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2 Floodplain Issues In Transportation Design Training Seminar.

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Presentation on theme: "2 Floodplain Issues In Transportation Design Training Seminar."— Presentation transcript:

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2 2 Floodplain Issues In Transportation Design Training Seminar

3 I. 3 Before we start…... Restrooms Fire Exits Water/soda machines Discussion/Comments/Questions Lunch Accreditation

4 I. 4 Presenters Information Bill Jenkins, ADWR Phone: (602) Chuck Williams, CL Williams Consulting Phone: (928) Jon Fuller, JE Fuller Hydrology & Geomorphology Phone: (480) John Wise, Stantec Consulting Phone: (520) LTAP (Local Technical Assistance Program) Annie Parris Phone: (602)

5 I. 5 Course Outline 8:00 am – Start I. Introduction – (15 minutes) II. Overview of Regulations – (30 minutes) IV. Overview of State Standards - (15 minutes) V. Flood Hydrology and Floodplain Hydraulics – (30 minutes) 9:45 am – Break (15 minutes) V. Flood Hydrology and Floodplain Hydraulics Continued – (40 minutes) VI. River Engineering and Geomorphology – (60 minutes) 11:40-12:50 pm – Lunch (70 minutes) VII. Effects of Transportation Structures on Fluvial Systems – (30 minutes) VIII. Overview of Design Guidelines – (30 minutes) 3:00 pm – Break (15 minutes) X. Illustrated Examples Continued – (90 minutes) 4:45 pm – Open Discussion/Comments/Questions (15 minutes) III. Overview of ADWR/ADEM Roles – (15 minutes) IX. Design Process – (55 minutes) X. Illustrated Examples – (15 minutes)

6 I. 6

7 I. 7 I. Introduction A.Purpose of Course 1.Introduce Floodplain Concepts in Transportation Design 2.Familiarize Students with Floodplain Regulations Important for Transportation Design 3.Introduce Technical References for Design and Analysis of Transportation Structures in Floodplains 4.Review Design Examples of Transportation Structures in Floodplains

8 I. 8 Mississippi River Channel near Commerce, Missouri. The river’s surface area was reduced by 50% in this area from 1884 to 1968 due to both natural reasons and development work reasons. HDS6-01 (Sections 1.2.1). I. Introduction B.General Description of Floodplain Issues in Transportation Design 1.Rivers are Naturally Dynamic

9 I. 9 I. Introduction B.General Description of Floodplain Issues in Transportation Design 1.Rivers are Naturally Dynamic River changes can affect transportation structures. Rivers may change due to: Shortened flow paths (cutoffs) making rivers less “curvy” and increase streambed slopes and velocities.

10 I. 10 The river may no longer “want” to cross under an existing bridge, but would “prefer” a crossing elsewhere causing erosion and scour of upstream abutments and embankments.

11 I. 11 I. Introduction B.General Description of Floodplain Issues in Transportation Design 1.Rivers are Naturally Dynamic River changes can affect transportation structures. Rivers may change due to: Shortened flow paths (cutoffs) making rivers less “curvy” and increase streambed slopes and velocities. Structural projects, such as transportation construction projects, may induce river changes.

12 I. 12 I. Introduction 1.Rivers Are Naturally Dynamic River changes may be induced by human activities including: channel alterations (i.e.,straightening, dredging, clearing) land use changes (i.e., urbanization, agriculture, mining, and logging) streambed mining/excavation construction of dams or reservoirs River changes can propagate upstream or downstream, sometimes quickly, sometimes over long periods.

13 I. 13 Examples of Watercourse Straightening

14 I. 14 Examples of Watercourse Changes with Time

15 I. 15 I. Introduction B.General Description of Floodplain Issues in Transportation Design 1.Rivers are Naturally Dynamic River changes can affect transportation structures. Rivers may change due to: Shortened flow paths (cutoffs) making rivers less “curvy” and increase streambed slopes and velocities. Structural projects, such as transportation construction projects, may induce river changes. Also: hydrologic change, geological shifting (such as uplift or warping of earth’s surface), climatic fluctuations (droughts, floods), erosion and deposition at bends, or in some cases even sea level changes.

