Groundwater Modeling

A simple groundwater model for a small site can be completed in 4-8 weeks. Regional aquifer models with detailed calibration typically take 3-6 months. Complex models involving contaminant transport or variable-density flow may require 6-12 months. Timeline depends on data availability, model complexity, and calibration requirements.

MODFLOW uses a finite-difference grid (rectangular cells) while FEFLOW uses finite elements (triangular/tetrahedral mesh). FEFLOW is better for complex geology, irregular boundaries, and problems requiring high resolution in specific areas. MODFLOW is often preferred for regional models and regulatory submissions. We recommend the appropriate tool based on your project needs.

Groundwater modeling requires geological/hydrogeological data (stratigraphy, aquifer properties), water level measurements, pumping records, recharge estimates, and boundary conditions. Pumping tests provide crucial aquifer parameters. We can work with existing data and recommend targeted field investigations to fill data gaps cost-effectively.

Yes, groundwater models can simulate contaminant transport when coupled with transport codes like MT3DMS or FEFLOW's transport module. These models predict how contaminants move through aquifers, helping design monitoring networks, evaluate remediation options, and assess risks to water supplies. Accurate transport modeling requires good characterization of aquifer properties.

Model calibration adjusts aquifer parameters (hydraulic conductivity, storage, recharge) until simulated water levels and flows match observed measurements. We use automated calibration tools like PEST alongside manual adjustments, targeting both steady-state and transient conditions. A well-calibrated model provides confidence in predictions for planning and design.

Safe yield is the amount of groundwater that can be sustainably extracted without causing unacceptable impacts like water level decline, reduced baseflow, or land subsidence. We determine safe yield through long-term model simulations that balance recharge with extraction while monitoring impacts on dependent ecosystems and existing users.

Wellfield design involves simulating different well configurations (number, spacing, depths, pumping rates) to optimize yield while minimizing interference between wells and impacts on neighboring users. Our models evaluate drawdown, capture zones, and long-term sustainability to recommend the most efficient wellfield layout.

A capture zone is the area from which groundwater flows to a pumping well. Capture zone analysis uses particle tracking in groundwater models to delineate wellhead protection areas and assess contamination risks. This is essential for protecting drinking water supplies and designing monitoring networks around production wells.

Groundwater and surface water are interconnected - rivers may gain water from aquifers (gaining streams) or lose water to aquifers (losing streams) depending on relative water levels. Our models simulate this interaction to assess impacts of pumping on streamflow, plan conjunctive use, and protect environmental flows.