Rainwater Harvesting System at Central Arid Zone Research Institute (CAZRI) campus (Low rainfall area)

August 12, 2016


 

Location: Jodhpur, Rajasthan
Scale: zonal level
Implementing organisation:
Average annual rainfall: 3,20 mm

Total volume of rainwater harvested:600,000 liters
Area: 1496 sqm (Director's office)+2500 sqm (Administrative Block)
Operational since : 1993 (Director's Office), 2005 (Administrative Block)
Capital cost : Rs. 2.28 lakh (Director's Office)+4.9 lakh (Administrative Block)
O&M: Rs. 3,000

 
 

The rain water harvesting system installed in Central Arid Zone Research Institute (CAZRI) caters the need of watering the medicinal plant for experimental purposes. The objective of the rain water harvesting here is to serve as model project for households in urban areas of arid zone climate with the same principles of the traditional system of Rajasthan known as tankas according to yearly rainfall intensity of 320 mm. The tankas are constructed in depressions following the natural slope of the site.

 
 

TECHNOLOGY & DESIGN

Technical details:

Collection/ catchment system:
The rain water is collected from the roof top of the two blocks of the main office of the CAZRI. The roof tops are cement finish with high runoff coefficient which collects almost 80 percent of rainfall which falls on it. The system is designed only for the two blocks for the demonstration purpose.

Conveyance system
The water from the roof top is directed to the vertical down-take pipes through the roof spouts placed at different intervals. The vertical drain pipes are connected to the spouts which take the water to the horizontal channel. Rain water runoff from each block flows through the respective horizontal channel.

The storage tank for administrative block is connected with underground channels while for Director’s block, it is connected by open channels. The design of channel was made according to existing building and site condition. The underground channel in the administrative block is made inside the courtyard where the runoff is carried to the nearby storage tank.

Filtration/ sedimentation tank
The rain water harvesting system has first flush mechanism as one of the preventive filtration, to avoid first rainfall of the first season of monsoon. The mechanism involves the use of flexible inlet pipe at the bottom, which can be diverted manually to avoid first half an hour rainfall to avoid the dirt and silt from catchment area.

Rain water is channelized from the respective conveyance systems and it first enters into the settlement tank (de-silting trap) and then from there the rainwater flows to the storage tank. The rectangular de-silting trap (settlement tank) helps in siltation and makes water cleaner for plant irrigation. The tank is made underground with 1 meter depth where the water is retained and the overflow goes into the storage tank.

Storage tank:
Each of the two blocks has their underground storage tanks constructed with the concept of tankas from traditional system of Rajasthan. The water from the roof top areas is diverted to collect in storage tanks.


Cross section of a 300 cubic meter storage tank (tanka)



Storage tank for the Administrative block RWH system

 
 

BENEFITS

The water from the storage tank is used for watering the medicinal plants for experimental purposes. The storage tank which collects water from admin block caters the watering need of technology garden lab and the water from district office block caters the need for horticulture block. The water collected is found to be of satisfactory quality according to the beneficiaries.

The water demand for the laboratory is around 30 litre for each plant in a month, which is supplied only for two pre monsoon months in a year, February and March. Around 400 plants are experimented upon and with water requirement for around two and half months.

 
 

Dr. Rajesh Kumar Goyal
Principle Scientist
Central Arid Zone Research
Jodhpur – 342003
Rajasthan
Phone: 9414410251
Email: rkgoyal24@rediffmail.com