Smart Rain Water Harvesting

Water is one of the natural resources and comes as a free gift like air. However, it is a basic ingredient of any living beings. According to the Atharva Veda, a life is believed to be first evolved and nourished in water. The Rig Veda says water has the lifesaving medicinal quality, so it needs to be conserved. Humans cannot survive without water as it is one of their basic needs. In the body of a human being, around 70% is water. In addition to that, water is necessary on a daily basis lifestyle like drinking, bathing, washing, planting, etc. Water is also required in large quantities for different sectors like irrigation, industries, transportation, and hydroelectricity plants. All great civilizations started and prospered near water bodies.

The current generation wants smartness in every aspect of life. Hence, the concept of smart city has approached. In a smart city, the following factors are very vital such as smart grid, e-health, e-environmental monitoring, smart home, smart water quality, smart air quality, etc. Among them the more vital issue is the supply of clean and sufficient water. A substantial increase in population in cities is the main problem of their water stress because the cities are usually designed for a particular population, but in most cases the actual masses dwelling there are many times that of the designed value, whereas the resources remain the same. Therefore, all problems started with it including water too. With the explosion of human population, it is becoming very difficult for providing usable quality of water even with values. Therefore, many parts of the world are facing high to extreme water stresses. This stress is due to scarcity of underground water, mismanagement of existing water bodies, increase in river water pollution by allowing industrial and urban pollutants to flow into rivers, lack of water recycling, no clever usage, and wastage of water.

Water is such a recurring type reserve that can be reused after proper treatment. However, water scarcity occurs due to mismanagement and overuse of the available resource. Therefore, it is often remarked that water can be better conserved by using it judiciously. In that manner, the irrigation sector needs revolution in water management as this sector needs the maximum share of water.

Most part of earth is covered by water bodies like oceans and seas. However, the water of these water bodies cannot be directly utilized in our daily needs like as drinking water and other purposes. Therefore, there is a persistent deficiency of water both for residential use and industrial use.

Rainwater harvesting is an expertise for collection and efficient storage of rainwater from different basement areas like rooftops of residential buildings, ground surface, rock catchments, etc. These techniques are very vast. They can be very artless techniques such as collection and storage using readily available, cheap utensils. They also can be some very intricate techniques such as building check dams. These methods are mostly used for water conservation. Usually, there are two basic ways of rainwater harvesting like surface runoff harvesting and rooftop rainwater harvesting. In the first method, rainwater flowing along the surface is collected in an underground tank. In the second method, rainwater is collected from roof catchment and stored in a tank. The harvested rainwater is the purest form of water source. So, it can be consumed directly. Rainwater collected from ground catchments may be poor in quality with respect to the bacteriological quality, whereas if rainwater is collected from well-maintained rooftop catchment systems and storage tanks, then that water is suitable for drinking. If water is collected from a dirty surface, then the collected water can be made utilizable by using a proper filtering system. Thereafter, it can be used for some the following purposes like drinking, culinary, bathing, laundry, toiletry purpose, watering gardens, compost making, birdbaths, recharging ponds and pools, washing vehicles, fire extinguishing, etc.

Rainwater collection technologies have a very long history. It is as early as Roman civilization. It means the period is earlier than 2000 BC. Rainwater harvesting in Asia has also been carried out since the ninth century. In rural areas of South and Southeast Asia, rainwater is collected and conserved by constructing brush dams. In Israel, rainwater is collected and used both for farming and residential use. In Istanbul of the country Turkey, the world’s largest tank is created for collection of rainwater. In India also rainwater collection and utilization are practiced since long back using conventional methods. Thailand is a pioneer in applying innovation in rainwater collection since many hundred centuries back. However, recently the most recognized utilization of the innovation is done in Africa

Objectives of rainwater harvesting

Increase volume of water bodies

Many parts of the world have two kinds of seasons like rainy season and dry season. During dry season, there is very little or no rain. Due to this, the water bodies like pond, rivers, etc. are dried. By using these techniques, the water bodies can be recharged, and their volume can be increased.

Lessen flood and soil erosion

By storing rainwater, it reduces the surface runoff. This reduces the surface erosion. By capturing rainwater in reservoirs, the flood problem in large rainfalls is also diminished.

Prevent overuse of underground water

As population of a locality increases, its demand for water increases too. To meet this, underground water is used. Due to this reason, the level of underground water is decreasing rapidly. By using rainwater, the demand on groundwater is reduced.

Save money

Pumping up of underground water is very costly than that of rainwater harvest. So, the use of rainwater saves money.

Type of Rainwater Harvesting 

Rooftop catchment

It is the most elementary method. Here, rooftop of any building serves as the catchment. Rainwater is accumulated using easily available and cheap pots kept at the side of the roof. The quantity and feature of this collected water are influenced by the location, size, and material of the roof. A bamboo-made roof gives the lowest quality of water. So, instead of using a bamboo-made roof, it must be made up with other materials like galvanized corrugated iron, aluminum, cement, etc. The catchments need to be cleaned frequently to wash from dirt, leaves, and birdie stools.

Land surface catchment

Here, rainwater is collected from the common surface of any ground or land. This method of water collection is also very intricate. This method can be improved by improving surface runoff capacity. That is done using a number of techniques. Runoff capacity can be enhanced by using drain pipes and storing the collected runoff water. Ground catchment area is larger than that of the rooftop area. Therefore, techniques involved with this catchment have more chance for improvement. In this method, water is kept either in small storage reservoirs or in small dams. This technique is usually applied for irrigation purpose. To increase the amount of rainwater runoff within ground catchment areas, it is required to clear or alter foliage cover, increase the slope of ground by artificial means, and reduce soil permeability by proper means.

Ground catchment system

The steeper the slopes of catchment areas, the quicker is the runoff and hence faster collection of rainwater. But, high-speed runoff may cause soil erosion. Therefore, its rate needs to be controlled using plastic sheets, asphalt, or tiles along with slope. This method further reduces evaporative losses as well. Since more than 60 years ago, flat sheets of galvanized iron with timber frames have been used in the State of Victoria, Australia, to prevent soil corrosion of ground catchment area. Conservation bench terraces may also be constructed along a slope perpendicular to runoff flow for this purpose. The soil of the catchment area must be made hard and smooth. Surplus runoff water is directed to a lower collector and stored there. In addition to this, soil treatment using sodium helps in reducing soil permeability.

Collection and storage equipment

The collected rainwater from the catchment area is required to be collected and stored in proper collection equipment. It can be a storage tank or a rainfall water container. Storage tanks for this purpose may be placed either above or under the ground. The tank needs to be fitted with tight cover for preventing algal growth and the breeding of mosquitos. Measure must be taken to reduce contamination of the stored water. Storage tanks can be cylinder-shaped containers made up of ferro-cement or mortar. The former container has a slightly armor-plated concrete base. On this base the cylindrical tank is mounted. Again two layers of light wire are enfolded over this tank surface.

This serves as a frame for the container. The latter type container is a large vessel made up of mortar. This vessel is also wounded with light wires, In some cases, the storage tanks are concrete tanks. The storing capacity of rainwater is calculated considering different factors like the dry spell span, the volume of rainfall, and the consuming demand.

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