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RE: [gwmodel] Modeling Nile Valley Aquifer

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  • Herath, Sudath
    Ashraf, I have experience in salinity control by means of reducing groundwater levels. What we are doing here in Victoria, Australia, is consider suitable
    Message 1 of 7 , Sep 30, 2001
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      Ashraf,

      I have experience in salinity control by means of reducing groundwater
      levels. What we are doing here in Victoria, Australia, is consider suitable
      groundwater pumps to control water levels. However, we recommend sub-surface
      drains only when there are no suitable aquifers available for pumping. This
      is mainly due to high costs associated with subsurface drains compared to
      groundwater pumps.

      I think, if you have 2 different distinct layers no harm using 2 layer model
      with different hydraulic conductivities, but careful about any anisotropy of
      the layers. However, if you are going to adopt groundwater pumps ,2D slice
      model may not be appropriate.

      Good luck with your project.

      Sudath Herath
      Goulburn-Murray Water Authority, Australia
      sudathh@...

      > -----Original Message-----
      > From: ashraf ghanem [SMTP:ghanem_ashraf@...]
      > Sent: Saturday, 29 September 2001 4:32 pm
      > To: gwmodel@yahoogroups.com
      > Subject: [gwmodel] Modeling Nile Valley Aquifer
      >
      > Dear colleagues,
      >
      > I want to model the Nile Valley aquifer in Upper Egypt with the purpose of
      >
      > suggesting solutions to lower the groundwater table in a City.
      > The study area is about 1 X 4 km, adjacent to the Nile.
      >
      > Field investigations showed that the main source for rise of groundwater
      > is
      > a canal running parallel to the Nile at about 1 km distance.
      >
      > The aquifer is composed of a silty-clay layer about 5 - 8 meters thick,
      > underlain by a sand aquifer, about 100m thick. The canal is about 3m
      > deep,
      > i.e. completely contained in the upper silty-clay layer.
      >
      > One solution I am thinking of is constructing a covered drain parallel to
      > the canal.
      >
      > Question
      >
      > Would a 2D two-layer aquifer be adequate? What would be the best way to
      > represent interaction between the upper and lower layer in this case(i.e.
      > thickness of 'leaky layer')?
      >
      > Sorry for the sort of long message, and thanks for any suggestions.
      >
      > Ashraf Ghanem,
      > Irrigation and Hydraulics Dept.
      > Cairo University
      >
      >
      > _________________________________________________________________
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      >
    • George Matanga
      Ashraf, I think you would get realistic results by using a 3D integrated surface and subsurface water model. The key point is how the two regimes are
      Message 2 of 7 , Oct 1, 2001
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        Ashraf,

        I think you would get realistic results by using a 3D integrated surface and subsurface water model. The key point is how the two regimes are integrated ( need fully coupled model). VanderKwaak and Sudicky (contact Professor Edward Sudicky) of Department of Earth Sciences at University of Waterloo in Canada have developed a 3D fully coupled model based on the control-volume finite element method. Dr Peter Huyakorn of HydroGeologic has also developed MOD-HMS based on MODFLOW. For subsurface, these models have capability to handle variably saturated flow and easily couple flow in the various geological layers. The website for HydrGeoloic is www.hdl.com. Attached is an abstract of a paper in which VanderKwaak and Sudicky model is described.

        George.

        --------------------------------------------------
        George B. Matanga Ph.D., P.E.
        Hydraulic Engineer
        U.S. Bureau of Reclamation, MP700
        2800 Cottage Way
        Sacramento, CA 95825

        Phone: (916) 978-5084
        Fax: (916) 978-5094
        e-mail: gmatanga@...

        >>> ghanem_ashraf@... 09/28/01 11:32PM >>>
        Dear colleagues,

        I want to model the Nile Valley aquifer in Upper Egypt with the purpose of
        suggesting solutions to lower the groundwater table in a City.
        The study area is about 1 X 4 km, adjacent to the Nile.

        Field investigations showed that the main source for rise of groundwater is
        a canal running parallel to the Nile at about 1 km distance.

