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The entire Indian sub-continent has been divided into total 15 agro-climatic regions based on variations in climatic characteristics. However, to promote the rainwater harvesting for enriching the water availability potential, especially the drinking water in rural areas, the Himalayan foot hills have also been additionally included in the total 15 agro-climatic regions. In other words, instead of 15, there are total 16 agro-climatic regions have been recognized in context to water harvesting and watershed development works.
The recommended water harvesting measures and watershed management works for these agro-climatic regions are outlined as under:
1. Humid Northern Himalayan Region:
This is basically the cold region of the India. The hilly areas of Jammu & Kashmir, Himachal Pradesh and Uttaranchal fall in this agro-climatic region.
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Different characteristics of this region are listed as under:
i. This region has skeletal soils, podsolic soils, mountain meadow soils and hilly brown soils.
ii. Dominated by highly undulating terrain with steep slopes.
iii. Soils are generally silty loam; are prone to erosion problem.
Landslide is very common, especially in denuded hill slopes with excessive human settlements and a good network of roads and hill tracks.
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Recommended Water Harvesting Measures:
The followings are the main measures for this region:
i.. Roof water harvesting
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ii. Diversion of perennial springs and stream water in the storage structures.
iii. Village or community ponds.
iv. Collection of water from hill slopes.
2. Himalayan Foot Hills Region:
The Himalayan Foot Hills region covers the foothill areas of Jammu & Kashmir, Himachal Pradesh, Punjab and Uttaranchal in the west; and parts of West Bengal, Assam and Arunachal Pradesh in the east.
Various features of this region are outlined as below:
i. Majority of soils are loose textured deposits underlain by boulders and pebbles. Percolation rate of these deposits is generally moderate to high, where soil cover is thin.
ii. In topographic lows, the thickness of soil is more, which creates a good scope for construction of dug ponds with fairly good water retention capacity.
iii. The ground water gradient is normally steep, as result there is quick drainage of ground water into nearby streams.
Recommended Water Harvesting Measures:
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The recommended measures for water harvesting are mentioned as below:
i.. Collection of rainwater from hill slopes.
ii. Construction of Village/community ponds.
iii. Contour trenching.
3. Humid High Rainfall North Eastern Region:
This region covers a large area of Sikkim, Darjeeling hills, Arunachal Pradesh, Meghalaya, Nagaland, Manipur, Tripura, Mizoram, Assam, and Jalpaiguri and Cooch Behar districts of West Bengal.
Various characteristics of this agro-climatic region are listed as under:
i. The geological formations of this region are complex in nature, i.e. they contain rocks, which are either exposed to the top ground surface or under moderately thick soil cover.
ii. Soils are generally fragile in nature; and prone to severe erosion.
iii. The rainfall is high, resulting into high surface runoff generation.
iv. In the areas having adverse topography and hydro-geological conditions, the ground water development is not techno-economically viable.
Recommended Water Harvesting Measures:
The recommended measures for good water harvesting are as below:
i. Roof water harvesting.
ii. Diversion of perennial springs and streams to storage structures. The storage structures may be the tanks, ponds etc.
4. Humid Assam Bengal Plain Region:
This agro-climatic region covers the parts of lower Gangetic plains falling in the states of Assam and Bengal.
Various features of this region are listed as under:
i. The soils of this region are in the nature of alluvium with diverse mix of sand, silt and clay.
ii. The main topographic feature of the region is the fluvial plains. The fluvial plains are dominated by abandoned river/channels, ox-bow lakes and the land surface carved by numerous perennials and seasonal streams.
iii. Although, there is good rainfall, but often a drought like situation, because of long gaps between successive rainfall events in the areas drained by small seasonal streams.
iv. The natural drains and stream flow through alluvial terraces, cause severe soil erosion.
v. In general, the topsoil is prone to erosion because of excessive agricultural activities coupled with unscientific land management practices.
vi. The ground water normally contains high concentration of Iron and Mica. Excessive Arsenic is also reported in about 1,000 habitations in West Bengal.
vii. The ground water development in Assam is constrained by lack of reliable power supply.
Recommended Water Harvesting Measures:
The recommended water harvesting measures are as below:
i. Construction of tanks.
ii. Use of check dams/anicuts.
iii. Gully plugging.
iv. Contour bunding.
