Rainwater harvesting (RWH) refers to collection of rain falling on earth surfaces for beneficial uses before it drains away as run-off. The concept of RWH has a long history. Evidence indicates domestic RWH having been used in the Middle East for about 3000 years and in other parts of Asia for at least 2000 years. Collection and storage of rainwater in earthen tanks for domestic and agricultural uses is very common in India since historical times. The traditional knowledge and practice of RWH has largely been abandoned in many parts of India after the implementation of dams and irrigation projects.
Rainwater harvesting can be done at individual household level and at community level in both urban as well as rural areas. At household level, harvesting can be done through roof catchments, and at community level through ground catchments.
Depending on the quantity, location and intended use, harvested rainwater, it can be utilized immediately or after storage. Other than as a water supply, RWH can be practiced with the objectives of flood control and soil erosion control.
Components of RWH Systems:
RWH system has three components –
a) the catchment,
b) the collection system and
c) the utilisation system.
Rainwater harvesting has been adopted by many countries as a viable means to save water. With the increasing population and dependence on water, it becomes pertinent for institutions and even households to start investing in rain-water harvesting systems (RWH). GuruJal has been taking proactive step towards installing Rainwater Harvesting Systems. Few models adopted by GuruJal are as below.
AREA REQUIRED : 400 sq. feet(20*20, L*B)
CAPACITY OF RECHARGE : 2000 to 10000 Sq. M. Example: Big Buildings, Shopping Complexes, Auditoriums etc.
TOTAL COSTING WITH BREAKUP : Rs. 3.74 lakhs including earth work, Labor, Material etc.
MAN DAYS REQUIRED FOR CONSTRUCTION : 10 Days
Format for Artificial Recharge proposal inside and outside the project premises
A. Within the Premises
1. Details of Area may be taken from application and unit should be taken as square meter (m2) as per application.
2. Annual Rainfall of the district may be taken from revenue record/from IMD website.
3. Rainfall unit be taken as meter .
4. Annual Runoff generated may be calculated for determining the quantum of rainfall available for recharge.
5. Runoff Coefficient may be taken for different type of areas as per following details :
6. Annual runoff generated within the premises of project may be calculated as Area (in sq. metre) * Runoff Coefficient *Rainfall(in m)
7. Hourly Rainfall generated may be taken from intensity of rainfall as mentioned on IMD website; in general for Punjab and Haryana 25 to 30 mm/hr Rainfall may be taken.
8. Then Hourly Runoff generated within the premises may be calculated as Area* Coefficient*Intensity of rainfall (i.e. 0.025 to 0.03 m for Punjab/Haryana)
9. From the quantum of Hourly rainfall generated rainfall number of AR structures to be constructed within the premises may be designed.
10. Quantum of Rainwater through individual Recharge structure should also be calculated.
11. For example : A recharge pit (Rectangular for this case) have 3 components (free board part, gravel filled part and recharge well part).
(i) Volume of water within free board will be = length *breath*depth
(ii) Gravel filled part will be (volume of water within the pore spaces of sand, gravel filled part)= length *breath*depth*0.35 (this is the porosity)
(iii) Recharge well through which ground water recharge may be done within Shallow aquifer; for this intake capacity of recharge well may be tested in field.
In general, intake capacity of recharge well may be taken as 5 to 10 LPS (i.e.,18 to 36m3 /hr) depending upon the hydrogeology.
Therefore, total volume to be Recharge through a RWH structure will be = (i) + (ii) + (iii).
Now no. of Recharge structure to be constructed within the premises will be Hourly Rainfall generated within the premises, as mentioned in point no. (9) Divided by point no. (11) (Quantity of water recharge as shown in calculation for individual RWH structure).
12. For design of the structure cgwa.gov.in website may be referred.
AREA REQUIRED : 100 sq. feet(10*10, L*B)
CAPACITY OF RECHARGE : 200 Sq. m Area at water logged of depth 2-3 feet.
TOTAL COSTING WITH BREAKUP : Rs. 17000 including earth work, Labor, Material etc.
MAN DAYS REQUIRED FOR CONSTRUCTION : 3 Days
AREA REQUIRED : 120 sq. m(10*12, L*B)
CAPACITY OF RECHARGE : Area more than 2000 Sq. M. Example: Govt. buildings, Schools, Corporates etc.