RAPID RECONNAISSANCE SOIL & LAND DATABASE OF TAMIL NADU

STATE

SOIL & LAND USE SURVEY OF INDIA

(DEPARTMENT OF AGRICULTURE, CO-OPERATION & FARMERS WELFARE)
MINISTRY OF AGRICULTURE & FARMERS WELFARE
GOVERNMENT OF INDIA
IARI Buildings, PUSA
NEW DELHI-110 012
 Most of the content of the publication
are in-house data of the organization available in
published RRS reports by SLUSI and on https://slusi.dacnet.nic.in/

ISBN:

TO OBTAIN COPIES OF THIS

Chief Soil Survey officer,

Soil and Land use Survey of India,
Department of Agriculture, Cooperation and Farmers Welfare,
Ministry of Agriculture and Farmers Welfare,
Government of India,
IARI Buildings, Pusa, New Delhi-110012
Phone: +9111-25841263, 25849486
Telefax: +9111-25843811
E-mail: csso-slusi@nic.in
 PREFACE
Soil is a key part of our natural environment and is a non-renewable resource. Soil loss due to erosion can have
major implications not just for soils and the benefits they provide but also for air and water quality as well as our climate,
biodiversity and economy. The acquisition of adequate information on soil and land characteristics is thus essential to
formulate a viable strategy to check the degradation of soil and land resources Proper consideration of soils through the
planning system is needed to make sure that soils can deliver essential functions vital for the sustainability of Indian
environment and economy.
Soil and Land Use survey of India (SLUSI), Department of Agriculture, Cooperation and Farmers’ Welfare,
Ministry of Agriculture and Farmers’ Welfare carried out Rapid Reconnaissance Survey (RRS) to identify & demarcate
the potential soil erosion in river catchment of different river basins using extensive ground truthing. The details on
various facets of soil & land have been assessed to fix sub /micro watershed wise priority in catchments based on the
assessed runoff using SYI/RPI index. The work for data acquisition on RRS has been completed by organization in 2010.
Subsequently SLUSI took up a national initiative to digitize the RRS maps and data on soils of the country at 1:50, 000
in different states.
With a view to provide details to users in various states, SLUSI took up the initiative to seamlessly compile the
digital soil & land character data base acquired on 1:50 scale during the decades. This state-level RRS guide contains
agro-climatic sub-zone wise information on various soil parameters such as landscape, physiography, slope, depth,
texture and erosion status.
The digital soil database can be vital input as considered in the National Disaster Management Plan and State
Disaster Management plan of Tamil Nadu, which recognizes soil as a physical asset and highlight the need to manage
our finite soil resource by maintaining and improving its condition.
The spatial database would play an effective role to support the decision makers to achieve the right development
in the right place and identifies the need to consider the implications of development on soil quality as one of its guiding
principles.
This enormous task is accomplished by officers and officials of Soil and Land Use Survey of India. I hope that
the RRS guide may serve as a guiding tool for user’s departments /agencies of the state.

Date: Rajni Taneja

Place: New Delhi Chief Soil Survey Officer
 CONTENT

Sl. No. Particulars Page No.

Overview

1. Prelude 1

2. Introduction 1

2.1 Objective 2

2.2 Background 2

2.3 Data Source 3

2.4 Methodology 3

2.5 Output 4

Hydrologic Frame Work of Watershed 5

Agro climatic Sub zones of Tamil Nadu 7

Outcomes of soil and Land Database 9

I. Landscape/ Parent material 9

II Soil Erosion 13

III Soil Depth 17

IV Soil Slope 19

V Land Use 21

VI Soil Texture 24

District-wise Categorization of Priority Class 26

 1

OVERVIEW
1. Prelude
The purpose of planning is to manage the development and use of land in long term public interest. Soil is a key part of
our environment and is effectively a non-renewable resource. Soil loss due to erosion can have major implications not just for
soils and the benefits they provide but also for air and water quality as well as our climate, biodiversity and economy. Proper
consideration of soils through the planning system is needed to make sure that soils can deliver essential functions vital for the
sustainability of Indian environment and economy.
The National disaster management plan (NPF) and Disaster Management plan of Tamil Nadu state recognize soil as a
physical asset and highlight the need to manage our finite soil resource by maintaining and improving its condition.
The acquisition of adequate information on soil and land characteristics is thus essential to formulate a viable strategy to
check the degradation of soil and land resources. To combat the situation development of spatial database would play an
effective role to support the decision makers to achieve the right development in the right place and identifies the need to
consider the implications of development on soil quality as one of its guiding principles.
2. Introduction
Soil and Land are important natural resources on the surface of the earth. The biomass covers the surface and act as
natural protector of soil in the area. But due to variety of reasons the vegetative cover distribution varies at various location in
the state. The area in state suffers from a variety of problems of soil erosion, soil salinity, sodicity/ alkalinity, shallow depth,
unfavorable texture responsible for increased land degradation. Tamil Nadu homes over 16% of countries population in an area,
which is 3.96% of TGA of the country. Per Capita arable land in state is around 0.15 ha at present.
There is ever growing need to new Watersheds technology in an integrated watershed management-tool for climate smart
solution in the entire river basin to treat the abiotic or physical component of a river basin including soil and water, and mineral
deposits and other compounds bound up with them. Water is a dynamic resource variable in time and space from season to
season in year, as the status of surface and ground water in a basin area follows a cyclic mode for replenishment and losses. But
in contrast to water, soils formation and development –take place from the physical weathering of parent material (rocks) to
chemical decomposition and biological transformation – is a drawn-out process that may take hundreds or thousands of years
[Jenny, 1994]; and taking into account of time required in the soil development, once formed, soils may be fairly durable if not
conserve it, once it protect from runoff due to precipitation and reduce the severity of related erosion. Thus, changes in a basin’s
water resource status is relatively fast and easily identified, while the soils those changes naturally slow and unnoticed with
significant human activity in many ecosystems (example, in agro-ecosystems and urban ecosystems), and climate change
phenomenon the complexity of human-technology-environment systems has increased manifold [Pahl-Wostl, 2006] resulted in
drastic change in soil quality status that has under gone degradation drastically. Now a days many land degradation problems
are being faced in our country such as salinity / alkalinity and waterlogging in command areas, severe erosion in catchments
leading to siltation of reservoirs, decrease in productivity of crops etc. As both soil and water are operating in ecosystem
synergistically to one another through many biotic and abiotic processes. Being thus interrelated, degradation of either soil or
water has a concurrent effect on the other; hence neither can be considered in isolation
Therefore, in recent years’ emphasis is laid on the information on the nature, extent, spatial distribution and magnitude of
land degradation which plays a vital role in planning the strategies for reclamation /conservation of degrade soil and land
characteristics.
Management of soil and water resources conservation under RVP/FPR catchments is completed by SLUSI to assess the
priority sub/ micro watersheds / Hydrologic unit’s area under various catchments of the state in last three decades on 1: 50,000
scale. In this context mapping of soil and land features as well as land use/cover information, adequate field visit/survey were
carried out for mapping.
 2

2.1 Objective
The basic objective of the Rapid reconnaissance mapping is to calculate the sediment yield of the catchment and
determine the status of runoff and soil loss in the country on 1:50,000 scale. Generating priority hydrologic units (sub/micro)
level spatial maps based on its assessed erosion through sediment yield potential and generating soil & land information with its
spatial distribution components helps to check soil erosion using conservation measures.

2.2 Background
A national policy was adopted to use watersheds for the development of land and water resources for conservation in all
possible river basins. The selection of watersheds in catchment areas of different river basin for development of water and soil
resources was done on the basis vulnerability assessment of soils for erosion, demographic setting of the area by prioritizing on
problem’s severity. Each priority watershed was surveyed and studied morphologically and topographically to generate
database. The development of Watersheds is applied not only to the geo-physical situation but also to the people’s need.
Watersheds are natural hydrological entities that cover a specific areal expanse of land surface form which the rain fall
runoff flows to a defined drain of channel, stream or river of any particular point. The size of watershed is governed by the size
of the stream/river or the point of intersection on the stream/river like dam/barrage etc. A workable size of watershed is defined
by aims and objectives of the development programs. The size of watersheds will also differ with the different stages between
macro to micro level of planning and implementation of watershed programs. (AIS&LUS, 1990).
The concept of a watershed as the planning unit for the development of land and water resources has been available for
long, but the watershed approach has gained importance since 1974.
The Soil and Land Use Survey of India (SLUSI erstwhile AIS&LUS) has initiated delineation and codification of
hydrologic units in the country, since launching of Centrally Sponsored Scheme on Soil and Water Conservation in the
catchments of River Valley Project during III Five-Year Plan. The delineation of a hydrologic unit is carried out following
hierarchical system of rivers/streams based on drainage network. The codification of hydrologic unit is made to assign a unique
code to all hydrologic units following Alfa-numeric Codification System. The drainage network helps in the delineation of a
watershed for a particular river system.
In an attempt to acquire soil and land resource information at reconnaissance level survey, SLUSI (1991) has developed
and published a methodology to map the potential soil erosion in different river catchment area using extensive ground truthing
method. The organization has carried out Rapid Reconnaissance soil survey to map various facets of soil and land to assess sub
/micro watershed wise priority in catchments of the states based on the assessed runoff using SYI/RPI index and plan to
complete the work of data acquisition by 2012. Subsequently SLUSI (2010) took up a national initiative to digitize the RRS
maps and data on soils of the country at 1:50, 000 in different states.
In recent times, SLUSI took up the initiative to seamlessly compile the digital national soil and land character data base
acquired on 1:50 scale during last three decades. Mapping of natural resources has been an on-going activity for more than
three decades.

