Scatter Data Spatial Analysis
This interface is used to import scatter data and apply several types of analysis or filtering techniques. The general work-flow is:- add scatter point data to interface and map display
- filter the data
- select a parameter to analyze
- select a tool or type of analysis
- click 'Apply'
- and engage with an updated map display and/or new graphical interface.
1. Add Data
2. Data Table
3. Show/Hide Data on Map
4. Filters
5. Parameter Select
6. Tool Select
7. Interpolation Options
1. Add Data
Wellogic
Selection this option to extract water wells from the MAGNET Data Center including information such as Static Water Levels, well depth, etc. Availability of data depends on geographic location. The figure below shows the current water well data availability in the MAGNET Data Center. Note that the amount or quality of information may vary from state-to-state (province-to-province). The data for the State of Michigan is most complete at this time.The user must zoom to a level greater than Zoom Level 9 to use this option. Once at a sufficient Zoom Level and the option is selected, the cursor will turn into a into a large plus-sign ('+') and the user can draw a polygon on the map to specify the area to be used for data extraction. Clicking on the map will place a vertex. Go to 'Conceptual Modeling Tools' > 'SaveShape' to finalize the extractoin polygon. This will start the extraction process. When the process is finished, it will automatically load the data markers into the map display and will populate the Data Table and Parameter select menu (see below).
Import Shapefile
Select this option to add a point shapefile. Once selected, check box next to 'Import' that appears. Then click 'Import' to browse to and select the file stored on your local machine. The required format is a zipped file (.zip) containing the following files types:- Shape: shapefile with a .shp extension
- DBF: database file with a .dbf extension
- PRJ: project coordinate system file with .prj extension
NOTE:
1 - Some projections may not be supported by IGW-NET, please report to us if you have difficulty to load a shape file. IGW-NET Contact Page
2 - If you failed to load a shapefile (i.e., you cannot "find" the shape or it was loaded in to a wrong location), try to transfer the shapefile to World 1984 projection.
Once the .zip file is succesfully uploaded, click 'Apply' to launch the Internal Filters menu that allows selecting a parameter/attribute for import and to assign shapefile fields to well attribute options (in the case of water wells, e.g., groundwater elevation or quality measurements).
Click the ' Use Uploaded File button to import a previously uploaded .zip file for analysis.
Load Data File
Use this option to import a text file (.txt) with scatter point information. The format is:WellID,Time,X,Y,Zf,Zt,LyrIndex,V,Icolor
One observation per line may be added after the first line.
• the 1st value is the well ID (WellID)
• the 2nd is the current time step in the case of transient modeling, expressed as the number of days from the simulation starting date (which is set in the Simulatoin Settings tab of the Domain Attributes menu). For steady simulations, a ‘0’ value is used to indicate that the comparison is for steady state.
• the 3rd is the x-coordinate of the observation (X), e.g., longitude
• the 4th is the y-coordinate of the observation (Y) , e.g., latitude
• the 5th is the well screen top elevation (Zf), in units of meters above sea level. Typically wells are screened across a depth interval; Zf ("Z from") is the elevation the at which the screen is first encountered as one moves into the surface ("screened from an elvation of...").
• the 6th is the well screen bottom elevation (Zt), in units of meters above sea level. Zt ("Z from") is the elevation the at which the screen terminates as one moves into the surface ("...to a deeper elevation of...").
• the 7th is the layer index (LyrIndex), which can be used if the well is to be placed in a specific geological/computational layer in the case that well screen top and bottom elevation information is not available. By default, this value is set to ‘0’ so that the Zf and Zt values are used
• the 8th is the parameter value (e.g., water level, concentration, hydraulic conductivity, etc.)
• the 9th is used to specify long-type RGB (Red-Green-Blue) color of the data markers in the calibration plot
The contents of the .txt file can also be directly copied into the Data Table (see below), but data markers will not be added to the map display.
Click the Map to Add Data
Select the 'Click on map to add data' button to interactively add scatter points. Click the button once and then click in the desired location on the map display to add a data marker. This automatically adds a row entry to the end of the data table. The attribute value can be assigned to the 2nd-to-last column in the entry. By default, a data point added in this way will be assigned a value of '-999999', which means "no value" (i.e., IGW-NET will ignore the data point in the analysis).2. Data Table
The central text field is populated upon succesful import of scatter point data by one of the methods described above. The format is described above (see Load Data File section). Only one attribute/parameter is included in the table at one time (the values in 2nd-to-last column). If multiple parameters are included in the dataset (e.g., Wellogic water well data), use the Parameter drop-down menu to change parameters and then click 'Apply'. This will perform the analysis and update the data table.3. Show/Hide Data on Map
If the Wellogic option, Import Shapefile optoin, or Load data File option is used to add data, the data will automatically be shown in the map display as markers or "pushpins". Click the 'Hide data on map' button to temporarily hide the data markers from the map display. To re-display the markers, click the 'Show data on map' button (same location as 'Hide data...', the button toggles back and forth depending on the display status).Note that clicking on a data marker in the map display will open its 'Properties' interface - a table of attributes for that specific marker.
