Modern methods of water storage
For two reasons, the water demand for humans increases, one is the rapid human population growth and improvement in the standard of living in different countries, which forced to increase of the water demand to meet new needs in the industry, domestic and agricultural use.
But the freshwater resource is in limited quantity and it is scarce in its availability on the Earth. People in Canada and the United States, for example, believe that clean water is available to them in an unlimited supply.
But the water supplies are not unlimited but finite. The increasing demand for this resource will soon create problems that can only be corrected by management and conservation.
Today, people started to recognize that water is vital, for things other than domestic, agricultural, and industrial purposes.
Water is important for maintaining fish and wildlife populations. Also for recreation, and for aesthetics. Today governments in many nations established water resource management programmes. Its aim is to provide a sustainable supply of high-quality water in an efficient and environmentally friendly manner.
Water Conservation Techniques
A number of techniques and technologies can be used to make agricultural, industrial, and domestic water use more efficient. Reductions can easily occur in the following areas:
Reducing Agricultural Waste
Agricultural irrigation accounts for 70% of the world’s water usage. Most irrigation systems deliver water to the crop field by flooding the land. Diverting the water to the open fields by open channels.
Also, sprinkler systems spray water into the crop fields. But these methods are highly inefficient. Because only 50% of water is consumed by the crops and the rest is lost by evaporation and running off the crop fields.
The amount of water applied to the crops can be reduced by 40 to 60% by Micro Irrigation techniques.
Some Strategies to reduce Water usage in Agriculture are:
The strategies include the cultivation of crops that consumes less water. Then reducing water losses by infiltration and evaporation. By using the covered canal and lined irrigation canal.
Also irrigating the crops during the night or early morning to avoid evaporation losses.
Water can be priced or water subsidies such as free electricity can be reduced to reduce the over usage of water. But this method affects poor farmers.
Reducing Industrial Waste
After farming or agriculture use, the Industries are the second-largest consumer of water resources. If the usage of water in the industries is reduced, water could be available for other purposes and also reduce water pollution.
Industrial water usage can be reduced by:
Recycling of water can be achieved by many methods, one such method is redesigning the industries to make use of water again. Such Used Water can be used for cooling purposes, also sewage water can be used for watering the plant after removing harmful chemicals.
Increasing the Water Price
Installing water meters and increasing the price of water, may reduce the consumption of water in the industries.
Recycling materials themselves can also reduce water usage. For example, manufacturing a ton of aluminium from scrap rather than from virgin ore can reduce the volume of water used by 97 per cent.
3. Reducing Domestic Waste
Strategies to reduce domestic water consumption are:
a.Replace lawns in semiarid and arid urban areas with xeriscaped surfaces.
b. Regulate and manufacture more efficient washing machines, showers, toilets, and dishwashers.
c. Repair of water distribution systems to reduce leakage issues as water distribution systems in urban areas around the world lose an average of 25 to 50% of their water during the supply to the consumers.
d. Pricing water for domestic usage at this price must reflect the environmental cost of overconsumption and resource degradation. Higher the price of water will make people conserve water.
Impact of Water MeterThe introduction of water meters in Boulder, Colorado reduced water use by about 30 %. In Canada, water is metered in approximately two-thirds of the municipalities.
e. Education can encourage people to reduce the amount of personal consumption. Increasing Water Supplies Humans have used several different methods to increase supplies of water.
Techniques involve the modification of the runoff process
a. Dams and reservoirs have been used for many centuries to trap runoff behind earth or concrete walls.
b. The stored water is then transferred via canals or aqueducts for use in agriculture, industry, or domestic processes. Worldwide there are now over 36,000 operational dams, some of which are also used to generate energy.
c. Several problems can occur with the storage of water in these human-created features.
d. In some reservoirs, sediments can accumulate to a point where they can no longer be used for water storage or hydroelectric production.
e. Other reservoirs have severe evaporation or leakage problems. Large amounts of water are annually lost from the Aswan High Dam in Egypt because of evaporation.
This problem has reduced the planned amount of irrigation water supplied by this dam by one-half. In recent years, many nations have increased their supply of freshwater by exploiting the water found beneath the Earth’s surface.
Groundwater contains more than 10 per cent of the freshwater found in the hydrosphere.
Saudi Arabia receives 75 per cent of its water supply from groundwater mining.
In many cases, withdrawal rates of this water greatly exceed the natural rates of recharge. Depleting groundwater reservoirs can lead to a number of problems, including subsidence, earthquakes, sinkhole development, and saltwater intrusion.
Many projects have used canals, aqueducts, and diversion techniques to move water to places of need. In the former Soviet Union, diversions on the Amu Dar’ya and Syr Dar’ya Rivers have been used to create irrigation water for cropland.
However, these diversions are also responsible for reducing the flow of runoff water to the Aral Sea. Because of the reduced flow, the Aral Sea has declined in area by over 50 %, has lost two-thirds of its volume, and has greatly increased in salinity. At current rates of reduction, the Aral Sea could be gone by 2020.
Rainwater harvesting may be defined as the process of augmenting the natural infiltration of rainwater or surface runoff into the ground by some artificial methods.
