2. Learning Objectives
1. What is watershed?
2. Concept
4. Objectives
5. Watershed Development Approach
3. Need in India
3. What is Watershed?
A watershed is a basin-like landform defined by highpoints and ridgelines that
descend into lower elevations and stream valleys.
In other words, a watershed describes an area of land that contains a common set of
streams and rivers that all drain into a single larger body of water, such as a larger
river, a lake or an ocean.
A watershed or catchments is defined as any surface (varying from a few hectares
to several thousand square kilometers) in which rainfall is collected and
conveyed to a common natural waterway
"Watershed is a geo-hydrological unit draining run-off water at a common point and it
could be demarcated based on ridge and gully lines".
6. Concept of Watershed
Watershed constantly undergoes the action and reaction of many
Hydrologic and Hydraulic Components or Phenomena.
Hydrologic Precipitation, Infiltration, Evaporation, Evapotranspiration
Hydraulic Components or Phenomena Floods, Erosion, Sedimentation,
Land slides, Water Scarcity, Water Quality Degradation
7. Watershed Degradation
Causes:
1. Natural
• Excess Runoff Floods, Erosion, Sedimentation etc.,
• Rainfall Shortage Drought
2. Man made Errors
• Ignorance
• Lack of knowledge about watershed, proper planning and
management
9. Land Degradation
Causes Effects
Improper Land use
Excessive Cropping
Shift Cultivation
Slope Cultivation
Overgrazing
Soil Erosion
Desertification
Siltation of Reservoirs
Floods
Droughts
Loss of Fertility & Soil Moisture
10. Water Quantity Degradation
Causes Effects
Excessive Irrigation
Overdevelopment of Groundwater
Improper use & transportation
Loss of Fertility
Decline in Groundwater Levels
Scarcity of Water
11. Water Quality Degradation
Causes Effects
Water logging
Lack of Proper Drainage
Excessive Manuring & Fertilizing
Effluents
Soil & Crop Damage
Deterioration of Soil & Water
Environmental Degradation
13. Need in India
Geographical Area: 329 million hectares
Physiographic Units:
Himalayas
Gangetic Plains
Central Highlands
Peninsular Plateau
Eastern and Western Coastal Belts
Islands
14. Need in India
India receives rainfall mostly from Monsoons:
Southwest June to September
Northeast October to December
Rainfall varies from 150mm (Western Rajasthan) to 3000mm (Assam,
Kerala, Coastal Karnataka, and Konkan)
Annual Normal Average Rainfall is 1345 mm
Reckless deforestation, dreadful soil erosion and careless land
management bared about 90% of lands in India
15. Need in India
Forestry:
Ecological requirement is 33% of 329 m.ha
Observations in the year:
1953 - 110 m.ha.
1970 - 60 m.ha.
1980 - 50 m.ha.
1990 - 32 m.ha.
Rate of Deforestation observed is 1.5 m.ha per year
Shift Cultivation is at 0.50 m.ha per year
16. Need in India
Soil:
Annual degradation of land is 2.5 m.ha.
Due to Deforestation - 1.5 m.ha.
Rest due to Floods, Glaciations, Wind Action, Over Cropping, River
Sedimentation, and Salinity Hazards.
Wastelands in the year
1985 - 146 m.pa.
1990 - 165 m.pa.
17. Need in India
Soil:
Flood alone carries 12 billion tonnes of soil i.e., 36.50 tonnes per year.
