You are by far the ever best tutor for concepts and analyses in hydrogeology. Another curious thing, you even bothered yourself teaching trick on excel where ppl might get stuck at the very beginning. What an approach of a great soul.
Thank you for all these videos!!! They’re absolutely wonderful at explaining the concepts clearly. A real lifesaver for me who’s a hydrology course this semester. It’s so much more fun watching these videos than reading a textbook
You're very welcome Ho Nga! Learning should be fun, and nowadays we have the technology to make it more interesting. However, I do hope that you still read your textbooks. All the best, Andreas
even tho, my english isnt that proper , i'd like to thank you for facilating your accent , because somehow i understood all of what u said , thank u sir and god bless
Happy to hear that Massin! You can always switch on the sub-titles if that helps. For this video currently available in English, French, Spanish, Arabic & Hindi.
Sir! I have to say that your friendly voice and detail instruction make me feel so comfortable to learn the lesson. Thank you very much and I feel so lucky knowing about this useful video. Wish you all the best!
I am interested in using Theis equation to estimate Transmissivity (T) and Storativity (S) for a single well but there is no observation well. Measurement of draw down and recovery data is available for borehole well used by community. Your guidance is welcome
Hi Joachim, as a rule of thumb you can only estimate Transmissivity from a pumping well. This is because it is very difficult to accurately correct for well losses and also well storage effects. I would not trust any storativity value calculated from a pumping well. All the best, Andreas
Your presentation is very helpful up to now sir. Thank you for making this video. I have some concerns or problem on how to interpret the table of values of Kruseman & de Ribber. I hope you can make a separate tutorial on this. Thanks a lot .
@abengineeral Thank you for your kind words. I assume that you are referring to the table in Annex 3.1 Values of the Theis well function W(u) for confined aquifers (after Walton 1962)? The values in this table are used to draw the type curves where you plot 1/u on the x-axis versus W(u) on the y-axis using log-log paper. Then you need to plot your water level drawdowns also on log-log paper and try to get a fit with the type curves, as I showed early in the video. This is a good training exercise for new hydrogeology students, but it takes time. We can use digital alternatives to do the same thing. Carlos Molano has a nice tool to do this - see his video: th-cam.com/video/iNhwT2yXlNA/w-d-xo.html My approach is slightly different. You select the Transmissivity and Storativity values for your aquifer using the sliders, and then the theoretical drawdown curve is calculated in the background using VBA. Once you have the best fit, you can use these T & S values for the pumping test. Note that you need observation well data to estimate Storativity and Transmissivity. If you only have pumping test data you can get the Transmissivity, but not the Storativity. Note that the VBA code locked, as I don't want people to edit the code and get the wrong answers. All the best, Andreas
Hi Guilherme, I found the code for the approximation of the Theis well function many years ago from a university course, but I have lost the source. Cannot find it on Google either so maybe it has been taken down. Anyway, please see VBA code below. All the best, Andreas **************************************** Function Wu(u As Double) As Double Dim a0 As Single, a1 As Single, a2 As Single, a3 As Single, a4 As Single, a5 As Single Dim b1 As Single, b2 As Single, b3 As Single, b4 As Single a0 = -0.5772156649 a1 = 0.99999193 a2 = -0.24991055 a3 = 0.05519968 a4 = -0.00976004 a5 = 0.00107857 b1 = 2.334733 b2 = 0.250621 b3 = 3.330657 b4 = 1.681534 If u < 1 Then Dim t As Double t = (a2 + (u * (a3 + (u * (a4 + (u * a5)))))) Wu = (-1 * Log(u)) + a0 + (u * (a1 + (u * t))) Else Wu = Exp(-u) / u * (u * u + b1 * u + b2) / (u * u + b3 * u + b4) End If End Function
@@GeosearchInternational I've found out the references of your VBA code couple days ago. The approximation comes from two works: (1) Hastings, C. Jr. 1955. Approximations for Digital Computers. Princeton University Press, Princeton, N.J. and (2) Allen, E. E. 1954. Analytical Approximations. Math. Tables Aids Comp., 8(48), 240-241. These references are quite hard to find online because they are a little bit old papers, but you can reach the same coefficients you used on excel sheets to the same range of u values.
