Laserfiche WebLink
with parameters that are associated with the features, such as flow rates and conductance terms. <br />An areal attribute layer type is used to define the spatial extent and properties for characteristics <br />such as recharge or evapotranspiration. Layer attributes are used to define hydraulic <br />characteristics that are defined using zones with constant values. Point GIS coverages maybe <br />used to define observed values for characteristics such as the land surface elevation or layer <br />elevations. These spatially distributed parameters, such as the elevation of a layer interface, <br />must be migrated into data layers that can be mapped to the model grid. GMS includes very <br />sophisticated interpolation capabilities, including kriging. Each of the layer types directly <br />correspond to similar coverages in ArcGIS, facilitating importing of this information. The tools <br />in GMS can be used to turn this conceptual model information into a ready to run MODFLOW <br />simulation with a few commands. <br />GMS is capable of using any version of MODFLOW, as long as the file formats are the same as <br />the standard USGS version, or can be converted to that format. The model is run as a separate <br />process, making use of custom versions of MODFLOW feasible. GMS supports MODFLOW- <br />2000 and provides the source code for the version of MODFLOW-2000 that is used. The current <br />version of MODFLOW-2000 included with GMS is version 1.15.00, which does not include the <br />more recent updates to several packages. Even though the included version of MODFLOW- <br />2000 includes some of the more recent packages, the user interface in GMS does not support the <br />following packages that may be used in the SPDSS models. <br />^ Streamflow routing (SFR1) <br />^ Multi-node well (MNW) <br />^ Evapotranspiration with segmentation (ETS1) <br />^ Drains with return flows (DRT1) <br />^ Reservoirs (RES1) <br />This lack of support is a significant shortfall for purposes of the SPDSS. However, since many <br />of these processes are currently addressed with external packages in the State process, this <br />package is retained for evaluation in later stages of Task 50. The State identified that GMS <br />generated stream package files were very difficult to work with, since version 3.1 did not order <br />these files sequentially by segment and reach. This problem has been rectified in version 5.1, <br />with the package files in useable order. It is likely that many of these unsupported packages will <br />be included in future versions of GMS, since development is ongoing. <br />This interface also supports other groundwater models, including finite element and finite <br />difference codes. GMS also includes PEST to conduct parameter estimation during the <br />calibration stage. GMS also includes graphical and reporting tools to compare model results and <br />calibration targets during the calibration stage. This automatic linkage only applies to <br />parameters that are supported in the graphical interface. GMS can generate cross-sections and <br />13 <br />