A Groundwater Response Estimator to Investigate Pavement Vulnerability to Shallow Groundwater Rise in Coastal Alabama

Abstract Submission: Coastal areas are particularly vulnerable to sea level rise, which is the case of AL-180, in Fort Morgan Peninsula, AL. In addition, extreme rainfall events may overwhelm infrastructure such as roads and stormwater conveyance. However, most studies look at surface flooding or demand complex groundwater evaluations. Fewer studies focused on how water table levels impact pavements by reducing loading capacity through base course, sub-base, and subgrade saturation. This research aims to produce an intuitive data-based methodology for groundwater level estimation and apply it to evaluate the exposure of AL-180’s pavement to elevated shallow groundwater levels (SGWL). The framework is based on GWL response to rainfall, distance to water bodies, tidal level fluctuations, and GWL drawdown characteristics. Data from two wells along AL-180 were used (February 2023 to February 2024) to calibrate the proposed formulation, and a third well dataset was used for validation. Results show that the Nash-Sutcliff efficiency (NSE) varied from 0.7 to 0.8 when the first two locations, which data were used to produce the equation terms, were predicted. For the validation location, the maximum NSE was 0.58. In addition to the proposed framework, data-derived SGWL exceedance probability curves from the whole period indicated the pavement may be saturated for 10% of the time in 50 years because of Sea Level Rise. This research can help guide policies and decision-making regarding coastal roadway management.

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