Thank you! For the excel workbook, I keep getting errors in the "s calc" and "error [m'" columns, with "#NAME?" appearing, do you happen to know why that might be? My theis curve isn't showing up on the graph either. Thanks!
#NAME? error appears when a formula or function cannot find the referenced data it needs to complete the calculation. Make sure that you add all the required data in the green cells. All the best, Andreas
Hi Chinthaka, you can use this Theis tool to estimate the Transmissivity of the aquifer. Just use the radius of the well as R. However, note that Storativity can only be calculated from observation well data. Have a look also at the Cooper-Jacob straight line method which has other advantages like being able to see aquifer boundaries. Here is the link: th-cam.com/channels/vnRoF32DJNLtNb-PGqEwjQ.html All the best, Andreas
Hi Chinthaka, if you look in the description below any of my videos you will find links to relevant documents and any excel tools which I use in the video. Link to Theis Macro-enabled Excel file: bit.ly/35sXDO5 You need to download it and then enable the macros when you open it in Excel. Link to the Theis (1935) paper: water.usgs.gov/ogw/pubs/Theis-1935.pdf All the best, Andreas
Transmissivity and Storativity are calculated by Excel. You need to put in the data & fit it to the Theis curve as shown in the video: th-cam.com/video/YMcRRIe4iAg/w-d-xo.html Good luck & all the best, Andreas
Hi Rudy, Assuming that you have enabled Macros in your Excel security settings, see if the original file works as I have shown in the video. If you put your own data in, make sure that all the GREEN cells have values. All the best, Andreas
u = r^2 S/4Tt, where r is the distance to the pumping well, S is storativity, T is transmissivity and t is the time since pumping began. If you want to dig into the maths behind it you should read the original paper by CV Theis (1935). You can find it here: water.usgs.gov/ogw/pubs/Theis-1935.pdf All the best, Andreas
Sorry, I'm doing some videos on resistivity surveys at the moment. Please have a look at Kruseman & de Ridder in the meantime: www.hydrology.nl/images/docs/dutch/key/Kruseman_and_De_Ridder_2000.pdf
Hi Andreas, I was just wondering about the basic question which is how to initially decide which aquifer is of which type? After this answer, we can apply specific well-pumping data analysis methods. Please answer and if possible make a video on this very basic question from Hydrogeologists. Thanks a lot
That is an important question & you are right it would make a nice short video. What type of aquifer it is (confined, leaky-confined, unconfined) can be guessed during the desk study. You will need to figure out the geological units and how the water levels in existing boreholes relate to them. If the static water level is within an aquifer, it is probably unconfined. If it is above the top surface of the aquifer, it is definitively confined but if it is leaky-confined or not depends on the permeability of the confining layer and if there is a source of water above it. Once we drill we can see what the water level does once we have drilled through the aquifer, to confirm the type. Be careful though in fracture aquifers as mostly we want to intersect the fracture at depth, so the water strike is usually well below the final static water level. It does not mean that it is confined. The final proof is the pumping test. If you only have one pumping well you should be able to tell from the shape of the drawdown curve what you are dealing with. e.g. in unconfined aquifers we should get delayed yield - a flat period in the middle of the test when the drawdown almost stabilises. However, it is best to have at at least one observation well so you can calculate the storativity. All the best, Andreas
@@GeosearchInternational Thanks Andreas for the explained reply. If you find time and ready to work on next video(s) then please explain this in your typical style as it will make things very easy and self explainatoy. It would be of help for me and many others. All the best!
You can unlock all the sheets and change the contents as you wish. It is not protected. The VBA code is locked, because any changes there will make the Theis calculations invalid. All the best, Andreas
Hi Michael, The design layout was inspired by an Excel tool from Carlos Molano (th-cam.com/video/iNhwT2yXlNA/w-d-xo.html), but the methodology is different. My tool does not move the data to fit on the Theis curve. It calculates the Theis curve based on the T & S entered by the user. The calculations are made by some VBA code in the background. All the best, Andreas
Hi Migelle, The Theis equation is for non-steady state conditions only. For steady state we use the Thiem equation for confined aquifers and the Dupuit-Forchheimer equation for unconfined aquifers. Please have a look at: th-cam.com/video/-tsLFsz-Ncs/w-d-xo.html th-cam.com/video/zVIHbhhR9-M/w-d-xo.html All the best, Andreas
@@GeosearchInternational @Geosearch International Thank you for your response! However I'm still stumped bc the well is unconfined and non steady state but we're expected to make drawdown curve. There are no tutorials on the newman method on the internet. Is it similar to this approach? I appreciate your help!
