Rainwater harvesting and watershed management

Detail

1. Rainwater harvesting: meaning and benefits

• Rainwater harvesting (RWH) means catching rain and storing it for use. It can also mean guiding rain into pits, wells and borewells so that it soaks down and refills the groundwater (water stored underground in soil and rock).
• It is low-cost and eco-friendly. Households, villages and towns can build it themselves.
• Benefits (NCERT Class 12):
• More water is available. Stored rain adds to supply in the dry season.
• It slows the fall of water tables. The water table is the top level of underground water. Recharge pushes it back up.
• Better water quality. Fresh rainwater mixes with groundwater and dilutes harmful fluoride and nitrates.
• Less soil erosion and flooding. Less rain runs off fast over the land.
• It stops saltwater intrusion. In coastal areas, heavy pumping lowers fresh groundwater, and seawater seeps into the aquifer (an underground layer of rock or sand that holds water). Recharge keeps the fresh water level up and pushes the seawater back.

• It saves energy. When the water table is higher, pumps lift water a shorter distance and use less electricity.

• It matters most in cities. In cities, demand for water has grown faster than supply. Roads and roofs also stop rain from soaking into the soil.

• Methods (NCERT Fig. 4.3): rooftop collection into tanks, recharge pits, recharge trenches, recharge through dug wells and hand pumps, and recharge shafts.

2. Rooftop rainwater harvesting

• How it works, step by step (NCERT Class 10, Fig. 3.3):
• Rain falls on the roof.
• Pipes carry it down to a filter made of sand and bricks, which removes dirt.
• The clean water goes into an underground sump (a storage tank) for daily use.

• Extra water is sent into a well, an old abandoned dugwell or a hand pump to recharge groundwater.

• Gendathur (Mysuru district, Karnataka):

• About 200 households harvest rooftop rain.
• The village gets about 1,000 mm of rain a year.
• With 80% collection efficiency and about 10 fillings of the tank a year, each house collects about 50,000 litres a year.
• Together, the 200 houses collect about 1,00,000 litres of water.

3. The Shillong paradox: heavy rain but short of water

• Location: Shillong is the capital of Meghalaya. Cherrapunji (Sohra) and Mawsynram lie about 55 km away on the southern slopes of the Khasi Hills. These places get the highest rainfall in the world.
• The paradox: even so, Shillong faces an acute shortage of water.
• Why:
• The slopes are steep, so rain runs off quickly.
• Hard rock and thin soil let little water soak in.

• The town has little room to store water.

• Response: nearly every household has a rooftop rainwater harvesting system. It meets about 15–25% of the household's total water need.

• Lesson for the exam: heavy rainfall alone does not make an area water-secure. Water security also depends on storage, terrain and how the water is managed.

4. Laws that make rooftop harvesting compulsory

Measure	Year	Main point
Tamil Nadu rainwater harvesting mandate	2001–03	First Indian state to make rooftop RWH compulsory for all houses and buildings. Defaulters face penalties. NCERT Class 12 says no building can be built without RWH structures.
Model Building Bye-Laws (MBBL), Ministry of Housing and Urban Affairs	2016	Every building on a plot of 100 sq m or more must include a complete RWH proposal. 33 States/UTs had adopted this feature by 2021 [6].

• Effect in Tamil Nadu: groundwater levels in Chennai rose after the law. Later, many structures were not maintained. Chennai still faced a severe water crisis in 2019, so a structure only helps if it is looked after.
• Building bye-laws are local rules that control how buildings are built. Through MBBL 2016, rooftop RWH has become a normal part of urban planning across India.

5. Watershed management

• Watershed: an area of land that drains all its rainwater into one stream, river or lake. A ridge (a line of high land) forms its boundary.
• Watershed management (narrow sense): using surface water and groundwater efficiently by:
• stopping runoff (rainwater that flows away over the surface), and

• recharging groundwater through percolation tanks and recharge wells.

• Watershed management (broad sense): conserving, regenerating and wisely using all resources in a watershed, including land, water, plants, animals and people. The aim is a balance between nature and society.

• The key condition: it succeeds only with community participation. The people who live in the watershed must plan the work, do it and look after it.

