topsoil, resulting in elimination of soil seed

bank and root stocks and due to soil profile disturbances, As many as 50 or

100 years can elapse before a satisfactory vegetation cover develops on

mine waste. Redevelopment of advanced communities may take a

millennium or more. An important goal of ecological rehabilitation is to

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accelerate natural successional processes so as to increase biological

productivity, reduce rates of soil erosion, increase soil fertility and increase

biotic control over biogeochemical fluxes within the recovering ecosystems.

Analysis of different natural successions on natural and artificial substrates

suggests that one of the important factors limiting the rate of development is

the process of immigration of taxa. There are genuine difficulties in

appropriate species reaching a particular site, especially if they have heavy

seeds, unless they already occur in the immediate vicinity. Artificial

revegetation is often used to facilitate the generally slow natural

rehabilitation process. Artificial seeding of grasses and legumes or both has

been a commonly used method to stabilize unconsolidated mine tailings and

to encourage natural invasion of tree and shrub seedlings. This ultimately

improves site fertility and moisture retention capacity. Once the abandoned

mine lands have vegetation growing on the surface, the regeneration of

these areas for productive use has begun and offsite damages are

minimized. In addition, establishment of the vegetation on an abandoned

mine land also improves the aesthetics of the area. Overburden is the

geologic material above coal seams and below the developed soil horizons.

Buried seeds and rhizomes are normally absent in overburden. This fact

makes seed reserves in the topsoil an important resource that, if handled

correctly, can be used successfully to recover disturbed areas by natural

vegetation50--52. Since most of the soil seed reserves are found in the

surface 5 to 10 cm , upper 5-10 cm topsoil is recommended to be removed

and replaced on the top of overburden material. However, the collection,

storage and use of topsoil for restoration of mine areas are limited in many

parts of the world. Therefore, recent reclamation strategies have centred on

creating soil that will support short -term establishment of native plant

species and will sustain long-term successional development. Plantation-

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related activities used in restoration of damaged sites are essential. The first

step should be stabilization of soil surface by contours, debris dams, mulch,

etc. Compaction of soil also needs to be reduced by mechanical disruption. If

needed, macroporosity of the soil can be improved by incorporation of wood

and shale. Soil toxicity in terms of pH, metals and salts has to be reduced by

suitable amendments and plantation of resistant species and cultivars.

Vegetation establishment and mulching with organic matter will increase soil

organic matter. Nutrient limitations imposed for the growth and establishment

of vegetation can be minimized by fertilization and other soil amendments.

One aspect in vegetation plantation is to improve micro site condition, which

can be done. by scalping, micro site preparation or by clump planting. Once

suitable vegetation starts growing, herbivory and physical damage can be

reduced by controlled access, fencing and trapping. 5.4 Conservation of mine site as surface water storage tanks

The larger limestone mines are located along the Ariyalur and Sendurai

blocks of the districts. The possibility of mine site as surface storage tanks

was carried out by conducting 10 geophysical surveys around the mine sites

in these regions. In the Ariyalur Panchayat union, the lime stone formation

belongs to the Uttatur geological stage, the thickness of the lime stone in

this region ranges from 5 to 35m depth and also in limited aerial extent. The

geophysical survey conducted reveals that the geological formation

available in the adjoining areas are, mostly consolidated sediments of clay,

shale and sandstone etc., The subsurface geological conditions do not

permit the groundwater recharge in the regions around this Panchayat union.

Hence it can only be used as a surface water storage body as a reservoir or

lake.

65

In Sendurai Panchayat union the lime stone formation belong to arenaceous

lime stone limestone of Niniyur geological stage, the deposits occur within an

average 40m from ground level mining is done in Adanakurichy,

Manakudaiyan and Alathiyur villages, where the lime stone is proposed to be

at 25m depth. The geophysical studies in 5 locations around the mine site

reveals that the porous sedimentary formations (aquifer material) at shallow

depth. Hence, in this region can act as both surface water storage tank and

with necessary recharge structures the shallow aquifer identified can be

recharged. The results of the surveys conducted are given in appendix.

66

- - - 6. CONCLUSION AND RECOMMENDATIONS

Soil erosion region are identified on micro watershed basis it reveals that the

major water sheds 4C1A7, 4C1A6, and 4B1A7 fall in the high soil erosion

zone, 4B1A5 in the moderate erosion zone, the micro water shed of the other

two watersheds 4B1A6 and 4C1A6 consist of all three categories with high

on the upstream side low near the mid stream and places where it joins the

main streams Coleroon and Velar respectively, other regions moderate

erosion is noted. The regions with high erosion are recommended for

prevention structures on an extensive scale.

The degradation area was identified nearly about 20 Sq.Km The Mine site in

Ariyalur region may be used as surface water storage tank but in the

Senduarai region mines will help in both surface water storage and for

recharge of groundwater with necessary precautions. Plantation is the oldest

technology for the restoration of lands damaged by human activity. A primary

objective for achieving satisfactory rehabilitation of a mined landscape is to

establish a permanent vegetation cover.

