Site-Specific Quantities and Tabular Data

To assist with analysis of groundwater data, we would like to know certain key site-specific quantities, such as each well's elevation, distance from the river, and distance from USGS river guages and groundwater level monitoring wells. Here we take advantage of ArcGIS's ability to both read from and write to a tabular data (dbf) format. This allows us to:

1. easily share relevant data with colleagues (who may not have access to ArcGIS but surely to MS Excel), and
2. easily use other analytical software on the resulting data.

Well Elevations

An area DEM was obtained from http://seamless.usgs.gov using coordinate ranges that were obtained from the ArcGIS basemap. After adding the DEM to the basemap, each well was individually queried to obtain its elevation (z-value), and the value was entered into a table. The z-value of the southern most well was used as a reference datum and subtracted from every z-value. This processed table was then imported back into ArcGIS and joined with the original well position table using a table join. The final table was visualized using ArcScene's Extrude feature, where elevation served as feature height.

We plan to survey well elevations to a 30cm vertical precision in the near future using mapping-grade GPS instruments. As this data becomes available we plan to add refined elevation data to the existing table, both to assess the accuracy and precision of the above methods and to tie into regional elevation data.

Rio Grande and Well Site Buffers

The New Mexico State Engineer's hydrography geodatabase was obtained from RGIS, and the Rio Grande was extracted via query. USGS monitoring site locations were obtained in tabular form. A 5km buffer was created around the river. In addition, a 1km buffer was created (boundaries dissolved) around each FRS site.

A number of features were clipped using the 5km buffer, including the

1. Stream and Canal feature class of State Engineer's hydrography geodatabase
2. USGS River Guages
3. USGS Groundwater Level Monitoring Wells

The results are shown in figures 1 and 2.

Figure: Overview of North Site 1km Buffers with Dams and USGS River Guages

Figure: Canals and USGS Monitoring Wells Within 5km River Buffer

Distance from Wells to River

Using ArcToolbox's Linear Referencing Tools, a route was created for the Rio Grande. Using the Locate Features Along Routes tool, we generated a 3 tables for:

1. FRS Sites
2. USGS River Guages
3. USGS Groundwater Level Monitoring Wells

Each table contains two key quantities:

1. distance from well to river
2. river distance from well to well

These tables are shown in figure 3.

Figure: Data collection sites by River Length and Distance from River

Using the aforementioned GPS instrument, we would also like to take site-specific measurements of the location of the river in relation to each well. To accomplish this, we will measure the river's top of bank and/or waterline at each well's latitude and 50m due North and South of each well's latitude. Again, the newly obtained data will be added to pre-existing tables, allowing us to increase site-specific accuracy while verifying regional data.