Water Harvesting System

Water Harvesting System – UPSC Indian Geography Notes

India possesses 4% of the world’s Water resources and makes up around 2.45% of its surface area.

Rainfall serves as India’s main supply of freshwater. India receives the second-highest quantity of rainfall for a nation its size.

The average annual rainfall in India is 1,170 millimeters (46 in), or over 4,000 cubic kilometers (960 cubic miles) of water. This translates to about 1,720 cubic meters (61,000 cu feet) of freshwater per person.

For most places in India, groundwater is the main source of water supply, and the country’s rapidly declining groundwater resources demand immediate attention if water security is to be ensured in the upcoming years.

Rainwater harvesting

The act of collecting and storing rainwater as opposed to letting it flow off is known as rainwater harvesting.

Rainwater is gathered from a surface like a roof and directed to a container with percolation, such as a tank, cistern, deep pit (well, shaft, or borehole), aquifer, or reservoir where it seeps down and replenishes the groundwater table.

The rainwater harvesting process includes the collection and storage of collected rainwater with the help of artificially designed systems.

The main components of the system are-

  • Catchment: Used to collect and store the captured rainwater.
  • Conveyance system: It is used to transport the harvested water from the catchment to the recharge zone.
  • Flush: It is used to flush out the first spell of rain.
  • Filter: Used for filtering the collected rainwater and removing pollutants.
  • Tanks and recharge structures: Used to store the filtered water which is ready to use.

Rainwater harvesting has significance in solving other related issues in a nation like food security, rapid urbanization, and industrial developmental demands. This method acts as a decentralized source of water for all needs.

Traditional water harvesting systems in India

  • Water Harvesting in India: Our ancestors, with expertise in water management, have been harvesting water in India since ancient times.
  • Rainwater Harvesting Techniques:
    • Roof Collection: Raindrops were directly harvested from rooftops.
    • Courtyard Tanks: The collected water was stored in tanks built in courtyards.
    • Community Lands: Water from open community lands was collected and stored in artificial wells.
    • Monsoon Runoff: Water from swollen streams during the monsoon season was captured and stored using various water bodies.
    • River Flooding: Water was also harvested from flooded rivers.

Paar System

  • The Paar system is a prevalent water harvesting practice in the western Rajasthan region.
  • Process of Paar:
    • Rainwater flows from the agar (catchment) and percolates into the sandy soil.
    • Rajani Pani: The percolated water, known as Rajani pani, is accessed through dug kuis or beris in the agor (storage area).

Talan/Bandhis (Reservoirs)

  • Natural Reservoirs: Ponds (pokhariyan) in Tikamgarh, Bundelkhand, serve as natural reservoirs.
  • Human-Made Reservoirs: Lakes in Udaipur are human-made examples.
  • Reservoir Size Classification:
    • Talai: Reservoir area of fewer than five bighas.
    • Bandhi/Talab: Medium-sized lake.
    • Sagar/Samand: Bigger lakes.
  • Utilization of Pokhariyan:
    • Pokhariyan serve purposes like irrigation and drinking water.
    • After the monsoon, when water dries up, the pond beds are cultivated with rice.

Saza Kuva

  • A crucial irrigation source in the Aravalli hills in Mewar, eastern Rajasthan, the saza kuva is an open well with multiple owners (saza meaning partner).
  • Construction of Saza Kuva:
    • The soil dug out for the well pit is utilized to create a substantial circular foundation or an elevated platform sloping away from the well.
  • Functional Components:
    • Rehat: The first component is built to accommodate the rehat, a traditional water lifting device.
    • Chada: The sloping platform is designed for the chada, a mechanism utilizing buffaloes to lift water.

Johads

  • These are small earthen check dams designed to capture and conserve rainwater, enhancing percolation and groundwater recharge.
  • Revival Initiative:
    • Commencing in 1984, the past sixteen years have witnessed the revival of approximately 3000 johads across over 650 villages in the Alwar district, Rajasthan.
  • Positive Outcomes:
    • This revival effort has led to a significant increase in the groundwater level by nearly 6 meters.
    • Additionally, there has been a remarkable 33 percent surge in the forest cover in the area.

Pat System

  • The Bhitada village in the Jhabua district of Madhya Pradesh pioneered the unique pat system.
  • This system, tailored to the terrain, diverts water from swift-flowing hill streams into irrigation channels known as pats.