Hi Migelle, For unconfined, non-steady state pumping tests you can use the Neuman method, or to start with just use the Cooper-Jacob straight line method. After the early data, you will see a flattering of the curve (delayed yield) and then it should go down again. Just put a straight line through this late data. For the Cooper-Jacob video see: th-cam.com/video/4pU336P_TX4/w-d-xo.html If you want to try the Neuman method, please have a look at the Excel tool by @Carlos Molano: th-cam.com/video/oFwnragYCss/w-d-xo.html All the best, Andreas
The Theis equation is for non-steady state groundwater flow in a confined aquifer. It means that groundwater is still coming out of storage and water levels have not reached equilibrium. The Thiem equation is for steady state groundwater flow in a confined aquifer. It means that the water levels have reached equilibrium & no water is taken out of storage. As it costs a lot of money to reach steady state, most pumping tests are analysed using Theis equation or equations based on Theis, such as the Cooper-Jacob straight line method. We would use Thiem to estimate long term inflows into excavations/mines. All the best, Andreas
Thanks for amazing teaching, Can we apply these & other conventional methods for recharge test ' where discharge to injected water and drawdown as draw rise????? any useful materials?
Hi Nahom, yes you can use the same techniques because injection is just like a (negative) pumping test. However, you should be aware that the aquifer transmissivities from injection tests are often only 50% of those calculated from the same well during a normal pumping test. I understand that it is probably due to aquifer clogging and entrainment of air bubbles. Have a look at this paper from Israel: www.mdpi.com/2073-4441/9/1/53/htm All the best, Andreas
@@GeosearchInternational Thanks , you are so generous to get your attention for my question , If you don't mind , is there any way to avoid disturbance of curve matching ,do we need like to change raw data like putting -ve ?
Hi Nahom, If you want to use the standard pumping test curves I guess you should just think of the rising water levels are drawdown - so just multiply by -1, so that they are positive numbers. All the best, Andreas
How are you sir, i am doing a self taught hydrogeology course, thanks very much for your video which is very clear, much appreciated. however I have a few questions. 1) I would love to know how best can I use the transmittivity and storativity data to size the pump that can be used to extract water from such a borehole? 2) is it always the case that whenever carying a borehole capacity test there should be an observation well? Thanks in advance sir.
Dear Dhuvayi, I'm happy that you like the video. I'm doing a couple of QGIS videos at the moment, but will come back to new pumping test videos soon. To answer your questions: 1) Transmissivity & Storativity is mostly used more for aquifer resources calculations, which includes modelling. For selecting a pump for a water well you need to look at the pumping (dynamic) water level and the pump discharge, as there can be high well losses especially in basement aquifers. If you do a 24h or 72h pumping test and the water levels are still declining you need to extrapolate that over the full length of the dry season so that you don't take a pump with a too high discharge. i.e. we need to look at projected pumping water levels & also do some sustainability calculations. I have Excel tools that do all this & will explain in future videos. As a rule of thumb it is best to take a pump which is about 70% of the maximum pumping test discharge. When you chose the pump, you should also consider head losses between the well and your water tank or wherever you will take the water to. There are many different pumps & they all have an optimum discharge-head relationship so you need to chose the correct one. 2) If we do a pumping test without an observation well, then we cannot calculate the Storativity of the aquifer. i.e. we can only estimate the Transmissivity. As observation wells are an additional cost, often they are not drilled and we need to guess the storativity. However, if you look around your project area, there could be existing wells which can be used for observation well data. All the best, Andreas
@@GeosearchInternational thank you very much sir for your crystal clear explanation, very insightful, I have downloaded excel sheets for both Cooper-Jacob Straight line method and Theis Method you posted on your videos, which I hope will be very useful for me in future. As for QGIS I have to follow as well as I'm a newbie to it, at college I learnt about ArcGIS.
