psinton@aquageo.us

You use the "Rate Budget" and "Period Budget" panels for boundary-condition flows based on the selection you make (there is selector at the top of these panels to focus the calculation on the current selection).  These panels only operate on nodes and only on boundary conditions.  Darcy-based [u]estimates[/u] of flows into and out of an element or selected elements is handled via the "Flow Rate" and "Flow Volume" panels.  These also have ways to focus the computation on selected elements.  A secondary selection called the "mask domain" is used for further focusing the calculation on specific element faces.  You may want to use the flow panels instead if you want an estimate of the rate of groundwater flow toward a lake (in a well balanced model, the rate of flow toward a lake should be nearly equal to the rate of water removed from the lake via boundary conditions).

try moving starting position(s) of the particles a little bit. you could probably also fix via an ifm module but that would be a serious programming effort.  upgrading to v6 would be most sensible.

phreatic mode does not work well where the water table crosses slices...use richard's equation instead and review white papers

Could be due to incomplete convergence (most likely) or energy loss to other boundary condition.

You haven't given enough information.  It could be that the observation is not in the area where you changed K and that my explain the result, but it is equally likely that your model is not working properly.

coding will be necessary

"Fixed drawdown" wells in feflow (a constrained "Well BC") are essentially the same as fixed head ("Hydraulic-head BC").  You set them up by adding a minimum (and/or maximum) constraint to a Well BC. When the head at the well node exceeds the constraint you set, the constraint, which is a fixed head equal to the value of the constraint, is put in effect.  If you want to fix the drawdown at the spring, set a hydraulic head BC.  If this does not help then the problem lies with convergence error, and so Blair's recommendations will likely help solve the problem.

two possibilities I can think of: 1) your model is poorly converged and so error controls the result, or 2) setting the transfer rate larger than the K of the surrounding elements will result in similar flow rates because the surrounding K will control the flow.  In the second case, if you decrease the transfer rate to a value that is based on a K that is 0.1 or smaller than the surrounding K you should see a decrease in the flow.

try 1st BC with maximum constraint set to zero

transient simulation only