The methods suggested are recharge through pits, trenches, and bore well shafts by directly diverting runoff water into existing or disused wells or conserving the rainwater by artificial storing and using the same for human use.
The choice and effectiveness of any particular method are governed by local hydrological and soil conditions and the ultimate use of water.
Need for Rainwater Harvesting: Nature replenishes the groundwater resources annually through rainfall; by way of infiltration through soil layers.
In urban areas, due to urbanization, the soil surface exposed to natural recharge gets reduced. Therefore, natural recharge is diminishing, resulting in the drying of wells.
Groundwater source has the benefit of availability where water is needed and during emergencies and scarcity period, the public at large or NGOs should take measures to improve the groundwater recharge by rainwater harvesting to maintain reliable and sustainable groundwater resources. Rainwater can be stored in tanks.
Rainwater Harvests and Techniques
In many countries, especially those countries where there are monsoonal climates and long dry seasons, there occurs water shortages. This is not because of a lack of rainfall but from a seasonally uneven supply. Rainfall in these countries is seasonal and water storage here is a difficult task.
Example: India receives around 2.1 Trillion Cubic metres of fresh water and the United States has 2.5 trillion cubic metres of fresh water every year. But the fact there is rainfall in the United States states throughout the year and also the United States is One-third larger than India.
But in India, almost one year of rainfall in the United State falls in just two months i.e Mid-June and Mid-September. Due to such rainfall in a short duration, the deluge runs off and is carried back to the sea by the rivers and their channels.
Even though there are thousands of Dams in India, only a fraction of that rainfall gets collected in them. But the construction of dams comes with a lot of issues such as:
- Sites became scarce and because the construction of large dams often inundates large areas,
- Construction displaces the local population,
- The construction of dams alters the local ecosystem irreversibly.
The construction of dams now has stopped to a large extent.
Local Water Harvesting
As the construction of dams has now been stopped due to a lot of issues that are mentioned above. Governments across the world are turning to local water harvesting to ensure adequate supply.
In Rajasthan, where water shortages constrain development and prevent people from escaping poverty. The villagers under the leadership of a movement helped design local water storage facilities. Once villagers helped select a site, they would organize to build an earthen dam. All the materials, the stone, and the earth were local. So too was the labour – sweat equity provided by the villagers.
The leader would help with the engineering and design. In addition to meeting their daily needs for water, the seepage from the small reservoir would gradually raise the water table, restoring wells that had been abandoned.
The initial success led to the creation of a local non-governmental organization with full-time employees and part-timers.
When the local topography is favourable for building successful small water storage structures, this can be a boon for local communities. This approach works not only in monsoonal climates but also in arid regions where low rainfall is retained for local use.
With a modest amount of engineering guidance, hundreds of thousands of communities worldwide can build water storage works.
Another technique to retain rainfall is the construction of ridge terraces on hillsides to trap rainfall near where it falls, letting it soak into the soil rather than runoff.
Using a plough to establish the ridges, local farmers can build these terraces on their own, but they are more successful if they are guided by a surveyor who helps establish the ridgelines and determines how far apart the ridges or terraces should be on the hill.
Once the terraces are established, the moisture that accumulates behind them can help support vegetation, including trees that can both stabilize the ridges and produce fruit and nuts or fuelwood. The terraces, which are particularly well adapted to the hilly agricultural regions of the semiarid regions of India, and Africa can markedly raise land productivity because they conserve both water and soil.
Tanks in Deserts
The practice of collecting rainwater where it falls is several hundred years old. In desert areas all over the world, where there is a shortage, communities have been collecting rainwater in open tanks, open wells, and from the rooftops of buildings for centuries.
With the coming of more so-called advanced technology including sophisticated groundwater survey and exploration equipment, with the installation of hand pumps and piped water supply schemes, the importance of people’s technologies and community solutions were devalued.
There is thus a need to go back to learn the important lessons from the past on how communities have solved their drinking water problems by collecting rainwater on a large scale.
Methods of Rainwater Harvesting in Cities
Broadly the rainwater can be harvested by two methods:
Store the rainwater in containers above ground or below ground. Recharge into the soil for withdrawal later by groundwater recharging basis.
Elements of a typical water harvesting system: Any rainwater harvesting will have four elements:
- Catchment area
- Settlement Tank
- Recharge facility or storage facility
Rainwater harvesting techniques are simple, labour-intensive, and cost-effective. By collecting water where it falls
(a) in underground tanks in rural primary schools,
(b) in artificial ponds deepened to collect more water, and (c) in unused and disused open wells where surface water is channelled for faster percolation into the ground, rainwater could be usefully harvested and at much lower costs.
What will this achieve?
It will be a long-term solution to drought-proof villages. It will allow for faster percolation into the ground which will revitalize dry hand pumps for drinking water and open wells for irrigation. It is a far more inexpensive and economic way of providing drinking water than drilling for new sources.
It will allow the community of users to manage and control the water and reduce dependency on the government.
The barefoot architects constructing the rainwater harvesting tanks using local materials, traditional knowledge, and skills, demonstrate how there is no need to bring urban skills from outside.
The traditional water conservation methods were mostly adopted in India. But in the last decade, things have changed. Now the cities and as well as villages started to adopt modern methods of water conservation.