You are welcome Dhuvayi! I also used ESRI software since 1999, but it is just too expensive, so I am now using QGIS which can do everything which I need. Also QGIS is much easier to learn. All the best, Andreas
Thanks Martin, the excel file is here: bit.ly/35sXDO5 I just tried it and it works. You will need to click on the download button (down arrow) on the top right of the screen to get the file from Google Drive. Then open in Excel & allow macros. All the best, Andreas
Hi Martin, For the pumping tests please have a look in the Hydrogeology 101 playlist. I have shared one on Theis and also the Cooper-Jacob straight line method. All the best, Andreas
You are welcome Abdikadir! All the links are in the description below the video. Link to Theis Macro-enabled Excel file: bit.ly/35sXDO5 You need to download it and then enable the macros when you open it in Excel. All the best, Andreas
Hi César, Glad you like the video. Here is the link to the Theis Macro-enabled Excel file: bit.ly/35sXDO5 You need to download it and then enable the macros when you open it in Excel. All the best, Andreas
@@GeosearchInternational Thank you very much Dr. Andreas, for the spreadsheet, it will be very useful for me to teach Theis equation to my undergraduate students. Regards from Chiriquí, Panamá.
You are most welcome. I made a Hydrogeology Toolbox many years ago - see www.geosearch.co.uk/resources/resources.htm - which I'm updating at the moment. So much can be done in Excel. Un saludo desde España, Andreas
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best video for S & T calculation through Theis method, i appreciate this and thanks to Mr Andreas
Thanks Samir!
You are by far the ever best tutor for concepts and analyses in hydrogeology. Another curious thing, you even bothered yourself teaching trick on excel where ppl might get stuck at the very beginning. What an approach of a great soul.
Thank you so much Sinana Yenigül! I really appreciate your kind words!!! All the best, Andreas
Thank you for all these videos!!! They’re absolutely wonderful at explaining the concepts clearly. A real lifesaver for me who’s a hydrology course this semester. It’s so much more fun watching these videos than reading a textbook
You're very welcome Ho Nga! Learning should be fun, and nowadays we have the technology to make it more interesting. However, I do hope that you still read your textbooks. All the best, Andreas
I needed a quick refresher on some hydrogeology concepts and this was incredibly helpful. Thank you for posting!
You're very welcome @cwood3988! All the best, Andreas
even tho, my english isnt that proper , i'd like to thank you for facilating your accent , because somehow i understood all of what u said , thank u sir and god bless
Happy to hear that Massin! You can always switch on the sub-titles if that helps. For this video currently available in English, French, Spanish, Arabic & Hindi.
احله شرح عاشت ايدك واضح جدا
شكرًا لك
Sir thank you very much.
Tomorrow is my exam and you have make my day by explaining in the simplest way.
The best video on you tube on this topic
You are most welcome & good luck with your exam!!!
All the best, Andreas
Sir! I have to say that your friendly voice and detail instruction make me feel so comfortable to learn the lesson. Thank you very much and I feel so lucky knowing about this useful video. Wish you all the best!
Thanks so much for your kind words! All the best, Andreas
Fantastically simple explanation of an otherwise complex topic, well done !!!
Glad you liked it Andres! All the best, Andreas
Me ayudo bastante. Gracias
de nada Mario! Un saludo, Andreas
Great presentation.
Thanks! All the best, Andreas
The way you teach is so good 🙏🏼😊
Thanks so much! Glad you enjoy it. All the best, Andreas
This is a hard work to convey aquifer test analysis...
Thanks a lot..
It's my pleasure Kaleem! All the best, Andreas
Very useful to finish my assignment :) Thanks for the lecture and files 😀
You are welcome! All the best, Andreas
This has been such a lifesaver, and helped me in a really intense (and open book) exam, thanks so much!
You're very welcome Toby! All the best, Andreas
Have u done it how much did you get?
@@Mahougnon I'm still doing it actually! But I can tell you when I get my results back if you wish ☺️
How do u plot the t/r2. It is against which value
Me too I'm still doing
Great, thank for make ez the work of my professor, please create more similar videos.😃
Hi Jesús, I would love to make more videos but I'm too busy at the moment with project work. All the best, Andreas
Thank you so much for All this exzellent content!
