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alexxander

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  1. Tprogs:lag distance X and Y

    Hello to everybody!! I am using T-PROGS to try to simulate a complicated geological situation within a context of outwash glacial deposit, with silt clay with intercalations of sand lenses. I have some boreholes with information but in some cases distance between wells for a valid correlation are too far (ca 500m) therefore i was advised to use T-PROGS which seems to be perfect for problems of horizontal correlation. main groundwater flow from N to south (Y+ to Y-), distance along the groundwater flow between wells is from 50m to 450m, but i am having some issues: 1- while deciding the lag distances (strike(x) Markov chain) i would like to know what could be useful to put as max lag distance?? because i have no way to see if the values i am using are valid or not, only until the end of the whole flow model of mod flow 2- in the same manner while putting the lag distance of Y (dip (y) Markov chain) can anyone shed some light here PLEASE 3- besides, while creating the grid and the successive T-PROGS for the unconfined aquifers i want to have different materials within the same layer is this possible with the HUF, to avoid dry cells. THANKS A LOT IN ADVANCE FOR YOUR COOPERATION AND REPLIES ALEXANDER
  2. Hello !!!!! I am making a simulation of a tracer test with three injection wells (north) and one pumping well (south). On the injection wells we have injected the salt and water for 16 hours and then successively water for two months. After 16 hours of injection (the initial concentration was 330g/l), we started to pump almost the same amount of water injected on the north on the same time span. we have found the Kx values that match the arrival times of the breakthrough curve at the observation points, according to the pathlines. The problem is that I am getting Nacl concentrations that are too high compared with the values I have measured (calculated from the electric conductivity at the observation point converted in Nacl concentration). The aquifer thickness is about 30 meters. My question is, according to the above mentioned; is there any way to reduce the concentration at the observation well (40 meters downgradient of the injection well). There should be no adsorption or other phenomena within the aquifer, or at least we expect that. The concentrations should be around 10mg/l, however, the concentrations I am getting are around 1800mg/L * could it be possible to use double density approach to solve that problem? * RT3D gave me better results than MT3D, setting in both cases NO reaction (tracer transport), but setting in the CHEMICAL REACTION PACKAGE A value for the Linear isotherm a first sorption value of 1e-3, could that value influence a lot? Thanks a lot for your reply and possible suggestions Alexxander
  3. transient transport

    i really like the tutorials of GMS, but you should put more information regarding the time steps for transport models. which is not very well explained if you want to decide the output time stes you should put in the column Max trans steps,( in the figure i used 120) and all the time i had a results of only 27 tstress periods, at least that numbre should be 400 or 500, in my case i have got a stress period each day, as i wanted, the model worked in maybe 30 minutes but the output times were as I wanted 120 , 1 every day to see the plume evolution once a day, dont forget to leave the column trans.step size =0 so mt3dms decides according to your output time
  4. transient transport

    Hello everybody I would like to know if there is a way to tell MT3D to pick up the same time steps i have in a transient flow model, i Have triend several options: * i have an injection occurring only during 2 days, and i want to see the behavior of that injection (Nacl) during 120 days within a field of injection and pumping wells * the transient model of flow has been calibrated for most of the time steps enclosed you can see the characteristics of the time steps at the end I get only 26 stress period in some case with many time steps (26 days) for the transport i dont understand why? though I need 120 day THANKS A LOT FOR YOUR HELP ALEXANDER
  5. How powerful is femwater?

    Hi Woodward, thanks a lot for your advice, then do you suggest to use FEFLOW instead, could be a most suitable for the problem i mentioned? the problem is the graphic possibilities offered by GMS are very nice and not included in feflow have a nice day fredy
  6. How powerful is femwater?

