Reservoir Seepage

Respected Dears,

We want to construct a water reservoir, which have area 29 Acre. The surface strata is loam soil and head is 15m.

My questions is , once this reservoir becomes full, in how many days would the reservoir be emptied because seepage. how to calculated it?

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5 Answers

1. Have you built a dynamic water balance model with mutli-year inflow analysis?

   1 Comment

   1. that is main problem

      sir

2. Dear Sultan,

    

   You can calculate if you know any measure or can assume any estimated value of the seepage in the place you are thinking construct the reservoir.

   Initially you must look for the appropiate seepage (or infiltration) measuring technical approved or used in your country to you can do any soil analysis and contract that service. Then using the obtained data and the appropiate calculation method you can calculate the required incognit.

   On the other hand you can do an intial approximationt using the data you can obtain in a visit to the site (soil and other data), and some local or experience assupmtions to use the seepage tables.

    

   Regards,

    

   Orlando D. Gutiérrez Coronado

3. Hi Sultan,

   For estimation, you can use the rate of 1200 liters/square meter/per day  as water loses from unlined canals and basins located on loam soils. In case of lining, then the values can be much lower. If you plan to line the basin with HDPE membrane the water loses can be only evaporation which can reach 70 - 80 l/m2 per day.

   1 Comment

   1. Thank you very much. there is any source for 1200 liter/square meter/day?

       

4. Hi Sultan,

   a few questions to help us understand your question better:

   • are you interested in calculating the seepage lost through soil at the bottom of the reservoir? or the seepage through an earthen dam /embankment that holds the water back? or both?
   • Also, are you looking for a quick "back-of-the-envelope" estimate that you can calculate in the office without collecting any additional field data? Or you are trying to come up with a detailed comprehensive estimate for a site already in development?
   • How is the reservoir going to be filled? (e.g. stream/river that will be blocked with dam?, pumping water in?, rainfall. etc..?, and will there be ongoing sources of inflow to the reservoir (e.g. streams, rainfall, etc..)?

   You will need to evaluate if the seepage rate will be greater or smaller than other inflow rates (such as from stream, rainfall, surface runnoff, etc..), and you most likely will need to assemble the following information (and possible other info as well).:

   • estimate the soil hydraulic properties (e.g. if you have no field measurements, then you can estimate  upper and lower bounds based on literature value for loamy soils)
   • develop estimates for other inflow rates to the reservoir (e.g. rainfall, streams, surface runoff, etc..)
   • you also need to establish the depth to shallow groundwater and if there are any impermeable to low permeability soil horizons in the top few meters of soil, as this may limit seepage.
   • you might also need to consider evaporation depending on the climate of the area where the reservoir will be constructed.

   Pascual

   1 Comment

   1. we are constructing dam of a stream which has estimated inflow around 1000Acft. reservoir area will be 27 Acres. with height of 15m. rock layer is deep around at 80m below NSL. 

5. Run multiple double ring infiltrometer tests and calculate the seepage.