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==<b>Literature Review</b>== | ==<b>Literature Review</b>== | ||
This is a review of the available literature pertinent to rainwater catchment/harvesting systems. | This is a review of the available literature pertinent to rainwater catchment/harvesting systems. | ||
<br> | |||
===<u>Overview & History of Rainwater Catchment</u>=== | ===<u>Overview & History of Rainwater Catchment</u>=== | ||
Rainwater catchment (rainwater harvesting) is an age-old technique of capturing precipitation and water run-off, and storing it for future usage. Various methods are used in rainwater catchment - from primitive construction to elaborate systems - depending on factors such as budget, usage, climate and geographical location. The captured run-off supplies societies and individuals with a fresh water source and helps enable sustainable living. These catchment methods have been practiced for thousands of years, recoded as far back in time as ancient Rome, where courtyards were paved and residencies had individual cisterns to capture rainwater. <ref>"Rainwater Harvesting Policy Resources", information on Australian law, http://www.oaecwater.org/rainwater-resources.</ref> | Rainwater catchment (rainwater harvesting) is an age-old technique of capturing precipitation and water run-off, and storing it for future usage. Various methods are used in rainwater catchment - from primitive construction to elaborate systems - depending on factors such as budget, usage, climate and geographical location. The captured run-off supplies societies and individuals with a fresh water source and helps enable sustainable living. These catchment methods have been practiced for thousands of years, recoded as far back in time as ancient Rome, where courtyards were paved and residencies had individual cisterns to capture rainwater. <ref>"Rainwater Harvesting Policy Resources", information on Australian law, http://www.oaecwater.org/rainwater-resources.</ref> | ||
<br> | |||
Globally, many civilizations are shaping their cultures and becoming keener on ecological modernization, which favors rainwater catchment and other appropriate technologies. Some regions have mandated collection of rainwater, such as in Gold Coast, Australia, where the City Council declared that all new homes past 2007 must have rainwater catchment set-up for non-potable usage. <ref>Rainwater Harvesting, information on history of harvesting, http://www.tn.gov.in/dtp/rainwater.htm.</ref> Laws such as these prove rainwater catchment is an important and necessary tool for many areas in the world. | Globally, many civilizations are shaping their cultures and becoming keener on ecological modernization, which favors rainwater catchment and other appropriate technologies. Some regions have mandated collection of rainwater, such as in Gold Coast, Australia, where the City Council declared that all new homes past 2007 must have rainwater catchment set-up for non-potable usage. <ref>Rainwater Harvesting, information on history of harvesting, http://www.tn.gov.in/dtp/rainwater.htm.</ref> Laws such as these prove rainwater catchment is an important and necessary tool for many areas in the world. | ||
<br> | |||
Rainwater catchment is mostly used in areas that are; arid or semi-arid, and that may not have a constant flow of run-off annually; areas that are dependent on a local, nearby stream or river; and when the catchment area, volume of storage and capital investment in the system is usually small-scale <ref>Boers, Th., Rainwater Harvesting in Arid and Semi-arid Zones. Environmental Engineering: Designing a Sustainable Future. New York. Page 1.</ref> | Rainwater catchment is mostly used in areas that are; arid or semi-arid, and that may not have a constant flow of run-off annually; areas that are dependent on a local, nearby stream or river; and when the catchment area, volume of storage and capital investment in the system is usually small-scale <ref>Boers, Th., Rainwater Harvesting in Arid and Semi-arid Zones. Environmental Engineering: Designing a Sustainable Future. New York. Page 1.</ref> | ||
<br> | |||
===<u>Capturing</u>=== | ===<u>Capturing</u>=== | ||
There are different ways to capture rainwater, and the most common systems are: roof catchment, ground catchment and rock catchment. | There are different ways to capture rainwater, and the most common systems are: roof catchment, ground catchment and rock catchment. | ||
<br> | |||
The following efforts of research have been focused on roof catchment systems, which are the most common. There are three main parts to this system, a catchment surface, a gutter and a down spout, and a tank. <ref>Gould, John. Rainwater Catchment Systems for Household Water Supply. Bangkok, Thailand, page 4.</ref> “Rainwater collection systems use gravity to do the work, making these systems easy to use and inexpensive. Rainwater collects into large cisterns, barrels or roof top tanks connected to a down spout that carries it to a holding tank on or under the ground.” <ref>Maczulak, Anne. Environmental Engineering: Designing a Sustainable Future. New York, Page 149.</ref> | The following efforts of research have been focused on roof catchment systems, which are the most common. There are three main parts to this system, a catchment surface, a gutter and a down spout, and a tank. <ref>Gould, John. Rainwater Catchment Systems for Household Water Supply. Bangkok, Thailand, page 4.</ref> “Rainwater collection systems use gravity to do the work, making these systems easy to use and inexpensive. Rainwater collects into large cisterns, barrels or roof top tanks connected to a down spout that carries it to a holding tank on or under the ground.” <ref>Maczulak, Anne. Environmental Engineering: Designing a Sustainable Future. New York, Page 149.</ref> | ||
<br> | <br> | ||
<u>Roof Materials:</u><Br> | |||
Galvanized corrugated iron sheets, corrugated plastic or tiles are all good catchment surfaces, as well as thatched roofs with the right type of palm (like coconut), and roofs with asbestos or lead based paints should not be used. <ref name="gould"/> | |||
