WRIR 02-4254


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Lewelling, B.R., 2003, Extent of Areal Inundation of Riverine Wetlands Along Cypress Creek and the Peace, Alafia, North Prong Alafia, and South Prong Alafia Rivers, West-Central Florida: U.S. Geological Survey Water-Resources Investigations Report 02-4254, 91 p.

ABSTRACT:

Riverine and palustrine system wetlands are a major ecological component of river basins in west-central Florida. Healthy wetlands are dependent upon the frequency and duration of periodic flooding or inundation. This report assesses the extent, area, depth, frequency, and duration of periodic flooding and the effects of potential surface-water withdrawals on the wetlands along Cypress Creek and the Peace, Alafia, North Prong Alafia, and South Prong Alafia Rivers. Results of the study were derived from step-backwater analysis performed at each of the rivers using the U.S. Army Corps of Engineers Hydrologic Engineering Center-River Analysis System (HEC-RAS) one-dimensional model. The step-backwater analysis was performed using selected daily mean discharges at the 10th, 50th, 70th, 80th, 90th, 98th, 99.5th, and 99.9th percentiles to compute extent of areal inundation, area of inundation, and hydraulic depth to assess the net reduction of areal inundation if 10 percent of the total river flow were diverted for potential withdrawals.

The extent of areal inundation is determined by cross-sectional topography and the degree to which the channel is incised. Areal inundation occurs along the broad, low relief of the Cypress Creek floodplain during all selected discharge percentiles. However, areal inundation of the Peace and Alafia Rivers floodplains, which generally have deeply incised channels, occurs at or above discharges at the 80th percentile. The greatest area of inundation along the three rivers generally occurs between the 90th and 98th percentile discharges. The decrease in inundated area resulting from a potential 10-percent withdrawal in discharge ranged as follows: Cypress Creek, 22 to 395 acres (1.7 to 8.4 percent); Peace River, 17 to 1,900 acres (2.1 to 13.6 percent); Alafia River, 1 to 90 acres (1 to 19.6 percent); North Prong Alafia River, 1 to 46 acres (0.7 to 23.4 percent); and South Prong Alafia River, 1 to 75 acres (1.5 to 13.4 percent).

TABLE OF CONTENTS

Abstract
Introduction

Purpose and Scope
Previous Investigations
Acknowledgments
Description of Study Area
Methodology
Cypress Creek
Peace River
Reach 1–Arcadia to Zolfo Springs
Reach 2–Zolfo Springs to Fort Meade
Reach 3–Fort Meade to Bartow
Inundated Area and Effects of Potential Discharge Withdrawals Along the Three Peace River Reaches
Alafia River System
Alafia River
North Prong Alafia River
South Prong Alafia River
Inundated Area and Effects of Potential Discharge Withdrawals Along the Alafia River System
Summary
Selected References
Appendices: A through T