2.3 Data Source

2.3.1 Acquisition of soil and land data
The work of mapping of areas in catchment areas was stared in 1985 in the state. The initial mapping of soil and land
characteristics was carried out using Survey of India topographic maps with extensive field ground truthing involving study of
profile/ mini pits and auguring at regular interval.
 3

The digitalization drive was undertaken by SLUSI in 2010 with NIC to place the soil and land character data on SLUSI
geo portal with Universal Traverse Mercator l (UTM 43 and 44 N) projection. The final outputs were later converted Albers
equal area with following parameters.

2.3.2 Specifications Table

Subject: Geographic Information System (GIS), Soil Mapping
Type of data: Image Figure Digital maps (quantitative), Metadata (Attributes)
How data were acquired: GIS digitization, raster to vector conversion ESRI ArcGIS 10.3.1
Data format: Raw Vector shape files (.shp); Soil database, Raster images (Tiff, JPEG)
Data Accessibility: Only the static graphic maps are included in this article. The main digital data are hosted on
https://slusi.dacnet.nic.in
Projection:
Universal Traverse Mercator Projection
Spheroid: WGS84
Datum: WGS1984
False _Easting: 500000.0
False _Easting: 0.0
Central Meridian: 81.0
Scale _Factor: 0.9996
Linear Unit Meter (1.0 Legacy/ancillary data)

For mapping of soil and land characteristics on 1: 50,000 scale, land use/land cover, wetland and wastelands thematic
information’s taken from SOI toposheets was used as base map. Besides this, forest cover map generated by Forest Survey of
India (FSI) was also referred.
The tabular distribution of area details of Geographic / landscape (parent material) and climate data acquired from district
level state government records/ district gazetteer used as reference information while mapping. Apart from this, district
boundary taken from Survey of India topographical maps, meteorological data use to assess the soil loss especially while
mapping of water erosion categories.

2.4 Methodology
The various steps followed in the methodology for mapping RRS on 1:50,000 scale. First of all, we select the area and
estimate the erosion intensity mapping units for Hydrologic unit’s delineation up to sub / micro watersheds and codification
done using Survey of India toposheets. This information was converted to digital layer using DEM downloaded from
BHUVAN. The steps includes were:
 Delineation of catchment areas / bigger hydrologic unit into small watersheds (hereinafter will be called as Sub
watersheds) on 1:50,000 scale topographic maps of Survey of India.
 Codification of different stages of delineation by using Alpha-numeric symbolic code.
 Rapid Reconnaissance survey using 1:50,000 scale topo-maps, satellite imagery/aerial photographs and other basic
material leading to the generation of a map indicating erosion intensity/ runoff potential mapping units.
 Assignment of weightage values to various Erosion Intensity Mapping Units (EIMU) or Run-off Potential Mapping Units
(RPMU) based on their relative Sediment Yield/ Run-off Potential.
 4

 Assignment of maximum delivery ratios to various Erosion Intensity Mapping Units and assessment of adjusted delivery
ratio for different sub/micro watersheds.
 Computation of Sediment Yield Index / Run off potential Index for individual sub/micro watersheds.
 Grading of sub/micro watersheds into very high, high, medium, low and very low Priority categories.
(Steps sourced from: Methodology of Priority Delineation survey manual published by erstwhile AISLUS in 1991)

2.5 Output
SLUSI carried out detailed study of soils and generate soil database for watershed management and other developmental
aspects in priority areas. The Rapid Reconnaissance survey helps in categorization of the areas in different classes on priority
basis such as very high, high, medium, low and very low. The areas which comes under very high and high priority classes
needs to check the runoff water through applying watershed approach.
SLUSI successfully completed development of state-wise Micro Watershed Atlas of India using 1:50 k scale drainage
map. The organization has also developed Web-enabled Micro Watershed Information system which is in public domain since
December, 2010 (https://slusi.dacnet.nic.in). It provides Micro watershed data & information in a national standardized format
that allows users to search, access, and visualize data and information for planning development of water resource
The reconnaissance level maps at their original scale showing spatial distribution of site features such as land scape,
physiography, slope, land use and soil characteristics namely colour, texture class, soil erosion status for indicating soil loss,
surface conditions and management also provided as thematic service available on https://slusi.dacnet.nic.in
The Tamil Nadu soil attribute and priority survey maps provide useful background information on the types and
properties of soils at regional scales. The more detailed Soil map of area can be accessed from detailed Soil Survey data.
 5

HYDROLOGIC FRAMEWORK OF WATERSHED

The digital spatial distribution land features such as landscape/parent material, physiography, slope, land use prevalent
during the time mapped with soil morphological characteristics such as soil depth, texture, erosion are the most important
physical health status indicators required in planning of area, hydrologically or district wise.

SLUSI has developed the model for fixing priority areas based on relative assessment of vulnerability of soils to erosion.
This has been done on sub/micro watershed wise in different catchments of the state. The Region, Basin, Catchment and Sub-
catchment wise distribution with number of Watersheds, Sub-watersheds and Micro-watersheds and their total area presented in
table given below. Catchment wise area of Watershed is given below in the table and in thematic map as figure no. 1.

S.No. Region Basin Catchment Sub-catchment Total No. of Watershed Total No. of Sub-watershed Total No. of Micro-watershed

4A1A 3 25 145
4A1B 5 73 369
4A1
4A1C 8 72 449
4A 4A1D 7 62 365
4A2A 9 84 477
4A2 4A2B 6 77 399
4A2C 6 65 340
4B1A 8 80 488
4B1 4B1B 4 52 264
4B1C 7 65 392
4B2A 8 87 434
4B2B 4 31 157
4B2C 6 65 307
4B2
4B 4B2D 5 60 306
4B2E 4 40 195
1 4 4B2F 6 64 272
4B3A 7 43 178
4B3B 5 56 249
4B3
4B3C 1 6 18
4B3F 2 10 32
4C1A 5 52 281
4C1B 6 54 301
4C1C 6 54 289
4C1
4C1D 6 70 394
4C1E 5 33 143
4C 4C1F 6 77 339
4C2A 8 83 450
4C2B 3 23 123
4C2 4C2C 6 40 164
4C2D 8 83 448
4C2E 2 11 52
5A1A 3 24 122
5A1
5A1D 2 12 57
2 5 5A
5A2B 5 43 180
5A2
5A2C 2 11 32
Total 2 4 9 35 184 1787 9212

The state comes under two water resource regions, i.e. Region no. 4 (All drainage flowing into Bay of Bengal) and
Region no. 5 (All drainage flowing into Arabian sea). Further, the state comes under 04 basins, 09 Catchments, 35 Sub
catchments, 184 Watersheds, 1,787 Sub watersheds and 9,212 Micro watersheds as depicted in the above table. Out of the total
catchment area, maximum area comes under catchment 4C2 having 31,82,332 ha. followed by 4C1 (28,32,543 ha.), 4B2
5,17,782 ha.), 4B3 (22,05,837 ha.), 4A1 (20,28,840 ha.), 4A2 (17,72,416 ha.), 4B1 (17,16,302 ha.), 5A1 (13,17,194 ha.) and
5A2 (10,17,440 ha.).
6
 7

AGRO CLIMATIC SUB-ZONES OF TAMIL NADU

Out of 15 agro climatic zones of country identified by Planning commission of India, two namely ACZ 10-southern
plateau and hill region and ACZ 11 east coast and hill region comes under Tamil Nadu state. The specific constraints in those 2
regions are poor water management, poor nutritional status of soils and saline lands. The state under National Agriculture
Research Program subdivided under seven agro climatic sub- zone, i.e. Cauvery delta zone, high altitude and hilly zone, high
rainfall zone, northeastern zone, northwestern zone, southern zone and western zone. The distribution of distrctwise catchment
shows the Cauvery delta area forms part of 4A2, 4B1, 4B2, 4C1 catchment area of rivers, covered under Trichirapalloi,
Perramballur, Arialur, Tanjavur, Puddukotai, Karur, Nagapattanam, Thiruvarur,

The major agro climatic features are:

I. Southern Plateau & Hills Region-X
(1) Features:
Large rainfed area;
Large scale cultivation of low value cereals; and
Tank led irrigation.
(2) Potential crops, fruits & Livestock:
(2.1) Agriculture crops: Rice, sweet sorghum, foxtail millet, maize, horse gram, green gram, sunflower, safflower, cotton &
groundnut.
(2.2) Horticulture crops: Tapioca, gherkins, onion, okra, chilies, brinjal, tomato, flowers (Gomphrena, crossandra & Jasmine),
garlic, ginger and medicinal & aromatic (Sandal wood, glory, Lilly, Senna, ashok, cinchona).
(2.3) Fruit crops: Mango, banana, grapes, guava, sapota, & citrus.
(2.4) Plantation crops: Rubber, coconut, mulberry, cashew nut, areca nut & cocoa.
(2.5) Livestock & others: Cattle, buffaloes, sheep, goat, poultry, piggery, fishery, beekeeping & Seri-culture.
(3) Farming systems:
Rice and Coarse cereals based cropping systems;
Piggery; and Marine fisheries.
(4) Cropping sequences:
(a) Rainfed Areas:
Sweet sorghum – cotton - groundnut; and
Sweet sorghum – green gram – fodder;
(b) Irrigated Areas:
Rice – Rabi maize – green gram; and
Cotton – Rabi maize – fodder.
(5) Sub-region specific development related priorities (all the 6 sub-regions):
Creation additional irrigation potential to harness full potential of agriculture;
In-situ water harvesting/conservation through adoption of cultural practices like ridge and furrow planting, inter-cropping
of legumes in uplands, planting against slope in undulating terrain/hilly tract;
Inter-culture in between rows to create soil mulch and vegetative/bio-mulching;
Reclamation of saline/alkaline/acidic/water logged/ill drained soils;
Productive use of barren and un-cultivated lands, cultivation of waste and permanent fallows through afforestation;
Diversification of crops to high value crops;
Diversification of sugarcane area by Cotton;
Adoption of Integrated farming system with a component of crops, livestock, silvipastoral system and agri-horticulture;
Promotion of Rice hybrids in conjunction with SRI method of cultivation;
Promotion of hybrids of maize, cotton, sorghum, sunflower; and ƒ Adoption of improved rainfed farming system.