        The aquifer is composed of a silty-clay layer about 5 - 8 meters thick,
        underlain by a sand aquifer, about 100m thick. The canal is about 3m deep,
        i.e. completely contained in the upper silty-clay layer.

        One solution I am thinking of is constructing a covered drain parallel to
        the canal.

        Question

        Would a 2D two-layer aquifer be adequate? What would be the best way to
        represent interaction between the upper and lower layer in this case(i.e.
        thickness of 'leaky layer')?

        Sorry for the sort of long message, and thanks for any suggestions.

        Ashraf Ghanem,
        Irrigation and Hydraulics Dept.
        Cairo University


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      • Zawadzki, Willy
        Ashraf, One thing that puzzles me in the description of your problem is that the canal is completely contained in the upper silty-clay layer . I have
        Message 3 of 7 , Oct 1, 2001
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          Ashraf,

          One thing that puzzles me in the description of your problem is that the
          canal is "completely contained in the upper silty-clay layer". I have
          difficulty understanding how leakage from the canal can significantly
          influence hydraulic head in the aquifer. From your description the aquifer
          is composed of sand and it is quite thick (100 m), indicating relatively
          high transmissivity. In that case leakage from the canal through silt-clay
          may not have significant impact on the hydraulic heads in the aquifer.
          Before your modeling exercise it would be useful to revisit the conceptual
          model and examine alternative reasons for the water table rise. Maybe there
          are holes in the silt-clay layer under the canal or another source of water
          to the aquifer?

          As for the modeling exercise, the trickiest part will be incorporating
          leakage from the canal in your model. Here you will likely have to use
          head-dependent boundary (river module) with conductance calculated based on
          properties of clay-silt layer and canal geometry. However, without field
          measurements of leakage this approach may not produce meaningful results.

          Once way to get around this it to measure leakage in the field and then
          compare field data with leakage calculated by the model. You can measure
          leakage from the canal using seepage meters. These can be build in a few
          minutes using plastic bucket, rubber stopper, piece of plastic tubing, and a
          plastic bag. I can sent you a reference on seepage meters -- please contact
          me directly at wzawadzki@.... Once you have field measurements of
          leakage you can also verify if the conceptual model is correct or not.

          Good luck,

          Willy

          --------------------------------------------------------
          Willy Zawadzki, M.Sc., CGWP, P.Geo.
          Hydrogeologist
          Golder Associates Ltd.
          web: www.golder.com
          mail: wzawadzki@...

          STANDARD DISCLAIMERS







          -----Original Message-----
          From: ashraf ghanem [mailto:ghanem_ashraf@...]
          Sent: Friday, September 28, 2001 11:32 PM
          To: gwmodel@yahoogroups.com
          Subject: [gwmodel] Modeling Nile Valley Aquifer


          Dear colleagues,

          I want to model the Nile Valley aquifer in Upper Egypt with the purpose of
          suggesting solutions to lower the groundwater table in a City.
          The study area is about 1 X 4 km, adjacent to the Nile.

          Field investigations showed that the main source for rise of groundwater is
          a canal running parallel to the Nile at about 1 km distance.

          The aquifer is composed of a silty-clay layer about 5 - 8 meters thick,
          underlain by a sand aquifer, about 100m thick. The canal is about 3m deep,
          i.e. completely contained in the upper silty-clay layer.

          One solution I am thinking of is constructing a covered drain parallel to
          the canal.

          Question

          Would a 2D two-layer aquifer be adequate? What would be the best way to
          represent interaction between the upper and lower layer in this case(i.e.
          thickness of 'leaky layer')?

          Sorry for the sort of long message, and thanks for any suggestions.

          Ashraf Ghanem,
          Irrigation and Hydraulics Dept.
          Cairo University


          _________________________________________________________________
          Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp



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        • Alsawaf, Daoud
          AsSalamuAlaikum: I think you need to check GW-Quality in both and consider the seasonal pressure in the deeper sand aquifer. If it is under pressure, your
          Message 4 of 7 , Oct 1, 2001
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            AsSalamuAlaikum: I think you need to check GW-Quality in both and consider
            the seasonal pressure in the deeper sand aquifer. If it is under pressure,
            your upper leaky aquiclude/aquifuge may be receiving its water flow below in
            the high water-season. You may end up running a trancient model in which
            the channal/river is loosing in some seasons and gaining in others. Let me
            know you progress. fakhri Daoud Alsawaf

            -----Original Message-----
            From: ashraf ghanem [mailto:ghanem_ashraf@...]
            Sent: Friday, September 28, 2001 11:32 PM
            To: gwmodel@yahoogroups.com
            Subject: [gwmodel] Modeling Nile Valley Aquifer


            Dear colleagues,

            I want to model the Nile Valley aquifer in Upper Egypt with the purpose of
            suggesting solutions to lower the groundwater table in a City.
            The study area is about 1 X 4 km, adjacent to the Nile.

            Field investigations showed that the main source for rise of groundwater is
            a canal running parallel to the Nile at about 1 km distance.

            The aquifer is composed of a silty-clay layer about 5 - 8 meters thick,
            underlain by a sand aquifer, about 100m thick. The canal is about 3m deep,
            i.e. completely contained in the upper silty-clay layer.

            One solution I am thinking of is constructing a covered drain parallel to
            the canal.

            Question

            Would a 2D two-layer aquifer be adequate? What would be the best way to
            represent interaction between the upper and lower layer in this case(i.e.
            thickness of 'leaky layer')?

            Sorry for the sort of long message, and thanks for any suggestions.

            Ashraf Ghanem,
            Irrigation and Hydraulics Dept.
            Cairo University


            _________________________________________________________________
            Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp



            To unsubscribe from this group, send an email to:
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          • ashraf ghanem
            Willy, Thank you for your informative message. In Egypt we have irrigated agriculture throughout the year. Water levels in canals are virtually constant
            Message 5 of 7 , Oct 3, 2001
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              Willy,

              Thank you for your informative message.
              In Egypt we have irrigated agriculture throughout the year. Water levels in
              canals are virtually constant throughout the year, i.e. we have a close to
              steady-state condition. Perhaps therefore a partially penetrating canal
              might eventually significantly affect the head in the lower layer??? I am
              not sure, but this is my interpretation.
              I would be greatful for any info on seepage meeters, as it will be very
              useful for this as well as another project I am working on, in which we want
              to test a newly lined canal.