Allowable limit is 4 tonnes per year
Soil nutrient loss is 10 to 16 m.ha. Per year
Siltation is reservoirs is 200% to 1500% higher than estimated rates
18. Need in India
Water:
Total rainfall - 3000 billion cum
Average natural flow - 1853 b. cum
Useful water - 1110 b. cum
Rivers carries about 80% of flow during monsoon months
Total Utilization water from Dams - 690 b. cum
Present Utilization water from Dams - 176.13 b.cum
19. Need in India
Groundwater:
Highly potential Sedimentary rocks - 210 m. ha
Low potential Sedimentary rocks - 120 m. ha
Total area - 329 m. ha
20. Need in India
Cultivation:
Total Area - 140.72 m.ha
Degraded forests - 35.16 m.ha
Non-available area for cultivation - 40.48 m.ha
Cultivable Waste Land - 15.74 m.ha
Fallow Land - 24.91 m.ha
21. Need in India
Droughts:
Causes: Rainfall and other climatic factors
99 districts of India are declared as Drought Prone
Severe Drought observed in: 1965-66, 1979-80, and 1985-86
Drought destroys greenery, agriculture, erosion of soils, and desertification
22. Need in India
Irrigation:
Potential area - 113 m.ha
Major & Medium Irrigation Projects - 58 m.ha
Minor Irrigation Projects - 15 m.ha
Ground Water - 40 m.ha
23. Watersheds in India
S. No. Hydrologic Units Size Range (ha) No. of Units
1 Water Resource Region 270,00,000-1130,00,000 6
2 Basins 30,00,000-300,00,000 34
3 Catchments 10,00,000-50,00,000 112
4 Sub-catchments 200,000-10,00,000 500
5 Watersheds 20,000-300,000 3237
6 Sub-watersheds 5,000-9,000 12000
7 Micro-watersheds 500-1,500 400000
24. Watersheds in India
Water Resources Regions (6) in India:
(1) Indus drainage, (2) Ganges drainage, (3) Brahamputra drainage, (4) All drainage
flowing into the Bay of Bengal except those at 2 & 3, (5) All drainage flowing into the
Arabian Sea except Indus drainage, (6) Western Rajasthan
Basins (34):
Barmer, Beas, Bhadar, Bhatsol, Brahimani, Brahmputra, Cauvery, Chambal,
Chenab, Churu, Ghagar, Godavari, Imphal, Indus, Jhelum, Krishna, Kutch, Lower
Ganga, Luni, Mahanadi, Mahi, Narmada, Pennar, Periyar, Qura-Qush, Ravi,
Sabarmati, Surma, Sutlej, Tapi, Upper Ganga, Vaipar, Vamsadhara, Yamuna.
25.
26.
27. CODE OF WATERSHED
Ex. 1A2B3a1
1A2B3a1 stands for a national code of a micro-watershed belongs to
Water Resource Region “1”,
Basin “1A”,
Catchment “1A2”,
Subcatchment “1A2B”,
Watershed “1A2B3”,
Subwatershed “1A2B3a” and
Microwatershed “1A2B3a1”
28. Watershed Management
“Watershed management is a concept which recognizes the
judicious management of three basic resources of soil, water
and vegetation for achieving particular objective for the well
being of plant, animal, and human communities within a
watershed boundary”
29. Objectives
1. Optimum utilization of natural resources such as water,
land, vegetation, etc.
2. Employment facility
3. Efficient and equal distribution of resources
4. Community’s living standard, food security, poverty
alleviation, hygiene, etc. of the community
30. 5. Unity, Integrity and harmony among villagers
6. Yield of Crop
7. Restoration of desert area
8. Maintenance of water table
9. Reclamation of wasteland
10. Recreation and Fishery Development
Objectives
31. 11. Water Harvesting
12. Water use control and conservation
13. Growing Greenery
14. Soil Erosion Control
15. Overall development of the community and watershed
Objectives
32. Watershed Management
Watershed Management includes,
Flood and its mitigation & control
Erosion & Sedimentation Control
Water Quality & Quantity Management
Irrigation and Water supply Management
Groundwater Harvesting
Land Management
34. Watershed Development Approach
Integrated Multi-disciplinary Approach
Watershed approach invites integrated inputs of various disciplines for the
development of watersheds in accordance with their characteristics.
Protect Natural Resources
Attain Good Yields
Coordinate Manpower with Limited Funds
Community Participation
35. Watershed Programmes in India
1973-74 Drought Prone Areas Programme (DPAP)
7.05 m.ha – 27,439 Projects
1977-78 Desert Development Programme (DDP)
5.67 m.ha – 15,746 Projects
1989-90 Integrated Watershed Management Programme (IWMP)
10.47m.ha – 1877 Projects
1992 Integrated Wastelands Development Programme (IWDP)