(6) Research priorities:

 8

Development of salt tolerant varieties of rice;

Delineation & mapping of multi-nutrient deficiency;
Water harvesting and recycling; and
Soil & water salinity management.

II. East Coast Plains & Hills Region-XI

(1) Features:
Rich water resources with relatively unfertile land;
Fragile ecology due to water logging, soil salinity/acidity and soil erosion; and
Tank led irrigation.
(2) Potential crops, fruits & Livestock:
(2.1) Agriculture crops: Rice, sweet sorghum, maize, sugarcane, black gram, green gram, groundnut, Niger, sunflower, cotton,
Jute & Mesta.
(2.2) Horticulture crops: Black pepper, turmeric, brinjal, okra, tapioca, chilies, onion, sweet potato, flowers (Tube rose,
Enthurium & Gompherina), medicinal & aromatics (Coleus & scented geranium).
(2.3) Fruit crops: Cashew nut, mango, sapota, banana, custard apple and pine- apple.
(2.4) Plantation crops: Cashew nut & coconut.
(2.5) Livestock & others: Cattle, buffalo, sheep, goat, poultry, duck & fishery.
(3) Farming systems:
▪ Rice based cropping systems;
▪ Fish and Prawn culture;
▪ Piggery; and
▪ Poultry.
(4) Cropping sequences:
(a) Rainfed Areas:
Sweet sorghum – cotton - groundnut; and
Sweet sorghum – green gram – fodder;
(b) Irrigated Areas:
Rice – groundnut - green gram;
Rice – green gram /black gram;
Cotton- green gram – green manure; and
Soybean – sunflower – green gram.
(5) Sub-region specific development related priorities (all the 6 sub-regions):
Productive use of barren and uncultivated lands, cultivable waste and permanent fallows through afforestation;
Reclamation soil salinity/alkalinity through use of Gypsum/Pyrites;
Reclamation of acidic soil through liming/mills sludge;
In-situ water harvesting/conservation through adoption of cultural practices like bed furrow in deep black cotton, uplands
and flat sowing and ridging later in red soils;
Diversification of the area of low value crops to high value crops;
Promotion of hybrid rice in conjunction with SRI method of cultivation; and
Development of Tribal agriculture.
(6) Research priorities:
Development of salt tolerant cultivars of rice;
Delineation & mapping of multi-nutrient deficiency;
Farming systems and
Crop management in flood prone areas.
 9

OUTCOMES OF SOIL AND LAND DATABASE

The management of sub/micro watersheds on priority wise in phased manner have been taken up on the analysis of
acquired soil and land parameters collected through Rapid Reconnaissance Soil Survey of the state. The outcomes such as
Landscape/parent material, Soil erosion, Depth, Slope class, Land use and Soil texture brought out during the survey. These
database can be used as a baseline for the development of soil and land quality in the state.
I. Landscape/ Parent Material
The geological formation of India is diverse, ranges from oldest Archean rocks to the recent Alluvium. The major
geological formation in the peninsula consists of Archean rocks comprising Gneiss, Schist, Igneous and Metamorphic rocks.
Western and Central India are covered by lava flows of the Deccan trap. A close relation exists between soil and physiography,
the diversities in physiography, climate and landscapes have enhanced the formation of widely diverse soils in India.
The tabular distribution of landscapes in the state are furnished gives account of landscape in different agro climatic sub zones.
These are seven subzones and it is observed that the effect of these zones on the soil development having identical landscape is
varying as every zone is having unique climatic features with respect to total rainfall, temperatures, and vegetation which
directly governs the soil development. This grouping not only helps in identifying the natures of soil type in different zones
under same landscape/parent material but its capacity to grow different crops/orchards etc.
Based on soil conditions, irrigation, cropping pattern, rainfall distribution and other ecological & social characteristics,
the state is falling under 7 agro-climatic sub zones exhibiting different geological formations namely, Aeolian, Alluvium,
Charnokite, Coastal Alluvium, Granite, Granite Gneiss, Laterite, Limestone and Sandstone. Out of these Seven (07) sub-zones,
maximum area of 33,26,724 ha. is under Southern zone covering districts Dindigul, Kaniyakumari, Madurai, Ramanathapuram,
Sivaganga, Teni, Triunelveli, Tuticorin and Virudhnagar followed by Northeatsern zone with an area of 30,77,652 ha covering
districts Cuddalore, Kanchipuram, Tiruvannamala, Vellore, Villupuram, Chennai and Trivallur. Third highest area is under
Cauvery Delta zone with an area of 23,84,060 ha. covering districts Pudukkotai, Thanjavur, Tiruchchirappli, Ariyalur, Karur,
Nagapattinum, Peramballur and Thiruvarur. Then under Northwestern zone having 18,30,759 ha area covering under Namakal,
Salem, Dharampuri and Krishnagiri districts; Western zone with an area of 12,92,614 ha covering districts Coimbatore,
Dindigul, Erode and Karur; High altitude and hilly zone with an area of 9,97,039 ha covering districts Kaniyakumari, Madurai,
Teni, Triunelveli, Virudhnagar, Dindigul, Coimbatore, Niligiri, Trivallur and Vellore. Least area of 1,08,495 ha is under high
rainfall area covering only one district Kaniyakumari.
Agro-climatic sub-zones/ district wise tabular distribution of area and thematic maps of geology shown in table: 1 and figure
no. 2.
Table: 1 Agro-climatic sub-zone/ Catchment wise tabular distribution of area under different landscapes in districts of
Tamil Nadu state
Agro climatic sub- Landscape Total
Catchment District Miscellaneous
zone Alluvium Coastal Alluvium Granite Laterite Limestone Area
Pudukkotai 17253 7687 284806 22635 58586 390968
4A2 Thanjavur 5573 10309 93236 9515 12080 130712
Tiruchchirappli 78 34662 2658 37398
Total 22904 17996 412704 32149 73325 559077
Ariyalur 22011 102493 20973 10439 155917
Karur 127 142642 7692 150461
Nagapattinum 163104 49516 44010 256631
Peramballur 1730 55791 3289 60810
4B1
Pudukkotai 2105 48659 12787 10632 74183
Thanjavur 117871 1900 39384 25206 26395 210757
Cauvery Delta
Thiruvarur 126793 54550 22022 8264 211629
Zone
Tiruchchirappli 25342 320500 9034 42240 397116
Total 459084 105967 731490 68001 152961 1517503
Karur 1975 131267 7043 140285
4B2
Tiruchchirappli 429 980 181 1591
Total 2404 132248 7224 141876
Ariyalur 616 19417 15925 2045 38003
4C1 Peramballur 1515 106471 337 5537 113861
Tiruchchirappli 13616 123 13740
Total 2131 139505 15925 337 7706 165604
Grand Total 486523 123963 1415946 116075 337 241216 2384060
Sub-zone-I:- Cauvery Delta zone : This zone accounts for 2384060 ha in state and five landscape classes such as
Alluvium, Coastal Alluvium, Granite, Laterite and Limestone have been identified. Among the landscape mapped major part of
 10

zone comes under Granite landscape (14,15,946 ha) followed by Alluvium landscape (4,86,523 ha) then Coastal alluvium,
Laterite and Limestone having 1,23,963 ha, 1,16,075 ha and 337 ha area, respectively.
The depth is main characteristics of soils in this zone where majority of area having shallow to moderately deep soils followed
by very shallow soil depth and good soil depth (moderately deep to deep), fine loamy to fine textured having medium to high
moisture and nutrient holding capacity and suited for most of crops/orchards. The soils of coastal alluvium are of sandy to
coarse textured subject to flooding.
Agro climatic Landscape Total
Catchment District Miscellaneous
sub-zone Alluvium Charnokite Granite Granite Gneiss Laterite Limestone Area
Kaniyakumari 333 21 354
Madurai 68 11 80
4A1 Teni 0 0
Triunelveli 140967 9960 150927
Virudhunagar 21865 17 620 22501
Total 163233 28 10601 173862
Dindigul 11 346 357
Madurai 33 33
4A2
Teni 6501 1569 143282 2621 153973
Virudhunagar 9 273 2 284
Total 6501 1589 143934 2622 154647
Coimbatore 1414 1132 94887 15970 731 5776 119910
Dindigul 16421 47 575 17043
4B2
Nilgiri 119335 36592 38677 4309 198913
High Altitude
Teni 74 24 98
and Hilly Zone
Total 1414 120467 147974 54718 731 10660 335964
4B3 Nilgiri 35 359 23415 103 23912
Total 35 359 23415 103 23912
Trivallur 7187 5720 11802 3598 28307
4C2
Vellore 892 21592 3615 26099
Total 8078 27312 11802 7213 54405
Coimbatore 42984 1495 44479
5A1
Kaniyakumari 4714 52149 3084 59947
Triunelveli 0 0
Total 4714 95132 4580 104426
Coimbatore 104368 4383 6383 115134
5A2
Nilgiri 187 34373 62 65 34687
Total 187 138741 62 4383 6448 149822
Grand Total 20708 120689 574341 222158 11802 5114 42227 997039
Sub-zone-II: -High Altitude and Hilly Zone: By and large this zone spreads out in Nilgiri and smaller extent in eastern ghat.
The High Altitude and Hilly Zone covers 9,97,039 ha total geographical area of the Tamil Nadu state and six landscapes such as
Alluvium, Charnokite, Granite, Granite Gneiss, Laterite and Limestone have been identified and mapped. Granite is the major
landscape having 5,74,341 ha area followed by Granite gneiss (2,22,158 ha) then Charnokite (1,20,689 ha), Alluvium (20,708
ha), Laterite (11,802 ha) and Lime stone (5,114 ha).
Maximum area are under shallow to moderately deep soil depth followed by very shallow to shallow soil depth, moderately
deep soil depth, shallow soil depth and deep soil depth with medium texture. The soils are distinctively different from that
observed in rest of the state. Agriculture and forestry/plantation are the major land use/cover reported.

