Recharge Structures for Groundwater Recharge – Awareness is a key here

 

“If there is a magic on this planet, it is contained in water “

– Loren Eiseley

Well! We all agree to that. Have you ever felt a void when suddenly the water supply disrupts your household? Though it is mostly because your daily work gets upset, that dried up sink gives you a lifeless look. Imagine, how difficult it would be when water goes scarce for irrigation. After all, whole agricultural produce depends on it, and so is our Indian economy.

Emerging Water Challenges

There have been few challenges in the supply of an adequate water quantity and quality, since last few years, such as

1. Depletion of Groundwater

Indiscriminate groundwater development has led to a long-term decline of groundwater levels in the states of Rajasthan, Gujarat, Tamil Nadu, Punjab, Delhi, and Haryana. In the parts of our country where there is a low percentage of surface water available, people tend to pump out excessive groundwater for domestic and agricultural purposes. Most of these places, especially 91 drought-prone districts of 13 states have water level being declined up to 30 meters and more. This is alarming.

2. Pollutants in Groundwater

Unchecked disposal of effluents from industries and urban sewerage, overuse of fertilizers and pesticides, are the major cause of groundwater pollution. When naturally occurring Arsenic, Fluoride, and Iron in ground water seeps in, more than permissible limits, it becomes unsuitable for drinking.

3. Shortage of clean drinking water in Urban Areas

There is a tremendous stress on groundwater in the urban areas where natural water resources are non-abundant, and the entire population has to depend on groundwater resources. The pace with which urbanization is advancing, it is attracting more and more population, but the water resources are not increasing with the same speed. The cities are struggling for portable clean drinking water.

4. Absorption of Seawater in Coastal Aquifers 

Coastal aquifers in parts of Gujarat, Tamil Nadu and Andhra Pradesh are already suffering from the problem of salinity ingress. The deltaic and coastal sediments in these areas form thick and regionally extensive aquifers which can sustain deep, moderate to high capacity tube wells. But they restrict the inherent quality problem of fresh groundwater.

 

The concept of Artificial Recharge & its need

The soil will only get completely saturated with water when the water supply is maintained for the prolonged periods. There is a very appropriate word being used for this process – Recharge. Since it is done by external factors, it is termed as Artificial Recharge. And it is a modern-day solution to the water challenges being faced in Urban and in rural areas.

Artificial recharge is a method of augmenting the natural movement of surface water into groundwater reservoir with some civil construction techniques. Monsoon in India lives for a short period of about three months in a year. This period may not produce sufficient water to infiltrate into the ground and replenish the high depleted amount.

Artificial recharge techniques enhance the sustainability of groundwater sources during the lean season. The rates of potential evapotranspiration (PET) are exceptionally high in arid areas, often ranging from 300 to 1300 mm; this is much higher than the actual total rainfall.

The hilly areas comparatively receive high rainfall, but the scarcity of water is often felt in the post-monsoon season. This is because most of the available water is lost as surface runoff.

Recharge Structures for groundwater recharge

The type of groundwater recharge setup needed in the area depends upon the type of soil, available land area, and the available water sources. The major structures are:

• Recharge through abandoned dug well – The dried up dug wells in alluvial and hard rock areas are used as recharge structures itself. The recharge water is guided through a pipe to the bottom of well. The rainwater collected on rooftop is guided via a transit pipe into the dried well.
• Recharge through trench – Trench of the dimension may be 0.5 to 1 m wide, 1 to 1.5m. deep and 10 to 20 m. long is suitable for buildings having a roof area of 200-300 sq. meter and the permeable strata are available at shallow depth. The excavated trench is filled with pebbles, brickbats, and boulders. The method suits for small houses and roadside drain and is constructed along the land slope.

 


 

• Recharge through the hand pump – The rainwater is diverted from the rooftop to the hand pump by suitable pipe arrangements, where pipes are generally 50 to 100mm in diameter. A closing valve is fitted in the system, near the hand pump. This helps in avoiding the entry of air into the suction pipe.
• Recharged pit – A recharge pit is a circular, square or rectangular structure constructed with brick and stone masonry wall. It is too filled with pebbles and boulders. There can be indirect or direct recharge pit and its capacity depends upon the catchment area, rainfall intensity, number of adjoining water sources and recharge rate of the soil. Generally, recharge pit is 1 to 2 meters wide and 2 to 3 meters deep.
• Recharge shaft – A shaft of diameter 0.5 meters and the depth varying from 10 to 15 meters, is constructed where the shallow aquifer is located below clay surface or where the upper layer of soil is alluvial or less permeable. The constructed bore is lined with slotted or perforated PVC/MS pipe to prevent the collapse of vertical side and is filled with boulders, gravels, and coarse sand. It should be constructed 10 to 15 meters away from the building.
• Gravity head recharge tube well – Gravity head recharge well is also known as Bore well/Tube wells. It is most suitable when groundwater level is much deep, land availability is limited, and the aquifer is deep overlaid by impermeable strata like clay. The rainwater flows down to the well, from rooftop and recharges under gravity flow condition. The well can also be used for pumping.

Before working on building the recharge structures, you should evaluate and investigate with the following considerations:

• Hydrogeological investigations of the selected site to identify depths of water table and the groundwater flows directions, maximum recharge rate of the selected site and presence or absence of impermeable layers.
• Assess the potential of rainwater harvesting & the quantity and quality of water available for harvesting
• Construction and engineering cost
• Its operating cost, maintenance & monitoring cost.

Chaitanya systems – Rainwater harvesting services & more

We are trusted by our hundreds of customers for rainwater harvest services which include preparation of rainwater harvesting reports, designing rainwater harvesting layout, designing detailed engineering drawings, conducting hydrogeological and borewell surveys and providing feasibility reports.

In case you are looking for Gravels of size ranges from 5mm to 10mm which are used for filling the borewell pit and other RWH systems, look no further. Furthermore, we have Fibre-reinforced plastic (FRP) Roof rainwater drainage gutters, Precasted RCC Hume Pipes collar rings  of 3 feet, 4 feet and 5 feet outer diameter sizes.