Rainwater harvesting

The technique of gathering and storing rainwater for uses such as irrigation, residential usage, and groundwater replenishment is known as rainwater harvesting typically in areas where water scarcity is a  concern. It is a useful technique for water conservation and reduces dependency on conventional    water sources

        As an example, Limited amounts of Saudi Arabia's annual rainfall of 215 billion m3 are used to replenish groundwater supplies. It is challenging to collect and use surface water runoff due to high evaporation rates and a lack of rainwater gathering. Particularly in the Kingdom of Saudi Arabia, where agriculture mainly depends on groundwater, the extraction of subterranean water from deep aquifers depletes resources. New technologies are required to create alternative supplemental water sources and lessen the risk of flooding in order to alleviate water shortages and expand the area under cultivation.

        Rainwater harvesting technology is crucial for utilizing rainwater as a water resource, especially in arid or remote areas where piped networks are uneconomic or technically feasible. It involves generating, collecting, and storing runoff from various sources, depending on local conditions. Various practices, such as farming terraced wadi beds, growing trees on micro-catchments, catching runoff from sheet metal catchments, tapping subsurface runoff, and storing runoff behind dams, share three common characteristics: utilizing rainwater as a water resource, reducing pollution, and promoting sustainable development.

        In our study, Rain Water Harvest final map in Wadi Nisah shows suitable rainwater harvesting areas in "excellent class" are in "dangerous class" for flash flood risk, requiring identification to protect lives and plants.

A rainwater harvesting system's design is influenced by variables like rainfall patterns, space accessibility, water consumption, and financial constraints. A rainwater harvesting system's essential parts include:

1. Catchment area: The surface area from which rainfall is gathered is referred to here. Rooftops, paved surfaces, and natural catchment regions like hills and slopes are some examples.

2. Gutters and downspouts: These are utilized to move rainfall from rooftops into reservoirs or storage tanks.

3. Storage tanks: These are containers used to store collected rainwater for later use. They can be above-ground or underground depending on available space and aesthetic preferences.

4. Filtration system: Rainwater requires to be filtered before usage since it could contain particles, pollutants, or toxins. This impurity removal is aided by a filtration system.

5. Overflow system: When storage tanks are full, surplus rainfall must be redirected away from the tanks by an overflow system.

6. Distribution system: consists of the pipelines, pumps, and valves that transport collected rainwater to various locations of usage, such as irrigation systems or household plumbing.

Rooftop collection, surface runoff collection, and subsurface storage are a few techniques for collecting rainwater. Rainwater from rooftops is collected and sent into reservoirs or storage tanks using a process known as rooftop collection. Surface runoff collection is gathering rainwater from concrete or other hard surfaces and directing it into storage facilities. Gathering rainwater and storing it underground in cisterns or tanks is known as underground storage.

There are several methods of rainwater harvesting, including:

1. Rooftop Rainwater Harvesting: Using this technique, rainwater from rooftops is collected and sent into reservoirs or storage tanks. A collecting system is utilized to direct the water using gutters and downspouts.

2. Surface runoff harvesting is a second technique that collects rainfall from paved or unpaved surfaces including driveways, open fields, and roadways. Through channels or trenches, the water is diverted into storage pits or recharge pits.

3. Watershed Harvesting: Using natural catchments like hillsides or valleys, this approach collects rainwater. To reduce the flow of water and allow it to seep into the earth, small check dams or contour bunds are built.

4. Infiltration Pits: These are subterranean containers that catch rainwater and let it gently seep into the soil. They are frequently applied in constrained-space urban locations.

Rainwater harvesting offers several benefits, including:

1. Water conservation: By collecting and storing rainfall, it minimizes dependency on freshwater sources like rivers or groundwater.

2. floods Mitigation: Rainwater harvesting lessens the hazard of floods by reducing surface runoff during periods of heavy precipitation.

3. Groundwater Recharge: By allowing rainwater to permeate the ground, it helps restore groundwater supplies.

4. Cost Savings: Using collected rainwater for non-potable uses like irrigation, toilet flushing, or car washing reduces the need for treated water and lowers utility costs.