5. Sub-Humid and Humid Sutlej-Ganga Alluvial Region:
The part of Punjab, Haryana, Uttar Pradesh and Bihar fall under this region. Also, the middle reaches of the Sutlej basin and the lower and middle reaches of the Ganga basin come under this region.
Different characteristics of this region are outlined as under:
i. Rainfall distribution is generally uneven, e.g. in its eastern parts the plains of Bihar and eastern Uttar Pradesh. Although, there is good rainfall but due to uneven tempo- spatial distribution of rainfall, few areas face the situation of sub-humid conditions and often with drought conditions during the periods of below-normal rainfall. The southern part of Sutlej basin bears this type of situation, is an example of this.
ii. The water-table position is very poor, because of excessive withdrawal of water for irrigation purposes during last 5 decades.
Recommended Water Harvesting Measures:
The recommended water harvesting measures for this regions are listed as under:
i. Construction of ponds.
ii. Construction of check dams.
iii. Gully plugging.
iv. Contour bunding.
6. North-Western Semi-Arid and Arid Region:
Under this agro-climatic region the western Rajasthan falls.
The important characteristics of this region are listed as below:
i. It consists of hot sandy desert.
ii. The rainfall is being erratic in nature.
iii. Evaporation rate is very high.
iv. Normally, the perennial rivers are not there.
v. Vegetations are very scanty.
vi. The natural ground water recharge is about to negligible, because of low rainfall and high evaporation.
vii. In most of the places the ground water-table is at considerable depth. At few locations the perched ground water are also found.
viii. There is rainfed agriculture practices except in the command area of Indira Gandhi Nahar Pariyojna (IGNP).
ix. In rural areas there is extensive exploitation of ground water for drinking purposes.
Recommended Water Harvesting Measures:
The recommended rainwater harvesting measures for this zone are as below:
i. Nadi/Talab
ii. Tanka
iii. Khadin
iv. Percolation tanks
v. Anicuts
vi. Gully plugging
vii. Contour bunding
7. Central Semi-Arid Vindhya Region:
In central semi-arid Vindhya region the south-eastern districts of Rajasthan, southern districts of Uttar Pradesh and central parts of Madhya Pradesh are included.
The special features of this region are outlined as below:
i. The land topography is diverse. In few parts of Narmada valley and hills there is dominancy of ravines. About 33% land is not suitable for cultivation.
ii. The irrigation and cropping intensities are low.
iii. The annual rainfall of the areas lying in Madhya Pradesh is fairly good, to the tune of about 900 mm. On the other hand, in the areas falling in Rajasthan and Uttar Pradesh the annual rainfall is as low as 350 mm. The monsoon runoff is high, because of predominantly hilly terrain. Also, there is severe soil erosion/loss from the hill faces and river banks.
Recommended Water Harvesting Measures:
The recommended water harvesting and watershed development measures are mentioned as below:
i. Construction of ponds.
ii. Construction of check dams.
iii. Contour bunding.
iv. Gully plugging.
v. Sub-surface dykes.
8. High Rainfall high Runoff Chhotanagpur Plateau Region:
The entire Jharkhand and adjoining hilly areas of Bihar, West Bengal and Orissa fall under this region.
This region is characterized by following features:
i. Soils are medium to shallow depths.
ii. Topography is undulating.
iii. The surface runoff and soil loss is very high because of steep slopes, high rainfall intensities and very short rainy spells. Also, there is formation of rills and gullies and stream bank erosion because of adverse features.
iv. The potential ground water sources are not in convenient reach of the rural mass, might be due to adverse topography and human settlements in the hilly terrain.
v. The measures for improvement of watersheds and local rainwater collection and storage are essential to improve water availability in the region.
Recommended Water Harvesting Measures:
The recommended water harvesting practices are:
i. Construction of tanks/ponds.
ii. Construction of check dams/anticuts.
iii. Gully plugging.
iv. Contour bunding.
9. Malwa Plateau & Narmada Basin Region:
This region forms a major part of peninsular India. Its main features are outlined as under:
i. The annual rainfall is about 900 mm.
ii. The predominant soil type is deep black soil.
iii. The ground water recharge is mainly through fissures and joints in exposed rocky strata and through streambeds.
Recommended Water Harvesting Measures:
The recommended water harvesting practices for this region are as below:
i. Construction of ponds.
ii. Check dams.
iii. Sub-surface dams.
10. South-Central Deccan Plateau Region:
In this region, the parts of Andhra Pradesh, Tamil Nadu, Karnataka and Maharashtra, are included.
