WATER CRISIS & RAIN WATER HARVESTING
- Published on December 16, 2021
Total volume of water in the earth is 1.386 billion cum, with 97.5% being salt water and 2.5% being fresh water.
India constitutes 16 per cent of the world’s population, but the country has only four per cent of the world’s freshwater resources. With the changing weather patterns and recurring droughts, India is water stressed. This means that fetching water in these districts have become harder as the water table has fallen.
As many as 255 of 756 districts have reported ‘critical’ or ‘over-exploited’ groundwater levels, according to the latest data from the Central Ground Water Board (2017). This means that fetching water in these districts has become harder as the water table has fallen.
A rural woman in Rajasthan walks over 2.5 kilometers to reach a water source, according to a report by the National Commission for Women. This is probably an underestimation, but the bottom-line is that our women and girls spend a significant proportion of their time fetching water.
India has been consistently working towards improving access to water. The Jal Jeevan Mission (JJM) guidelines released in 2019 provide provision of tap water connections to households, which hold promise for the women in the country.
If implemented to the last mile, women and girls will not have to go through the arduous job of fetching water. JJM stresses the need to involve women in leading the scheme’s activities, especially at the village level.
One in every five or 21.4 per cent households in India has piped drinking water connections, as the National Sample Survey Office’s (NSSO) 76th round. The situation is worse in rural India, where just 11.3 per cent households receive potable water directly at homes. In urban India, 40.9 per cent households have piped water connections. The latest figures project the herculean task that lies ahead of the Centre which plans to provide piped water connection to every household by 2024 under the “Nall se Jal Scheme”.
Around 58.3 per cent of households still rely on hand pump, tube well, public tap, piped water from neighbours, protected or unprotected well, and private or public taps. In rural areas, hand pumps, which accounted for 42.9 per cent usage, was the most relied principal source of drinking water. While hand pumps are the primary source of drinking water in rural areas (42.9 per cent), piped water was the primary source in urban India, as per the Drinking Water, Sanitation, Hygiene and Housing Condition.
Overall, 48.6 per cent rural households and 28 per cent urban households are without access to an improved source of drinking water throughout the year. Further, 11.3 per cent households do not get sufficient drinking water from their primary sources throughout the year.
The survey, conducted between July and December 2018, looked at the sources that provided drinking water to households for the past one year. It covered 27.1 crore households, with, on an average, had four family members. India is facing one of its major and most serious water crisis.
After two consecutive years of weak monsoons, 330 million people — a quarter of the country’s population — are affected by a severe drought. With nearly 50 per cent of India grappling with drought-like conditions, the situation has been particularly grim this year in western and southern states that received below average rainfall.
According to the Composite Water Management Index (CWMI) report released by the Niti Aayog in 2018, 21 major cities (Delhi, Bengaluru, Chennai, Hyderabad and others) are racing to reach zero groundwater levels soon, affecting access for 100 million people.
However, 12 per cent of India’s population is already living the ‘Day Zero’ scenario, thanks to excessive groundwater pumping, an inefficient and wasteful water management system and years of deficient rains. The CWMI report also states that by 2030, the country’s water demand is projected to be twice the available supply, implying severe water scarcity for hundreds of millions of people and an eventual six per cent loss in the country’s GDP.
The Union government recently formed a new Jal Shakti (water) ministry, which aims at tackling water issues with a holistic and integrated perspective on the subject. The ministry has made an approach to five intervention areas to improve water resources.
Jal Shakti Abhijan
The ministry has set a tough target at a time when hundreds of millions don’t have access to clean water. Aiming at laying huge pipeline networks for water supply means that yet again, we are giving more preference to infrastructure. Also, the moot questions are: what will happen if there is no water to supply? What will happen to all the wastewater that gets generated?
This indicates that there is a clear disconnect between water, society and economy. Currently, we are interested in laying large networks, constructing huge storage dams, fetching water from 150 kilometers and above, which involves a huge carbon footprint.
We are valuing land more than water, neglecting our local water bodies, which have either gone dry or encroached. Also, in many Indian cities, water is not properly distributed. Some areas of mega cities like Delhi and Mumbai are privileged to get more that than the standard municipal water norm of 150 litres per capita per day (lpcd) while other areas get 40–50 lpcd. Aggravating the problem is that the water being supplied currently is of drinking water standards.
The World Health Organization (WHO) states that an individual requires around 25 litres of water daily for meeting his/her basic hygiene and food needs. The rest is used for non-potable purposes like mopping and cleaning. This indicates that for most of the non-potable uses, a quality lower than drinking water is required. Thus, for economic efficiency and environmental sustainability, water must be treated and supplied according to usage.
To top this, are issues of leakage losses, water pricing and metering of water. Lack of proper maintenance of existing infrastructure causes further losses of almost 40 per cent of piped water in urban areas.