Recharge structures

Structure	What it is	How it works	Where it is common
Check dam	A small, low barrier of stone, earth or concrete built across a stream or gully	It slows the water. Silt settles behind the wall, erosion is checked and water soaks down to recharge groundwater.	Saurashtra (Gujarat), Rajasthan, Maharashtra
Percolation tank	A pond or small reservoir that stores runoff	Water is held long enough to percolate (seep slowly down) and refill nearby wells.	Hard-rock Deccan plateau areas, e.g. Maharashtra
Recharge shaft / well	A pit or bore that carries surface water straight down	It reaches deeper aquifers quickly.	Cities and alluvial plains

• Bridge-cum-Bhandaras are newer structures in Maharashtra that both store water and recharge groundwater [5].

6. Government programmes for watershed management and water conservation

NCERT-era programmes

• Haryali (2003):
• A watershed development project sponsored by the Central Government.
• It is carried out by gram panchayats (village councils), with people taking part.

• It helps villagers conserve water for drinking, irrigation, fisheries and afforestation (planting trees).

• Neeru-Meeru ("Water and You"): Andhra Pradesh's programme for water harvesting structures, which people build with their own labour.

Later national programmes

• IWMP and WDC-PMKSY:
• The Integrated Watershed Management Programme (IWMP) ran from 2009–10.

• In 2015–16 it was merged into the Watershed Development Component of Pradhan Mantri Krishi Sinchayee Yojana (WDC-PMKSY) [3].

• WDC-PMKSY 2.0 (approved 15 December 2021, for 2021–26):

• Target area: 49.50 lakh ha. Central outlay: ₹8,134 crore [3].
• Centre–state funding is 60:40. For hilly and North-Eastern states, including Sikkim, it is 90:10. Union Territories get 100% central funding [3].
• Springshed rejuvenation (reviving the land that feeds mountain springs) was added on NITI Aayog's advice [3].

• Results claimed for WDC-PMKSY 1.0: the groundwater table rose by about 3 m on average, and farmers' income rose by about 70% [4].

• Master Plan for Artificial Recharge to Groundwater (2020), CGWB:

• Artificial recharge means helping rainwater reach aquifers through human-made structures.
• The plan proposes about 1.42 crore rainwater harvesting and recharge structures to harness about 185 BCM (billion cubic metres) of water [5].

• The plan gives advice only. States build the structures using funds from schemes such as MGNREGS and PMKSY [5].

• Jal Shakti Abhiyan (JSA):

• JSA-I (2019) covered 1,592 blocks in 256 water-stressed districts [7].
• Its five focus areas were: water conservation and RWH; renovation of traditional water bodies; reuse of water and recharge structures; watershed development; and intensive afforestation [7].

• It ran in two phases. The first was 1 July – 15 September 2019 for the south-west monsoon. The second was 1 October – 30 November 2019 for states that get the north-east (retreating) monsoon, such as Tamil Nadu [7].

• Jal Shakti Abhiyan: Catch the Rain (JSA:CTR):

• Launched on 22 March 2021, which is World Water Day.
• Theme: "Catch the rain, where it falls, when it falls" [2].
• It is now held every year in all districts during the pre-monsoon and monsoon seasons [2].
• Work includes reviving traditional structures such as step-wells, geo-tagging water bodies (marking their exact location on a digital map), and setting up Jal Shakti Kendras [2].
• Funds come through convergence, meaning existing central and state schemes are pooled together [2].
• Work done by March 2022 [2]:
  • about 16.23 lakh water conservation and RWH structures
  • about 2.97 lakh traditional water bodies renovated
  • about 8.32 lakh reuse and recharge structures
  • about 19.18 lakh watershed development works

7. Community success stories

Ralegan Siddhi (Ahmednagar district, Maharashtra)

• Starting point: a poor, drought-prone village in the rain-shadow (dry) zone of the Deccan.
• Leader: from 1975, a retired army driver, Anna Hazare, led the change.
• Method: villagers gave voluntary labour (shramdaan). This "socialised the costs": everyone shared the work, so no outside money was needed.
• The water chain:
• The village repaired a leaking percolation tank.
• The tank held water through the season.

• The groundwater rose, and seven wells below the tank filled with water again.

• Rules the village made itself:

• No open grazing. Animals were stall-fed instead, so grass and soil could recover.
• No tree felling.
• No liquor.

• No sugarcane, because it uses a lot of water. Farmers grew pulses and oilseeds instead.

