High-flow discharge at the junction of the streams in the Pioneer Village at Spring Mill State Park during a storm event on February 18, 2000.
Photo by Mark Buehler.

Discharge, denoted by the red lines on the graphs, is the volume of water flowing through an aquifer or stream past a specific point in a given amount of time. The graphs show that the discharge from Donaldson Cave and at the junction of the streams in the Pioneer Village is low in the summer and fall. Discharge during the summer months is low because less rain falls to recharge the ground water aquifer. Also, during the summer months, both evaporation of water and transpiration of water from the ground into the atmosphere by plants increases.

Donaldson Cave discharge or outflow during low-flow (left) and high-flow periods.
Left photo by Mark Buehler; right photo by Jason Melady.

Stream flowing through Pioneer Village carrying outflow from Hamer Cave during low-flow (left) and high-flow periods.
Photos by Mark Buehler.