You are most welcome Tom! All the best, Andreas
thank you so much siir , can you tell me in 9:25 what is the value of E in (6.2E-0.4/1.440) please !
Hi Hayat, it is just scientific notation, so 6.2e-4 in decimal form = 0.00062
All the best, Andreas
Thank you sir
Welcome! All the best, Andreas
I am interested in using Theis equation to estimate Transmissivity (T) and Storativity (S) for a single well but there is no observation well. Measurement of draw down and recovery data is available for borehole well used by community. Your guidance is welcome
Hi Joachim, as a rule of thumb you can only estimate Transmissivity from a pumping well. This is because it is very difficult to accurately correct for well losses and also well storage effects. I would not trust any storativity value calculated from a pumping well. All the best, Andreas
good explaine _think you
Welcome Jovi! All the best, Andreas
Your presentation is very helpful up to now sir. Thank you for making this video. I have some concerns or problem on how to interpret the table of values of Kruseman & de Ribber. I hope you can make a separate tutorial on this. Thanks a lot .
@abengineeral Thank you for your kind words.
I assume that you are referring to the table in Annex 3.1 Values of the Theis well function W(u) for confined aquifers (after Walton 1962)? The values in this table are used to draw the type curves where you plot 1/u on the x-axis versus W(u) on the y-axis using log-log paper. Then you need to plot your water level drawdowns also on log-log paper and try to get a fit with the type curves, as I showed early in the video.
This is a good training exercise for new hydrogeology students, but it takes time. We can use digital alternatives to do the same thing. Carlos Molano has a nice tool to do this - see his video: th-cam.com/video/iNhwT2yXlNA/w-d-xo.html
My approach is slightly different. You select the Transmissivity and Storativity values for your aquifer using the sliders, and then the theoretical drawdown curve is calculated in the background using VBA. Once you have the best fit, you can use these T & S values for the pumping test. Note that you need observation well data to estimate Storativity and Transmissivity. If you only have pumping test data you can get the Transmissivity, but not the Storativity.
Note that the VBA code locked, as I don't want people to edit the code and get the wrong answers. All the best, Andreas
Thank you! I’m getting #NAME errors in the excel workbook in columns E and F, do you happen to know why that might be?
The Theis curve is calculated using VBA. Have you allowed VBA in the Excel settings? All the best, Andreas
Great explanation on that Theis
Glad you liked it Michael! All the best, Andreas
How do you calculate "s" (drawdown) from Theis formula in excel sheet? Do you use any approximation or truncation from original infinite series?
Hi Guilherme, I found the code for the approximation of the Theis well function many years ago from a university course, but I have lost the source. Cannot find it on Google either so maybe it has been taken down. Anyway, please see VBA code below. All the best, Andreas
****************************************
Function Wu(u As Double) As Double
Dim a0 As Single, a1 As Single, a2 As Single, a3 As Single, a4 As Single, a5 As Single
Dim b1 As Single, b2 As Single, b3 As Single, b4 As Single
a0 = -0.5772156649
a1 = 0.99999193
a2 = -0.24991055
a3 = 0.05519968
a4 = -0.00976004
a5 = 0.00107857
b1 = 2.334733
b2 = 0.250621
b3 = 3.330657
b4 = 1.681534
If u < 1 Then
Dim t As Double
t = (a2 + (u * (a3 + (u * (a4 + (u * a5))))))
Wu = (-1 * Log(u)) + a0 + (u * (a1 + (u * t)))
Else
Wu = Exp(-u) / u * (u * u + b1 * u + b2) / (u * u + b3 * u + b4)
End If
End Function
@@GeosearchInternational I've found out the references of your VBA code couple days ago. The approximation comes from two works: (1) Hastings, C. Jr. 1955. Approximations for Digital Computers. Princeton University Press, Princeton, N.J. and (2) Allen, E. E. 1954. Analytical Approximations. Math. Tables Aids Comp., 8(48), 240-241. These references are quite hard to find online because they are a little bit old papers, but you can reach the same coefficients you used on excel sheets to the same range of u values.
