Context: traditional water harvesting in India and its potential
In India, rainwater harvesting has been in practice for more than 4000 years. It is basically a simple process of accumulating and storing of rainwater. Rainwater harvesting systems, since ancient times, has been applied as a supply for drinking water, water for irrigation, and water for livestock.
What is the need for traditional water harvesting in India:
- Deep roots: Archaeological evidence shows that the practice of water conservation is deep rooted in the science of ancient India. Excavations show that the cities of the Indus Valley Civilization had excellent systems of water harvesting and drainage. The settlement of Dholavira, laid out on a slope between two storm water channels, is a great example of water engineering. Chanakya’s Arthasashtra mentions irrigation using water harvesting systems. Drawing upon centuries of experience, Indians continued to build structures to catch, hold and store monsoon rainwater for the dry seasons to come.
- Rising water demand: India has 16% of the total population of the world. But the country has only 4% of the water resources present on the earth. The population of India is expected to stabilize around 1640 million by 2050. As a result the gross per capita water availability will decline from 1820 cubic meter per annum in the year 2001, to as low as 1140 cubic meter in 2050.
- Rain fed agriculture in India: Rain fed agriculture occupies 67 percent net sown area, contributing 44 percent of food grains and supporting 40 percent of the population. Out of these 44% food grains, predominantly nutrient crops like pulses and oil seeds. In rain fed areas rainfall is very abnormal and scanty so traditional methods of water harvesting provide a good solution.
- Less expensive: The systems are easy to construct from locally sourced inexpensive materials, and it has proved to be a success in most areas. The prime advantage of rainwater is that the quality of water is usually good, and it does not necessitate any treatment before consumption. Household rainfall catchments can significantly contribute where the source of drinking water is contaminated and scarce.
- Urban water crisis: According to the Composite Water Management Index (CWMI) report released by the NITI Aayog in 2018, 21 major cities (Delhi, Bangalore, Chennai, Hyderabad and others) are racing to reach zero groundwater levels by 2020, affecting access for 100 million people. If we look at present Chennai, Chennai has been a water deficient city. The household water supply in the city was 55 litres per capita per day (lpcpd), much less than the Ministry of Urban Development Benchmark of 135 lpcpd, according to the 2011 census.
Some prominent Traditional water harvesting practices in India: below given is a brief account of the unique water conservation systems prevalent in India and the communities who have practiced them for decades before the debate on climate change even existed.
- JHALARA: Jhalaras are typically rectangular-shaped stepwells that have tiered steps on three or four sides. These stepwells collect the subterranean seepage of an upstream reservoir or a lake. Jhalaras were built to ensure easy and regular supply of water for religious rites, royal ceremonies and community use. The city of Jodhpur has eight jhalaras, the oldest being the Mahamandir Jhalara that dates back to 1660 AD.
- BAWARI: Bawaris are unique stepwells that were once a part of the ancient networks of water storage in the cities of Rajasthan. The little rain that the region received would be diverted to man-made tanks through canals built on the hilly outskirts of cities. The water would then percolate into the ground, raising the water table and recharging a deep and intricate network of aquifers. To minimise water loss through evaporation, a series of layered steps were built around the reservoirs to narrow and deepen the wells.
- AHAR PYNES: Ahar Pynes are traditional floodwater harvesting systems indigenous to South Bihar. Ahars are reservoirs with embankments on three sides that are built at the end of diversion channels like pynes. Pynes are artificial rivulets led off from rivers to collect water in the ahars for irrigation in the dry months. Paddy cultivation in this relatively low rainfall area depends mostly on ahar pynes.
- JOHADS: Johads, one of the oldest systems used to conserve and recharge ground water, are small earthen check dams that capture and store rainwater. Constructed in an area with naturally high elevation on three sides, a storage pit is made by excavating the area, and excavated soil is used to create a wall on the fourth side. Sometimes, several johads are interconnected through deep channels, with a single outlet opening into a river or stream nearby. This prevents structural damage to the water pits that are also called madakas in Karnataka and pemghara in Odisha.
Issues related to traditional water harvesting:
- Fragile creations: Water harvesting systems are fragile creations. They have to be continuously monitored, maintained and repaired. Regular inspection, cleaning, and occasional repairs are essential for the success of a system. But in India no clear guidelines and no importance was given by the government towards traditional harvesting methods
- Less priority: the state took control from the local community or the households as the provider or supplier. This meant that harvesting rain was no longer a priority.
- Changing water supply: local ground water, which was recharged using rain-water, was replaced by surface water, brought often from long distance canals.
- Government policies: central governments and state governments both focus on large scale irrigation projects (kaleshwaram project which costs almost 85000crore) and less importance was given to traditional water harvesting techniques either by providing proper coverage or finance.
Measures related to traditional water harvesting in India:
- Awareness campaign: Conducting mass awareness programmes on Rain Water Harvesting and Artificial Recharge of ground water throughout the country involving Central/State/ NGO’s, VO’s, resident welfare organizations, educational institutions, industries and individuals. Conducting Training programmes to generate resource persons as a measure of capacity building for designing Rain Water Harvesting structures to augment ground water in different terrains and diverse hydrogeological conditions.
- Policy framework: policy should involve local communities and measures to be taken to provide needed financial resources for the development of traditional methods. Empowering the local panchayats with financial autonomy.
- Spread: Action for Social Advancement (ASA), nongovernmental organization based in Madhya Pradesh, worked with 42 tribal villages (nearly 25,000 people) with a land area of nearly 20,000 hectares in Jobat, one of the sub-districts of Jhabua district in Madhya Pradesh, and carried out watershed work at the small river basin level. They focused on Land development, Water resources development, Agriculture intensification and diversification, as well as tried building and promoting people’s institutions around the natural resource interventions. As a result, the subsurface flow of water has improved significantly, indicated by the increased flows in the streams and rivers in the entire basin. So the both governments (central and state) should work together to spread the same success story of Jobat throughout India.
Way forward: It is high time now to fall for surface water usage instead of going for ground water resources to meet human demand on needs. Considered the main source of surface water, rainwater is deemed more or less as fresh; the cost of collecting rainwater too is very low. Rivers and canals, lakes and wetlands, ponds and drywells – all are potential catchments to hold direct rainwater and its indirect source, the run-off storm water. The closed tanks also doubly work as settlement tanks to innately clearing the contaminated water to some extent. Pebbles, gravels, sand and charcoal – all available in abundance – work great as natural filter for cleaning the rainwater before usage. Hence keeping an eye on the rapidly increasing day-to-day demand for water among fast growing human population, there lies a great opportunity to harvest rainwater to meet a potential scarcity and avoid destruction of the normal groundwater table level. The boon of rainwater harvesting is – the unused or extra water which remains after using by the human settlements – it can be send down the aquifer to charge the groundwater level too.