              Best regards,

              Ashraf

              >From: "Zawadzki, Willy" <wzawadzki@...>
              >Reply-To: gwmodel@yahoogroups.com
              >To: "'gwmodel@yahoogroups.com'" <gwmodel@yahoogroups.com>
              >CC: 'ashraf ghanem' <ghanem_ashraf@...>
              >Subject: RE: [gwmodel] Modeling Nile Valley Aquifer
              >Date: Mon, 1 Oct 2001 09:29:02 -0600
              >
              >Ashraf,
              >
              >One thing that puzzles me in the description of your problem is that the
              >canal is "completely contained in the upper silty-clay layer". I have
              >difficulty understanding how leakage from the canal can significantly
              >influence hydraulic head in the aquifer. From your description the aquifer
              >is composed of sand and it is quite thick (100 m), indicating relatively
              >high transmissivity. In that case leakage from the canal through silt-clay
              >may not have significant impact on the hydraulic heads in the aquifer.
              >Before your modeling exercise it would be useful to revisit the conceptual
              >model and examine alternative reasons for the water table rise. Maybe
              >there
              >are holes in the silt-clay layer under the canal or another source of water
              >to the aquifer?
              >
              >As for the modeling exercise, the trickiest part will be incorporating
              >leakage from the canal in your model. Here you will likely have to use
              >head-dependent boundary (river module) with conductance calculated based on
              >properties of clay-silt layer and canal geometry. However, without field
              >measurements of leakage this approach may not produce meaningful results.
              >
              >Once way to get around this it to measure leakage in the field and then
              >compare field data with leakage calculated by the model. You can measure
              >leakage from the canal using seepage meters. These can be build in a few
              >minutes using plastic bucket, rubber stopper, piece of plastic tubing, and
              >a
              >plastic bag. I can sent you a reference on seepage meters -- please
              >contact
              >me directly at wzawadzki@.... Once you have field measurements of
              >leakage you can also verify if the conceptual model is correct or not.
              >
              >Good luck,
              >
              >Willy
              >
              >--------------------------------------------------------
              >Willy Zawadzki, M.Sc., CGWP, P.Geo.
              >Hydrogeologist
              >Golder Associates Ltd.
              >web: www.golder.com
              >mail: wzawadzki@...
              >
              >STANDARD DISCLAIMERS
              >
              >
              >
              >
              >
              >
              >
              >-----Original Message-----
              >From: ashraf ghanem [mailto:ghanem_ashraf@...]
              >Sent: Friday, September 28, 2001 11:32 PM
              >To: gwmodel@yahoogroups.com
              >Subject: [gwmodel] Modeling Nile Valley Aquifer
              >
              >
              >Dear colleagues,
              >
              >I want to model the Nile Valley aquifer in Upper Egypt with the purpose of
              >suggesting solutions to lower the groundwater table in a City.
              >The study area is about 1 X 4 km, adjacent to the Nile.
              >
              >Field investigations showed that the main source for rise of groundwater is
              >a canal running parallel to the Nile at about 1 km distance.
              >
              >The aquifer is composed of a silty-clay layer about 5 - 8 meters thick,
              >underlain by a sand aquifer, about 100m thick. The canal is about 3m deep,
              >i.e. completely contained in the upper silty-clay layer.
              >
              >One solution I am thinking of is constructing a covered drain parallel to
              >the canal.
              >
              >Question
              >
              >Would a 2D two-layer aquifer be adequate? What would be the best way to
              >represent interaction between the upper and lower layer in this case(i.e.
              >thickness of 'leaky layer')?
              >
              >Sorry for the sort of long message, and thanks for any suggestions.
              >
              >Ashraf Ghanem,
              >Irrigation and Hydraulics Dept.
              >Cairo University
              >
              >
              >_________________________________________________________________
              >Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp
              >
              >
              >
              >To unsubscribe from this group, send an email to:
              >gwmodel-unsubscribe@yahoogroups.com
              >
              >
              >
              >Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
              >


              _________________________________________________________________
              Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp
            • Zawadzki, Willy
              Ashraf, I already posted to the group references that I have on seepage meters. They are included below just in case you did not see my previous post. If you
              Message 6 of 7 , Oct 4, 2001
              • 0 Attachment
                Ashraf,

                I already posted to the group references that I have on seepage meters.
                They are included below just in case you did not see my previous post. If
                you can not get these papers in Egypt sent me your surface address and I
                will send you a copy.

                Willy

                Lee, D. R. 1977. A device for measuring seepage flux in lakes and estuaries.
                Limnol. Oceanogr. 22: 140-147.

                Lee, D. R., and J. A. Cherry. 1978. A field exercise on groundwater flow
                using seepage meters and mini-piezometers. Journal of Geological Education
                27: 6-10

                Shaw, R. D., and E. E. Prepas. 1990. Groundwater-lake interactions: I.
                accuracy of seepage meter estimates of lake seepage. Journal of Hydrology
                119: 105-120.

                --------------------------------------------------------
                Willy Zawadzki, M.Sc., CGWP, P.Geo.
                Hydrogeologist
                Golder Associates Ltd.
                web: www.golder.com
                mail: wzawadzki@...

                STANDARD DISCLAIMERS



                -----Original Message-----
                From: ashraf ghanem [mailto:ghanem_ashraf@...]
                Sent: Wednesday, October 03, 2001 10:52 PM
                To: gwmodel@yahoogroups.com
                Subject: RE: [gwmodel] Modeling Nile Valley Aquifer


                Willy,

                Thank you for your informative message.
                In Egypt we have irrigated agriculture throughout the year. Water levels in

                canals are virtually constant throughout the year, i.e. we have a close to
                steady-state condition. Perhaps therefore a partially penetrating canal
                might eventually significantly affect the head in the lower layer??? I am
                not sure, but this is my interpretation.
                I would be greatful for any info on seepage meeters, as it will be very
                useful for this as well as another project I am working on, in which we want

                to test a newly lined canal.