Hi Guilherme, thanks so much for solving this mystery! All the best, Andreas
Thank you! For the excel workbook, I keep getting errors in the "s calc" and "error [m'" columns, with "#NAME?" appearing, do you happen to know why that might be? My theis curve isn't showing up on the graph either. Thanks!
#NAME? error appears when a formula or function cannot find the referenced data it needs to complete the calculation. Make sure that you add all the required data in the green cells. All the best, Andreas
Yes sir thanks for your kind message sent to me. I want an excel sheet regarding pumping well test analysis. not in an observation well.
Hi Chinthaka, you can use this Theis tool to estimate the Transmissivity of the aquifer. Just use the radius of the well as R. However, note that Storativity can only be calculated from observation well data. Have a look also at the Cooper-Jacob straight line method which has other advantages like being able to see aquifer boundaries. Here is the link:
th-cam.com/channels/vnRoF32DJNLtNb-PGqEwjQ.html All the best, Andreas
Dear Mr Andreas could you send me this excell sheet for calculation S and T for pumping well
Hi Chinthaka, if you look in the description below any of my videos you will find links to relevant documents and any excel tools which I use in the video.
Link to Theis Macro-enabled Excel file: bit.ly/35sXDO5
You need to download it and then enable the macros when you open it in Excel. Link to the Theis (1935) paper: water.usgs.gov/ogw/pubs/Theis-1935.pdf All the best, Andreas
Really good. Thank you so much
Most welcome Matheus! All the best, Andreas
please which software did you use
Hi Ibrahim, the presentation is PowerPoint and the Excel tool uses VBA to calculate the Theis curve. All the best, Andreas
I can't figure out how i can adjust the storativity and transitivity
Transmissivity and Storativity are calculated by Excel. You need to put in the data & fit it to the Theis curve as shown in the video: th-cam.com/video/YMcRRIe4iAg/w-d-xo.html
Good luck & all the best, Andreas
@@GeosearchInternational i have the same problem. I keep getting errors in the "s calc" and "error [m'" columns, with "#NAME?" appearing,
Hi Rudy, Assuming that you have enabled Macros in your Excel security settings, see if the original file works as I have shown in the video. If you put your own data in, make sure that all the GREEN cells have values. All the best, Andreas
What is 'u'?
u = r^2 S/4Tt, where r is the distance to the pumping well, S is storativity, T is transmissivity and t is the time since pumping began. If you want to dig into the maths behind it you should read the original paper by CV Theis (1935). You can find it here: water.usgs.gov/ogw/pubs/Theis-1935.pdf All the best, Andreas
Hello please for Theis - recovery test I did not see any video about it could show video similary to this test ?
Hi Mohammad, I will make a video on recovery analysis soon. All the best, Andreas
Sorry, I'm doing some videos on resistivity surveys at the moment. Please have a look at Kruseman & de Ridder in the meantime: www.hydrology.nl/images/docs/dutch/key/Kruseman_and_De_Ridder_2000.pdf
Welcome! All the best, Andreas
Thank you very much for video! I have a little question about Euler's constant (2:50). It looks like a variable for integral rather than constant.
Hi Oleg, have a look at the original Theis (1935) paper: water.usgs.gov/ogw/pubs/Theis-1935.pdf All the best, Andreas
Hi Andreas, I was just wondering about the basic question which is how to initially decide which aquifer is of which type? After this answer, we can apply specific well-pumping data analysis methods. Please answer and if possible make a video on this very basic question from Hydrogeologists. Thanks a lot
That is an important question & you are right it would make a nice short video. What type of aquifer it is (confined, leaky-confined, unconfined) can be guessed during the desk study. You will need to figure out the geological units and how the water levels in existing boreholes relate to them. If the static water level is within an aquifer, it is probably unconfined. If it is above the top surface of the aquifer, it is definitively confined but if it is leaky-confined or not depends on the permeability of the confining layer and if there is a source of water above it. Once we drill we can see what the water level does once we have drilled through the aquifer, to confirm the type. Be careful though in fracture aquifers as mostly we want to intersect the fracture at depth, so the water strike is usually well below the final static water level. It does not mean that it is confined.
