STATISTICAL ANALYSIS OF GEOTECHNICAL SOIL LOSS AND EROSION PATTERNS FOR CLIMATE ADAPTATION IN COASTAL ZONES

Abstract

This study addresses the pressing problem of quantifying geotechnical soil loss and shoreline erosion in coastal zones under contemporary hydro-climatic forcing, where planners need defensible evidence to design adaptation. The purpose is to explain spatial patterns of erosion by linking measurable substrate properties, exposure regimes, and land cover to decision-relevant outcomes. Using a geological-survey based, quantitative, cross-sectional, multi-case design, we analyzed four contrasting coastal cases instrumented with 76 shore-perpendicular transects, 380 laboratory soil tests, high-precision GNSS and GIS/remote-sensing products, hydro-meteorological reanalysis, and a parallel stakeholder survey of 418 respondents. A structured literature review of 64 peer-reviewed papers scoped variables and hypotheses. The sample comprised open sandy beaches, dune-backed barriers, marsh edges, and scarped bluffs. Key variables included erosion rate and a soil-loss index as outcomes, with predictors spanning runup proxies, significant wave height, rainfall intensity, vegetation cover, cohesion, median grain size, slope, and engineered defenses. The preregistered analysis plan progressed from data auditing, descriptives, and correlation screening to fixed-effects regression with cluster-robust inference, moderation tests, and robustness via GLM (Gamma/log), spatial error models, penalization, and quantile regression. Headline findings show runup exposure as the strongest positive correlate of erosion, rainfall intensity as a secondary contributor, and vegetation cover and soil cohesion as protective; critically, a negative Runup × Vegetation interaction indicates that vegetation buffers exposure effects. Upper-tail losses are disproportionately sensitive to exposure, slope, and substrate resistance. Implications include operational runup-aware monitoring, prioritization of nature-based measures where accommodation and supply permit, preservation of cohesive toes on bluffed coasts, and risk-tiered setbacks calibrated to directional exposure and morphology. Keywords: coastal erosion, soil loss, geological survey, cross-sectional analysis, vegetation buffering, runup exposure, cohesion, nature-based adaptation, spatial modeling, climate risk.