Rainwater Harvesting: A Solution to Sustainable Water Management in India

Table of Contents

• Introduction
• What is Rainwater Harvesting?
• What is the Status of Rainwater Harvesting in India?
• What is the Importance of Rainwater Harvesting?
• What are the Benefits of Rainwater Harvesting?
• What are the Popular Rainwater Harvesting Methods in India?
  • Ground Water Recharge
  • Surface Runoff Harvesting
• What are the Types of Rainwater Harvesting?
  • Rooftop Rainwater Harvesting
  • Contour Bunds
  • Gabion Structure
  • Percolation Tanks
  • Check Dams
  • Dugwell Recharge
• What are the Challenges Faced in Rainwater Harvesting in India?
• What are the Government Schemes to Promote Rainwater Harvesting?
• What are the Future Potentials of Rainwater Harvesting in India?

Introduction

The Earth is abundant with water, but ‘water for use’ is very scarce. With a growing population, urbanisation, over-exploitation of natural resources like groundwater, and climate change have made this precious natural resource scarcer. The need is to conserve water and sustainably use it to make it available for future human consumption and agricultural use. In this light, rainwater harvesting has become a critical solution for sustainable water management in India. Let us first see the meaning of rainwater harvesting.

What is Rainwater Harvesting?

 
Rainwater harvesting, a practise in vogue in India for the last 4000 years, is the method of collecting rainwater and storing it for later use. It is like you depositing money in your bank account when in surplus and withdrawing it when deficient. In this method, rainwater is harvested by constructing a tank over the surface or under the surface. The objective is to check the rainwater from being wasted as runoff.

Rainwater harvesting is one of the most widely used approaches to ensure sufficient water supply when required for different purposes such as irrigation, domestic use, and others.

What is the Status of Rainwater Harvesting in India?

Rainwater harvesting in India has become one of the most prominent methods of conserving water. In India, rainwater harvesting is done through recharging the groundwater and storing rainwater. But only 8% of the 1180 mm average annual rainfall is harvested in India. Thus, the Indian government has been promoting rainwater harvesting through campaigns like Jal Shakti Abhiyan (JSA) since 2019 with the theme “Catch the Rain - Where it Falls, When it Falls”.

Under the JSA, between 2022 and 2024, the government has constructed more than 18 lakh water conservation and rainwater harvesting structures with a total expenditure of INR 15.20 lakhs.

Also, around 33 States and Union Territories have made rainwater harvesting mandatory through laws and regulations. Moreover, states like Gujarat, Rajasthan, Maharashtra, Tamil Nadu, Karnataka, Andhra Pradesh, Madhya Pradesh, Odisha and Chhattisgarh have taken up rainwater harvesting programs on a large scale.

What is the Importance of Rainwater Harvesting?

• Rainwater harvesting is highly needed to mitigate the water scarcity crisis. It helps overcome the water inadequacy to meet the requirement.
• It is useful in preserving the declining groundwater level and helps enhance water availability in specific regions. The water can later be used for different purposes, promoting sustainable development.
• Rainwater harvesting helps increase the water level in the subsoil, which has been declining in urban areas because of the paving of the open areas.
• It is helpful in improving the water quality through dilution and increasing the productivity in agriculture.

What are the Benefits of Rainwater Harvesting?

Water Conservation: Rainwater harvesting helps reduce water runoff, as the water is collected in tanks or reservoirs. This ensures water conservation, which can be used for various required activities.

Increased Water Availability: When the rainwater is harvested and stored, it can be used according to the need without relying on other water sources.

Reduced Soil Erosion: When the rainwater is harvested, it helps stop soil erosion by reducing water runoff.

Sustainable Irrigation: Stored water collected from rainwater harvesting can be used for irrigation, thus offering a sustainable irrigation method with a steady supply of water.

Cost Savings and Community Engagement: Rainwater harvesting offers a cost-effective method to access high-quality water, allowing farmers to take advantage of it and use it responsibly for agricultural purposes. This also promotes community engagement as the farmers can create a single reservoir from where all farmers can use water for irrigation.

What are the Popular Rainwater Harvesting Methods in India?

Ground Water Recharge

This is one of the rainwater harvesting models, where water from the surface moves downward to the groundwater. Groundwater recharge, being a hydrologic process, allows water to reach an aquifer. This aquifer acts as a distribution system where the surplus water can be used to recharge the groundwater level using artificial methods.

Surface Runoff Harvesting

In this rainwater harvesting system, the rainwater flows away as runoff from the surface and is stored. The flow of the water from various streams is diverted towards the tank or reservoir present underground or at the surface. This collected water is then used for agriculture, cattle farming, or domestic work. This harvesting method is most useful in urban settings.

