Watershed Management - Major Areas

Watershed is defined as a geohydrological unit draining to a common point by a system of drains. All lands on earth are part of one watershed or other. Watershed is thus the land and water area, which contributes runoff to a common point.

A watershed is an area of land and water bounded by a drainage divide within which the surface runoff collects and flows out of the watershed through a single outlet into a lager river ( or ) lake.

TYPES OF WATERSHED

Watersheds is classified depending upon the size, drainage, shape and land use pattern.
1) Macro watershed (> 50,000 Hect)
2) Sub-watershed (10,000 to 50,000 Hect)
3) Milli-watershed (1000 to10000 Hect)
4) Micro watershed (100 to 1000 Hect)
5) Mini watershed (1-100 Hect)

Objectives of watershed management

The different objectives of watershed management programmes are:

1. To control damaging runoff and degradation and thereby conservation of soil and water.
2. To manage and utilize the runoff water for useful purpose.
3. To protect, conserve and improve the land of watershed for more efficient and
sustained production.
4. To protect and enhance the water resource originating in the watershed.
5. To check soil erosion and to reduce the effect of sediment yield on the watershed.
6. To rehabilitate the deteriorating lands.
7. To moderate the floods peaks at down stream areas.
8. To increase infiltration of rainwater.
9. To improve and increase the production of timbers, fodder and wild life resource.
10. To enhance the ground water recharge, wherever applicable.

Factors affecting watershed management

a) Watershed characters

i) Size and shape
ii) Topography
iii) Soils
iv) Relief

b) Climatic characteristic

i. Precipitation
ii. Amount and intensity of rainfall

c) Watershed operation

d) Land use pattern

i. Vegetative cover
ii. Density

e) Social status of inhability

f) Water resource and their capabilities.

Watershed management practices
1. Interms of purpose
1. To increase infiltration
2. To increase water holding capacity
3. To prevent soil erosion
2. Method and accomplishment

In brief various control measures are:
1. Vegetative measures ( Agronomical measures)
1. Strip cropping
2. Pasture cropping
3. Grass land farming
4. Wood lands
2. Engineering measures ( Structural practices 0
1. Contour bunding
2. Terracing
3. Construction of earthern embankment
4. Construction of check dams
5. Construction of farm ponds
6. Construction of diversion
7. Gully controlling structure
1. Rock dam
2. Establishment of permanent grass and vegetation
8. Providing vegetative and stone barriers
9. Construction of silt tanks dentension
Influence of soil conservation measures and vegetation cover on erosion, Runoff and Nutrient loss.

      
Rainwater harvesting is the main component of watershed management. Some of the watershed management structures are as follows.