Subsidence & Collapse Answer Sheet

• In which state is the Edwards Aquifer located?

• What type of topography occurs in this region?

• Are any of the major issues surrounding the Edwards Aquifer related to subsidence? If so, what are they?

2. Go to Images and view the Edwards Aquifer Region map which shows drainage areas of the aquifer, where it is recharged, the locations of springs, and the region where discharge takes place.

• What major city is located in the Edwards Aquifer discharge area?

• What groundwater-related features are found along the recharge/discharge boundary?

• Determine the average recharge, discharge, and precipitation rates of the numerical data.

• Average recharge:

• Average discharge:

• Average precipitation:

• Beside each entry place an "up-arrrow" if the value is above average, a "down-arrow" if the value is below average, and a dash or blank if the value is at or near the average.

• Based on your "arrow" data determine when the population of San Antonio began to grow.

• Year:

• What is the average discharge of the aquifer before the population growth?

• What is the average discharge since the population growth?

• Do you see similar changes in the Recharge/Precipitation columns?

• What is the overall effect on groundwater levels in the San Antonio area?

4. Go to Library of Images and Essays to view an Index to Regional Photos map. Select either the Topical Index and Faults and Caves or choose #3 on the map.

• What is the evidence that subsidence is possible in this area?

• Where do you predict the most likely area of subsidence to occur in the Edwards Aquifer region?