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INTRODUCTION(WATERSHED MANAGEMENT)
UNIT – I
Rambabu Palaka, Assistant ProfessorBVRIT
Learning Objectives1. 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 WatershedWatershed 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 DegradationCauses: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 DegradationKey Components:
1. Land / Soil
2. Water
a) Quantity
b) Quality
3. Greenery / Vegetation
Land Degradation
Causes Effects
Improper Land useExcessive CroppingShift CultivationSlope CultivationOvergrazing
Soil ErosionDesertificationSiltation of ReservoirsFloodsDroughtsLoss of Fertility & Soil Moisture
Water Quantity Degradation
Causes Effects
Excessive IrrigationOverdevelopment of GroundwaterImproper use & transportation
Loss of FertilityDecline in Groundwater LevelsScarcity of Water
Water Quality Degradation
Causes Effects
Water loggingLack of Proper DrainageExcessive Manuring & FertilizingEffluents
Soil & Crop DamageDeterioration of Soil & WaterEnvironmental Degradation
Greenery Degradation
Causes Effects
Unplanned DeforestationCutting of unripe trees & Forest fires
Soil ErosionDestruction 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 IndiaForestry: 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 IndiaSoil: 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 IndiaSoil: 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 IndiaWater: 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 IndiaGroundwater: Highly potential Sedimentary rocks - 210 m. ha Low potential Sedimentary rocks - 120 m. ha
Total area - 329 m. ha
Need in IndiaCultivation: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 IndiaDroughts: 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 IndiaIrrigation: 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 IndiaS. 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 IndiaWater 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 RajasthanBasins (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”
Objectives1. 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 ManagementWatershed Management includes, Flood and its mitigation & control
Erosion & Sedimentation Control
Water Quality & Quantity Management
Irrigation and Water supply Management
Groundwater Harvesting
Land Management
Watershed ManagementWatershed 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
Watershed Management By
J.V.S. Murthy
New Age Publications