Agro climatic Landscape

Catchment District Miscellaneous Total Area
sub-zone Aeolian Alluvium Coastal Alluvium Granite
4A1 Kaniyakumari 243 24 8181 1226 9675
Total 243 24 8181 1226 9675
High Rainfall
5A1 Kaniyakumari 1482 5311 83573 8455 98820
Zone
Total 1482 5311 83573 8455 98820
Grand Total 243 1482 5335 91754 9681 108495
Sub-zone-III: -High Rainfall Zone: High Rainfall Zone covers 1,08,495 ha total geographical area of the state in which
four landscapes have been identified such as Aeolian, Alluvium, Coastal Alluvium and Granite. Granite is the major landscape
covering 91,754 ha area followed by Coastal Alluvium having 5,335 ha, Alluvium and Aeolian landscapes having 1,482 ha and
243 ha area, respectively.
These areas received rains from both south-west to lesser extent and northeast in winter season. These areas are mostly under
orchard’s plantation. The soils are having shallow to moderately deep soil depth area with medium water & nutrient holding
capacity.

Agro climatic Landscape Total

Catchment District Miscellaneous
sub-zone Alluvium Coastal Alluvium Granite Laterite Sandstone Area
4B1 Cuddalore 43772 1858 9379 880 6331 62220
Total 43772 1858 9379 880 6331 62220
Cuddalore 19277 20643 191992 45064 32553 309529
Northeastern Kanchipuram 683 1694 59093 4779 10403 76652
Zone 4C1 Tiruvannamala 47 198450 16716 215213
Vellore 87859 2372 90232
Villupuram 19608 2435 602403 10944 2244 91526 729160
Total 39616 24771 1139797 56008 7023 153571 1420786
 11

Chennai 17517 17517

Kanchipuram 15129 20501 218844 13515 102946 370935
Tiruvannamala 7777 348761 47353 403891
4C2
Trivallur 24468 22009 155333 28022 734 80358 310925
Vellore 23259 426188 41821 491268
Villupuram 110 110
Total 70633 42510 1149236 41537 734 289996 1594646
Grand Total 154021 69139 2298412 98425 7758 449897 3077652
Sub zone IV: -North eastern zone: North eastern zone covers 30,77,652 ha area of the state which distributed in five
landscapes such as Alluvium, Coastal alluvium, Granite, Laterite and Sandstone. Granite is the major landscape identified in the
state having 22,98,412 ha area followed by Alluvium covering 1,54,021 ha area, Laterite landscape covering 98,425 ha area,
Coastal alluvium and Sandstone having 69,139 ha and 7,758 ha area, respectively.
The soils are distinctively different from sub zone I and utilized for growing different planation /forest etc. The major part of
area is having shallow to moderately deep depth soils followed by very shallow to shallow depth soils, deep depth soils and
moderately deep depth soils. The soils are fine loamy to coarse loamy texture, low to medium in nutrient and moisture holding
capacity.

Agro climatic Landscape

Catchment District Miscellaneous Total Area
sub-zone Alluvium Granite Limestone
Namakal 77260 3440 80700
4B1
Salem 1224 68 1292
Total 78484 3508 81991
Dharampuri 287 19 305
4B2 Namakal 4295 207193 3522 10546 225556
Salem 1231 224678 2607 13916 242432
Total 5527 432157 6129 24480 468293
Dharampuri 2416 178540 7492 188448
Northwestern
4B3 Krishnagiri 187429 3317 190746
Zone
Salem 1531 46344 10188 58063
Total 3946 412313 20997 437256
Dharampuri 3834 248984 214 8376 261408
Krishnagiri 955 305871 298 15829 322954
4C1
Namakal 35906 267 36172
Salem 2532 213802 6350 222684
Total 7321 804563 513 30822 843218
Grand Total 16794 1727517 6642 79807 1830759
Sub zone V: -North western zone: North western zone covers 18,30,759 ha geographical area of the state. Three landscapes
have been identified in the zone where Granite is the major landscape covering 17,25,517 ha area followed by Alluvium and
Limestone which covering 16,794 ha and 6,642 ha area, respectively.
Major part of the area covered under shallow to moderately deep depth soils followed by very shallow depth soils and
moderately deep depth soils.

Agro Landscape
Total
climatic Catchment District Coastal Miscellaneous
Aeolian Alluvium Granite Granite Gneiss Laterite Limestone Sandstone Area
sub-zone Alluvium
Dindigul 12 12
Kaniyakumari 9 9
Madurai 284 181368 193 18461 200306
Ramanathapuram 7497 27260 147949 11153 30275 224134
4A1 Sivaganga 1118 18278 3822 23217
Teni 229 3 232
Triunelveli 5870 6111 297 461336 6367 50872 530854
Tuticorin 38657 14818 32263 336142 903 2992 37683 463459
Virudhunagar 18091 338840 13021 32511 402463
Total 44527 47919 59820 1484162 196 20292 14145 173624 1844686
Dindigul 1406 157284 3579 162269
Madurai 12996 135541 3962 18462 170961
Southern
4A2 Ramanathapuram 26104 14205 125500 35324 201132
Zone
Sivaganga 18315 263740 42682 63139 387876
Teni 3782 62770 59040 7525 133116
Total 62602 14205 744835 63002 42682 128029 1055355
4B1 Dindigul 18278 787 19064
Total 18278 787 19064
Dindigul 6816 379768 20793 407376
4B2
Madurai 222 222
Total 6816 379990 20793 407598
Kaniyakumari 4 4
5A1
Triunelveli 17 17
Total 21 21
Grand Total 44527 117337 74025 2627286 63198 42682 20292 14145 323234 3326724
Sub zone VI: -Southern zone: Southern zone covers 33,26,724 ha geographical area of the state wherein eight landscape
have been identified and mapped. Granite is the major landscape which covers 26,27,286 ha area followed by Alluvium
landscape covering 1,17,337 ha area then Coastal-alluvium covering 74,025 ha area, Granite gneiss covers 63,198 ha area,
 12

Aeolian covering 44,527 ha area, Laterite covering 42,682 ha area, Limestone covering 20,292 ha area and Sandstone covering
14,145 ha area of the state.
Major part of the area having shallow to moderately deep depth soils followed by very shallow depth soils, moderately
deep depth soils and shallow soils depth soils.

Agro climatic Landscape Miscellaneous Total Area

Catchment District
sub-zone Alluvium Charnokite Granite Limestone
Coimbatore 18187 7254 314919 25719 22117 388196
Dindigul 21 21 42
4B2
Erode 32245 16163 571096 11328 24483 655316
Karur 256 256
Total 50688 23417 886036 37048 46620 1043809
Western Zone
4B3 Erode 289 50 164233 1994 166565
Total 289 50 164233 1994 166565
5A2 Coimbatore 53354 22314 6571 82239
Total 53354 22314 6571 82239
Grand Total 50977 23467 1103623 59362 55185 1292614
Sub zone VII:-Western Zone: Western Zone covers 12,92,614 ha geographical area of the state in which four landscapes
have been identified and mapped wherein Granite is the major land scape which covers 11,03,623 ha area followed by
Limestone covering 59,362 ha area then Alluvium and Charnokite having 50,977 ha and 23,467 ha area, respectively. Major
part of the zone is having shallow to moderately deep depth soils followed by very shallow soils depth soils and shallow depth
soils.
13
 14

