Watersheds An Introduction
Watersheds: An Introduction
What are Watersheds
NRM Class 13 Nov 1
Any surface area from which rainfall is collected
and drained through a common point. It is
synonymous with a drainage basin or catchment
area. A drainage basin can involve several
towns or regions or even countries.
It is a geo-hydrological unit draining at a
common point by a system of streams.
First used by American foresters for an area of
land which sheds water from rain into a single
outlet of a stream. Concept relatively new in
India (late 60s).
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Watersheds An Introduction
What are Watersheds
A watershed is a basin like landform defined by peaks which are
connected by ridges that descend into lower elevations and small
valleys.
It carries rainwater falling on it drop by drop and channels it into
soil, rivulets and streams flowing into large rivers and in due
course sea.
It affects the people living downstream of
It is a synonym of catchment or basin of a river coined for an
area restricted to 2000sq. Km.
What are Watersheds
Watershed development is nothing
but a process of Natural
Regeneration.
Watershed is a natural unit,
boundaries defined by topography.
No definite size for a watershed –
from few hectares to several
thousands. Even individual field can
be a watershed provided independent
drainage point.
NRM Class 13 Nov 1
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Watersheds An Introduction
WHAT IS WATERSHED
NRM Class 13 Nov 1
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Watersheds An Introduction
Watershed management
Is the integration of technologies within the natural boundaries of a
drainage area for optimum development of land, water and plant
resources to meet the basic needs of people and animals in a
sustainable manner.
A framework for an integrated, viable and decentralized pattern of
development of people living in a degraded area where water is a
scarce and mismanaged resource and where exploitation of
resources and people have resulted in overall degradation leading
to growing poverty, inequality and inability to cope with stress.
Sound Watershed management means controlling floods
in rainy season, droughts in dry seasons and reducing soil
erosion & sediment accumulation.
NRM Class 13 Nov 1
Agragamee’s own definition of watersheds
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Watersheds An Introduction
Objectives of watershed managements
NRM Class 13 Nov 1
Conserving soil and water
Improving the ability of land to hold water
Rain water harvesting and recharging
Coverage greenery –trees, crops and
grasses
Restore ecological balance within the
watershed boundary
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Watersheds An Introduction
NRM Class 13 Nov 1
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Watersheds An Introduction
Terms related to the concept
Ridge or Ridge line - boundary of a watershed
Contour or contour line – imaginary line joining points of equal
inclination
Isohyet – imaginary line joining points on earth surface receiving
equal precipitation, term used in hydrology particularly in maps as
isohyetal maps
Common point of discharge / mouth of watershed – the lowest
point of a watershed
Topography – study of features of a limited area, basically of the
undulations of the land surface
Precipitation – the component of water, which falls on earth
surface from atmosphere, the common form is rainfall
Runoff – flow of water(rainfall) over the surface
Percolation – movement of water through a column of soil
Infiltration – downward entry of water from ground surface to soil
Evaporation – water goes to sky in vapor form
Transpiration – the water exhaled by plants
Principles of watershed management
NRM Class 13 Nov 1
Utilising the land according to its capability.
Adequate vegetative cover during the rainy season.
Conserving as much rain water as possible where it
falls.
Draining out excess water and diverting it to storage
ponds.
Avoiding gully formation and checking at suitable
intervals to control soil erosion and recharge ground
water.
Maximising productivity per unit area, per unit time
and per unit of water.
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Watersheds An Introduction
Principles of watershed management contd
Increase cropping intensity and land equivalent ratio
through intercropping and sequence cropping.
Safe utilisation of marginal lands through alternative land
use systems.
Ensuring sustainability of the ecosystem benefiting the
man-animal-plant-land-water complex in the watershed.
Maximizing the combined income from the interrelated
and dynamic crop-livestock-tree-labour complex over the
years.
Stabilizing total income and cutting down risks during
aberrant weather situations.
Improving infrastructural facilities with regard to storage,
transportation and marketing.
Tools to enhance watershed management
NRM Class 13 Nov 1
Combining adequate amount of engineering,
technological inputs to maximize production but
keeping environment in mind .
It should actively seek to integrate stakeholders of
the watershed projects with the technology
implemented for enhancing biomass resource meant
for increasing agricultural activity .
Some self sustaining activities should be
implemented for beneficiaries during project
gestation period .
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Watersheds An Introduction
Benefits
NRM Class 13 Nov 1
Arrests soil erosion
Improves soil moisture
Reclaims vast tracks of eroded land
Reduces floods
Recharges ground water
Revives greenery
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