GMS:Defining Layer Elevations: Difference between revisions
From XMS Wiki
Jump to navigationJump to search
No edit summary |
|||
| Line 8: | Line 8: | ||
The following steps are used to interpolate elevation data: | The following steps are used to interpolate elevation data: | ||
===Step 1 | ===Step 1: Importing the Scatter Point Elevation Data === | ||
The fist step in [[GMS:Defining the Layer Elevations|defining MODFLOW layer elevation array data]] is to create a 2D scatter point set. The set should include a | The fist step in [[GMS:Defining the Layer Elevations|defining MODFLOW layer elevation array data]] is to create a 2D scatter point set. The set should include a dataset for the top elevation of the top layer and the bottom elevation array of the top layer and each of the underlying layers. A water table elevation corresponding to the desired initial condition (starting head) may also be defined. The simplest way to create such a scatter point set is to create a tabular scatter point file using a spreadsheet or a text editor. The scatter point file is imported '''''File|Open''''' menu command. A sample tabular scatter point file for a three layer model is shown below: | ||
{| class="wikitable" | {| class="wikitable" | ||
| Line 36: | Line 36: | ||
|} | |} | ||
===Step 2 | ===Step 2: Interpolating the Elevations to the MODFLOW Arrays === | ||
Once the scatter point file is imported to GMS, the next step in defining MODFLOW layer elevation arrays is to interpolate the elevations to the MODFLOW layer elevation arrays. The elevation values can be interpolated directly to the MODFLOW arrays using the '''''...to MODFLOW Layers''''' command in the ''Interpolation'' menu in the 2D Scatter Point module. When this command is selected, the Interpolate to MODFLOW Layers dialog appears. | Once the scatter point file is imported to GMS, the next step in defining MODFLOW layer elevation arrays is to interpolate the elevations to the MODFLOW layer elevation arrays. The elevation values can be interpolated directly to the MODFLOW arrays using the '''''...to MODFLOW Layers''''' command in the ''Interpolation'' menu in the 2D Scatter Point module. When this command is selected, the Interpolate to MODFLOW Layers dialog appears. | ||
The purpose of this dialog is to associate each of the | The purpose of this dialog is to associate each of the datasets in the scatter point set with one of the layer data input arrays. A dataset and the corresponding layer data array are selected in the top of the dialog and the Map button is selected. The defined relationship is then shown in the bottom of the dialog. Once this is completed for each dataset/layer data array combination, the '''OK''' button is selected and the scatter point data set values are interpolated directly to the MODFLOW arrays using the currently selected interpolation options. | ||
In some cases, GMS can automatically match the scatter point | In some cases, GMS can automatically match the scatter point datasets to the appropriate layer elevation arrays. GMS searches each dataset name to see if "top" or "bot" makes up any portion of the name. If so, it then searches for a number to determine the layer the array should be interpolated to. For example, the dataset names top1, top of layer 1, and top elevation of layer 1 would all automatically map correctly. | ||
It should be noted that the layer data can be set up using multiple scatter point sets. For example, it is possible to have one dense set of scatter points to define the ground surface (top of layer one), and a second, more sparse set of scatter points to define the layer bottom elevations. In this case, the to Layers command would need to be selected twice, once for each of the scatter point sets. | It should be noted that the layer data can be set up using multiple scatter point sets. For example, it is possible to have one dense set of scatter points to define the ground surface (top of layer one), and a second, more sparse set of scatter points to define the layer bottom elevations. In this case, the to Layers command would need to be selected twice, once for each of the scatter point sets. | ||
===Step 3 | ===Step 3: Fixing Layer Interpolation Errors=== | ||
When interpolating layer data for the purpose of [[GMS:Defining the Layer Elevations|defining MODFLOW layer elevation arrays]], there are often cases where the interpolated values overlap. For example, for some of the cells, the top elevation values for a particular layer may be lower than the bottom values for the layer. In some cases, the best way to fix such a problem is to experiment with the interpolation options or to create some "pseudo-points" to fill in the gaps between sparse scatter points. In other cases, the overlap may correspond to a pinchout or truncation in the layer. In such cases, the elevations need to be adjusted so that there is a small but finite thickness for all cells in the overlapping region. | When interpolating layer data for the purpose of [[GMS:Defining the Layer Elevations|defining MODFLOW layer elevation arrays]], there are often cases where the interpolated values overlap. For example, for some of the cells, the top elevation values for a particular layer may be lower than the bottom values for the layer. In some cases, the best way to fix such a problem is to experiment with the interpolation options or to create some "pseudo-points" to fill in the gaps between sparse scatter points. In other cases, the overlap may correspond to a pinchout or truncation in the layer. In such cases, the elevations need to be adjusted so that there is a small but finite thickness for all cells in the overlapping region. | ||