It assembles following important features:
i. The region has highly diverse geological features with predominance of hard basaltic rocks.
ii. The rainfall pattern is non-uniform.
iii. The availability of ground water varies, depth-wise.
iv. The surface strata and soil types are conducive to natural ground water recharge.
Recommended Water Harvesting Measures:
The recommended water harvesting measures are as below:
i. Construction of ponds.
ii. Construction of check dams.
iii. Construction of percolation tanks.
iv. Bandhara.
v. Gully plugging.
vi. Sub-surface dams.
vii. Contour bunding.
11. Chhattisgarh Plateau Region:
The Chhattisgarh state and South-Western Orissa hills fall under this region.
Special features of this region are mentioned as under:
i. The geological and geo-morphological characteristics are about to same to the South-Central Deccan Plateau Zone.
ii. The rainfall of the region is relatively high.
Recommended Water Harvesting Measures:
The recommended measures for water harvesting are the same to the South-Central Deccan Plateau Zone, i.e.
i. Construction of ponds.
ii. Construction of check dams.
iii. Construction of percolation tanks.
iv. Bandhara.
v. Gully plugging.
vi. Sub-surface dams.
vii. Contour bunding.
12. South-Eastern Brown/Red Soil Region:
In this region, the Pachamalai and Kadavur hills and pediplain areas of Tamil Nadu and Veligond hills and part of plains (excluding 4-5 km wide coastal belt) of Andhra Pradesh are included.
Different characteristics of this region are pointed as below:
i. The rainfall varies from about 818 mm in Perambalur district of Tamil Nadu to 1148 mm in Nellore district of Andhra Pradesh.
ii. Runoff coefficient varies from 0.066 to 0.1067 in plains; and from 0.20 to 0.45 in plateau and foothill areas.
Recommended Water Harvesting Measures:
The recommended water harvesting measures for this region are as below:
i. Traditional ponds/tanks.
ii. Percolation tanks.
iii. Sub-surface dams in the vicinity of drinking water sources such as dug wells, hand pumps and tube wells.
13. Southern Variable Rainfall Mixed Soil Region:
This region comprises the southern parts of Maharashtra and West-Central parts of Tamil Nadu.
Various characteristics are outlined as under:
i. Contains highly undulating and dissected landform with elaborated natural drainage system.
ii. Rainfall distribution is highly uneven.
iii. The land surface is diverse in composition. The main features being sandy or younger alluvial plains and rocky gravel pediments.
iv. Soils are friable and prone to erosion; because of this reason there is excessive gully formation.
Recommended Water Harvesting Measures:
The recommended water harvesting and watershed development measures are as below:
i. Construction of ponds/tanks/Kunta.
ii. Nadi.
iii. Construction of check dams.
iv. Construction of percolation tanks.
v. Construction of sub-surface dams.
vi. Gully plugging.
14. Southern Bi Modal Rainfall Region:
In this region the Southern most parts of Kerela, Karnataka and Tamil Nadu are included.
The prominent features are outlined as under:
Physiographic feature includes the southern plateau and hills; east coast plains and hills and west coast plains and hills.
Recommended Water Harvesting Measures:
The recommended water harvesting and watershed development measures are listed as below:
i. Construction of ponds/tanks.
ii. Construction of percolation tanks.
iii. Construction of check dams.
iv. Gully plugging.
v. Contour bunding.
15. Eastern Coromandal Region:
The entire coastal belt of Orissa, Andhra Pradesh and West Bengal fall under this agro-climatic region.
Recommended Water Harvesting Measures:
The recommended measures for water harvesting, ground water recharge and watershed development are mentioned as under:
i. Construction of ponds/tanks/Kunta.
ii. Nadi.
iii. Construction of check dams.
iv. Construction of percolation tanks.
v. Sub-surface dams.
vi. Gully plugging.
16. Western Malabar Region:
This region comprises the western Malabar area of Kerela and coastal areas of southern Karnataka.
Recommended Water Harvesting Measures:
The recommended measures for water harvesting, ground water recharge and watershed development are outlined as below:
i. Construction of ponds/tanks/Kunta.
ii. Construction of check dams.
iii. Use of K.T. Weirs.
iv. Bandhara.
v. Construction of percolation tanks.
vi. Construction of sub-surface dams.
vii. Contour bunding.