What are the Giophysics Survey needed before digging a well

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hello everyone, I'm living In North Sudan and  we are having dug wells in our area. We had constructed them 4 years back. Now all the wells are dried and there is no water. We are planning to dig new wells as these old wells were not constructed properly so there is no point in reutilising these wells. We don't want to repeat the failure in getting no water this time. Please suggest what are the geophysics analysis that should be done before digging wells? Also while constructing wells can we make provisions for well recharge?

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21 Answers

  1. Geophysics Analysis Needed before Digging a well

    I am giving my answer late, but I hope it serves some purpose.

    We conducted geophysics survey in 2009 to enables us locate promising borehole drilling sites using Geonics 34-3 electromagnetic equipment.

    First of all, the dry wells can serve as a model after you take their profiles which involves a plot of Horizontal dipoles (HD) and vertical dipoles as shown in the model for weathered ground layers below. This model of dry wells can be compared with other profiles taken at different sites. This can enable you locate promising sites for drilling or digging. For more information please contact me at yussif.abdul@gmail.com

     

     

  2. Hi Every body , first of all thank you all for your cooperation , I appreciate all the comments arises here and thanks allot for the valuable answers to my question From the answers of the question I came With This Conclusion 1- Geophysical Survey helps to delineate the depth of the water table in certain area 2- Electrical Conductivity or resistivity measured the Map to the depth of the water table. and the results should be tied with other Existing borehole . (Emery Cooper Jr ) " nothing is as accurate as the information collected during drilling of a well " 3 -the ground penetrating radar can helps detecting geological layering ,but it still devoid in developing countries due to lack of finance . The meanwhile solution for drop out well is to drilling it deeper up to semi or confined aquifer after making the water quality assessment or to convert it to an observation well and drilling numbers of test well to determinate the withdrawn of water cone in order to measure the yield and to assist for equilibrium between supply and demand However the Sophistical survey should be conducted during the dry season with adding a suitable depth factor for the results . for myself I have gained allot of knowledge and experiences from this answers I hope that every body here gained this knowledge in Ground Water . We will be following these suggestion, if i am missing something, please comment. Kind Regards, Hussein

  5. The electrical resistivity method, geological surveys and water balance analysis

  9. Water Dowsing

    Dear Husein,

    I think the most practical of groundwater well for personal use is start to locate the groundwater source and I found the water drowsing is the most one. 'Water dowsing" refers in general to the practice of using a forked stick, rod, pendulum, or similar device to locate underground water, minerals, or other hidden or lost substances,and has been a subject of discussion and controversy for hundreds, if not thousands of years. You can browse via google the key word "water browsing". Good luck.

    Wassallam,

    SS

  10. Groundwater hydrology

    Using the existing wells as "test wells", any well creates a down-draw cone near one so the groundwater level of the area is usually higher than where the active wells are.

    If you're not pumping your existing wells and they don't regain water over a few days that implies that the groundwater source itself isn't recharging to that depth. If they do recharge then you can ascertain the recharge rate to adjust your pumping volume to it in the meantime.

    This can be from other wells drawing it down or a lack of rain for too long, you have to figure this out before doing anything about it.

    For this situation I'd suggest using a topo map and try to figure out where the ridges are that confine your entire watershed as this is the area that feeds the groundwater system for your existing wells and any new well location, or, by studying that it seems most likely that the groundwater recharge isn't enough to supply all the wells using it, and if you locate existing wells on the map consider where your wells are in relation to them, this is a common occurrence in many areas now.

    Personally I'd recommend using rainwater collection regardless of how the groundwater situation turns out for households, using the groundwater for crops.

    In relation to crops, consider putting in water-saving methods of distribution, don't use ponds to store it and don't use open or dirt irrigation ditches except on the rows themselves, if they're open dirt line the ditches with clay/aggregate, concrete doesn't work very well, it cracks from settling & thermal expansion then is hard to fix leaks. Clay liners need to expand after being dry but then hold water well with few leaks, a technique used by the Pueblo Indians in Arizona on their canals for centuries.

    Many fields that are in semi-arid lands can get ruined from using surface irrigation due to long-term salt build-up from evaporation so a critical eye is needed to see this, and to then know that investing in water-saving methods is required.

     

  11. Sustainable Groundwater Resource

    Dear Hussein,

    As previous people noted, the lack of water in the wells is probably due to a decline in the water table.  This decline could be due to a combination of over-pumping in the region/area and/or decreased precipitation (drought?).  Geophysics can help you delineate major hydrogeologic units.  To be honest, I am not overly familiar with these methods.  I do know, however, that electrical resistivity is often used after the well has been drilled to further define the lithologic layers (to augment the cores collected during installation of the well).  And I believe ground penetrating radar can help detect geologic layering, etc.  However, nothing is as accurate as the information collected during drilling of a well.

    What I would suggest is that you not only drill the wells deeper, but if possible, screen them (and double case them) within a semi-confined aquifer that is relatively prolific.  In addition, I would also suggest groundwater analysis of the water quality to ensure there are no problems, either due to anthropogenic sources and/or natural (e.g., high arsenic).

    It may be more cost effective to drill smaller diameter pilot holes for hydrogeologic delineation.  You can then convert these wells to observation wells.  If possible, after confirming the water quality is acceptable,  I would then conduct an aquifer pumping test using a larger diameter well (e.g., possible supply well) to estimate aquifer parameter values like transmissivity and storatviity.  From these values, you could perform some relatively simple hydrogeologic modeling to project potential impacts of pumping, based upon expected water use/demand.  This can help you assess the long term feasibility of the supply, and also help you in spacing wells appropriately (preventing excessive overlapping of cones of depression).

