Principle - II : Recharging of Ground Water Aquifer

Method- 2 : Recharging of wells and tubewells

There are several recharging structures, which ensure percolation of rainwater in the ground Recharge trenches and porous layers permit entry of water to superficial level, while others like wells etc assist in deeper percolation of ground water. Rainwater available from rooftop harvesting can be directly used to recharge wells and tube wells by making suitable arrangements. If a tube well is being recharged then holes should be made in its outer pipe (casing pipe), so that there is sufficient space for water to leak into it. The development of tube wells enhances its recharging capacity. The process is to forcefully throw water or air on high pressure into the tube wells so that it loosens the structure of near by soil and increases the porosity of the soil. If a well is being recharged then holes are made on equal distance on the lining of the well so that there is proper flow of water year round. The mouth of the well should be covered to prevent leaves and other solid waste from entering the well. The base of the well should be cleared annually so that flow of water is uninterrupted. Precautions should be taken to prevent mixing of sand particles or any other waster also. It should be ensured that the depth of wells and tube wells being recharged is lesser then the local ground water level so that recharged water meets the ground water after crossing several layers of soil. Water quality can be ensured by attaching a filter, on the entry point and having a filter bed to clean water, besides making sufficient space for setting tank.

SETTLING TANK : is used to separate sand particles and other floating waste from the rainwater. It is similar to storage tank with an arrangement for entry of water from rooftop. It has alternate system to take additional water elsewhere. The base of the tank could be made of mud, so that water seeps into the ground. The setting tank apart from removing silt from the water, works as buffers in water harvesting system, specially in case of tube wells it stores additional water till every drop of water is utilized by the recharging structure.

Method-3:- Recharging of wells and Bawries

The dried wells and bawris  of urban area could be recharged by another simple technique. In this, a hole three meter deep and two meters long and wide is dug around six to eight meters afar from the well on height. The size of hole may vary in accordance with the local conditions. The base of the hole is connected to the well through a PVC pipe and then the hole is filled in layers with big stones followed  by gravel and then sand. The rainwater keeps on seeping through this filter. The rainwater after undergoing process on natural filtration keeps on mixing in the well. This technique could prove effective in the regions with scanty rainfall or the composition of soil in the well is very porous. Care should be taken to restrict human entry in such structures to prevent pollution & incidence of guinea worn disease.

Method - 4 : - Recharge structure for Multi storey buildings

Bore wells tube wells could be used, as recharge structure at places where there is limited space and ground water level is very low. At a distance of 10-15 feet from the rooftop rainwater is brought to collection chamber through PVC pipe. This  pipe has a valve attached so as to the water of first shower from entering the chamber. All chamber are to be interlinked through PVC. The water undergoes the process of filtration through a pit which has layers of pebbles gravel charcoal and sand of normal size. The filtered water is linked to the tube well it should be kept in mind that the pipe are linked with each other on slopes in a proper ratio.

Method - 5 :- Recharge shaft

These are most efficient and cost effective structure to recharge the aquifer directly. In the areas where source of water is available for some time only shaft is dug through hands auger or in alluvial tracts through rotatory process. The diameter of the shaft could vary between half to one feet depending on the availability of water. Recharge shaft is filled with gravel, pebbles and sand. The shaft should be 4-5 meters away from the house. Care should be taken that this shaft does not obstruct the foundation of the building. Shaft should be cleaned regularly and sand should be changed.