Road Ahead
Looking at the current situation, there is a need for a paradigm shift. We urgently require a transition from this ‘supply-and-supply-more water’ provision to measures which lead towards improving water use efficiency, reducing leakages, recharging/restoring local waterbodies as well as applying for higher tariffs and ownership by various stakeholders.
A recovery-based closed loop system is the need of the hour.
It is time to go back and start using our traditional practice of rainwater harvesting — catching water where it falls. Presently, India captures only eight per cent of its annual rainfall, among the lowest in the world.
Another aspect is the treatment and reuse of wastewater. About 80 per cent of the water that reaches households, leaves as waste and pollutes our waterbodies and environment. There is a huge potential in reusing and recycling this treated wastewater at least for non-potable purposes, which is cost effective.
All this leads to the fact that we need to promote a decentralised approach, with a key focus on water conservation, source sustainability, storage and reuse wherever possible.
It is important to understand that managing the water situation is not the job of only engineers but all stakeholders including hydrogeologists, economists, planners and most importantly, communities themselves.
Emphasis on behavioral change is not getting enough attention because it is complex. Citizens/ communities have a huge role to play by keeping in check their own usage and actions.
It is equally important to have hygienic water for the citizen, since it is estimated that waterborne diseases have an economic burden of approximately USD 600 million a year in India. This is especially true for drought- and flood-prone areas, which affected a third of the nation in the past couple of years.
The alternative path to contribute in solving water crisis is “Rain Water Harvesting”- (RHW) in addition to cutting down wastage/leakage through improved control, recycling of waste water after treatment for the uses of all non- potable purposes, connecting rivers better distribution and improved irrigation systems.
RAINWATER HARVESTING
Rainwater harvesting is a simple strategy by which rainfall is gathered and stored for future usage. The process involves collection and storage of rainwater with help of artificially designed systems, that runs off natural or man-made catchment areas e.g., rooftop, compounds, rocky surface, hill slopes or artificially repaired impervious/semi-pervious land surface. The collected rainwater from surfaces on which rain falls may be filtered, stored and utilized in different ways or directly used for recharge purposes. Rainwater Harvesting is unrestricted from any kind of impurity, with relatively less storage cost and no maintenance cost involved except for periodical cleaning.
With depleting groundwater levels and fluctuating climate conditions, this measure can go a long way to help mitigate the adverse effects rising water scarcity. Reserving rainwater can help recharge local aquifers, reduce urban flooding and most notably, ensure water availability in water-scarce zones.
Advantages of implementing rain-water harvesting
Reduced Water Bills
Rainwater harvesting systems are cost-effective, provide high-quality water, lessens dependence on wells and are considerably easy to maintain since they are not utilized for drinking, cooking or other sensitive uses. The all-around expenditures used in setting up harvesting methods are much cheaper compared to other purifying or pumping means. The cost of recharge to the subsurface reservoir is also lower than the surface reservoirs.
Ecological benefit
Storing water underground is environment-friendly. The ecological benefits of rainwater harvesting are immense. It minimizes the impacts of flooding by funneling the off water into large tanks for recycling and helps reduce the load placed upon drainage systems. No land is wasted for storage purpose and no population displacement is implicated therefore, groundwater is not directly exposed to evaporation and pollution. Additionally, it helps minimize the possibility of rivers drying up.
Reduces erosion and flooding around buildings
It reduces soil erosion and flood hazards by collecting rainwater and reducing the flow of storm water to prevent urban flooding. Most buildings that utilize rainwater harvesting systems have a built-in catchment area on top of the roof, which has a capacity of collecting large volumes of water in case of rainstorms.
An adequate means for Irrigation purpose
Harvesting rainwater allows the collection of large amounts of water and mitigates the effects of drought. Most rooftops provide the necessary platform for collecting water. Rainwater is mostly free from harmful chemicals, which makes it suitable for irrigation purposes.
Reduces demand on Ground Water
Another vital benefit is that it increases the productivity of aquifer resulting in the rise of groundwater levels and reduces the need for potable water. It is extremely essential, particularly in areas with low water levels.
Limitations of Rainwater Harvesting
In addition to the great advantages, the rainwater harvesting system has a few disadvantages like unpredictable rainfall, unavailability of the proper storage system, etc.
Listed below are few more disadvantages of the rainwater harvesting process.
- Regular Maintenance is required.
- Requires some technical skills for installation.
- Limited and no rainfall can limit the supply of Rainwater.
- If not installed correctly, it may attract mosquitoes and other waterborne diseases.
- One of the significant drawbacks of the rainwater harvesting system is storage limits.
