Local and non-local rainwater harvesting

India is a country with an exceptionally diverse climate, with tropical climates in the south, temperate in the center, and constant cold in the Himalayan regions to the north.  The climate of India is heavily influenced by the Himalayas and the Thar.  Rainfall is less unequal and unreliable in 60% of the state of Gujarat and hence drought occurs every third year in Saurashtra, Kutch, and North Gujarat area.  Water-food shortages have occurred in the state at least 30 times since 1900.

The water resources of the state of Gujarat are mainly concentrated in the areas of South and Central Gujarat, the availability of water is low in Saurashtra and Kutch areas.  In the last, five to six decades, below-average rainfall has been recorded. Due to low rainfall, groundwater levels in most parts of the state have dropped drastically.  Particularly in North Gujarat and the Kutch area, the groundwater level has gone down to a depth of 250 to 300 meters.  And farmers in this area are using tube-well-based irrigation, using submersible pumps of 85 to 100 horsepower, and consuming maximum electricity.  In these circumstances, it is imperative to collect the maximum amount of rainwater during the monsoon and recharge more and more water from the groundwater.

The total geographical area of ​​the State of Gujarat is 195 lakh hectares, out of which 124.5 lakh hectares are cultivable areas.  The main source of water in the state of Gujarat is surface water.  There are a total of 185 campuses in the entire state.  The available water resources in the state are 5,56,080 lakh cubic meters out of which 3,85,000 lakh cubic meters is surface water.  Which is only 2% of the total surface water of India.  The available watersheds are also not generally distributed. Gujarat, Saurashtra, and Kutch areas have 89%, 9%, and 2% water resources, respectively, against which the total geographical area of ​​these three areas is45% 34%, and 21%.  The groundwater resources of the state are 1,75,080 lakh cubic meters.  The available groundwater, as well as groundwater, is used for drinking water, agriculture, industry, hydroelectricity, fisheries, etc.  About 80% of this water is used only in the field of agricultural production in which irrigation is an important part.

In Gujarat, North Gujarat, Saurashtra, and Kutch are also water-deficient areas.  Where two to three years of drought occurs in 10 years.  While in South Gujarat almost every year due to the flood situation there is loss of life and property and with it invaluable water flows into the unused seas.  The state of Gujarat has experienced terrible times in the past between 1972-73, 1985 to 1988, and the year 1999-2000.

Accumulation of rainwater (Rainwater harvesting):

Rainwater harvesting is a practice in which rainwater is collected and stored in a suitable place and used for irrigation and agricultural production as well as for other household uses, in arid and semi-arid regions where there is less rainfall during the rainy season.  It is imperative to store the maximum amount of rainwater in the falling areas and use it for agriculture and local water supply.  Rainwater can be collected directly in open water reservoirs (in situ) as well as rainwater can be collected from the ground surface or roads and also stored in reservoirs.

Rainwater harvesting requirement:

It is a social responsibility to provide drinking water to all.  It is necessary to try to meet the demand for drinking water by using both groundwater and groundwater resources.  Due to the growing population and changing lifestyles, the daily demand of the common man for drinking water is always increasing.  In rural areas, the main source of drinking water is groundwater.  Demand is not enough due to limited availability.  The supply of drinking water in urban areas is usually from rivers huge tanks and large dams.  Withdrawal of water from deep groundwater to meet the drinking water needs of households, settlements or institutions has raised the groundwater level to alarming depths which poses a major threat to future generations.

This technology of seasonal rainwater harvesting in unpredictable weather conditions and changing climates is very important for sustaining water for different uses in difficult conditions.  Rainwater harvesting is a very important technique especially in arid and semi-arid areas where mixed rainfall with non-rainfall days are more prevalent with periods of heavy rainfall.  These challenges can be very useful in meeting the changing climate.

Rainwater harvesting techniques can be classified into three broad types.  (1) Macro Catchments (Large Scale) (2) Micro Catchments (Small Scale) and (3) Roof Top Storage (Using Roof ).

