Dear Friend,

While climate change affects surface water resources directly through changes in
the major long-term climate variables such as air temperature, precipitation,
and evapotranspiration, the relationship between the changing climate variables
and groundwater is more complicated and poorly understood. The greater
variability in rainfall could mean more frequent and prolonged periods of high
or low groundwater levels, and saline intrusion in coastal aquifers due to sea
level rise.

Groundwater resources are related to climate change through the direct
interaction with surface water resources, such as lakes and rivers, and
indirectly through the recharge process. The direct effect of climate change on
groundwater resources depends upon the change in the volume and distribution of
groundwater recharge. Therefore, quantifying the impact of climate change on
groundwater resources requires not only reliable forecasting of changes in the
major climatic variables, but also accurate estimation of groundwater recharge.
Quantification of the groundwater recharge will help in taking appropriate
adaptation strategies due to the impact of climate change.

There have been many studies relating the effect of climate changes on surface
water bodies. However, very little research exists on the potential effects of
climate change on groundwater.  The scientific understanding of an aquifer's
response to climate change has been studied in several locations within the past
decade. These studies link atmospheric models to unsaturated soil models (such
as Visual HELP), which were further linked into a groundwater model (Modflow).
The groundwater models used were calibrated to current groundwater conditions
and stressed under different predicted climate change scenarios. The
HELP-MODFLOW approach proceeds in the following manner -

1. Synthetic generation of daily values of precipitation, mean temperature, and
solar radiation (using a weather generator) for projected climate change.

2. Estimation of groundwater recharge based on available precipitation and
temperature records and anticipated changes to these parameters (using Visual
HELP).

3. Quantification of the spatially distributed recharge rates using the climate
data and spatial soil survey data.

4. Simulation of groundwater flow using each recharge data set and evaluation of
the changes in groundwater flow and levels through time.

Regarding the above approach, I would like to know the views of learned members
on the following aspects -

(a) Which is the most appropriate method to downscale GCM outputs for a basin?

(b) If there are any flaws associated with HELP-MODFLOW methodology (described
above) mostly used by various researchers during last few years?

(c) If the runoff generation process (rainfall-runoff modelling) needs to be
essentially incorporated in the study?

(d) Whether instead of HELP, distributed unsaturated modelling (Richards
equation) should be done for climatic impact studies? What are the relative
advantages of using HELP (e.g. simplistic approach and ease of use) and
disadvantages of distributed modelling (e.g. extensive data requirement and
large computation resources) and vice versa?

(e) Whether any comprehensive overland-unsaturated-saturated model such as
MIKE-SHE can be used for studying the impact of climate change on groundwater
recharge? And relative advantages and disadvantages?

I look forward for the comments on above.

Regards
Kumar
================================================
C. P. KUMAR
Scientist 'E1'
National Institute of Hydrology
Jal Vigyan Bhawan
Roorkee - 247667 (Uttarakhand)
INDIA

Web Page : http://www.angelfire.com/nh/cpkumar/
================================================

Dear Deter,

You are perfectly right about the definition of the observation point,
however, the definition and selection of it may be further refined based on
type of contamination (e.g., DNAPL vs. LNAPL), screen length, vertical
gradient, sampling method, etc.

András



From: visual-modflow@...
[mailto:visual-modflow@...] On Behalf Of Dieter Plass
Sent: Thursday, February 12, 2009 9:00 AM
To: visual-modflow@...
Subject: [visual-modflow] Screen Elevation

Hi,

what exactly is the definition of a screen elevation of observation
wells in VisualModflow? I assume it's the midpoint between top and
bottom of the screened interval when measuring with a dipper? And it
could be the position of a pressure transducer when measuring water
levels by these means? And in concentration observation wells it should
be the elevation where the sampling pump intake was placed?

Dieter

Hi,

what exactly is the definition of a screen elevation of observation
wells in VisualModflow? I assume it's the midpoint between top and
bottom of the screened interval when measuring with a dipper? And it
could be the position of a pressure transducer when measuring water
levels by these means? And in concentration observation wells it should
be the elevation where the sampling pump intake was placed?

Dieter

http://www.swstechnology.com/software_product.php?ID=29

Visual MODFLOW

Visual MODFLOW is the industry standard in three-dimensional
groundwater flow and contaminant transport modeling software.

Visual MODFLOW's three-dimensional groundwater flow and contaminant
transport modeling capabilities are trusted and used by more
groundwater professionals than any other modeling software in the
world thanks to several seamlessly integrated numeric engines with an
easy-to-use graphical interface.

