An examination of extreme floods, effects on land-use change and seasonality in the lower St. Johns River Basin, Florida using HSPF and statistical methods

Samantha Kovalenko,Cigdem Akan,Alexandra Schonning,Christopher James Brown

doi:10.1007/s12665-021-10038-5

Abstract

As population growth and urbanization are steadily rising, the need for dependable flood estimation techniques is crucial. This study evaluates extreme flood events in select sub-basins of the Lower St. Johns River in Florida, USA. The study considers the effect of urbanization on the natural hydrologic processes and flood magnitudes in the watershed. Additionally, the effects of varying seasonality into the hydrologic modeling procedure are also investigated. This research focuses on determining the 10-, 25-, 50-, and 100-year return frequency flood flows in Julington Creek, Ortega River, and Pablo Creek of the Lower St. Johns River Basin in Florida, USA. The major findings of this research indicate that by implementing a range of flood estimation methods one can better describe the inherent uncertainty with traditional estimates. Also, the research showed that varying seasonality in the hydrologic modeling procedure does not result in vast differences in the resulting flood estimates. However, various land-use scenarios may produce simulated flood flows of greater magnitude—especially when a more urbanized land-use scenario is modeled.

Highlights

Extreme flood estimation techniques are a crucial necessity for all communities
The most complete set of flood estimates obtained in the Black Creek sub-basin were the 10to 50-year flood estimates using the 1995 land-use condition, median precipitation frequency values, uniform rainfall distribution, and antecedent moisture conditions
This research assessed the significance of seasonality and land-use change when developing hydrologic flood estimating models in Hydrologic Simulation Program – FORTRAN (HSPF) for the 10, 25, 50, and 100-year flood frequency estimates at Black Creek, Julington Creek, Durbin Creek, Big Davis Creek, Ortega River, and Pablo Creek

Summary

Introduction

Extreme flood estimation techniques are a crucial necessity for all communities. The research presented was conducted in order to better assess flood flow estimates for portions of the Lower St. Johns River in Florida, USA. It is hoped that presenting the work in this venue will provide the research to a wider audience ensuring it helps to improve the state-of-the-art in flood estimating. A small portion of the thesis work has already been published and presented by Kovalenko et al (2020). The new research extends the previous work by looking more deeply into seasonality of flow events in Northeastern Florida and by studying the effects of projected urbanization in the watershed on flood estimates. This paper presents flood estimates developed using the model code HSPF as well as multiple statistical methods suggested by the literature

Results

Discussion

Conclusion