Importance of Rain Water Harvesting
Rainwater harvesting is important for several reasons but one of the biggest is the fact that we are tapping out water conservation gains inside our homes so we need to start looking outdoors for more opportunities.
The following graph shows the gains that have been achieved with our indoor water fixtures through the combination of governmental standards and innovation by fixture companies. As you can see, we don’t have much more room to go in terms of achieving more efficiency gains with our indoor fixtures. What’s next… the 0.2 gallon per flush toilet? Probably not!
· This phenomenon is known as the law of diminishing returns. So where will the next revolution in water conservation take place? We believe we offer services in the areas where this revolution will take place.
Uses of Collected Rainwater
One can essentially use rainwater anywhere you use tap water. The idea of using drinking water to flush our toilets and water our lawns is wasteful and irresponsible, especially in light of population growth and water shortages across the country. Rainwater collection is a technique to green your home and to lessen your environmental footprint.
There are basically three areas where rainwater can be used:
· Irrigation use
· Indoor, non-potable use
· Whole house, potable use
Here are some ideas for specific uses of rainwater:
· Hand water your lawn and garden
· Connect rainwater collection system to irrigation/sprinkler system
· Wash your vehicles
· Wash your pets
· Refill your fountains and fish ponds
· Refill your swimming pool
· Replace the use of tap water with rainwater to wash your driveways and sidewalks (if you don’t use a broom)
· Use it for all indoor non-potable fixtures (toilets and clothes washer)
· Use it for all potable needs when properly filtered and disinfected
· Use it for industrial processes instead of municipally treated water
Methods of Rain Water Harvesting
There are two major techniques of rainwater harvesting.
1.Surface runoff harvesting
In this method, rainwater flows away as surface runoff and can be stored for future use. Surface water can be stored by diverting the flow of small creeks and streams into reservoirs on the surface or underground. It can provide water for farming, for cattle and also for general domestic use. Surface runoff harvesting is most suitable in urban areas.
Rooftop rainwater/storm runoff can be harvested in urban areas through:
• Recharge Pit
• Recharge Trench
• Tubewell
• Recharge Well
2. Groundwater recharge
Groundwater recharge is a hydrologic process where water moves downward from surface water to groundwater. Recharge is the primary method through which water enters an aquifer. The aquifer also serves as a distribution system. The surplus rainwater can then be used to recharge groundwater aquifer through artificial recharge techniques.
Rainwater in rural areas can be harvested through:
• Gully Plug
• Contour Bund
• Dugwell Recharge
• Percolation Tank
• Check Dam/Cement Plug/Nala Bund
• Recharge Shaft
Although rainwater harvesting measure is deemed to be a desirable concept since the last few years, it is rarely being implemented in rural India. Different regions of the country practiced a variety of rainwater harvesting and artificial recharge methods. Some ancient rainwater harvesting methods followed in India which includes Madakas, Ahar Pynes, Surangas, Taankas, etc.
Characteristics of Catchment Areas
Calculation of Harvested Water
One of the significant drawbacks of the rainwater harvesting system is storage limits.
The amount of rainfall that one can collect is governed by the following formula:
1″ of rain x 1 sq. ft. = 0.623 gallons
To find out the closest weather station and use the 0.5 -0.6 row to determine your annual average precipitation.
Once the annual average rainfall is obtained in a specific area and the square footage of collection surfaces, it is easy to find out the total collection quantity.
Properties of Rain Water
Rainwater is a mixed electrolyte that contains varying amounts of major and minor ions. Sodium, potassium, magnesium, calcium, chloride, bicarbonate, and sulphate ions are major constituents, together with ammonia, nitrate, nitrite, nitrogen, and other nitrogenous compounds (Hutchinson, 1957).
The key properties of rain water are as follows:
- Rainwater is almost entirely just pure water. …
- Rainwater is soft water. …
- Rainwater has Nitrogen. …
- Rainwater leaches out salts in your soil. …
- Rainwater saturates your entire garden. …
- Rainwater literally washes your plants.
Characteristics of Rain Water
Rain water is extremely clean and safe. It is the purest form of distilled water. After 20 minutes of rain water becomes almost neutral to slightly alkaline. It is safe for any use like bathing, reuses and as potable water after filtering.
Conclusion
In view of current scenario of water crisis and future disaster, each citizen must be consciously encourage Rain Water Harvesting in every building to move away water crisis and as well as ground water recharging to improve underground water level and many other advantages as stated above.
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Published by DP Sengupta
M Tech in Chemical Engineering from IIT , BHU
Published • 17h
India is passing through a serious water crisis. A few Indian cities may turn out to having zero ground water soon. It is high time to look forward to improve alternative water resources.. Citizen should come forward to add strength to the efforts like Jal Jeevan Mission and Jal Shakti Abhijan by introducing Rain
