Seepage Rate Calculator
Calculate water flow through porous media using Darcy's Law.
The permeability of the soil or material.
m/day
cm/s
ft/day
The total area perpendicular to the direction of flow.
Square Meters (m²)
Square Feet (ft²)
The difference in water levels (Head Loss).
Meters (m)
Feet (ft)
The thickness of the barrier or distance of seepage.
Meters (m)
Feet (ft)
Calculation Results
Hydraulic Gradient (i):
0.000
Seepage Rate (Daily):
0.00 m³/day
Seepage Volume (Liters):
0 L/day
Seepage Rate (Imperial):
0 gal/day
What is Seepage Rate?
Seepage rate is a measure of the volume of fluid (usually water) that passes through a porous medium over a specific period. This calculation is critical in geotechnical engineering, hydrogeology, and civil engineering for designing earthen dams, canals, reservoirs, and drainage systems. Understanding the seepage rate helps engineers prevent structural failures, piping, and excessive water loss.
How to Calculate Seepage Rate (Darcy's Law)
The most common method for calculating seepage rate in saturated soil conditions is Darcy's Law. The formula describes the flow of fluid through a porous medium.
Formula: Q = K × A × i
Where:
- Q = Seepage Rate (Flow Rate) in volume per time (e.g., m³/day).
- K = Hydraulic Conductivity (Coefficient of Permeability). This represents how easily water moves through the soil.
- A = Cross-Sectional Area of flow perpendicular to the direction of flow.
- i = Hydraulic Gradient, calculated as h / L.
- h = Hydraulic Head Difference (Head Loss).
- L = Length of the flow path (e.g., thickness of the dam or soil layer).
Understanding the Variables
Hydraulic Conductivity (K)
The 'K' value varies significantly based on soil type. It determines the velocity at which water can travel through the material.
- Gravel: High K (very permeable)
- Sand: Moderate K
- Clay: Very Low K (nearly impermeable)
Hydraulic Gradient (i)
The gradient is the driving force of the flow. It is the ratio of the head loss (pressure drop) to the distance the water travels. A higher water level on one side of a dam compared to the other increases the gradient and, consequently, the seepage rate.
Why Calculate Seepage?
Accurate seepage calculations are vital for:
- Dam Safety: Excessive seepage can wash away soil particles (piping), leading to dam failure.
- Excavation Sites: Estimating the amount of water that needs to be pumped out of a construction pit (dewatering).
- Environmental Containment: Ensuring that contaminants in a landfill do not seep into groundwater aquifers.
- Irrigation Efficiency: Calculating water loss through unlined canals.