The final proof is the pumping test. If you only have one pumping well you should be able to tell from the shape of the drawdown curve what you are dealing with. e.g. in unconfined aquifers we should get delayed yield - a flat period in the middle of the test when the drawdown almost stabilises. However, it is best to have at at least one observation well so you can calculate the storativity. All the best, Andreas
@@GeosearchInternational Thanks Andreas for the explained reply. If you find time and ready to work on next video(s) then please explain this in your typical style as it will make things very easy and self explainatoy. It would be of help for me and many others. All the best!
thanks for this!
You are welcome Duncan! All the best, Andreas
is there any way we can get the password for unlocking the file????
You can unlock all the sheets and change the contents as you wish. It is not protected. The VBA code is locked, because any changes there will make the Theis calculations invalid. All the best, Andreas
Please who developed the excel for the theis method you are using?
Hi Michael, The design layout was inspired by an Excel tool from Carlos Molano (th-cam.com/video/iNhwT2yXlNA/w-d-xo.html), but the methodology is different. My tool does not move the data to fit on the Theis curve. It calculates the Theis curve based on the T & S entered by the user. The calculations are made by some VBA code in the background. All the best, Andreas
best explained
Hope it was useful
Can you use this equation to make a drawdown curve under steady state conditions
Hi Migelle, The Theis equation is for non-steady state conditions only. For steady state we use the Thiem equation for confined aquifers and the Dupuit-Forchheimer equation for unconfined aquifers. Please have a look at:
th-cam.com/video/-tsLFsz-Ncs/w-d-xo.html
th-cam.com/video/zVIHbhhR9-M/w-d-xo.html
All the best, Andreas
@@GeosearchInternational @Geosearch International Thank you for your response! However I'm still stumped bc the well is unconfined and non steady state but we're expected to make drawdown curve. There are no tutorials on the newman method on the internet. Is it similar to this approach? I appreciate your help!
Hi Migelle,
For unconfined, non-steady state pumping tests you can use the Neuman method, or to start with just use the Cooper-Jacob straight line method. After the early data, you will see a flattering of the curve (delayed yield) and then it should go down again. Just put a straight line through this late data. For the Cooper-Jacob video see: th-cam.com/video/4pU336P_TX4/w-d-xo.html
If you want to try the Neuman method, please have a look at the Excel tool by @Carlos Molano: th-cam.com/video/oFwnragYCss/w-d-xo.html
All the best, Andreas
thank you
You're welcome!
What is the differences between Theis method ans Thiem method ?
The Theis equation is for non-steady state groundwater flow in a confined aquifer. It means that groundwater is still coming out of storage and water levels have not reached equilibrium.
The Thiem equation is for steady state groundwater flow in a confined aquifer. It means that the water levels have reached equilibrium & no water is taken out of storage.
As it costs a lot of money to reach steady state, most pumping tests are analysed using Theis equation or equations based on Theis, such as the Cooper-Jacob straight line method.
We would use Thiem to estimate long term inflows into excavations/mines.
All the best, Andreas
very nice video
Thanks Ketan! All the best, Andreas
Thanks for amazing teaching, Can we apply these & other conventional methods for recharge test ' where discharge to injected water and drawdown as draw rise????? any useful materials?
Hi Nahom, yes you can use the same techniques because injection is just like a (negative) pumping test. However, you should be aware that the aquifer transmissivities from injection tests are often only 50% of those calculated from the same well during a normal pumping test. I understand that it is probably due to aquifer clogging and entrainment of air bubbles. Have a look at this paper from Israel: www.mdpi.com/2073-4441/9/1/53/htm All the best, Andreas
@@GeosearchInternational Thanks , you are so generous to get your attention for my question , If you don't mind , is there any way to avoid disturbance of curve matching ,do we need like to change raw data like putting -ve ?
Hi Nahom, If you want to use the standard pumping test curves I guess you should just think of the rising water levels are drawdown - so just multiply by -1, so that they are positive numbers. All the best, Andreas
How are you sir, i am doing a self taught hydrogeology course, thanks very much for your video which is very clear, much appreciated. however I have a few questions.
1) I would love to know how best can I use the transmittivity and storativity data to size the pump that can be used to extract water from such a borehole?
2) is it always the case that whenever carying a borehole capacity test there should be an observation well?
Thanks in advance sir.