Jhalaras (Rectangular Step-Wells)

  • These step-wells, with tiered steps on three or four sides, collect subterranean seepage from upstream reservoirs or lakes.
  • Jhalaras were constructed to ensure a consistent water supply for religious rites, royal ceremonies, and community use.
  • Notably, Jodhpur boasts eight jhalaras, with the oldest, Mahamandir Jhalara, dating back to 1660 CE.

Bawari (Unique Step-Wells)

  • Bawaris were integral to ancient water storage networks in Rajasthan cities.
  • Rainfall in the region would be directed to man-made tanks through canals on hilly city outskirts, promoting percolation into the ground.
  • Layered steps around the reservoirs were built to minimize water loss through evaporation, narrowing and deepening the wells.

Taanka (Traditional Rainwater Harvesting)

  • Indigenous to the Thar desert region of Rajasthan, Taanka is a cylindrical underground pit.
  • Rainwater from rooftops, courtyards, or artificially prepared catchments flows into the Taanka.

Ahar Pynes (Floodwater Harvesting)

  • Indigenous to South Bihar, Ahar Pynes are traditional floodwater harvesting systems.
  • Ahars, reservoirs with embankments on three sides, are constructed at the end of diversion channels like pynes.
  • Pynes, artificial rivulets from rivers, channel water into ahars for dry-month irrigation, crucial for paddy cultivation.

Panam Keni (Kuruma Tribe Well)

  • The Kuruma tribe in Wayanad uses Panam Keni, a unique well, for water storage.
  • Wooden cylinders are crafted by soaking toddy palm stems, allowing the core to rot away, leaving a durable outer layer.

Khadin (Runoff Harvesting)

  • Khadins are innovative structures for harvesting surface runoff water in agriculture.
  • Features include a long earthen embankment (dhora) across gravelly upland hill slopes, with sluices and spillways.
  • Originating in the 15th century by the Paliwal Brahmins of Jaisalmer, it resembles ancient Ur’s irrigation methods (present Iraq).

Kund (Saucer-shaped Catchment)

  • A kund is a saucer-shaped catchment area sloping towards a central circular underground well.
  • Primarily designed for drinking water, kunds are found in sandy tracts of western Rajasthan and Gujarat.
  • Raja Sur Singh is credited with building the earliest known kunds in Vadi Ka Melan in the year 1607 CE.

Baoli (Stepwells)

  • Nobility constructed baolis for civic, strategic, or philanthropic purposes, making them secular structures accessible to everyone for water.
  • These stepwells are adorned with beautiful arches, carved motifs, and sometimes feature rooms on their sides.
  • Village baolis serve utilitarian purposes and social gatherings, while those on trade routes are resting places.
  • Agricultural stepwells have drainage systems directing water into fields.

Nadi (Village Ponds)

  • Found near Jodhpur in Rajasthan, Nadis are village ponds storing rainwater from adjoining natural catchment areas.

Zings (Glacier Water Tanks)

  • Located in Ladakh, Zings are small tanks collecting melting glacier water.
  • A network of channels guides water from the glacier to the tank, and collected water is used in fields the following day.
  • In this dry region, a water official known as a Chirpun ensures equitable distribution of water from melting glacial sources to meet farming needs.

Kuhls (Mountainous Water Channels)

  • Kuhls are surface water channels in the mountainous regions of Himachal Pradesh.
  • These channels transport glacial waters from rivers and streams to irrigate fields.
  • The Kangra Valley system boasts approximately 715 major Kuhls and 2,500 minor kuhls, irrigating over 30,000 hectares.
  • Kuhls are a significant cultural tradition, constructed through public donations or by royal rulers.

Zabo (Run-off Impounding)

  • Zabo, also known as the Ruza system in Nagaland, integrates water conservation with forestry, agriculture, and animal care.
  • Rainwater from forested hilltops is collected by channels, directing run-off water into pond-like structures on terraced hillsides.

Eri (Tank System)

  • Eri is an ancient tank system in Tamil Nadu, representing one of India’s oldest water management systems.