• Social change:

• Tarun Mandal, a youth group, worked against dowry, caste discrimination and untouchability.
• Local bodies were elected by consensus (common agreement, without contests).

• Nyay panchayats (village courts) settled disputes.

• Limitations: farmers used a lot of chemical fertiliser, and the model depended heavily on one leader.

Arvary Pani Sansad (Alwar district, Rajasthan)

• Setting: the semi-arid Aravalli hills of Alwar district in north-east Rajasthan.
• The process:
• From the mid-1980s, villagers worked with the NGO Tarun Bharat Sangh, led by Rajendra Singh.
• They built johads, traditional crescent-shaped earthen dams that catch runoff.
• Water soaked into the ground and recharged aquifers.
• The groundwater then fed the river in the dry months.

• The Arvari river, which had dried up, began to flow again.

• In 1999 the villages formed the Arvary Pani Sansad, a "water parliament". It makes rules on water use, the choice of crops and the digging of wells.

• Link to the past: johads continue India's long tradition of community water harvesting, which includes khadins, kunds, tankas and step-wells.

Why success is still limited

• Such success stories are still few (NCERT Class 12).
• People need to be made aware of these methods to achieve Integrated Water Resources Management (IWRM). IWRM means managing water, land and related resources together, across the whole river basin.

Prelims Hooks

• Tamil Nadu was the first state to make rooftop RWH compulsory for all buildings (2001–03).
• Shillong (Meghalaya) is short of water even though Cherrapunji and Mawsynram, about 55 km away, get the world's highest rainfall. Rooftop RWH meets 15–25% of household needs there.
• Gendathur is in Mysuru, Karnataka: about 200 households, 1,000 mm of rain, about 50,000 litres per house per year.
• Ralegan Siddhi is in Ahmednagar, Maharashtra (Anna Hazare, from 1975). Arvary Pani Sansad is in Alwar, Rajasthan (Tarun Bharat Sangh, 1999). These are a common place–state matching trap.
• Neeru-Meeru belongs to Andhra Pradesh. Haryali (2003) is a Central programme carried out by gram panchayats.
• IWMP (2009–10) was merged into WDC-PMKSY in 2015–16. WDC-PMKSY 2.0 runs for 2021–26 and added springshed rejuvenation [3].
• Jal Shakti Abhiyan-I (2019): 256 water-stressed districts, 1,592 blocks [7]. JSA: Catch the Rain was launched on 22 March 2021 (World Water Day) [2].
• Under Model Building Bye-Laws 2016, rooftop RWH is mandatory for plots of 100 sq m and above [6].
• CGWB Master Plan 2020: about 1.42 crore structures to harness about 185 BCM [5].
• Trap: a check dam slows a stream and lets water percolate. It is not a storage dam for canals. A percolation tank is built to recharge wells, not to supply water directly.

Mains Points

• Why decentralised harvesting is needed (GS-III):
• Groundwater levels are falling, cities are short of water, coastal aquifers are getting salty and groundwater has fluoride and nitrate problems.
• RWH and watershed works are cheap and local, so they complement large multipurpose dams.

• Examples: Tamil Nadu's 2001–03 law, MBBL 2016 (33 States/UTs) [6] and the CGWB Master Plan 2020 [5].

• Community participation decides success:

• In Ralegan Siddhi, shared labour and social rules (no grazing, no sugarcane) made the work last.
• In the Arvari basin, johads and a "water parliament" revived a river.
• In Chennai after 2019, structures were neglected and failed.

• Lesson: institutions and upkeep matter as much as building structures.

• The policy approach has changed:

• Haryali and Neeru-Meeru (panchayat-led) → IWMP → WDC-PMKSY 2.0 (springsheds; 60:40 and 90:10 funding) [3] → Jal Shakti Abhiyan and Catch the Rain (convergence, geo-tagging of water bodies) [2][7].

• These programmes connect supply-side water security with the Jal Jeevan Mission (2019) target of tap water for every rural home.

• Regional fit:

• Hard-rock Deccan plateau and semi-arid Rajasthan and Saurashtra: check dams, percolation tanks and johads.
• Steep, high-rainfall North-East hills (Shillong): rooftop storage and springshed revival.
• Cities: bye-law-based rooftop RWH and recharge shafts.