16 I. 16 In summary, archaeological, botanical, geological, and geomorphic evidence supports the conclusion that: most rivers are subject to constant change as a normal part of their morphologic evolution. “Therefore, stable or static channels are the exception in nature.” HDS6-01 (Sections 1.2.1)

17 I. 17 I. Introduction B.General Description of Floodplain Issues in Transportation Design 1.Rivers are Naturally Dynamic 2.Example of Bridge Crossing Effects: Bridge crossings are among the most common types of river encroachments.

18 I. 18 I. Introduction B.General Description of Floodplain Issues in Transportation Design 1.Rivers are Naturally Dynamic 2.Example of Bridge Crossing Effects: Bridge crossings are among the most common types of river encroachments. Some Possible Immediate Responses: Bridge construction may cause a contraction leading to local scour, water level changes (backwater), lateral instability, bank erosion, abutment scour erosion, and deposition downstream.

19 I. 19 This watercourse may be shifting to accommodate the available flow path under the bridge.

20 I. 20 Scour Protection for the Abutment was necessary to protect the bridge.

21 I. 21 I. Introduction B.General Description of Floodplain Issues in Transportation Design 1.Rivers are Naturally Dynamic 2.Example of Bridge Crossing Effects: Bridge crossings are among the most common types of river encroachments. Some Possible Immediate Responses: Bridge construction may cause a contraction leading to: local scour, water level changes (backwater), lateral instability, bank erosion, abutment scour erosion, and deposition downstream. Some Possible Delayed Responses: Constrictions may cause higher local velocities, which may affect tributaries, the main channel, and other transportation crossings.

22 I. 22 Resulting erosion and soil degradation in channels may adversely affect other transportation crossings of the tributaries or main channel.

23 I. 23 Some Worst Case Results For Bridges

24 I. 24 Some Worst Case Results For Bridges

25 I. 25 [Handout 16 Pictures from Table 9.1 of HDS6-01]

26 I. 26 I. Introduction B.General Description of Floodplain Issues in Transportation Design 1.Rivers are Naturally Dynamic 2.Example of Bridge Crossing Effects: 3.Example of Culvert and Dip Crossing Effects: Culverts and dip crossings may not be of such grand scale as a bridge, but are a far more common type of roadway crossing improvement.

27 I. 27 Example of Culverts

28 I. 28 I. Introduction B.General Description of Floodplain Issues in Transportation Design 1.Rivers are Naturally Dynamic 2.Example of Bridge Crossing Effects: 3.Example of Culvert and Dip Crossing Effects: Culverts and dip crossings may not be of such grand scale as a bridge, but are a far more common type of roadway crossing improvement. Some Possible Responses to culvert and dip section designs may include sedimentation, streambed degradation, increased magnitudes and frequencies of flooding upstream, or undermining of roadway foundations.

29 I. 29 Some Worst Case Results For Culverts

30 I. 30 Some Worst Case Results For Culverts

31 I. 31 C.Examples of cases that demonstrate floodplain issues, problems and constraints Nowood River near Ten Sleep, Wyoming I. Introduction

32 I. 32 C.Examples of cases that demonstrate floodplain issues, problems and constraints Nowood River near Ten Sleep, Wyoming Lee Moore Wash near Sahuarita, Arizona I. Introduction Lee Moore Wash Crossing – After

33 I. 33 Lee Moore Wash Crossing – After

34 I. 34 I. Introduction D.Design Process Preview (a.k.a. An ounce of prevention, is worth a pound of cure!) Overview of Design Guidelines A. Bridge Design B. Culvert Design C. Dip Crossing Design D. Low-Flow Channel Crossing Design Overview of Design Process A. Project Initiation B. Principal Factors to be Considered in Design C. Resources (Data checklists and sources)

35 I. 35 I. Introduction E.FITD Class CD Preview Class CD provides a searchable data base of reference literature Interactive browser (Electronic Navigator) assists learning about key issues in the design of roadways and other transportation structures in floodplain environments Issues are arranged by topic Direct links open relevant documents listed under each topic CD suggests websites to monitor for document updates

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