4. Filters
Spatial Filter
Once data has been added/loaded into the Data table, clicking the 'Draw polygon to select data' button allows the user to draw a polygon on the map display to select a subset of data for analysis. Once this option is selected (clicked), the cursor will turn into a large plus-sign ('+') and clicking on the map will place a vertex. Go to 'Conceptual Modeling Tools' > 'SaveShape' to finalize the selection polygon.A prompt will appear indicating that the original data that was not included in the selection will be removed from the data table and map display. You can restore the orginal data by re-loading the original dataset; select your option from the 'Data Source' drop-down menu:
For the Wellogic option, follow the on-screen prompt to load the orignal dataset
For Import from Shapefile and Load Data File options, follow the steps described above.
Raw, Invalid, Wellogic, and Univerisal Options
The Raw option means no filtering will take place.The Invalid option will remove invalid data (data in the wrong format).
The Wellogic data option should be used when selecting the Wellogic Database as the data source. Selecting this option opens a submenu for filtering water well data by aquifer type, construction date, etc.
The Universal option provides a number of options for filtering based on values in specific numeric fields (attributes). Selecting this option opens a new interface, which can calso be used to perform simple or mulitple linear regression analysis (see next section below).
5. Parameter Select
The Wellogic and Import Shapefile options for adding data allow for more than one parameter to be imported and analyzed. Use the provided drop-down menu to change the parameter. A prompt will specify the number of data points available and the 'V' column values (parameter values) will update. Then click 'Apply' to perform the analysis specified under 'Tools' (e.g., PDF/CDF, Density Distribution, etc.).6. Tool Select
There are several data analysis tools available. Use the drop-down menu to select a tool, then click 'Apply' to perform the chosen analysis. Note that the options for each tool differs, so the Options panel will update accordingly as a new tool is selected. In some cases, applying a tool will launch a new interface (e.g., PDF/CDF, Data Distribution).PDF/CDF
This option enables grahpical/statistical exploration of the data: probability density function (PDF), cumulative distribution function (CDF), histogram, and more. A new interface will open after clicking Apply (a slight delay is expected).Density Distribution
To visualize and explore data distribution density, choose the ‘Density Distribution' option and click Apply. This will launch the Data Density Chart after a few moments (the more data, the longer it will take).IDW
This tool is for spatial interpolation based on the Inverse Distance Weighted (IDW) method that assumes the interpolating surface should be influenced the most by the nearby points and less by the more distant points. The interpolating surface is a weighted average of the scatter points and the weight assigned to each scatter point diminishes as the distance from the interpolation point to the scatter point increases.IDW options : There are two parameters that need to be set when using the Inverse Distance interpolation method: 1) the power parameter, p, in the weighting function (typically p=2), set in the ‘Power’ field next to the Inverse Distance radio button; and the number of nearest scatter points to use for interpolation, set in the ‘Nearest Pts’ field (default value is 30).
By default, spatial interpolation is done in 2D, but 3D interpolation can also be applied (see Advanced Options under Interpolation Options).
Interpolation domain size can be set in two ways:
1 - by using the selected data extent (bounding box)
2 - by drawing a groundwater model domain and using that as the interpolation domain (this needs to be done before performing interpolation): 'Conceptual Model Tools' > 'DrawDomain' > ...
Kriging
Kriging is another method for spatial interpolation based on the assumption that points that are near each other have a certain degree of spatial correlation, however points that are widely spread are statistically independent. Kriging that provides estimates of values at any given point as a weighted sum of input values at surrounding points, with weights assigned based on spatial trends and correlations. The weights are derived from fitting a model variogram to the empirical variogram, which are graphical depictions of separation distance, or lag, and semivariance (or dissimilarity) in values between pairs of input data.To apply the kriging, you first need to create a variogram model. Click on the 'Variogram Modeling' button to start the process (a new interface will open).
Kriging options : By default, IGW-NET assuming stationary kriging is being used. In stationary kriging, a single variogram developed using the global dataset is utilized for spatial interpolation.
Another option is a nonstationary kriging approach, in which a different model variogram is developed for each estimation point. Select this option by checking the box next to 'Nonstationary Variogram'. The number of nearest scatter points in the ‘Variogram Nearest Pts’ will be used develop the variograms.
After the variogram modeling is complete, spatial interpolation (kriging estimation) is performed using the nearest number of points, N, (N=30 by default). Or, the user can instead specify a selection radius around each estimation point.
The user may choose to use all points for kriging estimation by selecting the 'All points' option.
Interpolation domain size can be set in two ways:
1 - by using the selected data extent (bounding box)
2 - by drawing a groundwater model domain and using that as the interpolation domain (this needs to be done before performing interpolation): 'Conceptual Model Tools' > 'DrawDomain' > ...
