The role of antecedent groundwater heads in controlling transient aquifer storage and flood peak attenuation in karst watersheds

Abstract

Transient storage of floodwaters in aquifers is known to attenuate peak flows in rivers and drive subsurface dissolution. Transient aquifer storage could be enhanced in watersheds overlying karst aquifers where caves facilitate surface and groundwater exchange. Few studies, however, have examined controls on, or magnitudes of, transient aquifer storage or flood peak attenuation in karstic watersheds. Here we evaluate flood peak attenuation with multiple linear regression analyses of 10 years of river and groundwater data from the Suwannee River, which flows over the karstic upper Floridan aquifer in north‐central Florida and experiences frequent flooding. Regressions show antecedent river stage exerts the dominant control on magnitudes of transient aquifer storage, with recharge and time to peak having secondary controls. Specifically, low antecedent stages result in larger magnitudes of transient aquifer storage and thus greater flood attenuation than conditions of elevated antecedent stage. These findings suggest subsurface weathering, including cave formation and enlargement, caused by transient aquifer storage could occur on a more frequent basis in aquifers where groundwater table elevation is lowered due to anthropogenic or climatic influences. Our work also shows that measures of groundwater table elevation prior to an event could be used to improve predictive flood models. © 2018 John Wiley & Sons, Ltd.

Quantifying Long‐Term and Event‐Scale Baseflow Effects across the Flood Frequency Curve

“…Because flood risk models use the historical record in its entirety for estimating parameters of a distribution, models may not capture the wide variability that could occur over short time scales due to reduction in flows and overall basin subsurface storage. Additionally, lowered water tables which result in reduced baseflow delivery can enlarge vadose zone storage increasing the amount of rainfall that can be stored during an event (Beven et al 1984) further affecting flow predictions (Verdi and Dixon 2011; Spellman et al 2019). Thus, further work using more detailed hydrological models to simulate groundwater changes and subsequent peak flow alterations due to the myriad of processes that groundwater elevation changes can cause would be of benefit to assess the time scales of groundwater flux changes and resulting alterations to the IAMF frequency curve.…”

“…In the event scale model, the IAMF data for all sites are related to primary catchment variables including the three‐day leading precipitation and drainage area as well as antecedent stage and rate of subsurface flux through the rising limb which serve as a proxy for basin wetness prior to an event (Spellman et al 2019) and basin permeability, respectively.…”

“…The antecedent discharge of a river can serve as a relative indicator of wetness of the basin prior to an event (Spellman et al 2019). The antecedent discharge was determined as the discharge immediately before the rising limb of the associated IAMF event using the continuous flow dataset obtained from USS NWIS online system.…”

A comparison of the hydrodynamic characteristics of surface runoff generated by flash floods in geologically different areas of the Bohemian Massif (crystalline rocks) and the western Carpathians (flysch)

“…For example, in the conditions of the Czech Republic, where in one part of the country (Bohemian Massif), there are mostly resistant crystalline rocks (but with aquiferous fractures), and in other parts, there are poorly permeable sedimentary rocks of the Flysch belt (western Carpathians). Much of the literature (Kourgialas and Karatzas, 2011;O'Connor et al, 2002;Spellman et al, 2019) has emphasised the fact that the geological environment may significantly contribute to the formation of riverine floods and thus form one of the basic factors that influence these events. We know that it can also affect flash floods in highly permeable rocks, i.e.…”

“…From this point of view, the most important role is played by superficial geology (Ruman et al, 2020). Direct effects are also notable due to the formation of a hydrogeological environment, which can have a significant retention capacity (Lauber et al, 2014;Spellman et al, 2019).…”