II. Soil Erosion

Two types of erosion occur in nature which as follows. Most part of the state suffers from (i) water erosion, whereas (ii)
wind erosion noticed in Coastal-Aeolian landscape, Water erosion on agricultural lands takes place through rain water. Intensity
of rainfall by rain drops create a pressure and finally make an impact on the surface soil. Soil surface condition and water
infiltration depends on the properties of soil surface, part of the water received as precipitation percolate into the soil and
remaining water lost by runoff. Evidently surface runoff is negligible wherever water infiltration. On the basis of soil particles
disintegration from soil surface water erosion classified as splash, sheet, rill and gully erosion.
The effects of water erosion which are interrelated are briefly as follows (i) loss of surface soil (ii) loss of rain water (iii)
loss of soil nutrients and (iv) exposure of less fertile sub soil. A time period an extreme situation create ultimately soil become
unproductive.
Wind Erosion is also a serious problem which adversely affect the soil productivity of agricultural lands. It is responsible
for removal of the top fertile soil and depletion in the soil water content. There are three types which affect the soil movement
viz. saltation surface creep and suspension. Thematic map of spatial distribution of soil erosion and their area shown in figure
no. 3 and table. 2.
Table: 2 Agro climatic sub-zone/ Land use class wise tabular distribution of area under different erosion classes in Tamil
Nadu state
Erosion class
Agro climatic Total Area
Land use None to slight Slight to moderate Moderate Moderate to severe Severe Severe to very
sub-zone
erosion erosion erosion erosion erosion severe erosion
Deciduous forest (10-40% canopy cover) 8088 4979 3731 16798
Plantation-forest 2798 320 10538 13655
Forest(teak,eucalyptus,casuarina,etc) 101 34208 34310
Estates(tea,coffe,rubber,cashew) 38 39109 39147
Orchards(coconut,citrus,mango,arecanut) 79 79
Single crop cultivation (rf/single crop) 289467 193842 409875 869 2959 897012
Multiple crop cultivation(ir/multi crop) 881420 1949 883369
Cauvery delta zone Terraced cultivation (ir/multiple crop) 1086 1086
Grasslands/pasture (<10% canopy) 281 71678 105744 10404 2700 190809
Unculturable wastelands 1135 199 124 1457
Barren lands and scrub lands 18 30290 34447 155 64910
Brick kilns/quarries 71 142 213
Salt pan 9155
Miscellaneous 232060
total 1183308 304460 637847 11273 5801 155 2384060
Sub zone I: -Cauvery Delta Zone: Erosion is the process that transforms soil into sediment and its deposited into coastal
areas where lands of plain to nearly level slope class are dominant. The severity of erosion got reduced in these plain areas
known as River Delta. In Cauvery delta zone, six erosion classes have identified in state. Majority of the area comes under none
to slight sheet erosion followed by moderate intensity sheet and rill erosion. Whereas moderate to severe erosion, and severe
rills and gully erosion noticed in stream and river banks affecting about 7 % area of zone. It is mainly ascribed to fact that speed
of water flux is reduced due to reducing the slope in delta region which increase sediment deposition. The density of forest
vegetation also affects the severity of erosion. In deciduous dense forest none to slight erosion covers maximum area followed
by slight to moderate and moderate sheet & rill erosion.

Erosion Class
Severe water Total Area
Agro climatic None to Slight to Moderate to Severe to
Land use Moderate Severe erosion to
sub-zone slight moderate severe Very severe
erosion erosion Severe wind
erosion erosion erosion erosion
erosion
Deciduous forest (10-40% canopy cover) 162547 69715 34493 13050 14546 294351
Deciduous forest (>40% canopy cover) 55544 29760 16733 161 4245 106443
Plantation-Forest 3756 585 4410 8752
Forest(Teak,Eucalyptus,Casuarina,etc) 672 6717 970 8359
Estates(Tea,Coffe,Rubber,Cashew) 42689 50545 25943 6917 1654 127748
Orchards(Coconut,Citrus,Mango,Arecanut) 46893 20350 10383 1275 78901
Single crop cultivation (RF/Single Crop) 39412 13614 27927 18000 1404 19 100376
High Altitude and Hilly Zone Multiple crop cultivation(IR/Multi Crop) 92018 5476 3526 101021
Terraced cultivation (IR/Multiple Crop) 8631 10750 3664 5835 1538 30418
Grasslands/Pasture (<10% canopy) 4324 18330 44866 14792 3721 669 86701
Open scrub lands (when canopy is <10 %) 2833 869 1429 133 5264
Unculturable wastelands 5368 756 6124
Culturable wastelands 353 353
Miscellaneous 42227
Total 464688 219125 176231 65869 23833 4397 669 997039
 15

Sub zone II: -High Altitude and hilly zone: Seven erosion classes were found in the area in which none to slight sheet
erosion class covers maximum area, followed by slight to moderate sheet and rills erosion, Moderate rills erosion, moderate to
severe rills and gully erosion, severe gully erosion, severe to very severe gully and ravines erosion. The area also witnessed
severe water erosion to severe wind erosion respectively. Altitude is directly associated with the slope, type of vegetation and
depth of soils, if altitude is high the slope also increases and depth of the soil get reduced. This study confirms that deep to very
deep soils covers largest area due to tropical climatic conditions. The temperature is very high and the range of annual
temperature is minimum. These conditions enhance the weathering of rocks. Type and density of vegetation also controls soil
erosion. In Tamil Nadu state mainly broad leaves forest vegetation are observed in the zone, which forms a dense cover on the
soil surface and protect soils from erosion hazards. The vegetation reduces the intensity of gravitation force which creates by
rain drops.

Agro climatic Erosion Class Total Area

Land use
sub-zone None to slight erosion Slight to moderate erosion Moderate erosion Moderate to severe erosion
Deciduous forest (10-40% canopy cover) 4397 2755 7153
Deciduous forest (>40% canopy cover) 2714 16194 18908
Estates(Tea,Coffe,Rubber,Cashew) 129 4145 4275
Orchards(Coconut,Citrus,Mango,Arecanut) 5335 24250 8336 37921
Single crop cultivation (RF/Single Crop) 920 1296 914 3130
Multiple crop cultivation(IR/Multi Crop) 1482 13446 14928
High Rainfall Zone
Grasslands/Pasture (<10% canopy) 115 47 161
Open scrub lands (when canopy cover is <10 %) 12338 12338
Barren lands and Scrub lands 0 0
Salt Pan 9
Miscellaneous 9672
Total 12133 41951 29636 15094 108495
Sub zone III: -High rainfall zone: Intensity and amount of rainfall directly affect to the soil erosion and vegetation, if
intensity of rainfall is high the severity of erosion also high. The zone area experiencing high rainfall where amount & intensity
of rainfall are more. But due to occurrence of high canopy vegetation and less (Shallow/very shallow) soil depth or thickness on
sloping lands, moderate loss of soil through soil erosion reported in the zonal area. Four major erosion classes have been
identified in high rainfall zone in which slight to moderate erosion class covers maximum area followed by moderate erosion,
moderate to severe erosion and none to slight erosion classes.

Erosion Class
Agro climatic Total Area
Land use None to slight Slight to Moderate Moderate to Severe Severe to Very
sub-zone
erosion moderate erosion erosion severe erosion erosion severe erosion
Deciduous forest (10-40% canopy cover) 67100 16524 126953 7893 218470
Deciduous forest (>40% canopy cover) 5893 14189 20081
Plantation-Forest 23051 588 1180 24818
Forest(Teak,Eucalyptus,Casuarina,etc) 15927 35971 357 52255
Estates(Tea,Coffe,Rubber,Cashew) 11 85164 85175
Orchards(Coconut,Citrus,Mango,Arecanut) 5133 977 22622 28733
Single crop cultivation (RF/Single Crop) 23539 69007 311885 59606 12364 1186 477587
Multiple crop cultivation(IR/Multi Crop) 1404823 30409 82 1435314
Northeastern Zone Grasslands/Pasture (<10% canopy) 4429 71689 130566 20403 3074 3097 233259
Open scrub lands (when canopy cover is <10 %) 2338 10378 4685 996 18398
Culturable wastelands 2187 4217 1705 8110
Unculturable wastelands 13702 13702
Barren lands and Scrub lands 11311 11311
Rock outcrop 543 543
Salt Pan 1816
Miscellaneous 448082
Total 1565935 191392 754518 94292 15981 5636 3077652
Sub zone IV: -North-eastern Zone: North Eastern zone of Tamil Nadu state are under five type of landscapes, these are
Granite, Alluvium, Laterite, Coastal-alluvium and Sandstone. Among the different land uses, none to slight erosion covers
major part of the zone whereas moderate erosion is second most dominant erosion class followed by slight to moderate erosion,
moderate to severe erosion, severe erosion and severe to very severe erosion class.

Erosion Class
Agro climatic
Land use None to slight Slight to moderate Moderate Moderate to severe Severe Severe to Very Total Area
sub-zone
erosion erosion erosion erosion erosion severe erosion
Deciduous forest (10-40% canopy cover) 103540 5034 70864 179438
Deciduous forest (>40% canopy cover) 33007 8153 41160
Plantation-Forest 20 20
Forest(Teak,Eucalyptus,Casuarina,etc) 6316 134398 71 140785
Estates(Tea,Coffe,Rubber,Cashew) 3067 6794 1363 45 11269
Orchards(Coconut,Citrus,Mango,Arecanut) 658 46447 602 47707
Single crop cultivation (RF/Single Crop) 114484 108178 478816 32664 10357 744498
Northwestern Zone
Multiple crop cultivation(IR/Multi Crop) 367148 4885 372033
Grasslands/Pasture (<10% canopy) 40512 152565 14787 239 457 208560
Unculturable wastelands 204 204
Barren lands and Scrub lands 1241 3446 4686
Brick kilns/Quarries 245 347 591
Miscellaneous 79807
Total 627562 167321 896500 48098 10943 528 1830759
 16

Sub zone V: -North-western Zone: Amongst the various landscapes, the erosion classes identified and mapped are slight
erosion, slight to moderate erosion, moderate erosion, moderate to severe erosion, severe erosion and severe to very severe
erosion. Moderate erosion covers maximum area of the zone where as none to slight erosion is second most dominant erosion
class followed by slight to moderate erosion, moderate to severe erosion, severe erosion and severe to very severe erosion,
respectively.

