Chapter 8 Solutions to Odd Numbered Problems

These solutions were done by Dr. Todd Rayne of Hamilton College

1. At a tropical coastal aquifer the ground water is stagnant. The density of fresh water is 0.998 g/cm³ and that of the underlying salt water is 1.024 g/cm³. If the fresh-water head is 14.2 ft above mean sea level, what is the depth to the salt-water interface?

3. A coastal aquifer has a mean hydraulic conductivity of 2.61 m/day. The density of fresh water is 1.000 g/cm³ and the density of underlying saline water is 1.024 g/cm³. The ground-water discharge per unit width of the coastline is 0.00345 m²/day.

(A) What is the depth to the salt-water interface at a point 125 m inland?

(B) What is the elevation of the water table above mean sea level at a point 125 m inland?

(C) What is the depth to the salt-water interface at the shoreline?

(D) What is the width of the outflow face?

Given

A. Using Eqn. 8-5:

B. Using Eqn. 8-7:

where

C. Using Eqn. 8-5:

where

D. Using Eqn. 8-6:

5. The aquifer beneath a circular oceanic island has a mean hydraulic conductivity of 312 ft/day. The amount of recharge is 0.00831 ft/day. The density of fresh water is 1.000 g/cm³ and the density of underlying saline water is 1.024 g/cm³. If the island is 8715 ft in diameter, what is the depth to the salt-water interface in the center of the island?

Using Eqn. 8-9:

and Using Eqn. 8-1: