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Elizabeth Khaka
Elizabeth Khaka
Topic: Rainwater Harvesting
Elizabeth Khaka is an expert on rainwater harvesting. She has experience in integrated water resources management, water assessment, water reuse, women and water management, environmentally sustainab...
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Number of questions: [6]
Posted on 06/01/2007 12:42:15
how can i design a rain water harvesting system for my industry. Is road rain water can be collected in rain harvesting pits. my industry is situated in punjab (india) city patiala. can i get the metorlogical data of this city to design the RWH.
parveen saluja
Yes rainwater can be collected from road runoff and stored in ponds. However this will depend on the available area, what the water will be used for as this will determined the water quality required, the rainfall etc. The Center for Science and Environment (CSE) in India has done a lot of work on rainwater harvesting in urban areas and also for industry.
The CSE website is:
http://www.cseindia.org/.

Rainfall data can be obtained from http://www.worldclim.org/

Posted on 06/01/2007 09:38:06
Dear Ms. Elizabeth,
Could you please suggest a reasonable large scale system design on rainwater harvesting?
Mahmood Yazdandoost
The basic components of rainwater harvesting systems are (i) the catchment from which the water is collected, (ii) the conveyance system for guiding the water from the catchment to the storage and (iii) the storage facility that range from tanks to ponds to underground. Domestic water quality can be maintained by installing first flush devises, wire meshes, filtration systems etc. Water quality flowing into ponds can be maintained by building silt traps to allow the silt to settle before flowing into the ponds. The rainfall pattern number of users, evaporation, costing are other parameters to be considered.

It is not possible to provide you with a systems design as this depends on the number of users, rainfall pattern, what the water will be used for etc. There are various manuals which can guide you including the following: http://www.twdb.state.tx.us/publications/reports/RainwaterHarvestingManual_3rdedition.pdf
http://www.rainwaterharvesting.org/urban/Design.htm

Posted on 05/01/2007 09:18:14
I read the first question and answer for and from todays expert and that brought another
question to mind. What to do about mosquitos. This is not only a problem in tropical
areas. We collect rainwater (for the garden) in Europe and have several times
inadvertantly ended up raising mosquitos. We don't want to add anything to the water
and so far haven't discovered a truly effective way to keep mosquitos out. Do you
have any suggestions?
Mary Mays
Controlling mosquito breeding is a major challenge. This depends on the they type and size of the water body. Without adding chemicals, you can use biological control methods such as introducing fish that prey on the mosquito larva. Further, agitating the water will reduce mosquito breeding as they breed in stagnant water. Covering the water body will also help.

Where and how do you store your rainwater?

Posted on 05/01/2007 08:16:31
Dear Ms. Khaka, my question is on linking diets/calories to Rainwater Harvesting.
How can the concept of virtual water be used to determine/plan for the amount of harvested water needed to produce certain crops(and thus foods) in order to have sufficient diet for a human being on a daily, seasonal and annual basis?
Oduor Raymonds
It is prudent to estimate food production in terms of calorie needs and virtual water for rainwater and other water sources. Though the virtual water required for different foods can be found in literature, these are guidelines as the actual amount needed differs from country to country depending on the diet and cultural preferences. By calculating the virtual water for meeting the dietary requirements in a country, it is possible to determine the amount of water required to produce the particular food. Conventionally, water availability was estimated from blue water only. Considering rainwater gives a more realistic view of the water available and might result in a decision to produce instead of importing more water-demanding foods. This system works well if it is done on a regional scale and can form part of trade agreements

Posted on 05/01/2007 08:07:34
UNEP is host to the Rainwater Partnership. What are the key activities of this partnership? I attended the 10th SEARNET conference in Mombasa and was a beneficiary of support from UNEP to attend this conference. During this conference it was recommended to start up journal on RWH. How is Rainwater Partnership intending implement this action?
Cherogony Kipruto
The Rainwater Partnership has membership from all regions. Its main activities are facilitating exchange of information and expertise between its members and supporting members to develop and implement rainwater harvesting projects on request. The 10th SEARNET conference recommended the establishment of the Rainwater Journal. UNEP as the Secretariat will present this recommendation for adoption by the Rainwater Partnership. Meanwhile members are encouraged to prepare good quality papers to illustrate the type of papers that will be published in the Journal. If the Rainwater Partnership agrees, a scientific committee will be established in accordance with the governance rules. Non members can be invited to participate where necessary to ensure high standards are maintained.

Posted on 05/01/2007 06:59:48
Is water quality a problem in rainwater systems, and how can I improve water quality?
David Parker
The quality of rainwater is not a major problem depending on what you want to use it for. Rainwater is not limited to drinking water and can be used for non potable purposes such as washing cars, irrigation and industrial purposes. It quality depends on:

(a) the quality of the atmosphere. Rain may contain impurities from the atmosphere and can include lead and arsenic. This is an important issue in industrialized areas and use of rainwater should be determined from the quality.

(b) quality of the catchment (e.g. roof, roads) , conveyance( gutters, canals, pipes) and storage system(tanks). There are several methods for ensuring good water quality. In the case of roof top rainwater harvesting systems, the roofs, gutters and tanks should be cleaned periodically. A first flush devise should be installed to prevent the first few liters of water that are likely to be contaminated from entering into the storage tank. Screens can be fitted at the tank inlet to prevent pollution from coarse objects such as leaves and mosquitoes from breeding in the tanks. The water can also be filtered.

    
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