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