Karst Feature Calculator

Sinkhole risk from limestone depth and water table.

Limestone thickness (m)

Depth to bedrock (m)

Water table depth (m)

Annual rainfall (mm)

Average temperature (°C)

Tab to move between fields

Sinkhole susceptibility (0-100)

63.23

Risk category (0-3)2

Dissolution rate (mm/kyr)41.25

Time to dissolve (kyr)1,212

Cavity volume (m³/kyr/ha)20.63

CO₂ factor1.83

How to Use This Calculator

Enter Limestone thickness (m) from geologic maps or borehole logs.
Set Depth to bedrock (m) — the thickness of soil or sediment overlying the limestone.
Enter the Water table depth (m) from surface; when the water table sits within the limestone, sinkhole risk increases sharply.
Input Annual rainfall (mm) and Average temperature (°C) for the site.
Interpret the Sinkhole susceptibility index (0–100) and Risk category (0=Low to 3=Very High) to guide site assessment decisions.

How the result changes with Water table depth (m)

Limestone thickness (m): Total thickness of the soluble carbonate rock layer.
Depth to bedrock (m): Thickness of soil/sediment overburden above the limestone.
Water table depth (m): Depth from surface to the water table.
Annual rainfall (mm): Total annual precipitation in millimeters. More rain = faster dissolution.
Average temperature (°C): Mean annual temperature. Warmer climates have higher CO2 in soil water.

Sinkhole susceptibility (0-100): Composite index of sinkhole formation risk. Higher = more susceptible.
Risk category (0-3): 0=Low, 1=Moderate, 2=High, 3=Very High sinkhole risk.
Dissolution rate (mm/kyr): Estimated limestone surface lowering rate in mm per thousand years.
Time to dissolve (kyr): Very rough estimate of time to dissolve through the entire limestone thickness.
Cavity volume (m³/kyr/ha): Estimated rate of underground cavity development per hectare.
CO₂ factor: Relative CO₂ partial pressure factor driving dissolution aggressiveness.

Identify Input Parameters
4 parameters
Limestone thickness (m) = 50, Depth to bedrock (m) = 10, Water table depth (m) = 15, Annual rainfall (mm) = 1000 = 5 input(s) provided
Calculate Sinkhole susceptibility
Sinkhole susceptibility = min(100, max(0,
63.23 = 63.23
Calculate Risk category
Risk category
2 = 2
Calculate Dissolution rate
Dissolution rate = 20 * (annualRainfall / 1000) * pCO2Factor *
41.25 = 41.25