How to Use This Tool
Enter all required site-specific data into the input fields, selecting the appropriate units for each measurement. Choose the dropdown options that best match your site’s soil type, coastal defenses, and aquifer configuration. Click Calculate to generate your risk assessment, or Reset to clear all inputs. Use the Copy Results button to save your assessment for reports or planning.
Formula and Logic
The risk score is calculated using a weighted sum of seven key environmental and operational factors, each normalized to a 0-100 scale:
- Distance from coast (25% weight): Higher risk for sites within 100km of the coastline, with score decreasing linearly to 0 at 100km.
- Groundwater depth (20% weight): Higher risk for shallow groundwater tables, with score decreasing linearly to 0 at 50m depth.
- Sea level rise rate (15% weight): Higher risk for faster sea level rise, capped at 10mm/year for maximum score contribution.
- Groundwater pumping rate (15% weight): Higher risk for increased pumping, capped at 1000 m³/day for maximum score contribution.
- Soil permeability (10% weight): High permeability soils score 10, medium 5, low 0.
- Coastal defense type (10% weight): No defenses score 10, seawalls 7, dune restoration 4, mangrove buffers 2.
- Aquifer type (5% weight): Unconfined aquifers score 5, semi-confined 2, confined 0.
Total risk score ranges from 0 (lowest risk) to 100 (highest risk). Contamination probability is derived by multiplying the total score by 0.95, and time to intrusion is calculated as (100 - total score) divided by the sea level rise rate.
Practical Notes
Saltwater intrusion risk varies significantly by regional coastal geography, local tidal patterns, and aquifer characteristics. This tool uses generalized global averages for permeability and aquifer behavior; consult local hydrogeological surveys for site-specific calibration. Emission factors and sea level rise projections vary by region, so pair results with local climate data for accuracy. Mangrove and dune-based defenses provide co-benefits for biodiversity and carbon sequestration, which are not quantified in this tool.
Why This Tool Is Useful
Coastal communities, farmers, and policymakers need accessible tools to assess climate-related groundwater risks without specialized software. This calculator provides a standardized, transparent risk assessment for non-experts, supporting informed decisions on land use, conservation planning, and infrastructure investment. It helps prioritize mitigation resources for high-risk sites and track changes in risk over time as sea levels rise or pumping rates change.
Frequently Asked Questions
How accurate is this risk assessment?
This tool provides a screening-level estimate based on widely accepted intrusion risk factors. It is not a substitute for site-specific hydrogeological modeling, which accounts for local aquifer geometry, tidal cycles, and historical water quality data.
What unit conversions are used for imperial measurements?
Imperial units are converted to metric standard units using fixed conversion factors: 1 mile = 1.60934 km, 1 foot = 0.3048 m, 1 inch/year = 25.4 mm/year, 1 gallon/day = 0.00378541 m³/day.
Can this tool be used for agricultural land assessments?
Yes, the calculator is designed for both coastal agricultural lands and residential/industrial sites. Shallow groundwater tables and high pumping rates common in agriculture are explicitly accounted for in the risk model.
Additional Guidance
Reassess risk annually as sea level rise rates and local pumping patterns change. Combine results with local groundwater salinity monitoring data to validate risk levels. For sites with critical risk scores, consult a licensed hydrogeologist to develop site-specific intrusion prevention plans, such as injection wells or reduced pumping schedules.