Hallo Jeane,

The drain boundary package in MODFLOW is designed to simulate the effects of
features e.g. agricultural drain, which remove water from thw aquifer at a rate
proportional to the difference between the head in the aquifer and the median
drain elevation (assuming the drain is partially full), so long as the head in
the aquifer is above that elevation, but which have no effect if the head of the
aquifer falls below the median of drain elevation.

So if hydraulic head (either water table or piezometric head) in aquifer beneath
the mine is below the head of river/spring (surface water level elevation) then
flow from the aquifer to the river/spring will show as ZERO. So I think in this
case, taking river/spring as "DRAIN boundary" is not appropriate.

Your objective is " to evaluate the impact of a mine in the water supply of the
rivers & springs around the mine"..so u have to account for the amount of flow
in stream/spring around the mine and to simulate the interaction
between stream/spring & groundwater in the aquifer beneath the mine ...for
which I think "STREAM boundary" will be appropriate for your objective. After
running the model u can get inflow/outflow to/from the model from "MASS BALANCE
REPORT" from which u can justify the effect of mine on discharges of its
surrounding river/springs.

Thank u
S.HALDER



--- On Wed, 18/6/08, Jeane Santos <jepenoff@...> wrote:

From: Jeane Santos <jepenoff@...>
Subject: [visual-modflow] impact of a mine on springs
To: visual-modflow@...
Date: Wednesday, 18 June, 2008, 1:18 AM

Hello.

I'm working in a model to evaluate the impact of a mine in the water supply of
springs and rivers around the mine. My question is: what is better - put the
rivers and springs like river or like drains?

Thanks
Jeane