<br> | <br> | ||
The amount of rainwater available to collect for supply depends on the amount of rainfall, the area of the catchment and the runoff coefficient, which is usually considered to be 0.8, based off of factors such as leakage, evaporation, etc.. <ref name="gould"/> | |||
<br> | <br> | ||
One equation that demonstrates the amount of supply available: S = R x A x C | Here are a few methods to calculate the amount of runoff/rainwater catchment supply available: | ||
*One equation that demonstrates the amount of supply available: S = R x A x C | |||
Where S = Rainwater Supply, R = Mean annual rainfall, A = roof area in sq meters and C = the runoff coefficient. | Where S = Rainwater Supply, R = Mean annual rainfall, A = roof area in sq meters and C = the runoff coefficient. | ||
<br> | <br> | ||
*Graphical Method | |||
<br> | |||
Obtaining Mean monthly roof runoff. This is calculated from Mean monthly rainfall times roof area catchment. Graphing on a monthly basis can display how much water you have during the year to use. A usage line can be draw on the graph to show the extra and the insufficiency's of your system and at what time of the year they will occur. In order to determine potential rain water supply reliable rain fall data are required preferably for a period of at least 10 years.<ref> Schiller and Latham, (1982) </ref> Note, in mountainous regions considerable rainfall variations can occur over short distances. | Obtaining Mean monthly roof runoff. This is calculated from Mean monthly rainfall times roof area catchment. Graphing on a monthly basis can display how much water you have during the year to use. A usage line can be draw on the graph to show the extra and the insufficiency's of your system and at what time of the year they will occur. In order to determine potential rain water supply reliable rain fall data are required preferably for a period of at least 10 years.<ref> Schiller and Latham, (1982) </ref> Note, in mountainous regions considerable rainfall variations can occur over short distances. | ||
<br> | <br> | ||
*Statistical and Computerized Methods* | |||
*PEquals.com is an efficient way to calculate the estimated runoff amount your roof may supply: www.pequals.com/rain | <br> | ||
*Another way to calculate water usage: http://www.harvestingrainwater.com/rainwater-harvesting-inforesources/rainwater-harvesting-online-calculator/ | **PEquals.com is an efficient way to calculate the estimated runoff amount your roof may supply: www.pequals.com/rain | ||
< | **Another way to calculate water usage: http://www.harvestingrainwater.com/rainwater-harvesting-inforesources/rainwater-harvesting-online-calculator/ | ||
<br> | |||
===<u>Diversion</u>=== | ===<u>Diversion</u>=== | ||
<u>Gutters:</u><br> | <u>Gutters:</u><br> | ||
Revision as of 08:09, 13 February 2012
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The Mattole Valley Community Center in all of its glory!
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The projected project site!
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The project site from the back
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Height of building & gutter in place
Background
The Mattole Valley Community Center is looking to install a rainwater catchment system on site in Petrolia, California. The Mattole Board of Directors is interested in having a working rainwater catchment system to water a community garden and also to utilize the project for community outreach and education about the benefits of appropriate technology. This project is starting in January of 2012 and is projected to be finished by May 2012.
Problem statement
The objective of this project is to catch rainwater from the roof of the Mattole Valley Community Center in Petrolia. The water storage will help water and accommodate extra irrigation for a flower garden located on site. This project will be a demonstration for the local community and other organizations to learn about the benefits of rain water catchment, visually show the rain water catchment process, and along with the utilization of the instructions laid out on this Appropedia site other individuals will potentially be able to produce a system for their own usage.
Ideas for the future
Options to educate also include the creation of an instructional pamphlet or on site graphic image board that explains details on the project or how to make your own system.
Project Evaluation Criteria
The following Criteria will be used to assess the success of this project. These criteria were chosen based on the suggestions of the project coordinator as well as the diligent students who are working on the catchment system. The scale (1-10) represents the importance level of meeting the constraint of each listed criteria.
Literature Review
This is a review of the available literature pertinent to rainwater catchment/harvesting systems.
Overview & History of Rainwater Catchment
Rainwater catchment (rainwater harvesting) is an age-old technique of capturing precipitation and water run-off, and storing it for future usage. Various methods are used in rainwater catchment - from primitive construction to elaborate systems - depending on factors such as budget, usage, climate and geographical location. The captured run-off supplies societies and individuals with a fresh water source and helps enable sustainable living. These catchment methods have been practiced for thousands of years, recoded as far back in time as ancient Rome, where courtyards were paved and residencies had individual cisterns to capture rainwater. [1]
Globally, many civilizations are shaping their cultures and becoming keener on ecological modernization, which favors rainwater catchment and other appropriate technologies. Some regions have mandated collection of rainwater, such as in Gold Coast, Australia, where the City Council declared that all new homes past 2007 must have rainwater catchment set-up for non-potable usage. [2] Laws such as these prove rainwater catchment is an important and necessary tool for many areas in the world.
Rainwater catchment is mostly used in areas that are; arid or semi-arid, and that may not have a constant flow of run-off annually; areas that are dependent on a local, nearby stream or river; and when the catchment area, volume of storage and capital investment in the system is usually small-scale [3]
Capturing
There are different ways to capture rainwater, and the most common systems are: roof catchment, ground catchment and rock catchment.
The following efforts of research have been focused on roof catchment systems, which are the most common. There are three main parts to this system, a catchment surface, a gutter and a down spout, and a tank. [4] “Rainwater collection systems use gravity to do the work, making these systems easy to use and inexpensive. Rainwater collects into large cisterns, barrels or roof top tanks connected to a down spout that carries it to a holding tank on or under the ground.” [5]
Roof Materials:
Galvanized corrugated iron sheets, corrugated plastic or tiles are all good catchment surfaces, as well as thatched roofs with the right type of palm (like coconut), and roofs with asbestos or lead based paints should not be used. [6]
The amount of rainwater available to collect for supply depends on the amount of rainfall, the area of the catchment and the runoff coefficient, which is usually considered to be 0.8, based off of factors such as leakage, evaporation, etc.. [6]
Here are a few methods to calculate the amount of runoff/rainwater catchment supply available:
- One equation that demonstrates the amount of supply available: S = R x A x C
Where S = Rainwater Supply, R = Mean annual rainfall, A = roof area in sq meters and C = the runoff coefficient.
- Graphical Method
Obtaining Mean monthly roof runoff. This is calculated from Mean monthly rainfall times roof area catchment. Graphing on a monthly basis can display how much water you have during the year to use. A usage line can be draw on the graph to show the extra and the insufficiency's of your system and at what time of the year they will occur. In order to determine potential rain water supply reliable rain fall data are required preferably for a period of at least 10 years.[7] Note, in mountainous regions considerable rainfall variations can occur over short distances.
- Statistical and Computerized Methods*
- PEquals.com is an efficient way to calculate the estimated runoff amount your roof may supply: www.pequals.com/rain
- Another way to calculate water usage: http://www.harvestingrainwater.com/rainwater-harvesting-inforesources/rainwater-harvesting-online-calculator/
Diversion
Gutters:
A small slope on the roof will help save on costs when it comes to buying materials for gutters. All gutters will divert water into the water holding tank and should have a constant gentle slope to ensure that the water reaches it’s destination and to aide in prevention of blockages. [6]
A general rule is that all gutters should have 1cm^2 of guttering for every m^2 of roof area [8], or they should have a cross-sectional area of about 200 cm2 to minimize overflow when downpour of rain is very heavy. [6]
PVC and Downspout
These lead to the storage tank and incorporate a first flush into the catchment system.
First Flush:
This ensures that the waste entering the system that has accumulated on the rooftop between rains diverted from entering the tank and are often simply designed, even a downspout from the root that has a small hand operated diversion valve will suffice. [9]
Filter:
An important thing to keep in mind when capturing rainwater keeping as much waste and debris from entering the system as possible. There are different filtration methods available, such as installing screens on each of the gutters or downspouts to keep large particulates out of the system.[10]
=
References
| Criteria | Constraints | Weight (1-10) |
|---|---|---|
| Community | Will be able to hook up to two inch fire hose from fire truck to supply extra water. | |
| Maintainability | Must be easy to clean the filter and remove debris, no more than 2 hours maintenance per month | |
| Aesthetics | Must be pleasing to the eye and look professional | |
| Educational Aspect | Must include an educational piece for community (something to explain or highlight the benefit or creation of a rainwater catchment system) | |
| Safety & Placement | Must not interfere with walking paths, stairwells, or people's heads! | |
| Reproducability | The structure could be reproduced by local builders | |
| Usability | Must sufficiently water the garden on site (with use of hose attachment) | |
| Budget | Must not exceed budget | |
| Functionality | Successfully captures and stores rainwater |
- ↑ "Rainwater Harvesting Policy Resources", information on Australian law, http://www.oaecwater.org/rainwater-resources.
- ↑ Rainwater Harvesting, information on history of harvesting, http://www.tn.gov.in/dtp/rainwater.htm.
- ↑ Boers, Th., Rainwater Harvesting in Arid and Semi-arid Zones. Environmental Engineering: Designing a Sustainable Future. New York. Page 1.
- ↑ Gould, John. Rainwater Catchment Systems for Household Water Supply. Bangkok, Thailand, page 4.
- ↑ Maczulak, Anne. Environmental Engineering: Designing a Sustainable Future. New York, Page 149.
- ↑ 6.0 6.1 6.2 6.3 Cite error: Invalid
<ref>tag; no text was provided for refs namedgould - ↑ Schiller and Latham, (1982)
- ↑ Hasse, 1989
- ↑ Nagy, Erik. An Analysis of Three Slow-sand Rooftop Rainwater Catchment System Filters. Page 10
- ↑ A Simple Rainwater Harvesting Design, http://www.harvesth2o.com/simple_system.shtml