Compound flood modeling framework for surface–subsurface water interactions

• Published in: Natural hazards and earth system sciences Vol. 22; no. 3; pp. 775 - 793
• Main Authors: Peña, Francisco, Nardi, Fernando, Melesse, Assefa, Obeysekera, Jayantha, Castelli, Fabio, Price, René M, Crowl, Todd, Gonzalez-Ramirez, Noemi
• Format: Journal Article
• Language: English
• Published: Katlenburg-Lindau Copernicus GmbH 10.03.2022; Copernicus Publications
• Subjects: Analysis; Aquifers; Coastal flooding; Coastal inlets; Coasts; Creeks & streams; Elevation; Flood risk; Flooding; Floods; Future climates; Geomorphology; Groundwater; Groundwater table; High tide; Hydrology; Impact damage; Infiltration; Infiltration capacity; Karst; Land surveys; Mathematical models; Modelling; Numerical models; Physics; Precipitation; Rain; Risk assessment; River discharge; River flow; Sea level; Sea level changes; Sea level rise; Shallow water; Social interactions; Soil; Soil absorption capacity; Soil infiltration; Soil water; Soils; Storm surges; Storms; Subsurface water; Topography; Two dimensional models; Urbanization; Water levels; Water table; Water, Underground; Everglades; Florida; United States > US; Biscayne Bay
• ISSN: 1684-9981; 1561-8633; 1684-9981
• DOI: 10.5194/nhess-22-775-2022

Compound floods are an active area of research in which the complex interaction between pluvial, fluvial, coastal and groundwater flooding are analyzed. A number of studies have simulated the compound flooding impacts of precipitation, river discharge and storm surge variables with different numerical models and linking techniques. However, groundwater flooding is often neglected in flood risk assessments due to its sporadic frequency (as most regions have water tables sufficiently low that do not exacerbate flooding conditions), isolated impacts and considerably lower severity with respect to other types of flooding. This paper presents a physics-based, loosely coupled modeling framework using FLO-2D and MODFLOW-2005 that is capable of simulating surface–subsurface water interactions. FLO-2D, responsible for the surface hydrology and infiltration processes, transfers the infiltration volume as recharge to MODFLOW-2005 until the soil absorption capacity is exceeded, while MODFLOW-2005 returns exchange flow to the surface when the groundwater heads are higher than the surface depth. Three events characterized by short-duration intense precipitation, average tide levels and unusually high water table levels are used to assess the relevance of groundwater flooding in the Arch Creek Basin, a locality in North Miami particularly prone to flooding conditions. Due to limitations in water level observations, the model was calibrated based on properties that have experienced repetitive flooding losses and validated using image-based volunteer geographic information (VGI). Results suggest that groundwater-induced flooding is localized, and high groundwater heads influence pluvial flooding as the shallow water table undermines the soil infiltration capacity. Understanding groundwater flood risk is of particular interest to low-elevation coastal karst environments as the sudden emergence of the water table at ground surface can result in social disruption, adverse effects to essential services and damage to infrastructure. Further research should assess the exacerbated impacts of high tides and sea level rise on water tables under current and future climate projections.