Watershed Divisions in Nilgiris


                        Since, watersheds forms a basic unit for better planning, management and development of land and water resources, it was felt essential and necessary to delineate the watershed boundaries for the entire district.  Therefore, watershed has been taken as the unit of development and is managed as per the potentiality, capability, and suitability of the land resources.  These watershed boundaries have been delineated by joining the boundary line along topographical ridge separating adjacent drainages in such a way that drainage is not dissected and the respective watershed has a single point of discharge into a large stream or river.  The Nilgiris district is drained by major rivers like Bhavani and Moyar which are the tributaries of Cauvery and Pandiar respectively and Punnam Puzha, Karim Puzha and Chaliyar of Chaliyar basin.  The entire district has been delineated into 75 major watersheds on the basis of the above drainage pattern and is detailed as follows:


Sl. No.

Reservoir

Sub Catchment

Watersheds Code Nos.

Total No.

1.

Lower Bhavani

Lower Bhavani

1 to 8

8

2.

Lower Bhavani

Moyar

37 to 75

39

3.

Pillur

Upper Bhavani

16 to 18

3

4.

Kundah & Geddai

Kundah

9 to 15

7

5.

Chaliyar River Basin

Chaliyar

19 to 36

18

 

Total

 

 

75

                       
In view of the implementation of the action plans in a phased manner, these 75 macro watersheds have been prioritized according to their decreasing order of their Silt Yield Index (SYI) and graded in order of priority into 5 categories such as very high, high, medium, low and very low.  Accordingly, out of 75 macro watersheds, 37 macro watersheds have been identified as priority macro watersheds.
It is a fact that maximum soil erosion takes place in areas where annual crops are grown on steep slopes (more than 10% area) with improper soil and water conservation measures.  All the macro watersheds were arranged in the descending order of area under annual crops with more than 10% slope and top 10 watersheds were identified as high priority watersheds.  Subsequently, on field verification, certain changes were also made and finally the following 10 watersheds have been identified as high priority watersheds.

 

Sl. No.

Watershed No.

Name of the Watershed

Total Area

Annual Crop Area

1.

1/75

Saraganihalla

2579.70

“Tribal”

2.

13/75

Sillahalla

6802.59

3217.16

3.

58/75

Thuneri

5358.95

2753.05

4.

54/75

Sandinallah

11909.00

2521.20

5.

57/75

Kadanad

2346.82

1347.25

6.

6/75

Marappalam

4680.71

1173.87

7.

66/75

Kuruvenuhalla

5196.29

 907.07

8.

12/75

Kundahpalam Free Basin

4751.80

 724.00

9.

65/75

Kagguchi

2039.00

407.30

10.

9/75

Neerallipallam

5015.20

 353.90

                       
It is evident that the watersheds identified are big in size, it is virtually impossible to prepare any workable plan for effective implementation of these big watersheds.  Therefore, it was decided to further sub-divide these big watersheds into micro watersheds having area in the range of around 500 HA.