The word “watershed” introduced in 1920 was used for the “water parting boundaries”. Watershed is that land area which drains or contributes runoff to a common outlet. Watershed is defined as a geo-hydrological 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.
Objectives
- Production of food, fodder, fuel.
- Pollution control
- Over exploitation of resources should be minimized
- Water storage, flood control, checking sedimentation.
- Wild life preservation
- Erosion control and prevention of soil, degradation and conservation of soil and water.
- Employment generation through industrial development dairy fishery production.
Types
- Macro watershed: 1000 -10,000 ha
- Micro watershed: 100 -1000 ha
- Mini watershed: 10 -100 ha
- Mille watershed: 1 -10 ha
Main Components of Watershed
- Soil and water conservation,
- Water harvesting and water management,
- Alternate land use system.
Watershed Management Practices:
In Terms of Purpose
Method and Accomplishment:
- To increase infiltration
- To increase water holding capacity
- To prevent soil erosion
Vegetative measures/Agronomical measures:
- Strip cropping
- Pasture cropping
- Grass land farming
- Woodlands
Engineering measures/Structural practices:
- Contour bunding
- Terracing
- Construction of earthen embankment
- Construction of check dams
- Construction of farm ponds
- Construction of diversion
- Gully controlling structure
- Rock dam
- Establishment of permanent grass and vegetation
- Providing vegetative and stone barriers
Rainwater Harvesting:
Rainwater harvesting means collection and storage of rainwater by some mechanism to make water available for future use. An appreciable amount of precipitation, which is generally lost as surface flow, can be harvested and stored for useful purposes like drinking and providing supplemental irrigation to the crops.