    As far as performing recharge to augment groundwater supply, you would likely need to perform a feasibility study, which would include hydrogeologic delineation of the groundwater system and groundwater modeling.  Alternatively, can you use the water that you would recharge as a direct source of water?

    If you need any further suggestions or assistance, feel free to contact me directly.

    Sincerely,

    Emery

     

     

     

  12. Geophisics survey

    Hi Hussain

    1. Geophysics is: The subsurface site characterization of the geology, geological structure, groundwater, contamination, and human artifacts beneath the Earth's surface, based on the lateral and vertical mapping of physical property variations that are remotely sensed using non-invasive technologies. Many of these technologies are traditionally used for exploration of economic materials such as groundwater, metals, and hydrocarbons.
    2. Geophysics is: The non-invasive investigation of subsurface conditions in the Earth through measuring, analyzing and interpreting physical fields at the surface. Some studies are used to determine what is directly below the surface (the upper meter or so); other investigations extend to depths of 10's of meters or more.

    Both of these definitions have a common component, namely that geophysics represents a class of subsurface investigations that are non-invasive (i.e. that do not require excavation or direct access to the sub-surface). The exceptions are borehole geophysical methods that expand the use of holes already drilled to access the subsurface on a very localized basis

     

  14. Dear Hussein, We are a company in the Netherlands developing systems for Rainwater Harvesting and water purification. We have developed RainCaps which are foil sheet tanks 15m³ and 50m³ placed into the ground and a solar driven UV WaterBox for water purification. Our system might be a good solution for your problem as groundwater is getting more scarce. Please have a look at our website and don't hesitate in contacting us if you need more information. www.aaws.nl Kind regards, Aqua-Aero WaterSystems BV Kiki Ruysch Lehman de Lehnsfeld

  15. Aqua-Aero WaterSystems BV

    Dear Hussein,

    We are a company in the Netherlands developing systems for Rainwater Harvesting and water purification.
    We have developed RainCaps which are foil sheet tanks 15m³ and 50m³ placed into the ground and our solar driven UV WaterBox for water purification.
    Our system might be a good solution for your problem as groundwater is getting more scarce.
    Please have a look at our website and don't hesitate in contacting us if you need more information.

    www.aaws.nl

    Kind regards,

    Aqua-Aero WaterSystems BV
    Kiki Ruysch Lehman de Lehnsfeld

  16. Aqua-Aero WaterSystems BV

    Dear Hussein,

    We are a company in the Netherlands developing systems for Rainwater Harvesting and water purification.
    We have developed RainCaps which are foil sheet tanks 15m³ and 50m³ placed into the ground and our solar driven UV WaterBox for water purification.
    Our system might be a good solution for your problem as groundwater is getting more scarce.
    Please have a look at our website and don't hesitate in contacting us if you need more information.

    www.aaws.nl

    Kind regards,

    Aqua-Aero WaterSystems BV
    Kiki Ruysch Lehman de Lehnsfeld

  17. Giophysics Survey

    Hi Hussain,

    You will have to go for conducting a detail geophysics survey next time before digging borehole. The survey would be requiring use of technical tools to estimate the depth of the available aqua level in different seasons, mainly rainy and dry seasons. Moreover, you will have to collect periodic long back relevant information to assess the trends and nature of the ground water. Of course, you will also have to estimate the increasing pattern of going the water level. Based on these issue, will be able to take decision about what can be the best alternative option in this regards.

    Best wishes

    Waled Mahmud, WASH Expert 

  18. What are the Giophysics Survey needed before digging a well

    Hi Hussein,

    In short, geophysics is used to determine geological incontinuities / discontinuities that may serve as a preferential pathways to groundwater. I don’t know what the predominant geology is in your area but for the most parts a combination of magnetic, electromagnetic and resistivity techniques are used for groundwater exploration. If you have a large exploration area at your disposal, you can consider airborne geophysics and then follow up with ground geophysics. This will increase the probability of drilling sustainable production boreholes. There are many geophysicists in Africa able to conduct your exploration project for you.

    As a side note, the existing boreholes may have dried up because they were not pumped in a sustainable manor. When new wells are drilled, a yield test/pumping test should be conducted on the borehole. The data from this test can be interpreted and used to determine a sustainable/safe yield for the well. If this yield is used, the likelihood that the well will dry up is significantly reduced as the software used to determine the yield takes into account rainfall, recharge, other users etc.

    I hope this helps. If you have more questions, feel free to contact me.

    Regards,

    Marius.

     

     

  19. Hi Hussein. To answer your question directly, Geophysics helps you to delineate the depth to the water table in the area. Mostly resistivity is measured to map to the depth to the water table, however, the result should be tied with other existing boreholes or Geological features as it is not 100% accurate. Saying that, I do not have the detailed Geological census of the area but from my experience the issue that you are facing is the drop down of the water level in side the borehole and generally the whole area. Hence, I would recommend you to conduct the Geophysical studies during dry seasons as this is the period where the water table recedes the farthest. You might want to add a depth safety factor to your studies depending on the recharge which range from 0.25 to 0.75 and to start drilling at any other time that you see fit. I hope that answers the question, cheers Tesfaye

  20. Hi Hussein Ibrahim The technical reason is simple. In our context , Many farmers do not conduct the technical survey before well excavation. They took help of religious leaders, astrologists to find out the place for well. Many times it went fell. The technical survey is essential to reduce the risk of investment failure (Natural financial, and human) Regards Ganesh