A common task for agencies managing water resources is to assess how new groundwater wells will affect groundwater availability, groundwater flow, and the effect on streamflow in sensitive areas. In many cases, agencies make use of groundwater simulation models to assess these impacts.
In a previous post we described a workflow where MODFLOW models are used to estimate the effects (either the change in water levels, drawdown, or flow) of new wells or increasing pumpage in existing wells. The workflow is based on MODFLOW Analyst tools to import, edit, and run MODFLOW models and visualize the simulated results. Because the tools are developed as Geoprocessing tools we can create different workflows that combine MODFLOW Analyst tools with the standard ArcGIS tools, scripts, and other 3rd party tools.
In addition, the Geoprocessing tools can be executed on ArcGIS Server. The advantage of creating a web-based application is that you do not need to have MODFLOW or ArcGIS installed on your computer to perform an analysis and create a map. In fact, anyone with a Web browser can run the model and analyze the results.
The Environmental Modeling Research Laboratory (EMRL) at BYU together with the Utah Division of Water Rights (DWRi) have created a web-based system to analyze the impact of new wells for permitting, based on ArcGIS Server (http://utahdwr.groups.et.byu.net/app/). The application automates editing and execution of a MODFLOW model used by the DWRi for well permitting, and makes it easy to submit a task and view the output geometries (drawdown contour lines, change in spring/drain discharge points). Outputs can be used with other established permitting criteria to evaluate a well permit application.
The following example shows an application developed for the Northern Utah County aquifer. The primary concern in this area is the effect of groundwater drawdown on streamflow discharging from springs feeding Utah Lake. The following figure shows the simulated effect of two new wells. Results include drawdown contours and springs effected by the new wells.
Figure 1: Web-based application for well permitting. The application runs MODFLOW for a set of wells and the results are: drawdown contours, drain points, and drain polygons. The workflow runs on ArcGIS Server and results are displayed in Google Earth.
In addition, you can click on each spring (modeled as a drain in MODFLOW) to see the change in flow to the spring.
Figure 2: Information on simulated effects of the permitted wells to spring flow (modeled as drain cells in the model). For each spring the initial flow, change in flow, and simulated flow is reported.
You can also click on the polygon surrounding the springs to get the total change in flow for all springs. The map is customizable, so you can toggle on/off different map layers related to the model and water rights in Utah. For example the blue dots on the map represent existing wells in the MODFLOW model.
Figure 3: Report showing change in spring flow for all spring cells within the polygon. Additional layers of information can be toggled on/off, for example the blue dots on the map represent existing wells in the MODFLOW model.
EMRL and DWRi are in the process of applying this workflow to other models used by the DWRi in different locations in the state.
Thanks to Norm Jones (njones@byu.edu) and James Greer (jamesgreer@utah.gov) for contributing the material for this post. Additional information can be found at the documentation part of the website: http://utahdwr.groups.et.byu.net/app/.
If you are interested in creating similar web-based applications using MODFLOW Analyst and ArcGIS Server please visit the Aquaveo website (http://www.aquaveo.com).
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