Introduction to Watershed Management

INTRODUCTION
(WATERSHED MANAGEMENT)
UNIT – I
Rambabu Palaka, Assistant ProfessorBVRIT

Learning Objectives
1. What is watershed?
2. Concept
4. Objectives
5. Watershed Development Approach
3. Need in India

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".

Ridgeline
Common Point
Streams

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

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

Watershed Degradation
Key Components:
1. Land / Soil
2. Water
a) Quantity
b) Quality
3. Greenery / Vegetation

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

Water Quantity Degradation
Causes Effects
Excessive Irrigation
Overdevelopment of Groundwater
Improper use & transportation
Loss of Fertility
Decline in Groundwater Levels
Scarcity of Water

Water Quality Degradation
Causes Effects
Water logging
Lack of Proper Drainage
Excessive Manuring & Fertilizing
Effluents
Soil & Crop Damage
Deterioration of Soil & Water
Environmental Degradation

Greenery Degradation
Causes Effects
Unplanned Deforestation
Cutting of unripe trees & Forest fires
Soil Erosion
Destruction of Green-Forests &
Environment

Need in India
 Geographical Area: 329 million hectares
 Physiographic Units:
 Himalayas
 Gangetic Plains
 Central Highlands
 Peninsular Plateau
 Eastern and Western Coastal Belts
 Islands

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

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

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.

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

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

Need in India
Groundwater:
 Highly potential Sedimentary rocks - 210 m. ha
 Low potential Sedimentary rocks - 120 m. ha
 Total area - 329 m. ha

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

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

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

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

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.

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”

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”

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

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

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

Watershed Management includes,
 Flood and its mitigation & control
 Erosion & Sedimentation Control
 Water Quality & Quantity Management
 Irrigation and Water supply Management
 Groundwater Harvesting
 Land Management

Watershed Management includes,
 Landslides Management
 Ecosystem Management
 Fish & Wild Life
 Forestry
 Agriculture
 Wasteland Management

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

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)

Reference
By
J.V.S. Murthy
New Age Publications

Introduction to Watershed Management

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