FLOOD07520

• County: Statewide
• Basin: Statewide
• Title: Roughness Coefficients for Densely Vegetated Flood Plains
• Date: 1/1/1987
• Prepared By: USGS
• Floodplain - Doc Type: Floodplain Report/Masterplan

CONTENTS

Page

Symbols and units--------------------------------------------------- V
Introduction-------------------------------------------------------- 1
Methods examined---------------------------------------------------- 3
Vegetation density------------------------------------------------ 3
Roughness concentration------------------------------------------- 6
Estimating procedure---------------------------------------------- 8
Regression analysis----------------------------------------------- 9
Summary of methods-------------------------------------------------- 11
Collection of data-------------------------------------------------- 12
Analysis of data---------------------------------------------------- 16
Discussion of results----------------------------------------------- 21
Conclusions--------------------------------------------------------- 29
References cited---------------------------------------------------- 31
Other literature reviewed------------------------------------------- 33
Hydrologic data----------------------------------------------------- 35
ILLUSTRATIONS

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Flow resistance model----------------------------------- 3
Pea Creek near Louisville, Ala., cross section 2-------- 15
Plot of effective-drag coefficient versus hydraulic
radius for wide, wooded flood plains using
verified n values------------------------------------ 21
Plot of computed n by vegetation-density method versus
verified n values------------------------------------- 24
Plot of n versus roughness concentration using Tseng's
flume data and field data----------------------------- 26
Plot of effective resistance using field data and a
C* = 1.25--------------------------------------------- 28

Plot of effective-drag coefficient versus hydraulic
radius using Tseng's flume data and field data-------- 29
Pea Creek near Louisville, Ala., cross section 4-------- 37
Pea Creek near Louisville, Ala., cross section 5-------- 38
Yellow River near Sanford, Ala., cross section 2-------- 39
Yellow River near Sanford, Ala., cross section 12------- 40
Poley Creek near Sanford, Ala., cross section 2--------- 41
Poley Creek near Sanford, Ala., cross section 3--------- 42
Poley Creek near Sanford, Ala., cross section 4--------- 43
Poley Creek near Sanford, Ala., cross section 5--------- 44
Yockanookany River near Thomastown, Miss.,
cross section 300------------------------------------ 45
Yockanookany River near Thomastown, Miss.,
crosS section 400------------------------------------- 46
Yockanookany River near Thomastown, Miss.,
crosS section 500------------------------------------- 47
Coldwater River near Red Banks, Miss.,
cross section 2, sample area 1------------------------ 48
Coldwater River near Red Banks, Miss.,
croSS section 2, sample area 2------------------------ 49

III