Erosion Class
Agro climatic
Land use None to slight Slight to moderate Moderate Moderate to severe Severe Total Area
sub-zone
erosion erosion erosion erosion erosion
Deciduous forest (10-40% canopy cover) 86181 90983 2578 15 5690 185447
Deciduous forest (>40% canopy cover) 33 167 201
Plantation-Forest 2726 87 12633 15446
Forest(Teak,Eucalyptus,Casuarina,etc) 3266 1370 146 4782
Estates(Tea,Coffe,Rubber,Cashew) 7660 26730 8483 42873
Orchards(Coconut,Citrus,Mango,Arecanut) 11081 3211 7155 967 22415
Single crop cultivation (RF/Single Crop) 1059177 230222 458497 8023 1759 1757677
Multiple crop cultivation(IR/Multi Crop) 349892 66 349958
Terraced cultivation (IR/Multiple Crop) 2986 8974 6796 1611 20368
Southern Zone
Grasslands/Pasture (<10% canopy) 71399 142344 223087 2963 941 440734
Open scrub lands (when canopy cover is <10 %) 3 3
Culturable wastelands 1205 2531 2346 6082
Unculturable wastelands 1932 2685 887 5504
Barren lands and Scrub lands 882 37868 111763 150513
Brick kilns/Quarries 1488 1488
Salt Pan 7474
Miscellaneous 315760
Total 1597182 544343 830706 21112 10148 3326724
Sub zone VI: -Southern Zone: Southern zone have dominated by laterite landscape, whereas majority of soils comes under
deep to very deep soil class followed by moderately deep soils which are moderately fine to moderately coarse in texture. The
moderately coarse texture enhances the infiltration rate which reduces the overflow of surface water. Due to decreasing the
overflow water flux intensity also slow which reduce the soil erosion. The southern zone affected by none to slight erosion
which covers highest area followed by slight to moderate erosion, moderate erosion moderate to severe erosion and severe
erosion.

Erosion Class
Agro climatic None to Slight to Severe water
Land use Moderate Moderate to Severe Severe to Very Total Area
sub-zone slight moderate erosion to Severe
erosion severe erosion erosion severe erosion
erosion erosion wind erosion
Deciduous forest (10-40% canopy cover) 94788 17546 30928 1514 144776
Deciduous forest (>40% canopy cover) 16 16
Plantation-Forest 3308 3308
Forest(Teak,Eucalyptus,Casuarina,etc) 44646 983 45629
Estates(Tea,Coffe,Rubber,Cashew) 9877 9983 16 19876
Orchards(Coconut,Citrus,Mango,Arecanut) 24856 4895 92 29842
Single crop cultivation (RF/Single Crop) 80799 167362 269720 28855 35065 4410 586211
Western Zone
Multiple crop cultivation(IR/Multi Crop) 262037 1537 263575
Grasslands/Pasture (<10% canopy) 49813 27758 9763 2522 132 89988
Culturable wastelands 1414 1414
Unculturable wastelands 1193 1193
Barren lands and Scrub lands 51601 51601
Miscellaneous 55185
Total 518212 254444 382511 40133 37587 4410 132 1292614
Sub zone VII: -Western Zone: Six erosion classes have been identified and mapped in the zone. None to slight erosion class
covers maximum area followed by slight to moderate erosion, moderate erosion, moderate to severe erosion, severe erosion,
Severe to Very severe erosion and Severe water erosion to Severe wind erosion. Western zone of Tamil Nadu state has
dominated by Granite landscape which is responsible for coarse textured soils and enhance the infiltration rate & reduce erosion
hazards.
The agro-climatic zones are specific combinations of moisture availability zones and temperature zones. Agro-climatic
zones show how climate variability shapes agricultural landscape of an area. The main factor that caused the changes in the agro
climatic zones is soil erosion which was influenced by climatic factors, i.e. rainfall and temperature. It was observed that out of
7 zones, erosion severity is mainly in Western zone covering an area of 42,129 ha followed by high altitude & hilly zone
covering an area of 28,899 ha, Northeastern zone covering an area of 21,618 ha and Northwestern zone covering an area of
11,471 ha. This might be attributed to excessive run-off of soil, higher slopes where vegetation cover is reduced, low soil
organic matter. Based on the difference in characteristics of zonal variations, it is quite evident that maximum acreage of severe
and very severe erosion is observed under western zone and high altitude & hilly zone. This might be due to the high altitude &
rainfall along with rolling & undulating topographical formations. This is followed by northeastern zone, north western zone,
southern zone and Cauvery delta zone.
17
 18

III. Soil Depth

Weathering is a key part of the process of soil formation. Soil forms through accumulation and decay of organic matter
and through the mechanical and chemical weathering processes. Soil slope affect to the depth & stability of soil by the way of
erosion. In high slope, lands increases water erosion leading to loss of the fertile top soil and at places sub-surface soil expose
by erosion the movement of soil and water in catchment area. The silting/ deposition of sediments are irreversible and
particularly in the lower part of the catchment. In this way redistribution of soil in various depth categories and soil type takes
place, where by some portions of the land losses the soil depth and other portion gain. Along with soil loss in the runoff from
catchment area carries the plant nutrients. The quantity of soil particles of a given size lost in runoff varies the fifth power of
runoff.
Out of the total area of the state, among different soil depth classes maximum area is reported under deep to very deep
class covering an area of 83,66,520 ha. These are the soils that are 50-100 cm and >100 cm deep from the soil surface. Next to
this class, an area of 28,36,378 ha is mapped under shallow to moderately deep soils followed by shallow soils covering an area
of 4,53,163 ha that area < 25 cm from the soil surface, moderately deep to deep soils covering 1,39,203 ha area and deep soils
covering 20,832 ha. Area of the soils under different identified geological formations, Granite and Alluvium shows maximum
area under deep to very deep soils. Whereas, very shallow to shallow soils shows maximum acreage under Granite and
Charnokite. Spatial distribution of soil depth class and their area are shown in figure no. 4 and table 3.
Table: 3 Landscape/ Agro-climatic sub-zone wise tabular distribution of depth classes in Tamil Nadu state
Depth Class
Agro climatic Miscellan
Landscape Shallow Shallow to Moderately Moderately Moderately deep Deep to very Very Total Area
sub-zone Deep eous
(<25cm) deep deep to deep deep deep
High Rainfall Zone 243 243
Aeolian Southern Zone 44527 44527
Total 44771 44771
Cauvery Delta Zone 8 143736 342779 486523
High Altitude and Hilly
5368 2540 12799 20708
Zone
High Rainfall Zone 1482 1482
Alluvium Northeastern Zone 2282 124368 27370 154021
Northwestern Zone 16146 648 16794
Southern Zone 57813 59524 117337
Western Zone 46178 4798 50977
Total 8 7650 390782 449400 847840
High Altitude and Hilly
18925 427 841 99845 651 120689
Zone
Charnokite
Western Zone 3622 1613 18233 23467
Total 22547 2040 841 118078 651 144156
Cauvery Delta Zone 89 83 123791 123963
High Rainfall Zone 5335 5335
Coastal
Northeastern Zone 11419 57720 69139
Alluvium
Southern Zone 1085 72940 74025
Total 89 11419 1168 259785 272461
Cauvery Delta Zone 35884 393610 79 10532 418082 557760 1415946
High Altitude and Hilly
31212 175268 1729 277123 89009 574341
Zone
High Rainfall Zone 19501 44274 27979 91754
Granite Northeastern Zone 68751 638808 1443 7048 1762 895012 685588 2298412
Northwestern Zone 126485 637506 658 39861 679013 243994 1727517
Southern Zone 97895 501697 3211 411 1368150 655922 2627286
Western Zone 46902 377035 2285 16795 473967 186639 1103623
Total 407128 2743427 7676 76375 1762 4155620 2446891 9838879
High Altitude and Hilly
16866 11279 47541 125156 21316 222158
Granite Zone
Gneiss Southern Zone 4855 1363 13317 28214 15448 63198
Total 21722 12642 60858 153370 36764 285356
Cauvery Delta Zone 1843 113614 619 116075
High Altitude and Hilly
1864 869 133 8937 11802
Zone
Laterite
Northeastern Zone 4565 10378 996 82486 98425
Southern Zone 986 41695 42682
Total 9257 11247 1129 246732 619 268985
Cauvery Delta Zone 266 71 337
High Altitude and Hilly
353 4453 308 5114
Zone
Limestone Northwestern Zone 441 6200 6642
Southern Zone 1886 18406 20292
Western Zone 1414 42211 15737 59362
Total 1767 49258 40722 91747
Northeastern Zone 734 7023 7758
Sandstone Southern Zone 5446 8699 14145
Total 734 5446 15722 21903
Miscellaneous Total 1201246 1201246
Grand Total 453163 2817455 18923 139203 20832 5111917 3254603 1201246 13017343
19
 20