What are the Types of Rainwater Harvesting in India?

There are different types of rainwater harvesting, which are as follows:

Rooftop Rainwater Harvesting

In this type of rainwater harvesting, the water is collected from the rooftop of a house or any infrastructure. The water is collected through pipes or gutter directly connected to the reservoir. This water is then used later for different purposes.

Contour Bunds

This type effectively conserves soil moisture during long-duration watersheds. In low rainfall areas, these are well suited as the farmers can easily hold the runoff by creating bunds along the contour with equal elevation. Adequate spacing between buds prevents water from reaching speeds that can erode the land.

Gabion Structure

This is a form of check dam constructed at around 0.5 m height over a stream less than 10 m wide. The bund here is created using steel wires and boulders locally available by farmers, which are then anchored at the stream's banks. The excess water overflows the dam, and the remaining water is stored as a recharge source. The slit deposits over time and vegetation growth make the bund impermeable, assisting in greater water retention.

Percolation Tanks

These tanks are created on the water body to recharge the groundwater. It allows water to infiltrate the ground and replenish the groundwater. These are formed at a significant height from where the water can run down to cultivable lands or wells for the majority of the benefits of the farmlands.

Check Dams

Also known as nala bunds or cement plugs, these are constructed on the gentle slope of a small stream. With a height usually less than 2 m, allowing excess water to overflow, it is made to recharge the stored water quickly. Shallow trenches are created to form low-cost check dams. A series of these dams are constructed in the stream to gain maximum water recharge using clay-filled cement bags.

Dugwell Recharge

These are the wells that already exist and are used as recharge structures after proper cleaning and desilting. The water is guided to the structure using pipes from the desilting chamber. This structure helps farmers easily gain access to water when required. However, periodic chlorination is required to control bacteriological contaminations.

What are the Challenges Faced in Rainwater Harvesting in India?

Limited Storage: The storage facility is usually limited, which restricts the amount of water collected.

Frequent Maintenance: The storage units, tanks, or reservoirs are susceptible to algae growth, insects, and lizards, which means regular maintenance is necessary.

High Initial Cost: The initial cost is high and varies based on the storage size, location, and technology.

Infrastructure issues: Different materials are used in different rainwater harvesting systems, and thus, some roofs or walls are prone to chemical seepage, dirt, and insects.

What are the Government Schemes to Promote Rainwater Harvesting?

• Jal Shakti Abhiyan: Launched in 2019 with the theme “Catch the Rain”, the scheme envisages construction and repair of rainwater harvesting structures through community participation.
• AMRUT 2.0: To harvest rainwater into water bodies through storm water drain under the Atal Mission for Rejuvenation and Urban Transformation. This programme also includes raising awareness about rainwater harvesting.
• Atal Bhujal Yojana: The programme is in implementation on 8213 stressed Gram Panchayats in 80 districts of 7 states, namely, Gujarat, Haryana, Madhya Pradesh, Uttar Pradesh, Karnataka and Rajasthan.
• Enacting of Guidelines: Under the direction of the Union Ministry of Housing & Urban Affairs has states like Delhi have enacted laws such as Unified Building Bye Laws (UBBL) of Delhi, 2016 for rainwater harvesting.
• Pradhan Mantri Krishi Sinchai Yojana (PMKSY): One of the key focuses of the Pradhan Mantri Krishi Sinchai Yojana is on introducing sustainable water conservation practices with focus on rainwater harvesting.
• Mission Amrit Sarovar: Aims to create and rejuvenate at least 75 Amrit Sarovars in every district with the purpose of harvesting rainwater.
• National Aquifer Mapping (NAQUIM) Project: The project has mapped about 25 lakh square kilometer of groundwater locations for recharging them.

Besides, 15^th Finance Commission, and the Mahatma Gandhi National Rural Employment Guarantee Scheme includes water harvesting as one of the objectives to achieve.

What are the Future Potentials of Rainwater Harvesting in India?

Water Shortage: With the increasing population, the demand for water is only increasing. A sustainable water source is required for agriculture; thus, rainwater harvesting becomes an easy solution. The water is collected and used for different purposes, reducing the dependence on municipal water supplies.

Cost Saving: The lack of sufficient water for everyone's use has resulted in increasing water costs in several areas. Collecting rainwater allows farmers to reduce expenses associated with municipal water supply and use collected water for agriculture.

Water Security: Lack of access to clean water is a common issue faced by several people, and thus, rainwater harvesting provides a sustainable and more accessible answer to water security. It offers a dependable water source for communities, households, and farming needs.

Climate Change: Water availability is affected due to changes in climatic conditions. From changing rainfall patterns to droughts, rainwater harvesting allows farmers to tackle these changes through a reliable water source, thus maintaining their farms.