Regression
This tool is used to perform simple or mulitple linear regression analysis. The tool requires input data from an uploaded .txt file or created using the Univerisal Filters interface after importing data into the data table.Select the 'Load local data filter' option to open the Regression Chart and load the .txt file of proper format (see Regression Chart interface help page for more details). Select 'Use current data' to open the Universal Filters interace and use the help page to prepare the data for regression analysis.
Outlier Analysis
This tool is used to filter outliers from the selected dataset. A moving statistical analysis is used to identify and remove data values that are above a factor of standard deviations (e.g., three standard deviations) from the local average, using the nearest number of points to establish the local trend (linear averaging).Data Export
These capabilities are not available at this time.7. Interpolation Options
These options are only available for the IDW and Kriging tools.Interpolation Grid Option
Spatial interpolation is done on a grid with a specified number of estimation points ( centered on grid cells). Use the NX and NY input fields to assign the number of estimation points in the X- (west-east) and Y- (north-south) directions, respectively.The grid cell size in the X- and Y-directions is indicated by the DX and DY values, respectively. The origin or bottom-left corner of the interpolation domain is specifed with the X0 and Y0 values. The domain length in the X- and Y-directions is indicated by the Xlength and Ylength values, respectively. NOTE: You must apply spatial interpolation at least once to see these values. They are updated after each 'Apply'.
Interpolation Draw Option
The interpolation results can be displayed as a color map, a set of contour lines, or a combination of both. Use the provided drop-down menu to change from the default setting (color map and contours).Users can customize the contour line style, color, and width.
By default, the results are shown for the entire range of interpolated values ('Data Limits' option). Choose the 'Data Given' option to use a custom range of values. You can control the color contour/color interval,i, by specifying the number of breaks and max and min values: i=(max-min)/(breaks-1).
Check the box next to 'Legend' to display a color legend. The 'Label Filter' allows controlling the number of equal intervales to divide the data range for display purposes, computed as i/(label filter). For example, if i=30, and (label filter)=2, 15 color intervals will be used in the legend and map display.
Click 'Apply' to update/reflect changes to the interpolation draw options.
Advanced Options
The first set of Advanced Options relates to how duplicated data points (i.e., entries sharing the exact same location) are handled. By default, there is no action - all duplicated points are included in the interpolation. The other options available are:Mean - the average value is calculated and used for the single "effective" data point at that location.
Max - the entry with the maximum value is identified and used; the other one(s) are removed from the analysis.
Min - the minimum value is identified and used; the other one(s) are removed from the analysis.
First - the entry that is listed first in table / data file is used, and the other one(s) are removed from the analysis.
Last - the entry that is listed last in table / data file is used, and the other one(s) are removed from the analysis.
Remove - all locations that have duplicated points are removed from the analysis.
Check the box next to 'Log Scale' to display the interpolation results (values) using a log scale.
If checked, the 'Detrend' option removes the effects of the long-range trend to show only the differences in values from the trend.
3D
Check the box next to '3D' to perform 3D spatial interpolation. There are two options are for defining the 3D grid of estimation points to be generated:1) Defined by Model means that they 3D grid is defined by the groundwater model grid that is assigned in the Domain Attributes interface. This requires specifying i) the Top Elevation (e.g., DEM), Bottom Elevation (e.g., bedrock surface from the Data Center) in the Aquifer Attributes tab; ii) the number of grid cells in the X- (west-east) direction, NX (Simulation Settings tab); and iii) the number of of SubLayers (also in Simulation Settings tab). Make sure to save the settings in the Domain Attributes interface before returning to the Scatter Data Spatial Analysis tool.
2) The Zmin/Zmax option also uses the maximum and minumum aquifer elevation values found in the global dataset of imported scatter points. The 'NZ' suboption indicates the number of sublayers for subdividing; or the user may specify the layer thickness ('DZ' suboption).
The remaining options deeal with distortions or compressions that should be applied to one or more 3D directions to acount for large differences in the horizontal and/or vertical extents of the data. (For example, the horizontal extent of the data is typically much larger than the vertical extent in regional studies, so compression of the data in the horizontal direction is needed for accurate 3D interpolation) A ratio of extents can be specified to calculate a compression ratio.
The XYZ dependent means no a non-distorted domain is used.
The XY dependent --> Z ratio option means that there is no distortion in the X-direction relative to the Y-direction, but there is distortion relative to the Z- (vertical) direction. The value in the associated text field indicates the compression ratio that will be applied in horizontal directions.
The Independent X/Y ... options allows for distortion in the X-direction relative to the Y-direction in addition to distortion relative to the Z direction. For example, if the X-direction extent is twice the Y-direction extent and 280 times the Z-direction), an value of 2 for X/Y and 280 for X/Z can be used.