| Summary: | A water resources assessment of the Casa Grande Ruins National Monument (CAGR) was conducted using historical and recent data. The data were sorted and analyzed to determine whether the monument grounds have the potential for subsidence, and in particular, differential subsidence. Further research was conducted to ascertain the cause of the loss of the mesquite woodland on the monument grounds in the 1940's. To determine the potential for subsidence at the monument, a subsidence model was constructed based on geology developed from well logs of local wells. The model allowed the water table to fall from the predevelopment level to the present, and to possible future levels. The region of the Casa Grande Ruins National Monument has the potential for subsidence and differential subsidence on a geological basis, should the water table drop sufficiently. The majority of the mesquites on the monument grounds died in the 1940's. This has been attributed to groundwater pumping that lowered the groundwater table, but may also have been caused by drought, loss of a perched aquifer, disruption of overland flow by construction around monument grounds, and construction of the contour dykes at CAGR.
|
|---|
