BGS: About the Project

About the Project

Introduction

Bobcat Geospatial Solutions (BGS) was assigned a project by the Hill Country Alliance (HCA) to collect data and analyze groundwater level conditions within the HCA area of study. We were asked to create a map-based product that would show color-coded groundwater levels given in a percentile range.

Purpose and Scope

BGS undertook this project to assess recent groundwater level conditions in the Texas Hill Country for HCA. Our study includes 17 counties that encompass the HCA area of study (Burnet, Mason, Llano, Kimble, Gillespie, Blanco, Travis, Hays, Comal, Bexar, Kendall, Medina, Uvalde, Bandera, Real, Edwards, Kerr)(Figure 1). HCA set out the following criteria for us: The wells for which we collect data must have 40 or more water level measurements over a 10-year span and must be currently measured by local groundwater districts. We utilized spreadsheets and Geographic Information Systems to create our maps and attribute tables.

Figure 1. Area of study

Methodology

Our methods for executing this project began with the collection of historic well data from the United States Geological Survey (USGS) and Texas Water Development Board (TWDB) groundwater databases. We collected well data that only contained 40 or more measurements over a 10-year span. When that was completed, we contacted participating groundwater districts to help provide us with recent water level measurements for the wells currently being monitored within the HCA study region. We then created a set of Excel files to combine and record qualifying well data obtained from USGS, TWDB, and the groundwater districts

The Excel files contain the Texas State Well Number, date of measurement, name of the aquifer that provides the water, surface elevation, depth from land surface, latitude and longitude coordinates, water elevation and the percentile value for each well (Figure 2). The percentile values are based on the water elevation calculated by subtracting the depth from the land surface elevation. The next task was to import the well data collected into ArcGIS 10 in order to create a layer that will display wells with the most recent data and corresponding color based on the percentile value (please refer to the final report document for further information).

Figure 2. Snapshot of an Excel file used for our project

Using ArcGIS 10, we were able to import, locate and create a layer out of the Excel data to display wells that meet the criteria set by the HCA. We utilized Excel spreadsheets to create an informational pop-up for each well that will include the Texas State Well Identification Number, county name, water level and location. In order for the HCA to readily identify well locations, roads, urban areas and county boundary layers were collected from the Texas Natural Resources Information System (TNRIS) website to be part of our map-based product. In ArcGIS 10, SQL equations were calculated from the data collected from TNRIS to ensure the layers don’t extend out of the HCA study area. We used Wessa.Net to help calculate the percentile values for the wells.

Our last step was to import the ArcGIS 10 layers into Manifold System in order to create an interactive map for the HCA to use in their research.