Watershed area development: - an approach for sustainability

In India 70% of landmass is underlain by hard rocks so percolation is very slow

Millions of hectares of prime agricultural land being laid waste due to over-irrigation induced waterlogging and salinity.

Why we talk about dry lands only• Worlds major land mass is part of dry land• Major biodiversity located in this system• Dry land system is most fragile system • Desertification is an irreversible process• Extinction of species is reduction of gene pool for future• Water and soil are most essential input for food grain

Social characteristics of dry-land

Common outlet

Geology of India

S tatus of irrig ation in India

Irrigated36%

Non irrigated

64%

60-90%

20-30%

10-20%

0-10%

30-60%

NA

Status of irrigation

Hydrosphere: water in earth’s environment…some hard facts

• Global water balance– Average precipitation less than

1000mm annually– More than 95% is sea water

• Of all fresh water– Large part locked up as ice-

caps– More than 95% of usable fresh

water is groundwater– Less than 1% is surface water– Not all groundwater is

accessible to man

P = E + RO + GW + ET + SMP= Precipitation E= EvaporationRO= Run off GW= Ground WaterET= Evapo-transpiration SM= Soil moisture

Water balance

• Input: – Rainfall

• Output: • Evaporation• Percolation (ground water)

• Evapotranspiration• Soil moisture• Run off

Nomenclature of watershed in IndiaCategory Numbers Size (000 ha)Region 6 25000-100000Basin 35 3000-25000

Catchments 112 1000-3000

Sub Catchments 500 200-1000

Watershed 3237 50-200

Sub Watershed 12000 10-50

Mille watershed 72000 1-10

Micro watershed 400000 0.5-1

The life of a river is its catchment area or watershed, that is the area from where it literally catches its water

Watershed development is aimed at treating these catchments areas to slow down the intensely flowing water at every point to make it walk rather than run so that it remains available for use in the village for a longer period of time

Different order of streams in a watershed area

What is watershed development

Watershed development is not an activity Watershed development is not just a program

Watershed development is a conceptIt is an approach for sustainability

Objectives• To reduce run off• To reduce soil erosion• To increase soil moisture• To make water streams perennial• To increase ground water level• To rejuvenate the past flora and fauna• To enhance productivity of land• Overall sustainability of ecosystem

Ridge Valley

PRINCIPLE OF SOIL AND WATER CONSERVATION MEASURE

Increase the time of concentration and thereby allowing more runoff water to be absorbed and held in the soil profile.

Intercepting a long slope into several short ones, so as to maintain less than a critical velocity for the runoff water.

Protection against damages owing to excessive runoff.

Prevent excessive soil and water losses.

Natural treatment

. . . Protective Regeneration and Afforestation

On slightly lower gradients, staggered or continuous trenches along contour lines are recommended.

Continuous Contour Trenches with Plantation

On gentle slopes, contour bunds are recommended

Gully plugs or boulder checks are small rock dams made on small

drainage lines or gullies

GULLY PLUGS ( Stone Wall Terrace )

Increased cultivation Area

Gully treatment in progress

GABION STRUCTURE

Breaking run-off velocity

Increase in irrigated area

On larger streams and flatter land, rock and wire dams called gabion structures are recommended using local stones

Low cost masonry gabion structure

PERCOLATION TANK

Pre Operational status

Post Operational status

Types of Farm ponds• Dugout farm ponds• Embankment type farm ponds

Dugout farm ponds harvest rainwater within the farm for protecting the crop from gaps

in rain

Farm pond meant for protective irrigation and the seven harvests

1.With the first major rains, fish fingerlings are released

2.The second harvest is of edible water plants3.The major harvest is, of course, the kharif crop4.Rice is grown at the edge of the pond5.There is sufficient water to irrigate the rabi crop6.Unirrigated rabi crops like gram after the water

recedes7.The seventh harvest is of silt deposits

Stone masonry check dams built on larger streams can used to support Community Lift Irrigation

Projects

Design of Masonry Check dam

BUNDING

Acts as barrier to check run-off

Reduced soil erosion and increased soil

moisture, productivity and biomass

LAND LEVELING AND BUNDING

Increased infiltration and time of concentration

BRUSHWOOD CHECK DAM

LOOSE ROCK DAM

Reduce runoff velocity and stabilize the gully

Increase cultivated Area

GRADE STABILISATION STRUCTURE

Bench terracing

Bench terracing is practised on steep hilly slopes where agriculture has replaced natural forest and grasslands since time immemorial. Thus, more reduction in slope length will not be able to reduce the intensity of runoff water.

Bench terracing involves converting the original ground into level step like fields constructed by half cutting and half filling, which reduces the degree of the slope. In hilly areas of Nilgiri hills, in North East hill areas of India and in Himachal Pradesh, this approach of bench terracing for agro-forestry models is gradually getting popular.

DIRECT OPEN WELL

RECHARGING

RECHARGING PIPE

RECHARGING CHAMBER

INCREASE IN WATER LEVEL IN

WELL

INCREASE IN IRRIGATED AREA

watershed management has been defined as an integration of technology with in the natural boundaries of a drainage area for optimum development of land , water and plant resources to meet the basic minimum needs of the people in a sustainable manner

Villager resting under energy plant to restore his energy.

Lets save each and every drop of water for next generation