watershed management

WATER SHED MANAGEMENTWATER SHED MANAGEMENT(Special emphasis on soil ( p pand water conservation)WRE-IUNIT- VIII

Prof S S JAHAGIRDARBE (CIVIL) ME(ENV ) PhD(persuing)BE (CIVIL), ME(ENV.),PhD(persuing)NK Orchid college of Engg. and Tech. , Solapur

Watershed:

• Definition:“ h d b d fi d i“Watershed can be defined as a unit

of area covers all the land which contributes runoff to a common point or outlet and surrounded by a point or outlet and surrounded by a ridge line”.

Deterioration of watershed takes place due Deterioration of watershed takes place due to faulty and bad management through h i i f d hi i l the activity of man and his animals.

Causes of watershed Deterioration:Causes of watershed Deterioration:These activities are:

l i l f d• Faulty agriculture, forestry and pasture (Grass land) management leading to g gdegradation of land.

• Unscientific mining and quarryingUnscientific mining and quarrying.• Faulty road alignment and construction.

I d t i li ti• Industrialization• Forest Fires• Apathy (less interest) of the people.

Results of watershed D t i tiDeterioration:

• Less production from agriculture, forests, grass lands etc.

• Erosion increases and decreases biomass production

• Rapid siltation of reservoirs lakes • Rapid siltation of reservoirs, lakes and river beds. L f d l i f • Less storage of water and lowering of water table.

• Poverty as a result of less food production.

WATERSHED DEVELOPMENTWATERSHED DEVELOPMENT

Possible range of treatment Possible range of treatment measures

• Contour bunding • Contour trenching • Contour stone walls • Bench terraces • Land levelling • Summer ploughing Summer ploughing

• Agro forestry with suitable species Agro forestry with suitable species • Vegetative barriers

Ch k d (T d • Check dams (Temporary and Permanent)

• Retaining walls • Farm ponds and Percolation Farm ponds and Percolation

ponds • Renovation of existing water • Renovation of existing water

bodies and inlet channels

COMPONENTS OF WATERSHED DEVELOPMENT:

• • Human Resource Development (Community p ( yDevelopment) • Soil and Land Management W M • Water Management

• Crop Management• Afforestation • Afforestation • Pasture/Fodder Development • Livestock Management

R l E M • Rural Energy Management • Farm and non-farm value addition activities

• All these components are interdependent and • All these components are interdependent and interactive.

DEVELOPED WATERSHED

Methods for hill slopesp• CONTOUR TRENCHES AND

STONE WALLS• BENCH TERRACING

CONTOUR TRENCHES AND STONE CONTOUR TRENCHES AND STONE WALLS

S it bl i t l i •Suitable erosion control in hills

•Adopted for hill slopes % >20%

•Continuous or interrupted •Continuous or interrupted

BENCH TERRACING

• It helps to bring sloping land into• It helps to bring sloping land intodifferent level strips to enable

lti ticultivation.• It consists of construction of step

like fields along contours by halfcutting and half filling.g g

• Original slope is converted intolevel fields The vertical andlevel fields. The vertical andhorizontal intervals are decidedb d l d lbased land slope.

Methods for agric lt ral landMethods for agricultural land• Check dam• Percolation pond• Micro catchments• Contour bund• Broad beds and furrows

G ll l• Gully plugs• Tree plantation

S l hi • Summer ploughing • Agro forestry • Vegetative barriers• Vegetative barriers• Farm ponds

Check dam

• A low weir normally constructed across the ygullies

• Constructed on small streams and long gullies formed by erosive activity of flood water

• It cuts the velocity and reduces erosive activity

• The stored water improves soil moisture of the adjoining area and allows percolation

h h if to recharge the aquifers • Height depends on the bank height, varies

f t d l th i f from a 1 m to 3 m and length varies from less than 3m to 10m

Percolation pond

• To improve the ground water To improve the ground water recharge.Shallow depression created at lower • Shallow depression created at lower portions in a natural or diverted

stream course • Located in soils of permeable nature p• Adaptable where 20-30 ground

water wells for irrigation exist with water wells for irrigation exist with in the zone of influence about 800 X 900 m 900 m

Micro catchments

• To conserve insitu moisture and reduce soil loss

• Circular basin of one meter diafor level lands depending upon infiltration and rainfall

• Ditches of size 5m x 5m with trees planted centretrees planted centre

• Saucer basins / semi circular bunds with 2m diameter to a bunds with 2m diameter to a height of 15-20cm across the slopeslope

B d b d d fBroad beds and furrows

• To control erosion and to To control erosion and to conserve soil moisture in the soil during rainy dayssoil during rainy days

• The broad bed and furrow system is laid within the field system is laid within the field boundaries.

• Conserves soil moisture in dry • Conserves soil moisture in dry land. Controls soil erosion• Controls soil erosion.

• Acts as a drainage channel d i h i dduring heavy rainy days.

Contour bundContour bund

•To intercept the runoff flowing p gdown the slope by an embankmentembankment.

•It helps to control runoff velocity.

•It can be adopted in light and •It can be adopted in light and medium textured soils.

•It can be laid up to 6% slopes. •It helps to retain moisture in the It helps to retain moisture in the field.

Gully plugsy p g

• Gully plug is one of the simple method of Gully plug is one of the simple method of soil and water conservation. It plays an important role in soil and water important role in soil and water conservation.G lli f d d i f • Gullies are formed due to erosion of top soil by the flow of rain water. In course of time, a gully assumes a big shape and erosion goes on increasing. To prevent erosion goes on increasing. To prevent erosion, barriers or plugs of different types of material are put across the gully types of material are put across the gully, at certain intervals.

Tree plantationTree plantation•Instead of uneconomical agriculture, g ,

farmers can grow grass in this hilly area and can use that as a fodder for area and can use that as a fodder for cattle.

•Farmers can go for dairy development if good quantity and quality of grass is if good quantity and quality of grass is available.

•For soil and water conservationthis activity will help. Plantation

l d ill ti f b ion common land will satisfy basicneed of fuel wood.need of fuel wood.

•Cheapest method for soil andwater conservation

Summer ploughing p g g

•Main objective of field •Main objective of field preparation is to control weeds

•Facilitate easy sowing and to establish good seed soil contact establish good seed soil contact

•For easy absorption of moisture y p•To provide sufficient aeration

i h ldi•To improve water holding capacity capacity

Agro forestry g y

• Agroforestry is an integrated h f i th i t ti approach of using the interactive

benefits from combining trees and h b ith d/ li t k shrubs with crops and/or livestock.

• It combines agricultural and forestryh l i di technologies to create more diverse,

productive, profitable, healthy and i bl l d sustainable land-use systems.

Vegetative barriersg

•Vegetative barriers are also an geffective inter-terrace land treatment in place of earthen treatment in place of earthen barriers.

Farm ponds p

• Rain water is harvested and storedUsed for storing water for longer duration• Used for storing water for longer duration.

• Covered with polythene sheet to prevent evaporationevaporation.

Roof top rainwater harvestingp g

• To recharge the wells (open and tube wells) particularly abandoned wells by a runoff ycollection system.

• Direct on-use of collected water Direct on use of collected water if storage facility is available.

RECHARGE TUBE WELL RECHARGE TUBE WELL • To directly feed depleted

aquifers to fresh water fromground surface so that thegrecharge is fast without anyevaporation lossevaporation loss

• Depth of recharge tube welldepends on the present depth ofdepends on the present depth ofbore wells in the area