Hydrology and Physiography of Groundwater and Wetland Habitats - Freshwater Ecology: Concepts and Environmental Applications - page 57

FIGURE 4.8

The extent of the High Plains Aquifer. Zones of depletion 20 m depth are

shown in dark (data from the U.S. Geological Survey).

FIGURE 4.9 Discharge of the Arkansas River as it flows through a region of the High
Plains Aquifer that has been utilized heavily for center-pivot irrigation since the 1960s. Note
that the logarithmic scale of discharge is modified so that it reads 0.1 m 3 s 1 when the
river is dry. The river downstream of the aquifer has flowed only during periods of flooding
since the early 1970s; it was almost never dry prior to that (data from the U.S.
Geological Survey).