How quickly can I recharge the groundwater?
While there is no easy or quick answer to this, let me try to explain whatever little I know .
As I have mentioned many times earlier, there are essentially two types of aquifers that we have to take into consideration. One the confined aquifer and the other unconfined aquifer .
A confined aquifer , commonly called a Bore-well taps into the water under pressure present in the rocks below. The recharge points for this kind of aquifer will be very far, sometimes even a few or several kilometers away. An artificial method of recharge is to cut the casing of the bore-well and push the water under relatively lower velocity . The water here will be generally hard . Recharged water will take many many many years or even decades to reach the deep aquifer.
The other aquifer is called an Un-confined aquifer commonly called an open well. Here the water , if available will be at atmospheric pressure . The recharge points for this aquifer are very local and in the immediate neighborhood. It is this aquifer that was the source of fresh , sweet water in our country for many many generations.
An open well or a recharge well can be used to push the water (Rainwater) into this unconfined aquifer. The recharge rates depend on two critical parameters, the porosity of soil and the hydrostatic pressure. For example, if the soil is clay, the recharge rates are almost zero while if it is lateritic soil, the recharge rates are quite good.
The recharged water saturates the soil and in due course yields as sweet , clean water back into the aquifer. This is the normal course of water for an open well and was practiced for several centuries.
Here, I filled up a recharge well of 3 feet diameter upto 15 feet and measured the recharge of water into the soil. I observed the recharge rate for 3 mins (The video is full 3 mins )In 3 mins time, about 1 feet of water had recharged into the soil. That translates to about 200 Liters in 3 mins or 66 Ltrs per minute.
To put it in perspective, if I have a roof area of 100 Square meters, in 20 mm per hour rainfall intensity, the rainwater run off will be (100 x 20 x 0.9) = 1800 ltrs. For the well under consideration, this run off will be theoretically recharged into the ground in 1800/66 = 27 mins. In other words, an hour of rain will be recharged in half an hour.
Please note that this is not universal. The recharge rates depend on many parameters like porosity, hydrostatic pressure etc. This analysis is true for the well under consideration.
The point however is , nature has solutions and nature is the best engineer. We just have to not tinker with nature and give it enough time to recoup. If we normalize tree cutting and pouring concrete and asphalt in every inch of the earth, nature will normalize drought , heavy metals and pollution.
Негізгі бет Watch As Water Fills Our Aquifer! (Water recharging soil pores of shallow aquifer)
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