The macro catchment is a method of storing large amounts of rainwater.  This water is mostly used for the irrigation of crops.  Rainwater is collected from large vistas transported to suitable places and stored for a long time.  Rainwater is usually carried far and wide and stored on a large scale.

Micro-catchment is a system of small-scale collection of rainwater in which storage and storage areas are close to each other as well as water use space is located in close proximity.

Rooftop type is used to store rainwater on the roof,  or flat space near the house.  Generally, water stored in this way can be used for household consumption or for small-scale irrigation of vegetables.

In situ Water Harvesting :

In arid and semi-arid regions where rainfall is low or insignificant during the dry season, it is very important to store rainwater during the rainy season.  The method of storing water in the same place where it rains is Insitu water storage.  This method is widely used in countries like Brazil, Argentina, Paraguay.  In-situ water storage can also be called water conservation in the true sense.  In this technology, water is stored at the place where it is to be used.  Some water conservation methods like molding, deep tillage, contour cultivation, etc. are often referred to as in situ rainwater harvesting methods.  The main purpose of this method is to keep the rainwater in the soil for a long time and to recharge the soil by discharging more and more water into the soil.

Ex-situ Water Harvesting :

This type of system collects rainwater runoff stores it in storage and then uses it for field irrigation as well as other domestic use.  This type of rainwater harvesting provides supplementary or protective irrigation to the crop during the dry season.  The extra water stored in this system can be used for drinking water, agriculture, sanitation, etc.  Rainwater can be stored directly in open storage as well as from roofs, ground surfaces, or roads.

Conveyance and filter:

After collecting the rainwater, it is conveyed to the filter unit by a proper transport system.  It is advisable not to store rainwater first to avoid possible contamination of the atmosphere and contaminated water through the roof and to avoid contaminating the water.  Garbage, impurities, and sand that can contaminate stored or groundwater can be stored well for a long time and the wastewater can be filtered through a filter if a proper filtering system is not adopted before it enters the storage area.  Gravel, sand, or mesh filters are designed and placed on top of the storage tank.  This filter is very important in keeping the plain water in the storage tank clean.

Storage area :

Large tanks are used as most storage devices for harvesting freshwater.  These storage tanks are usually made of plastic, but they are also made of fiberglass, wood, iron, concrete, or plastered tie depending on the availability and cost of the source.  Plain tanks are generally used for water storage and storage, while large farm ponds built on land, ponds are used extensively for agricultural purposes.

Rainwater harvesting using roof:

The roof area above the building is an excellent place for rainwater harvesting.  RCC, Tiles, and G.I.  The sheet roof is well suited.  Inch, loose wooden, or bamboo roofs should be avoided.  Even the place where the possibility of acid rain exists is not considered favorable.  Particular care should be taken when planning to collect rainwater in or around industrial areas.  Also suitable for planning rainwater harvesting in fluoride, iron, arsenic, and other specific problem areas.  Garbage and floating materials can also be used for drinking purposes by storing rainwater in tanks after the use of removable filters or excess rainwater from the roof or other surfaces can be used to recharge the ground through pits, wells, or bores.

Summary:

Rainfall and its other characteristics are changing a lot with the changing weather.  In some places, the intensity of rain has increased while in other places the rainfall is decreasing.  Rain is the main source of water in many districts of Gujarat.  The availability of water for agriculture is declining day by day due to growing industries.  Thus, due to the growing population and demand for food grains, the burden on agriculture is increasing.  Under such circumstances, many problems of water can be solved by stopping the flow of rainwater and storing it in a suitable place.

To make maximum use of available water resources through check dams, small, medium, and large irrigation schemes in as many places as possible to utilize the available natural water resources.  Raising awareness among farmers on water conservation through various irrigation systems used, preventing evaporation of water through evaporation in reservoirs with low storage capacity and drought-prone areas, constructing farm ponds, deepening existing ponds, preventing water droplets and water droplets.  Construction of check dams, implementation of link canal schemes for the inter-basin transfer of water is essential for today's times.