## Hh Hh

K 3t

3t Ss where Ss [(1/m)] is the coefficient of specific storage

If the compressibility of water 3 is ignored, then Ss = pgmv.

Some typical values of mv are given in Table 9.7.1. Equation 9.7(5) can also be written in terms of ^ as

where Se = coefficient of elastic storage = Ss • H.

Transient Unconfined Flow (Phreatic Storage)

The vertical movement of a phreatic surface results in water being stored in soil pores without causing the soil to m

TABLE 9.7.1 TYPICAL VALUES OF COMPRESSIBILITY (mv)

Compressibility, (m2/N or Pa1)

TABLE 9.7.1 TYPICAL VALUES OF COMPRESSIBILITY (mv)

Compressibility, (m2/N or Pa1)

Clay |
10-6-10-8 |

Sand |
10-7-10-9 |

Gravel |
10-8-10-10 |

Jointed rock |
10-8-10-10 |

Sound rock |
10-9-10-11 |

Water (ß) |
4.4 X 10-10 |

Source: R.A. Freeze and J.A. Cherry, 1979, Groundwater (Prentice-Hall, Inc.).

Source: R.A. Freeze and J.A. Cherry, 1979, Groundwater (Prentice-Hall, Inc.).

deform. Phreatic storage is, therefore, several orders of magnitude greater than elastic storage, which can be ignored.

The basic differential equation for the transient uncon-fined flow (Strack 1989), such as shown in Figure 9.7.1, can be given as

where Sp = coefficient of phreatic storage.

Equation 9.7(9) can be linearized in terms of the potential $ as or

K dt

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