With the ability to simulate groundwater and surface water
interactions and the added capability of calculating changes to
groundwater chemistry, groundwater professionals now have a complete
set of tools necessary for addressing water quality, groundwater
supply, and source water protection initiatives.

Please contact Schlumberger Water Services at www.swstechnology.com to
buy this software.

Hi,

You don't need initial condition if you do a steady state simulation; in this
case you can apply an initial condition in order to minimize elaboration time.



-----Messaggio originale-----
Da: visual-modflow@...
[mailto:visual-modflow@...]Per conto di Water Talk
Inviato: mercoledì, 17. dicembre 2008 23:04
A: visual-modflow@...
Oggetto: [visual-modflow] initial conditions question

dear group,

started learning groundwater modeling. To begin modeling, I need initial
condition. I know the following:

- observation well data
- one river stage and bottom data taken at older date than the observed head
data

with measurements taken from different period (river information in 1998 and
observation head information is in 2004)

How can I use the initial conditions for a steady state simulation?

dear group,

started learning groundwater modeling. To begin modeling, I need initial
condition.  I know the following:

- observation well data
- one river stage and bottom data taken at older date than the observed head
data

with measurements taken from different period (river information in 1998 and
observation head information is in 2004)

How can I use the initial conditions for a steady state simulation?

Dear group members,

I am just starting to use MODFLOW and I am hoping to find some support
here, since I seem to run from one problem into the next, with what
seems quite basic. I am experiencing difficulties with importing
DXF-maps and JPG-maps alike. There are three problems:
1- converting shape-files into dxf-files.
2- JPG map is not visible
3- error message "worksheet exceeds base map"

1. For converting .shp-files into .dxf-files I used the DXFAuthor, a
free software offered by the state of Massachusetts. I have converted
line, polygon and point shape-files and the program always produces
the same output…the geometrical shape you choose in the third step of
the conversion. It is impossible NOT to choose a geometrical shape, or
at least I haven't found a way to do so. So when I import the dxf file
into MODFLOW I get a circle or square from what used to be groundwater
contour lines, the shape of a lake or wells.
Is there another software I can use to convert the shape files? Or
anything else I could try?

2. Then I tried importing a JPG map. The map shows up in the raster
graphics tab, I can set the geo reference points (not sure if I do
this right), but when I click o.k. it is nowhere to be seen. I have
already tried making the worksheet very large and very small to find
the missing map. No luck so far.

3. No matter what kind of map I try to import, I always get this error
message: "The extend of the worksheet (…coordinates of the worksheet…)
exceeds the georeferenced base map. The base map cannot be displayed.
Would you like to continue anyway?" When I press "Yes" I get the
circles and squares when the .dxf-maps are activated.
No matter what size the worksheet is, even when I make it really small
it gives me the same error message.

I greatly appreciate any advice!
Rike

Hi,

1.- That difference always occurs, but is very little (in my cases is
in the second decimal, with head ranging between 0 to 900 m.), so it
must be a software or cell inspector problem. A similar issue occurs
when you change the option to report the head of the dry cells as the
bottom of the cell, the cell inspector always report a value a little
higher than the cell bottom.

2.- Try changing the option of dry cells value to "cell bottom" in the
steady model. With this I solve the same problem you have.

Y. Yukishiro

--- In visual-modflow@..., "Amparo Edwards"
<aedwards@...> wrote:
>
> Hi,
>
> I am a civil engineer from Chile, I work in groundwater exploration.
>
> I have two doubts about Visual MODFLOW:
>
> 1.- I found a difference between the water level in a cell if I see
it from
> the cell inspector and from the data exportation (in a steady
model). Which
> of these is the real water level?
>
> 2.- When I run a model in the transient condition the water level in the
> initial time at a point is different from the level in the steady
condition
> (which was used as initial condition). Why?
>
> I hope someone can tell me something about the problems I am facing.
>
> Thanks!
>
> Amparo Edwards S.
> Ingeniero Civil Hidráulico U. de Chile
>

Hello everybody,

I would like to ask which is the better computer configuration to run
visual modflow as fast as possible. I'm actually working with a very
huge model (1008x588 cells, 100x100 m. each one, and 117.468 active
cells) and I curious if AMD CPU is better than Intel CPU for running
models. What I can say is that Intel Core2 duo CPU is faster than the
Pentium 4. The difference, comparing two of that CPU with the same
speed, range between 2 to 5 times, depending on the size of the model.
Has someone did a performance comparision between a Core2 duo CPU with
a Phenom or Athlon 64 CPU??