                Best regards,

                Ashraf

                >From: "Zawadzki, Willy" <wzawadzki@...>
                >Reply-To: gwmodel@yahoogroups.com
                >To: "'gwmodel@yahoogroups.com'" <gwmodel@yahoogroups.com>
                >CC: 'ashraf ghanem' <ghanem_ashraf@...>
                >Subject: RE: [gwmodel] Modeling Nile Valley Aquifer
                >Date: Mon, 1 Oct 2001 09:29:02 -0600
                >
                >Ashraf,
                >
                >One thing that puzzles me in the description of your problem is that the
                >canal is "completely contained in the upper silty-clay layer". I have
                >difficulty understanding how leakage from the canal can significantly
                >influence hydraulic head in the aquifer. From your description the aquifer
                >is composed of sand and it is quite thick (100 m), indicating relatively
                >high transmissivity. In that case leakage from the canal through silt-clay
                >may not have significant impact on the hydraulic heads in the aquifer.
                >Before your modeling exercise it would be useful to revisit the conceptual
                >model and examine alternative reasons for the water table rise. Maybe
                >there
                >are holes in the silt-clay layer under the canal or another source of water
                >to the aquifer?
                >
                >As for the modeling exercise, the trickiest part will be incorporating
                >leakage from the canal in your model. Here you will likely have to use
                >head-dependent boundary (river module) with conductance calculated based on
                >properties of clay-silt layer and canal geometry. However, without field
                >measurements of leakage this approach may not produce meaningful results.
                >
                >Once way to get around this it to measure leakage in the field and then
                >compare field data with leakage calculated by the model. You can measure
                >leakage from the canal using seepage meters. These can be build in a few
                >minutes using plastic bucket, rubber stopper, piece of plastic tubing, and
                >a
                >plastic bag. I can sent you a reference on seepage meters -- please
                >contact
                >me directly at wzawadzki@.... Once you have field measurements of
                >leakage you can also verify if the conceptual model is correct or not.
                >
                >Good luck,
                >
                >Willy
                >
                >--------------------------------------------------------
                >Willy Zawadzki, M.Sc., CGWP, P.Geo.
                >Hydrogeologist
                >Golder Associates Ltd.
                >web: www.golder.com
                >mail: wzawadzki@...
                >
                >STANDARD DISCLAIMERS
                >
                >
                >
                >
                >
                >
                >
                >-----Original Message-----
                >From: ashraf ghanem [mailto:ghanem_ashraf@...]
                >Sent: Friday, September 28, 2001 11:32 PM
                >To: gwmodel@yahoogroups.com
                >Subject: [gwmodel] Modeling Nile Valley Aquifer
                >
                >
                >Dear colleagues,
                >
                >I want to model the Nile Valley aquifer in Upper Egypt with the purpose of
                >suggesting solutions to lower the groundwater table in a City.
                >The study area is about 1 X 4 km, adjacent to the Nile.
                >
                >Field investigations showed that the main source for rise of groundwater is
                >a canal running parallel to the Nile at about 1 km distance.
                >
                >The aquifer is composed of a silty-clay layer about 5 - 8 meters thick,
                >underlain by a sand aquifer, about 100m thick. The canal is about 3m deep,
                >i.e. completely contained in the upper silty-clay layer.
                >
                >One solution I am thinking of is constructing a covered drain parallel to
                >the canal.
                >
                >Question
                >
                >Would a 2D two-layer aquifer be adequate? What would be the best way to
                >represent interaction between the upper and lower layer in this case(i.e.
                >thickness of 'leaky layer')?
                >
                >Sorry for the sort of long message, and thanks for any suggestions.
                >
                >Ashraf Ghanem,
                >Irrigation and Hydraulics Dept.
                >Cairo University
                >
                >
                >_________________________________________________________________
                >Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp
                >
                >
                >
                >To unsubscribe from this group, send an email to:
                >gwmodel-unsubscribe@yahoogroups.com
                >
                >
                >
                >Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
                >


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