Solution to Exercise 3

3) Rank the materials from the sediment with the largest value (1) to the material with the smallest value (3) for hydraulic conductivity, K, specific yield, Sy, and porosity n.

K Sy n
Silty Sand ____2____ ____2____ ____2____
Clay ____3____ ____3____ ____1____
Equally mixed sand and gravel ____1____ ____1____ ____3____

Estimation of these orders requires a number of assumptions and depending on one’s thinking slight differences in ordering are acceptable.

For hydraulic conductivity see Figure 32 of this book, the order is fairly clear.

For specific yield see Table 3 of this book. Sand infilling the pores of the gravel will decrease its hydraulic conductivity compared to either sand or gravel, decrease its porosity and decrease its specific yield. Also, the materials have a wide range of values. Consequently, the proper ordering is not entirely clear.

For porosity see Tables 1 and 2 in this book

Return to Exercise 3

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Hydrogeologic Properties of Earth Materials and Principles of Groundwater Flow Copyright © 2020 by The Authors. All Rights Reserved.