Difference between revisions of "Natural ground catchment and Open water reservoir"
(→Suitable conditions) |
(→Suitable conditions) |
||
Line 5: | Line 5: | ||
* The rock that makes up the catchment should be bare and free of vegetation/soil. It should have no fractures or cracks that would result in a loss of water through seepage. | * The rock that makes up the catchment should be bare and free of vegetation/soil. It should have no fractures or cracks that would result in a loss of water through seepage. | ||
* Site the dams for rock catchments to maximize the natural topography – to get the best volume, make dams on the lower side of existing rock pools. | * Site the dams for rock catchments to maximize the natural topography – to get the best volume, make dams on the lower side of existing rock pools. | ||
+ | |||
+ | {{procontable | pro= | ||
+ | - High runoff coefficient = similar to roof catchments in that even small showers produce water <br> | ||
+ | - Minimal seepage <br> | ||
+ | - Maintenance is simple and cheap <br> | ||
+ | - Rock catchments do not occupy farmland and often no one owns the land, so it easy to implement<br> | ||
+ | | con= | ||
+ | - Not many sites suitable <br> | ||
+ | - If building tanks that store water directly, storage capacity is limited compared to an open reservoir<br> | ||
+ | - Cost is high – experience from Kenya shows that a 56 m3 dam cost $4,000 including labour (= $71 per m3 of storage) <br> | ||
+ | - Vectors can breed in open water<br> | ||
+ | - Microbiological and chemical water quality is likely to not be acceptable for direct consumption (see “Natural ground catchment & open water reservoir”) | ||
+ | }} | ||
==Construction, operations and maintenance== | ==Construction, operations and maintenance== |
Revision as of 07:38, 5 April 2012
These are naturally occurring catchments of bare rock that have high runoff coefficients (around 0.9). Water can be stored as an open reservoir behind a retaining structure, with storage capacities ranging from 20 – 4,000 m3, or can be stored directly in a covered storage tank that collects water directly from the catchment.
Contents
Suitable conditions
- The rock that makes up the catchment should be bare and free of vegetation/soil. It should have no fractures or cracks that would result in a loss of water through seepage.
- Site the dams for rock catchments to maximize the natural topography – to get the best volume, make dams on the lower side of existing rock pools.
Advantages | Disadvantages/limitations |
---|---|
- High runoff coefficient = similar to roof catchments in that even small showers produce water - Minimal seepage |
- Not many sites suitable - If building tanks that store water directly, storage capacity is limited compared to an open reservoir |