IV. Soil Slope

Soil can only develop where the rate of soil formation is more than the rate of erosion. The formation of soils are based
on the slope gradient & relief of land. Steeper slopes lands having excessive relief develops well drained soils with deep soil
depth whereas plain slope having normal to sub-normal relief develops moderately well to well drained soils with very deep soil
depth.
The factors that affect the nature & kind of soil and the rate of formation of soils include the slope of the surface. In the
state different slope classes ranging from nearly level to very-very steep slope class identified & mapped in the area. From here,
when related to soil depth class identified in the state it is quite evident that maximum area of 89,333,20 ha is mapped under
plain-nearly level to gentle slope class having not more than 5% slope gradient.
Slope class between 5-15 % slope gradient, have an area of about 8,45,056 ha. is mapped. Whereas, >15 % slope
gradient covering an area of 3,45,649 ha and under >30 % slope gradient area have an area of about 16,92,071 ha. Thematic
map of spatial distribution of Slope classes and their area shown in figure no. 5 and table 4.
Table: 4 Landscape/ Agro-climatic sub-zone wise tabular distribution of slope classes in Tamil Nadu state
Slope Class
Nearly
Plain to Very Steep to Very steep
level to Gentle to Moderate Strong Moderately Very very Miscella Total
Landscape Agro climatic sub-zone nearly gentle to Very to Very
Very Moderate to strong to steep steep to steep neous Area
level Gentle steep very steep
gentle slope slope slope steep slope slope
slope slope slope slope
slope
High Rainfall Zone 198 45 243
Aeolian Southern Zone 15510 29018 44527
Total 15708 29063 44771
Cauvery Delta Zone 326869 152674 6867 114 486523
High Altitude and Hilly
20684 24 20708
Zone
High Rainfall Zone 1482 1482
Alluvium Northeastern Zone 17000 136321 699 154021
Northwestern Zone 16590 204 16794
Southern Zone 31967 82998 2372 117337
Western Zone 47669 3308 50977
Total 375836 458417 13473 114 847840
High Altitude and Hilly
2104 6016 21537 55673 35359 120689
Zone
Charnokite
Western Zone 1 6203 3707 5586 7971 23467
Total 2105 12219 25243 61259 43330 144156
Cauvery Delta Zone 82873 25681 15320 89 123963
High Rainfall Zone 5335 5335
Coastal
Northeastern Zone 1787 66209 1142 69139
Alluvium
Southern Zone 13485 50871 9668 74025
Total 98146 148096 26130 89 272461
Cauvery Delta Zone 557521 264125 455583 74931 10532 10110 43146 1415946
High Altitude and Hilly
55051 79399 62219 62224 1477 42571 4262 211215 50905 5019 574341
Zone
High Rainfall Zone 722 21526 7999 18940 3605 12338 26623 91754
Granite Northeastern Zone 670515 596960 539518 146751 4890 52918 286860 2298412
Northwestern Zone 243835 248547 461479 264940 8759 93762 406194 1727517
Southern Zone 649512 948786 580864 138420 411 45212 3 264077 2627286
Western Zone 159423 317274 377570 72391 294 32049 137302 11 7308 1103623
Total 2336580 2476617 2485231 778598 26362 280228 16603 1375418 50916 12327 9838879
High Altitude and Hilly
43342 26210 8848 836 13847 113179 15285 612 222158
Granite Zone
Gneiss Southern Zone 23815 15422 2413 3737 13101 4294 415 63198
Total 67156 41633 11262 836 17584 126281 19579 1026 285356
Cauvery Delta Zone 619 7002 108238 217 116075
High Altitude and Hilly
1390 5786 4627 11802
Zone
Laterite
Northeastern Zone 20159 76862 39 1365 98425
Southern Zone 20263 22419 42682
Total 619 48814 213304 256 5992 268985
Cauvery Delta Zone 337 337
High Altitude and Hilly
1057 2121 1935 5114
Zone
Limestone Northwestern Zone 987 5655 6642
Southern Zone 17762 1886 644 20292
Western Zone 5243 42296 11822 59362
Total 23992 51232 14587 1935 91747
Northeastern Zone 7023 734 7758
Sandstone Southern Zone 814 13331 14145
Total 7837 13331 734 21903
Cauvery Delta Zone 241216 241216
High Altitude and Hilly
42227 42227
Zone
High Rainfall Zone 9681 9681
Miscellaneous Northeastern Zone 449897 449897
Northwestern Zone 79807 79807
Southern Zone 323234 323234
Western Zone 55185 55185
Total 1201246 1201246
Grand Total 2811180 3248742 2873398 817858 27197 329046 16603 1564893 70495 56684 1201246 13017343
 21

5.
 22

V. Land Use
Land use affects to the depth of soils if soil develop under forest vegetation the litter fall is high it affects the temperature
and enhance microbial activity and form few acids which enhance the process of weathering. Out of total surveyed area
(1,30,17,343 ha.) under different land use classes observed in the state, maximum area is covered under cultivation (single crop/
multiple crop) having an area 79,86,667 ha. followed by 12,50,166 ha area is under grassland/pasture having <10% canopy
cover. This may be contributed to land degradation and reduce available area under crop production. Next to this is an area of
6,36,905 ha and 4,09,527 ha covered under forest lands, i.e. having 10-20% canopy cover and 20-40% canopy cover,
respectively. An area of 3,30,409 ha. is mapped under estate, i.e. tea, coffee, rubber, cashew etc. this depends on the climatic
conditions of agro-climatic zone which falling in the state and soil type varies on climatic conditions. Red lateritic slightly
acidic soil type is best suited for its production, therefore, Tamil Nadu state is one of the largest cultivator & producer of
plantation crops like coffee, tea, rubber etc. whereas 2,86,120.03 Area comes under forest tree plantation like Teak, Eucalyptus,
etc. followed by an area of 2,81,236 ha. under barren lands. An area of 1,65,440 ha. is under orchard cultivation like coconut,
Mango, Arecanut whereas, an area of 1,38,690 ha is under deciduous forest type having >50 % canopy cover. Remaining area is
mapped under cultural/ uncultivable wastelands and scrub lands. Spatial distribution of Land Use classes and their area shown
in figure no. 6 and table 5.

Table: 5 Landscape/ Agro-climatic sub-zone wise tabular distribution of land use classes in Tamil Nadu state
Land Use
Deciduous forest (Double Storey
Grasslands/Pastur

Orchards(Coconu

Orchards(Coconu

Plantation-Forest
Barren lands and

(RF/Single Crop)
t, Citrus, Mango,

t, Citrus, Mango,
e (<10% canopy)

land
Crop)

cover is <10 %)

Arecanut) with
Coffe, Rubber,

Casuarina etc)
kilns/Quarries

Veg)

(when canopy

>10% canopy
Multiple crop

Rock outcrop
Forest (Teak,

Unculturable
Barren lands

(IR/Multiple
Estates(Tea,
Scrub lands

Eucalyptus,

Single crop
Culturable
wastelands

wastelands
cultivation

cultivation

cultivation
Arecanut)
Agro climatic Total

Terraced
Cashew)

Open scrub
Landscape Misc

Crop)
Brick

F2 (10- F3 (20- F4 (40- F5

(IR/Multi
sub-zone Area
20% 40% 60% (>60%
canopy canopy canopy canopy
cover) cover) cover) cover)
High Rainfall
45 198 243
Zone
Aeolian
Southern Zone 29018 15510 44527
29063 15708 44771
Cauvery Delta
4608 741 4723 457739 426 16952 1334 486523
Zone
High Altitude
151 11951 193 484 5368 18147
and Hilly Zone
High Rainfall
1482 1482
Zone
Alluvium Northeastern
682 150680 377 2282 154021
Zone
Northwestern
444 12516 3630 204 16794
Zone
Southern Zone 2745 2663 8071 13493 13074 637 11 75699 943 117337
Western Zone 298 11829 3308 34349 1193 50977
2745 7271 8812 19790 659270 637 193 3745 131492 11323 845280
High Altitude
24829 25091 50155 10349 2104 4410 3750 120689
and Hilly Zone
Charnokite
Western Zone 9564 7054 2248 4599 1 23467
Total 34393 32146 52403 14948 2105 4410 3750 144156
Cauvery Delta
1303 1683 13966 87562 2490 16834 124 123963
Zone
High Altitude
2557 2557
and Hilly Zone
Coastal High Rainfall
0 5335 5335
Alluvium Zone
Northeastern
383 813 9897 16871 5133 22188 2437 11419 69141
Zone
Southern Zone 22568 3490 10346 33948 3674 74026
Total 24254 813 1683 27353 114779 5133 7892 24678 53219 15217 275022
Cauvery Delta
61745 142 7679 2828 1036 20560 164274 337038 79 10739 808740 1086 1415946
Zone
High Altitude
136318 33170 29010 45581 48408 4751 70074 75565 4262 22823 30568 73810 574341
and Hilly Zone
Granite High Rainfall
4397 2755 18908 4275 116 13446 12338 32587 2932 91754
Zone
Northeastern
9174 1779 7258 76713 141757 20081 51003 31251 215593 1251908 23600 2631 543 465123 2298412
Zone
Northwestern 4686 347 39010 140428 41160 11316 140785 208070 359518 47707 20 734471 1727517
 23

Zone
Southern Zone 113919 6082 162170 1123 201 25882 4636 393642 306138 3 10367 15359 1587353 381 31 2627286
Western Zone 51601 74774 53384 16 8671 45629 85091 250207 20925 8917 504408 1103623
Total 241125 1779 489 13340 501062 375445 48119 106838 150590 247612 1136860 2593820 16603 125501 72071 28749 543 4176836 1467 31 9838879
High Altitude
72396 610 31852 22387 3608 3207 10011 22757 4341 19814 30418 756 222158
Granite and Hilly Zone
Gneiss Southern Zone 19047 444 494 146 1092 137 11411 76 9477 19986 887 63198
Total 91443 1054 31852 22881 3754 4299 10148 34168 4417 29291 50405 1643 285356
Cauvery Delta
1861 37370 13750 7845 1030 54219 116075
Zone
High Altitude
6491 2920 1390 1002 11802
and Hilly Zone
Laterite
Northeastern
39 34172 21004 7087 15855 11375 8893 98425
Zone
Southern Zone 11250 8426 20263 2743 42682
Total 13112 39 86459 34753 17852 38537 12376 65855 268985
Cauvery Delta
71 266 337
Zone
High Altitude
353 1053 882 308 2518 5114
and Hilly Zone
Limestone Northwestern
245 6397 6642
Zone
Southern Zone 1488 18803 20292
Western Zone 1414 8957 1537 47455 59362
Total 1804 1767 1053 882 9264 1537 75439 91747
Northeastern
7024 734 7758
Zone
Sandstone
Southern Zone 14145 14145
Total 7024 14879 21903
Cauvery Delta
241216 241216
Zone
High Altitude
42227 42227
and Hilly Zone
High Rainfall
9681 9681
Zone
Misc Northeastern
449900 449900
Zone
Northwestern
79807 79807
Zone
Southern Zone 323231 323231
Western Zone 55185 55185
Total 1201246 1201246
Grand Total 281236 1779 2292 15959 636905 409527 48119 138691 330409 286120 1250166 3420197 36003 165440 80156 65999 543 4566469 51872 28183 1201276 13017343
 24

