Eagerly waiting for the next video. Sir, these videos help me clarify my concepts. Your explanations and spot-on 3-D diagrams make me understand each concept easily. Keep uploading, sir, and I would like to know if there is another way to learn more from you, like paid courses. 2:54
Hi Maddy, Thanks for your kind words. At the moment I have not started any official courses yet as am very busy as a consultant on several projects in Asia. All the best from Tajikistan, Andreas
Hi Don, yes it is possible to use it with pumping well data & you use the borehole radius as "r". However, you should ignore any storativity values calculated in this way. For that you need observation well data. All the best, Andreas
Can I plot superposition of q_0 + q_well in order to find the distance of the 50 day line ragarding traveltime. I did this in an confined aquifer. But I don't know if I can use the same matlab script for unconfined aquifer.
Hi Tom, sorry I cannot advise you as I don't know the method or the equation which you are using. In any case you need to be very careful with the main input parameters T, K, i, effective porosity, presence of other wells, boundary conditions etc. All the best, Andreas
Thank you for your reply. I solved the equation analytically. It turned out that dupuit-thiem for confined is also for phreatic aquifer if the drawdown is beding corrected by Jacob 1963 equation since it uses the piezometric height relatively to the distance R and und constant pumping well discharge. It follows the law from Darcy. The analytical integral relstes therefore only for the radius. All the rest ist a constant value. The radius is replaced by x and y cartesian system using the Pythagoras and the rule for the rectangular triangle relationship of the intercept theorem.replacing the r the formula can be used for x and y as distance to the well. The integral of derived function leads to the traveltime formula along the center line to the well. tau=-x-ln(1-x) using this formula along the axis includes the downstream speed of the ambiant groundflow as a superposition with the velocity induced by the well pumping rate. This formula gives the information at which point the particle along the y achses and about the traveltime. With this the d50 line can be calculated. Its valid for confined aquifer. But also in phreatic aquifer as long as jacob 1963 drawdown correction is applied. I finished the program with matlab and i wrote the analytical induction that the approach is legitimate. If Ur interested id send you the script and the solution. This is probably the analytical and numerical core of modflow except that modflow uses more information input. But still the derivation of the above formula is the heart piece of any hydrological approach for the traveltime
Hi Tom, you should double check your output with a numerical model just to be sure. It’s so easy to make programming errors. Here is a good overview of different methods for capture zone delineation: www.envirolink.govt.nz/assets/Envirolink/R6-2-Capture-Zone-Delineation-Technical-Report.pdf all the best, Andreas
Hi Assia, if your observation well is close to the pumping well you will need to correct the observed drawdown data for partial penetration effects. However, I would always do the first interpretation without any corrections & then compare later. You can find more details on partial penetration corrections here: www2.alterra.wur.nl/Internet/webdocs/ilri-publicaties/publicaties/Pub47/Pub47-h10.pdf All the best, Andreas