There is increasing evidence that forest plantations can playa key role in

harmonizing long-term forest ecosystem rehabilitation or restoration goals

with near-term socio-economic development objectives. Plantations can play

a critical role in restoring productivity, ecosystem stability and biological

diversity to degraded areas. Relative to unplanted sites, plantations have a

marked catalytic effect on native forest development (succession) on

severely degraded sites. Numerous studies have demonstrated that land

rehabilitation benefits from plantations because it allows to jump-start

succession. The catalytic effects of plantations are due to changes in

67

microc1imatic conditions (increased soil moisture, reduced temperature, etc.),

increased vegetational-structural complexity, and development of litter and

humus layers that occur during the early years of plantation growth. The

development of a plantation canopy can alter the microclimate and the soil

physical and chemical environment to facilitate recruitment, survival and

growth of native forest species. Otherwise, native species would only very

slowly, if ever, regenerate on degraded sites. Thus, plantations may act as

'foster ecosystems', accelerating development of genetic and biochemical

diversity on degraded sites. Plantations have an important role in protecting

the soil surface from erosion and allowing the accumulation of fine particles.

They can reverse degradation process by stabilizing soils through

development of extensive root systems. Once they are established, plants

increase soil organic matter, lower soil bulk density, moderate soil pH and

bring mineral nutrients to the surface and accumulate them in available form.

Their root systems allow them to act as scavengers of nutrients not readily

available. The plants accumulate these nutrients and re-deposit them on the

soil surface in organic matter, from which nutrients are much more readily

available by microbial breakdown. This is exhibited in the levels of available

phosphorus and potassium in afforested colliery spots. Most importantly,

some species can fix and accumulate nitrogen rapidly in sufficient quantities

to provide a nitrogen capital, where none previously existed, more than

adequate for normal ecosystem functioning. Once the soil characteristics

have been restored, it is not difficult to restore a full suit of plant species to

form the required vegetation. The advantages are that establishment of

desirable tree species capable of maintaining the site will slow or prohibit

invasion of less desirable weedy species, will provide economic returns in the

long term, will aid in developing wildlife habitat and will promote hydrologic

balance in the watershed.

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Taluk : Ariyalur Village : Kallankurichi Revenue Village Lime Stone Mined Pit I : Size : 500 metres X 500 metres Depth : 5 metres to 8 metres Location : Southern side of the TANCEM Factory Present Stage : Abandoned by Tamilnadu Cements Ltd., Ariyalur Present Use : The storage rainwater in the pit is used by washerman and cattle.

79

Taluk : Ariyalur Village : Kallankurichi Revenue Village Lime Stone Mined Pit II : Size : 600 metres X 300 metres Depth : 7 metres to 8 metres Location : Western side of the road between Ariyalur and Kallankurichi Distance : 5 Kms from Ariyalur Present Stage : Abandoned by Tamilnadu Cements Ltd., Ariyalur Present Use : Protected drinking water source, maintained by factory.

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Taluk : Ariyalur Village : Kairalabad Revenue Village Lime Stone Mined Pit III : Size : 750 metres X 300 metres Depth : 3 metres to 5 metres Location : Southern side of the road between Ariyalur and Kallankurichi Distance : 4 Kms from Ariyalur Present Stage : Abandoned by Tamilnadu Cements Ltd., Ariyalur Present Use : The storage rainwater in the pit is used by washerman and cattle.

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Taluk : Ariyalur Village : Periyanagalur Revenue Village Lime Stone Mine Pit : Size : 500 metres X 250 metres Present Depth : 18 metres to 19 metres Estimated Depth : 34 metres Location : Southern side of the road between Ariyalur and Kallankurichi Distance : 8 Kms from Ariyalur in Jeyamkondam road Present Stage : Not abandoned. The mine will be further used for another 6 to 8 years

82

Taluk : Ariyalur Village : Reddipalayam Revenue Village Location : Velipringiyam Lime Stone Mine Pit Executed by : Grasim - Industries cement factory Size : 500 metres X 250 metres Present Depth : 20 metres Estimated Depth : 34 metres to 36 metres Distance : 14 Kms from Ariyalur in Jeyamkondam road Present Stage : Not abandoned. The mine will be further used for another 8 years

83

Taluk : Sendurai Village : Manakudiyan Revenue Village Location : Thamaraipoondi Lime Stone Mine Pit Executed by : India cements Ltd Size : 350 metres X 200 metres Present Depth : 18 metres to 20 metres Estimated Depth : 35 metres Distance : 14 Kms from Ariyalur in Jeyamkondam road Present Stage : Not abandoned. The mine will be further used for another 8 years Additional Information : Trees planted / maintained over the bunds

84