Thanks a lot!!!

Y. Yukishiro

Hello. I am designing a model in modflow (using pmwin) for a 1 layer
confined aquifer with known thickness and transmissivity, recharge and
evt. I have some borehole observations with piezometric levels and the
acuifer has relation with 5 stream-rivers crossing it and 2
reservoirs. i have flow level at different measuring stations at the
rivers and the water level at the reservoirs. Approximate bottom
elevation of rivers is also known. All the acuifer is head active, and
most of the rivers-reservoirs take water from the acuifer. I do not
understand how can i integrate my flow data for the rivers and water
levels in the model. Someone can give some advice?. Thanks in advance.

Hello. I´m new to this group and also pretty new to vmf. I have a
problem that I´m looking at and I feel I could use some guidance.

I´m planning to do a simulation of the groundwaterflow through an
area. The ground consists of three layers with different hydraulic
conductivity (decreasing towards the bottom).


In the end of my simulations I would like to know:

1) The groundwaterflow through the model, the flow in each layer.

2)How will the groundwatertable change if I excavate a ditch
prependicular to the groundwaterflow in the downstream parts of the
model. At wich distance from the ditch will the lowering of the
groundwatertable be close to zero.

I know the hydraulic conductivity of each layer, and I know the
different gradients in the area. I also now that the groundwatertable
is approx 0,4 m below the ground surface and I have elevation data för
each layer.

Is there any way that I could assign groundwater levels the same way
that i import ground surface elevation data?

My initial plan to solve this problem is as follows:
1) Set up the model for the case without the ditch, that means the
model consists of known groundwater surfaces, or if that is not
possible, two parallell lines with constant head. This will give me
the groundwaterflow using Zone budget?

2) Then I create a model for the case with the ditch. In this case i
enter the horisontal groundwaterflow calculated in 1) using a line of
injectionwells one one side of the model. In the other side of the
model I enter a drain.
How do I estimate the conductance per unit length for my drain? Is the
hydraulic conductivity of the material surrounding the ditch a good
estimation?


I hope that someone could give me some advice.
Best regards
/Thomas

Dear Dr. Srilert

Contaminant transport in hydrogeologic systems requires knowledge of
transmissivity, storage coefficient, and dispersivity. Techniques for
evaluating transmissivity and storage coefficient under field
conditions are well known. However, the evaluation of dispersivity
under field conditions is a costly and time consuming job.

You may look into the documentation of few contaminant transport
models for further details.

Regards
Kumar


--- In visual-modflow@..., Srilert Chotpantarat
<lertc77@...> wrote:
>
> Dear Dr.Kumar,
>
> I have visited your web site. I am interesting your works. Could
you please suggest me about simulate contaminants in field
condition ? Appreciated if you give me some details.
>
> Best regards,
>
> Srilert

Dear Dr.Kumar,

I have visited your web site. I am interesting your works. Could you please
suggest me about simulate contaminants in field condition ? Appreciated if you
give me some details.

Best regards,

Srilert


--- On Mon, 10/13/08, C. P. Kumar <cpkumar@...> wrote:
From: C. P. Kumar <cpkumar@...>
Subject: [visual-modflow] Studying the impact of artificial recharge and
rainwater harvesting structures
To: visual-modflow@...
Date: Monday, October 13, 2008, 11:33 PM


Good Day,

I invite suggestions from the learned members regarding most

appropriate methods to estimate groundwater recharge from artificial

recharge and rainwater harvesting structures (such as anicuts, field

bunds, gabions etc) in a hard rock area for studying their impacts on

groundwater resources. Whether any specific softwares are available

for such purpose?



Copies/links to any relevant literature (case studies/papers/ web

resources) or software will also be useful.



Thanks & Regards

Kumar

============ ========= ========= ========= =========

C. P. KUMAR

Scientist 'E1'

National Institute of Hydrology

Jal Vigyan Bhawan

Roorkee - 247667 (Uttarakhand)

INDIA



Web Page : http://www.angelfir e.com/nh/ cpkumar/

============ ========= ========= ========= =========

Unfold the Goddess Within:

http://groups. yahoo.com/ group/Shambhavi/

============ ========= ========= ========= =========

Good Day,

I invite suggestions from the learned members regarding most
appropriate methods to estimate groundwater recharge from artificial
recharge and rainwater harvesting structures (such as anicuts, field
bunds, gabions etc) in a hard rock area for studying their impacts on
groundwater resources. Whether any specific softwares are available
for such purpose?

Copies/links to any relevant literature (case studies/papers/web
resources) or software will also be useful.