Government policies for Rainwater harvesting

  • The Central Government has established the National Water Policy 2012, incorporating provisions for rainwater harvesting. Key aspects include:
    • Revival Incentives: States are encouraged to incentivize the revival of traditional water harvesting structures.
    • Urban and Industrial Areas: There is a push for rainwater harvesting in urban and industrial areas to enhance utilizable water availability.
    • Water Supply Preference: The policy promotes a preference for supplying water to both urban and rural areas through a combination of surface water, groundwater, and rainwater harvesting.
  • Despite water being a State subject, the responsibility for augmentation, conservation, and efficient management of water resources primarily rests with the respective State Governments.
  • Some noteworthy steps taken by the Government of India in the domain of rainwater harvesting include:
  • The Jal Shakti Abhiyan evolved into “Jal Shakti Abhiyan: Catch the Rain” (JSA: CTR) in 2021, emphasizing the theme “Catch the Rain Where it Falls When it Falls.” This expansion aims to encompass all blocks in every district, spanning both rural and urban areas throughout the country.
  • The Atal Bhuj Yojana operates as a Central Sector Scheme, allocating Rs. 6,000 crores for identified water-stressed areas in 8,220 Gram Panchayats across 229 blocks in 80 districts of Gujarat, Haryana, Karnataka, Madhya Pradesh, Maharashtra, Rajasthan, and Uttar Pradesh. Its objective is to halt the decline in groundwater levels through community-led sustainable groundwater management.
  • The Watershed Development Component of the Pradhan Mantri Krishi Sinchayee Yojana (WDC-PMKSY) includes rainwater harvesting in its Natural Resource Management (NRM) activities.
  • Surface Minor Irrigation (SMI) and Repair, Renovation & Restoration (RRR) of Water Bodies serve multiple objectives, such as expanding cultivable areas through assured irrigation, improving and restoring water bodies, increasing groundwater recharge, and reviving lost irrigation potential.
  • The Master Plan for Artificial Recharge to Groundwater- 2020 has been collaboratively prepared by the Central Ground Water Board, in consultation with States/UTs. This macro-level plan outlines various structures tailored to different terrain conditions across the country.
  • Atal Mission for Rejuvenation and Urban Transformation (AMRUT):
    • Launched in 2015, AMRUT prioritizes the development of basic urban infrastructure, with a specific focus on water supply and ensuring tap connections to every household in 500 cities.
  • Mahatma Gandhi National Rural Employment Guarantee Scheme (MGNREGS):
    • MGNREGS incorporates water conservation and water harvesting structures within its activities under the natural resource management (NRM) component.
  • Mission Amrit Sarovar:
    • Launched on National Panchayati Raj Day on April 24, 2022, as part of the Azadi ka Amrit Mahotsav celebrations, Mission Amrit Sarovar is designed to conserve water for the future.
    • The mission’s objective is to develop and rejuvenate 75 water bodies in each district across the country.

Way forward

  • To address the pressing issue of depleting water supplies in India, there is an urgent need to promote rainwater harvesting. This involves combining ancient rainfall-saving techniques, such as percolation tanks, injection wells, and subsurface barriers, with modern rainwater-saving methods.
  • Relying solely on conventional techniques is inadequate. The key to solving India’s ongoing water challenges lies in the effective integration of these various approaches.
  • Efforts should be intensified to reduce dependence on groundwater, emphasizing the improvement of water security.
  • Strategies should include the rejuvenation and replenishment of both built-up and natural water bodies, alongside an increased repurposing of treated wastewater by local sewage treatment facilities.
  • Properly constructed rainwater collection systems should be installed across residential and business locations.
  • Collaboration between federal and state governments is crucial to enable and support these initiatives.
  • For long-term and sustainable solutions, strict policy actions are necessary, and local government entities should propose and implement integrated water management strategies.

FAQs on Water Harvesting System

Q1: What is rainwater harvesting?

Rainwater harvesting refers to the accumulation and storage of rainwater for reuse, diverting it from runoff.

Q2: What are the various methods of rainwater harvesting?

Different methods of rainwater harvesting include:

  • Rooftop Rainwater Harvesting: Involves using rooftops as catchments, with components like first flush, transportation, catchment, and filters.
  • Surface Runoff Harvesting: Collects rainwater flowing as surface runoff, which is then caught and utilized to recharge aquifers through suitable techniques.

Q3: Why is rainwater harvesting important?

Rainwater harvesting is a sustainable practice crucial for preserving water for future needs. Given the current concerns about water scarcity, this method plays a vital role in water conservation.

Q4: What are the benefits of rainwater harvesting?

The advantages of rainwater harvesting include:

  • Cost-effectiveness
  • Water conservation
  • Providing a water source for landscape irrigation
  • Simplicity and ease of implementation
  • Reduction of soil erosion and pollution of water bodies caused by fertilizers and pesticides.

Q5: What factors influence the amount of harvested rainwater?

The factors impacting the amount of rainwater harvested encompass:

  • Features of the catchment area
  • Quantity of runoff
  • Storage tank capacity

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