6.
 25

VI. Soil Texture

Soil parent materials can include all different types of bedrock and any type of unconsolidated sediments. Soils
developed on parent material that are coarse grained and composed of minerals resistant to weathering most likely
exhibit coarse grain texture. Fine grain soil develops where the parent materials are composed of unstable minerals that readily
weather. The severity of erosion and runoff depends on soil texture it influences the rate of percolation of water through the soil
and enhance the stability of soil.
It was observed that more area of the state is showing textural class towards more accumulation of clay content in the
soils, i.e. fine to fine loamy having 18 to >35 % clay covering an area of 47,50,518 ha under varied landscapes predominantly in
Granite and Alluvium.
An area of about 859 ha is also observed under very fine textural class having >60% clay. This clearly indicates that
clays area the predominant soils in the state and apart from the rich alluvial soil of the river deltas, Granite is dominant in the
area.
An area of 46,10,597 ha is mapped under coarse loamy to fine loamy textural class having clay content ranging between
<18% to 35%. An area of 59,439 ha is mapped under sandy to coarse loamy textural class.
Based on the per cent gravels, i.e. 15-25% observed in the soil profile during the survey, the textural class is further
categories into gravelly textural classes like gravelly fine to gravelly fine loamy covering an area of 13,92,233 ha and gravelly
coarse loamy to gravelly coarse loamy covering an area of 9,40,650 ha.
For gravels percent more than 35 %, textural class like sandy skeletal to loamy skeletal textural class is mapped covering
an area of 61,801 ha.
Spatial distribution of textural classes and their area shown in figure no. 7 and table 6.

Table: 6 Landscape/ Agro-climatic sub-zone wise tabular distribution of textural classes in Tamil Nadu state
Textural Class
Agro climatic Fine Sandy to Gravelly fine Gravelly coarse Sandy skeletal Miscella
Landscape Very fine Coarse loamy Total Area
sub-zone Fine loamy to coarse to gravelly loamy to gravelly to loamy neous
to fine to fine loamy
fine loamy fine loamy fine loamy skeletal
High Rainfall
243 243
Zone
Aeolian
Southern Zone 44527 44527
Total 44771 44771
Cauvery Delta
4676 446201 25061 9702 39 844 486523
Zone
High Altitude
6819 1740 5997 6151 20708
and Hilly Zone
High Rainfall
1482 1482
Zone
Alluvium Northeastern
32721 42265 72065 6969 154021
Zone
Northwestern
2532 5917 7697 648 16794
Zone
Southern Zone 17347 12403 79470 11 3080 4388 637 117337
Western Zone 1193 45889 289 3606 50977
Total 65288 554416 192060 20937 9270 5232 637 847840
High Altitude
26440 79129 785 10110 4225 120689
and Hilly Zone
Charnokite
Western Zone 3682 12948 2491 635 3711 23467
Total 30121 92076 3277 10745 7936 144156
Cauvery Delta
18284 64626 26350 14614 89 123963
Zone
High Rainfall
5335 5335
Coastal Zone
Alluvium Northeastern
13338 997 54804 69139
Zone
Southern Zone 12558 3884 57583 74025
Total 44180 69506 144072 14614 89 272461
Cauvery Delta
452915 98584 484360 3414 147657 229016 1415946
Zone
High Altitude
106090 61568 345839 31301 29543 574341
and Hilly Zone
High Rainfall
11742 1389 64978 1296 12349 91754
Zone
Granite
Northeastern
389992 527494 1053317 9160 162240 156209 2298412
Zone
Northwestern
859 417534 75086 821319 86 316990 95643 1727517
Zone
Southern Zone 704904 620293 590670 31 492101 219286 2627286
Western Zone 129330 162646 522041 214828 74777 1103623
 26

Total 859 2212508 1547060 3882525 12690 1366413 816823 9838879

High Altitude
88 76661 57856 5989 7546 35333 38686 222158
Granite and Hilly Zone
Gneiss Southern Zone 199 25025 4954 5208 13269 14542 63198
Total 286 101686 62810 11198 7546 48602 53228 285356
Cauvery Delta
16222 7901 60926 31027 116075
Zone
High Altitude
133 11670 11802
and Hilly Zone
Laterite
Northeastern
24241 3127 66332 2381 2343 98425
Zone
Southern Zone 21249 21432 42682
Total 40596 32277 160360 2381 33370 268985
Cauvery Delta
266 71 337
Zone
High Altitude
397 353 4364 5114
and Hilly Zone
Limestone Northwestern
987 5655 6642
Zone
Southern Zone 18803 1488 20292
Western Zone 31326 5843 1414 20779 59362
Total 51779 11569 3255 25143 91747
Northeastern
7023 734 7758
Zone
Sandstone
Southern Zone 814 13331 14145
Total 814 20355 734 21903
Miscellaneous Total 1201246 1201246
Grand Total 859 2415451 2335068 4610597 59439 1392233 940650 61801 1201246 13017343
 27

7.
 28

DISTRICT-WISE CATEGORIZATION OF PRIORITY CLASS

Identification and demarcation of priority area is based on the assessed Sedimentary Yield Index (SYI) and Runoff
Potential Index (RPI) values of hydrologic units have been carried out in state. The state area has been divided in to into five
priority classes, i.e. very high, high, medium, low and very low. SLUSI has identified areas of higher runoff and sediment load
mostly covering hills/ forests/ scrub lands.
Based on the priority assessment, it was observed that about 5 % of state’s total geographical area is identified under very
high priority and about 10 % is identified under high priority areas. These area showing degradation due to active soil erosion
and can be taken up for conservation measures. Whereas, about 17 % is identified under medium priority area that needs to be
protected from further soil loss and requires conservation measures.
Spatial distribution of priority categorization of watersheds and district-wise area are shown in figure no. 8 and table 7.
District-wise area covered under very high and high priority area is highlighted in the form of bar-diagram.

Table: 7 District wise tabular distribution of priority classes in Tamil Nadu state
Distribution of Priority Watersheds in Tamil Nadu
Priority Total Area
District
Very Low Low Medium High Very High (ha)
Ariyalur 124188 43134 14093 12493 12 193920
Chennai 17518 17518
Coimbatore 268117 143504 189876 95944 52518 749959
Cuddalore 294157 21927 24884 21790 8989 371747
Dharampuri 62580 85865 119941 103970 77805 450161
Dindigul 165214 214598 99870 99064 27417 606164
Erode 295175 164660 172802 133418 56090 822144
Kanchipuram 394241 38221 13018 2108 447588
Kaniyakumari 140 55846 36928 60326 15565 168805
Karur 59955 56224 89271 80601 4695 290746
Krishnagiri 60297 166581 166343 59475 61004 513699
Madurai 101045 114690 91601 45662 18603 371602
Nagapattinum 256631 256631
Namakal 59836 72551 128400 62973 18668 342428
Nilgiri 85599 29539 30325 39005 73045 257513
Peramballur 69448 42299 29842 27951 5131 174671
Pudukkotai 219242 62902 92375 68032 22608 465158
Ramanathapuram 275122 132130 15587 1169 1255 425263
Salem 179977 147604 98946 51498 46446 524470
Sivaganga 203210 95855 55793 31328 24907 411093
Teni 138908 46849 61069 32315 8272 287414
Thanjavur 298772 14668 23009 5017 341466
Thiruvarur 211631 211631
Tiruchchirappli 122695 96538 120782 85918 23912 449844
Tiruvannamala 338242 157694 64466 28521 30181 619103
Triunelveli 109027 301410 228143 43021 197 681797
Trivallur 335322 1882 2029 339233
Tuticorin 85196 286644 61743 29872 463456
Vellore 306281 112722 119123 40271 29201 607598
Villupuram 522248 92337 45527 19499 49659 729271
Virudhunagar 59596 259438 74563 31651 425249
Grand Total 5719612 3058312 2270351 1312892 656177 13017343
 29

Identification and demarcation of Very high and high priority Watershed/Micro-Watershed in 1:50K
scale based on Sediment Yield Index (SYI)/Run-off Potential Index (RPI) of Tamil Nadu

% of Priority (Very High and High)

0.00 2.00 4.00 6.00 8.00 10.00 12.00

ERODE

DHARAMPURI

COIMBATORE

DINDIGUL

KRISHNAGIRI

NILGIRI

TIRUCHCHIRAPPLI

SALEM

PUDUKKOTAI

KARUR

NAMAKAL

KANIYAKUMARI
District

VELLORE

VILLUPURAM

MADURAI

TIRUVANNAMALA

SIVAGANGA

TRIUNELVELI

TENI

PERAMBALLUR

VIRUDHUNAGAR

CUDDALORE

TUTICORIN

ARIYALUR

THANJAVUR

RAMANATHAPURAM

KANCHIPURAM

CHENNAI

NAGAPATTINUM

THIRUVARUR

TRIVALLUR
 30

8
..