Thanks & Regards
Kumar
================================================
C. P. KUMAR
Scientist 'E1'
National Institute of Hydrology
Jal Vigyan Bhawan
Roorkee - 247667 (Uttarakhand)
INDIA

Web Page : http://www.angelfire.com/nh/cpkumar/
================================================
Unfold the Goddess Within:
http://groups.yahoo.com/group/Shambhavi/
================================================

Dear Sir
How can I find SUB package of MODFLOW in Visualmodflow3.1
How can I calculate earth subsience of drawdown by VisualModflow3.1
sincerly yours

Well, I suggest you to check the water velocity to see if the time scale
that you are using in the transport simulation is compatible with it. It
could be just a matter of extending the simulation time. Other possibility
is that if you are applying a very high adsorption coeff., causing a further
reduction of the effective velocity of the plume.

Regards,
Stela Cota


2008/9/8, rory_valerias <A.Oord@...>:
>
>   Hello,
>
> I'm trying to run a Visual Modflow model in RT3Dv2.5 using
> Instanteneous aerobic decay of BTEXN. I've put in a constant
> concentration for BTEXN and oxygen in one layer. I've tried several
> solvers and it gives no problems during calculation. However, I never
> get a concentration value in my output. Can anyone help me with this
> problem?
>
> Regards,
>
> Arjen Oord/Cedrick Gijsbertsen

Hi Arjen,

have you checked the *.ot file in order to know if RT3D makes the computation ?

Daniele



-----Messaggio originale-----
Da: visual-modflow@...
[mailto:visual-modflow@...]Per conto di rory_valerias
Inviato: Monday, September 08, 2008 10:44 AM
A: visual-modflow@...
Oggetto: [visual-modflow] No concentration in output RT3D model

Hello,

I'm trying to run a Visual Modflow model in RT3Dv2.5 using
Instanteneous aerobic decay of BTEXN. I've put in a constant
concentration for BTEXN and oxygen in one layer. I've tried several
solvers and it gives no problems during calculation. However, I never
get a concentration value in my output. Can anyone help me with this
problem?

Regards,

Arjen Oord/Cedrick Gijsbertsen

Hello,

I'm trying to run a Visual Modflow model in RT3Dv2.5 using
Instanteneous aerobic decay of BTEXN. I've put in a constant
concentration for BTEXN and oxygen in one layer. I've tried several
solvers and it gives no problems during calculation. However, I never
get a concentration value in my output. Can anyone help me with this
problem?

Regards,

Arjen Oord/Cedrick Gijsbertsen

Yes, it is a steady-state simulation. Am I right in assuming that
steady-state simulation means that water levels are calculated for a
quasi infinite time span? Or do my settings for start and end times in
VisualModflow influence steady-state calculation?

Although I considered 1 mm/a of recharge quite a low value it seems it
is far too high for a aquitard of  say k=1e-8. Can someone point me to
the formula that calculates the recharge that an aquitard of k=1e-8 can
take?

Anyway - in my model I have a quaternary layer on top of the aquitard.
Where the aquitard crops out I initially changed the k-value of the top
layer to that of the aquitard. I will reset this to a reasonable value
that allows lateral runoff in the quaternary layer.

Dieter


Stela Cota schrieb:
> Because you are probably talking about a steady-state simulation, isn´t it?
> I had a problem like this too. If the K is too low, the porous material is
> not able to conduct the water to the boundary conditions and it just can
> accumulate, rising the water level. What happens in this case is that water
> will be removed by runoff and will not infiltrate in the soil. But I agree
> that it seems a little strange not being able to infiltrate any water at
> all?
>
> Stela.
>
>
> 2008/8/25 Dieter Plass <plass@...>
>
>
>>   It seems I am lacking some basic understanding of hydraulics: Why does 1
>>
>> mm/a of recharge to an aquitard result in a water level rise of 1.000 m?
>>
>> Dieter

Because you are probably talking about a steady-state simulation, isn´t it?
I had a problem like this too. If the K is too low, the porous material is
not able to conduct the water to the boundary conditions and it just can
accumulate, rising the water level. What happens in this case is that water
will be removed by runoff and will not infiltrate in the soil. But I agree
that it seems a little strange not being able to infiltrate any water at
all…

Stela.


2008/8/25 Dieter Plass <plass@...>

>   It seems I am lacking some basic understanding of hydraulics: Why does 1
>
> mm/a of recharge to an aquitard result in a water level rise of 1.000 m?
>
> Dieter
>[Non-text portions of this message have been removed]

It seems I am lacking some basic understanding of hydraulics: Why does 1
mm/a of recharge to an aquitard result in a water level rise of 1.000 m?

