# Critical Hydraulic Gradient

Critical hydraulic gradient, abbreviated as \(i_c\), is the change in height (pressure) to length between any two points.

## Critical hydraulic gradient formulas

\(\large{ i_c = \frac{ \gamma_{sub} }{ \gamma_w } }\) | |

\(\large{ i_c = \frac{ SG_s \;-\; 1 }{ 1 \;-\; e } }\) |

### Where:

Units |
English |
Metric |

\(\large{ i_c }\) = critical hydraulic gradient | \(\large{ dimensionless }\) | |

\(\large{ \gamma_{sub} } \) (Greek symbol gamma) = submerged unit weight | \(\large{ lbm }\) | \(\large{ N }\) |

\(\large{ \gamma_w } \) (Greek symbol gamma) = unit weight of water | \(\large{ \frac{lbm}{ft^3} }\) | \(\large{ \frac{N}{m^3} }\) |

\(\large{ SG_s }\) = specific gravity of soil | \(\large{ dimensionless }\) | |

\(\large{ e }\) = void ratio | \(\large{ dimensionless }\) |

Tags: Water Equations Hydraulic Equations Soil Equations Geotechnical Equations