Assume that a losing stream exists in physical connection with groundwater in an isotropic unconfined aquifer. Assume that several contour lines of equal head cross the stream and intercept it. These contour lines of equal head are "V-shaped", with the point of the "V" facing downgradient, or downstream. True or False: The lines of equal head have lower values as the stream is approached at right angles.

A

To determine whether the statement is true or false, we need to understand the characteristics of the contour lines and how they relate to the stream.

Contour lines of equal head depict points in the aquifer that have the same hydraulic head, which is a measure of potential energy of the groundwater. These contour lines show how the hydraulic head varies across the aquifer.

In this scenario, we have a losing stream, which means that water is flowing from the aquifer into the stream. The contour lines intersect the stream, indicating that the hydraulic head is changing as it interacts with the stream.

Since the contour lines are "V-shaped," with the point of the "V" facing downgradient or downstream, this means that the values of the hydraulic head decrease as you move closer to the stream. This is because the water is flowing from the higher hydraulic head areas away from the stream towards the lower hydraulic head areas near the stream.

Therefore, the statement is true. The lines of equal head have lower values as the stream is approached at right angles.