    Hello Everybody! I need some help, because I have to decide where to spend very well my money!! I want to know if the package FEMWATER would allows me to simulate finite elements: in areas with complicated geological conditions; in a coastal aquifers dealing also with transport of contaminants and MAINLY WITHOUT HAVING TO WORRY FOR A WATER TABLE NEAR THE SURFACE GOING DOWN BELOW THE 1ST LAYER , Do you suggest me to use FEMWATER, it is capable to do all this things as well as to simulate transport of contaminants? I REALLY LIKE THE CAPACITIES OF GMS FOR CONCEPTUALIZATION OF GROUNDWATER ISSUES, IT HAS BEEN VERY USEFUL THROUGHOUT MY ACADEMICAL CAREER, but now i need to work on a project where the geological conditions requires a detail in the upper layers, with pinch out towards the sea, near to a coastal area, with intercalations of clays and sand above a huge volcanic Unit. is there any limit of nodes or elements? have any of you used FEMWATER before for problems of contamination and sea water intrusion? thanks a lot IN ADVANCE FOR ALL YOUR SINCERE SUGGESTIONS, !!! fredy
  7. Hello to all, i have an issue with a TRANSIENT model that runs WITHOUT PROBLEMS IN MODFLOW for a problem of for years pumping and injecting water within a site. I am now using a STEADY FEMWATER model to simulate a complex stratigraphy present on the unsaturated aquifers that could influence some contamination present in the site due to the presence of clay lenses. The model is well defined the whole conceptual model followed according to the femwater tutorials, the only change is that I am defining the layers top and bottom from solids obtained from stratigraphic data, defining specific clay lenses top/bottom scattered within the site. WHEN I run the check femwater there are no errors, only some warnings regarding the fact that I have some injection wells with positive flow-rate and some areas with recharge equal to zero, the femwater start and then I got the message that I have to change the MAXNPK to 14842, I HAVE NO IDEA WHERE I CAN CHANGE THOSE SETTINGS, seems to be that this is the only issue avoiding my model to run ( i hope so!), does anybody could give a hint to fix this problem? . besides i would also accept other suggestions when using injection and pumping wells within a transient model (not this one but the one i want to set up after this steady-state converges) i REALLY would appreciate your help IN ADVANCE THANKS A LOT ALEXXANDER
  8. transient model MT3D

    hello Alan, thanks a lot for your tip, i'm trying without any success, i don't not why mt3d does not use the same time steps as in modlfow, instead generates me only few transport time steps ill be sending you today another question. thanks in advance for you help. alexander
  9. transient model MT3D

    Hey Alan, thanks a lot for your reply, i am still stuck with this mt3d problem, ill try to figure out in other way, if not ill come to you alexander
  10. transient model MT3D

    Hello everybody I'm trying to generate a transient MT3D model within a transient Modflow model, I am getting some troubles obtaining the transient time steps that i would like as same as of my transient flow time steps, i am using 48 time steps in my modflow model, but when I'm getting the results the MT3D gave me only 1 time step it is possible to calibrate this transport model somehow?, because i have no idea about the initial concentrations but i know the area where the contaminant comes from; i know only concentrations observed in some observation points, how could i approach this issue? Thanks a lot to whom would give me a light in this case. have a nice day alexander
  11. hello everybody I'm making a transient model for a contaminated area (North and south constant heads, west and east no flow boundary conditions, and flow direction from north to south). i have already a calibrated steady model with maximum differences between observed and calculated heads of about 66cm. in this area i have threee pumping wells that controlled mostly the groundwater behaviour. when i run the transient model it runs without any problem but the calibrations are not as satisfactory as in the steady state. what i would like yo ask you is how could i try to reppresent the constan variation of the water table if i have a fixed water table in the north and south for the whole time steps. Also i have fixed constant the recharge for all the time steps. K remain the same. when i see the results of my transient calibraion on the plot wizard for the time series, i can see that for all the observation wells that i have there is no variation on the head level. The head of any selected observeation well remains stable during all the time steps while the observed values and the calibrated vary. HOW can i constraint my model to represent THOSE UP AND DOWNS IN THE OBSERVED WATER TABLES? thanks a lot in advance for your reply. could be useful to use time varian specific heads for my initial conditions at north and south? ALEXANDER and keep saving water!
  12. seawater intrusion

    Hello everybody! I would like to know if someone have ever come across of modelling a coastal/gravelly-sand aquifer with initial conditions already with a saline intrusion. My problem is the following: **I have a coast where the groundwater levels near( the shoreline already present values around -5m a.s.l ** i have points where the observed groundwater table is 0m a.s.l at 3km away from the shoreline with that kind of data, which is quite disperse I would like to initialize my model in steady state, using those observation points As starting heads, but the results do not match the real conditions. does anyone have any idea how could I constraint my model to the above mentioned characteristics? thanks a lot in advance. Alexander
  13. solids modeling

    why dont you try to make from the limits in your boreholes simple tins and from those tins it is not so complicated to create solids, i did it also with complicated geological setings. also in that case you dont have to worry for the horizons that are quite time consuming if you have severals. i hope it will helps
  14. Hello tod@s I'm dealing with a tracer test with Nacl, and i got some values that i would like to use to calibrate my model. at some wells i have different concentrations at different times, in order to calibrate my model i would like to use those values to calibrate other parameters as Longitudinal dispersivity and maybe hydraulic conductivity (k), I am working in an area with gravels with several orders of K variation, which make the problem a bit complicated. Do you have any idea what would be the best way to proceed i though estimation parameters or transport observation points! thanks for your advice. Alexander
  15. 3D Grid

    hae you tried instead od 3d scatter points to use tin, convert all your scatter points and dont forget to give them an horizon ID and then you get it a 3d mesh
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