Dieter

Hi Paulo,

During 'creation of a new model' in 'model domain' window, u might put such a
value of "Zmax" (i.e bottom) in layer 1, which is above the initial hydraulic
head/s. Please u check.

S.Halder


--- On Mon, 4/8/08, Stela Cota <stelacota@...> wrote:

From: Stela Cota <stelacota@...>
Subject: Re: [visual-modflow] Problems with the initial condition
To: visual-modflow@...
Date: Monday, 4 August, 2008, 5:09 PM

Paulo, I guess this can happen is you have had dry cells in your previous run.
Have you checked for this reason?

Stela

2008/7/24 Paulo Leal <pjvleal@hotmail. com>

> Hello, I'm having problems when I try to use initial heads from a
> previous run. I get a messenge like this "your initial heads are below the
> bottom of layer 1 at col=xx row=xx". Can anyone help me?
>
> Paulo Leal

Hi there,

     Regarding ur boudary condition, you have a constant horizontal flux. But u
can't find such type of  boundary in visual modflow. The thing u need to do is
to calculate the head gradient based on the constant flux u have and using
darcy's equation and other related theory to get the head gradient. (
q=flux/A(area of ur domain) and q=Ki(where K is hydraulic conductivity and i is
the head gradient).

      Then set one side of boundary head as a constant like 5m, and using head
gradient i times the length of ur domain(horizontal length  like x) then you
have the constant head boundary with the other boundary. So in this case, visual
modflow will maintain the constant flux.

      Good luck!
      Chao

riccardog1983 <riccardog1983@...>
                        hi..
  I'm a student and i'm using visualmodflow for my thesis..
  can anyone tell me how plan as boundary a CONSTANT HORIZONTAL FLUX
  (m3/sec)? Can i use GENERAL HEAD?How can i do it?

hi..
I'm a student and i'm using visualmodflow for my thesis..
can anyone tell me how plan as boundary a CONSTANT HORIZONTAL FLUX
(m3/sec)?Can i use GENERAL HEAD?How can i do it?

I would set up the model with at least two layers, as unconfined aquifer. Then,
in the top layer, assign two conductivity areas: one with high, for the
unconfined part, and one with very small, for the confined part.

Cris.


----- Original Message ----
From: fabrice.compere <fabrice.compere@...>
To: visual-modflow@...
Sent: Wednesday, August 6, 2008 5:05:23 AM
Subject: [visual-modflow] Help required to modelize an unconfined then becoming
confined aquifer


Hi to the members of this group.
That's my first post ever here !

I'm performing a preliminary research concerning the possibility to
modelize a chalk aquifer unconfined in its west part, then becoming
confined in its East part.

At this day, I have not found any serious reference describing such a
problem. Obviously, I would tend to a simplistic (?) approach
involving strong contrast in storage coefficient between the two
areas.

How to treat this type of configuration with ModFLow ?
Does anybody knows a reference (article, book,...) dealing with this
problem ?

Thanks a lot to answer.

Best regards

Fabrice

Hi to the members of this group.
That's my first post ever here !

I'm performing a preliminary research concerning the possibility to
modelize a chalk aquifer unconfined in its west part, then becoming
confined in its East part.

At this day, I have not found any serious reference describing such a
problem. Obviously, I would tend to a simplistic (?) approach
involving strong contrast in storage coefficient between the two
areas.

How to treat this type of configuration with ModFLow ?
Does anybody knows a reference (article, book,...) dealing with this
problem ?

Thanks a lot to answer.

Best regards

Fabrice

Paulo, I guess this can happen is you have had dry cells in your previous run.
Have you checked for this reason?

Stela


2008/7/24 Paulo Leal <pjvleal@...>

>   Hello, I'm having problems when I try to use initial heads from a
> previous run. I get a messenge like this "your initial heads are below the
> bottom of layer 1 at col=xx row=xx". Can anyone help me?
>
> Paulo Leal

Does anyone know how to add lake 3 package into Visual Modflow 4.2 ?
Thanks,
Daniele

Hello Members,

I would like to know does anybody has some experience in using HSSM, case
studies or reliability of software. Also, some alternatives are welcome.

Kind Regards
Dragan Kaludjerovic

Hello, I'm having problems when I try to use initial heads from a previous run.
I get a messenge like this "your initial heads are below the bottom of layer 1
at col=xx row=xx". Can anyone help me?

Paulo Leal