Dear Dhuvayi, I'm happy that you like the video. I'm doing a couple of QGIS videos at the moment, but will come back to new pumping test videos soon. To answer your questions:
1) Transmissivity & Storativity is mostly used more for aquifer resources calculations, which includes modelling. For selecting a pump for a water well you need to look at the pumping (dynamic) water level and the pump discharge, as there can be high well losses especially in basement aquifers. If you do a 24h or 72h pumping test and the water levels are still declining you need to extrapolate that over the full length of the dry season so that you don't take a pump with a too high discharge. i.e. we need to look at projected pumping water levels & also do some sustainability calculations. I have Excel tools that do all this & will explain in future videos. As a rule of thumb it is best to take a pump which is about 70% of the maximum pumping test discharge. When you chose the pump, you should also consider head losses between the well and your water tank or wherever you will take the water to. There are many different pumps & they all have an optimum discharge-head relationship so you need to chose the correct one.
2) If we do a pumping test without an observation well, then we cannot calculate the Storativity of the aquifer. i.e. we can only estimate the Transmissivity. As observation wells are an additional cost, often they are not drilled and we need to guess the storativity. However, if you look around your project area, there could be existing wells which can be used for observation well data.
All the best, Andreas
@@GeosearchInternational thank you very much sir for your crystal clear explanation, very insightful, I have downloaded excel sheets for both Cooper-Jacob Straight line method and Theis Method you posted on your videos, which I hope will be very useful for me in future. As for QGIS I have to follow as well as I'm a newbie to it, at college I learnt about ArcGIS.
You are welcome Dhuvayi! I also used ESRI software since 1999, but it is just too expensive, so I am now using QGIS which can do everything which I need. Also QGIS is much easier to learn. All the best, Andreas
Hello, can you reaupload your excel file? Link already doesnt work...excelent presentation! Thanks
Thanks Martin, the excel file is here: bit.ly/35sXDO5
I just tried it and it works. You will need to click on the download button (down arrow) on the top right of the screen to get the file from Google Drive. Then open in Excel & allow macros. All the best, Andreas
Thank you, got it! May I ask you one more question - does also exist spreadsheet for pumping well analysis?
Hi Martin, For the pumping tests please have a look in the Hydrogeology 101 playlist. I have shared one on Theis and also the Cooper-Jacob straight line method. All the best, Andreas
thx a lot
You're welcome!
Well understood! Thanks to @Geosearch International. May I get please where I can get the excel - may links.
You are welcome Abdikadir! All the links are in the description below the video.
Link to Theis Macro-enabled Excel file: bit.ly/35sXDO5
You need to download it and then enable the macros when you open it in Excel. All the best, Andreas
big big big big likeeeeee
Thank you! All the best, Andreas
@@GeosearchInternational
I have exam and your video was very helpful, it maks the concept clear for me
You are welcome! All the best, Andreas
Where can I download the spreadsheet! Great video.
Hi César, Glad you like the video. Here is the link to the Theis Macro-enabled Excel file: bit.ly/35sXDO5
You need to download it and then enable the macros when you open it in Excel. All the best, Andreas
@@GeosearchInternational Thank you very much Dr. Andreas, for the spreadsheet, it will be very useful for me to teach Theis equation to my undergraduate students. Regards from Chiriquí, Panamá.
You are most welcome. I made a Hydrogeology Toolbox many years ago - see www.geosearch.co.uk/resources/resources.htm - which I'm updating at the moment. So much can be done in Excel. Un saludo desde España, Andreas
Thanks for the great video and files :)
Is there any video that explain about step drawdown test?
No, sorry Wijayanti, though it is planned. All the best, Andreas
@@GeosearchInternational thank you for the reply 🙏
Welcome, All the best, Andreas
COOOOL
Welcome!
ياريت لو تترجم جميع فديواتك للعربي
I will try to see if it possible to translate the subtitles. All the best, Andreas
هل يمكنك إلقاء نظرة على الترجمة باللغة العربية وإخباري إذا كانت الترجمة صحيحة؟ يمكنك اختيار اللغة في الإعدادات - وهذا هو الرمز الذي يشبه الترس.
نعم جدا واضحه وصحيحه @@GeosearchInternational
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