How to estimate the amount of groundwater recharge through a recharge pond?

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I need your expert suggestions for calculating groundwater recharge over a set period.  

In our project area, we have a pond managed by the community and the primary objective of this pond is to help ground water recharge.

In this case, how do we calculate the amount of water recharged into the ground for a particular year?
We have the yearly rainfall data and topographic details of the catchment. What is the best way to estimate groundwater recharge in this case? 

Also, how can we estimate groundwater recharge when artificial recharge techniques are adopted?

Best,

Amit

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16 Answers

  1. Measure water table (daily) in a near by open well and apply Hantush (1969) method.

  3. Dear Amit,

    What is the construction of POND?

    What is the daily activity in the pond or is it a restricted area?

    If it is a lined pond or if it is restricted area and can have mineral layers making it impervious, then, Pond will not contribute tyo recharge of ground water as happens in case of Rajasthan and Kutch area ponds.However, if cattle and men are allowed to go into the pond and its surface is unlined, deep percolation shall take place and you can estimate the peak storage plus subsequent inflows less daily surface evaporation and subtract the minimum level to arrive at possible recharge.

    If you want to recharge ground water, you should inject water into the borehole with pvc strainer duly screened, filled with gravel and sand and allow injection to the extent you want water to go into the acquifer.

  4. I did that 20 years ago. I had a way to measure the volume of the water in the pond every day with an estimate of water evaporation plus water quantity arriving in the pond. The difference was the recharge. The piezometric method described below was more difficult to analyse as water goes horizontaly in different directions on an heterogeneous maner and I needed too many piezo to close my balance. In winter the water evaporation can be assumed = 0

  5. The simplest method to calculate the recharge is by piezometric wells.. There are many other parameters we can consider.. First measure the water intake and volume on daily basis in the pond. Then knowing the soil porosity, texture, hydraulic conductivity, infiltration rate (m/m per day), evapo-transpiration, the recharge could be measured by putting values in different equations... thanks

  6. I am surprised by the complex solutions proposed to a simple problem. Easiest method is to push or insert by hand (digging a hole) a series of piezometers made out of perforated PVC running to the depth of the bottom of the pond (if too deep may need a pushing device and using perforated steel pipes), run slug tests on them, and then monitor daily changes in elevation of the water table in these piezometers. Calculate hydraulic conductivity with these data. Inexpensive and simple.

  7. Dear Amit, While I agree on the need of detailed studies for a detailed estimation, following is a rule of thumb that could work for your case. -Vertical hydraulic condutivity of the base establish an upper threshold of the infiltration. You can easily determine it by using double ring infitrometers. Methodology can be found elsewhere. -Free surface water balance (Precipitation-Evaporation) provides you the net water input to the pond. Should there be additional inputs (surface water, ...) must be added -A balance between the inputs and the maximum output gives you a range of the infiltration loses For managed aquifer recharge, the methodology is approximately the same. The more resources you have, the more instruments you can use ... We run some projects here in Spain and results are OK. Should you or any of the group need some info, just let me know. Best regards, Jordi Guimera

  8. Dear Amit The estimation of Recharge is depend on various hydraulic properties of surface and subsurface formation , topographic information and amount of rainfall. For estimation recharge for a pond it needs detail investigation of the area such as geological , Hydrological , previous years water level data , area of recharge zones and amount and duration of rainfall.

  9. Dear Amit Ji,

    There might be different views by different experts, what I feel that It can be slightly not easy task to calculate an exact amount.

    Still an Increase in groundwater table than earlier, could be one sing that it is getting recharge in that area. But if you put some simple calculations, then using average rain fall, water holding capacity of the designed pond and the rate of percolation of the pond water (this can be calculated by analysing soil for some specific parameters) to the groundwater table. This all might helpful to calculate total of recharged water. Also keeping track of water table for some interval, it will also help to monitor groundwater recharge quantity.

  10. Dear Amit, Recharge of Pond In places where the withdrawal of water is more than the rate of recharge an imbalance in the groundwater reserves is created. Recharging of aquifers is undertaken with the following objectives: • To maintain or augment natural groundwater as an economic resource • To conserve excess surface water underground • To combat progressive depletion of groundwater levels • To combat unfavourable salt balance and saline water intrusion Design of recharge structures and settlement tank For designing the optimum capacity of the tank, the following parameters need to be considered: 1.) Size of the catchment 2.) Intensity of rainfall 3.) Rate of recharge, which depends on the geology of the site The methodology of design of a recharge pond is similar to that for a settlement tank. The difference is that the water-holding capacity of a recharge trench is less than its gross volume because it is filled with porous material. A factor of loose density of the media (void ratio) has to be applied to the equation. The void ratio of the filler material varies with the kind of material used, but for commonly used materials like brickbats, pebbles and gravel, a void ratio of 0.5 may be assumed. Using the same method as used for designing a settlement tank: Assuming a void ratio of 0.5, the required capacity of a recharge tank = (100 x 0.025 x 0.85)/0.5 = 4.25 cu. m. (4,250 litres) In designing a recharge trench, the length of the trench is an important factor. Once the required capacity is calculated, length can be calculated by considering a fixed depth and width. Regards, Prem Baboo

  15. Estimating recharge is a topic of intense research. I would suggest a simplistic approach: the Net Recharge would be Rainfall - Runoff - ET. Rainfall - runoff, that is, the captured volume can be calculated from the topographic details of the catchment using GIS tools. ET can be estimated using meteorological data such as solar radiation, temperature, wind speed etc using Penman-Monteith equation (https://en.wikipedia.org/wiki/Penman%E2%80%93Monteith_equation). Another way (and perhaps this can be used in case of an artificial recharge site) is to establish a monitoring system by measuring the water levels (and thereby the volume) in the pond over a period of time to provide potential recharge volume and also putting a pan evaporation station (https://en.wikipedia.org/wiki/Pan_evaporation) on site to provide the potential evaporation rate. Assuming there is low to no vegetation around the pond, recharge would be volume in storage - (potential evaporation rate * surface area of pond * correction factor). Correction factor of 0.75 is generally used. Note: the pan evaporation rate and surface area would vary over time so this requires a little bit of calculations. Depending on the conditions, you could also put a few tensiometers in the pond at various depths to check the movement of the infiltration front - this would provide an idea of recharge too. Conducting infiltrometer or permeameter tests would also help in developing an idea of recharge conditions of the pond site. Hope this helps and good luck!

  16. Use the Recharge Package in MODFLOW: http://water.usgs.gov/nrp/gwsoftware/modflow2000/MFDOC/index.html?rch.htm See attached files.