Nearshore Berm Sediment Transport & Migration: Measurements & Modeling. Nearshore Berm Workshop 13 February 2013

Transcription

1 Nearshre Berm Sediment Transprt & Migratin: Measurements & Mdeling Nearshre Berm Wrkshp 13 February 2013

2 Reprt Dcumentatin Page Frm Apprved OMB N Public reprting burden fr the cllectin f infrmatin is estimated t average 1 hur per respnse, including the time fr reviewing instructins, searching existing data surces, gathering and maintaining the data needed, and cmpleting and reviewing the cllectin f infrmatin. Send cmments regarding this burden estimate r any ther aspect f this cllectin f infrmatin, including suggestins fr reducing this burden, t Washingtn Headquarters Services, Directrate fr Infrmatin Operatins and Reprts, 1215 Jeffersn Davis Highway, Suite 1204, Arlingtn VA Respndents shuld be aware that ntwithstanding any ther prvisin f law, n persn shall be subject t a penalty fr failing t cmply with a cllectin f infrmatin if it des nt display a currently valid OMB cntrl number. 1. REPORT DATE 13 FEB REPORT TYPE 3. DATES COVERED t TITLE AND SUBTITLE Nearshre Berm Sediment Transprt & Migratin: Measurements & Mdeling 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) U.S. Army Crps f Engineers,Jacksnville District,701 San Marc Bulevard,Jacksnville,Fl, PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR S ACRONYM(S) 12. DISTRIBUTION/AVAILABILITY STATEMENT Apprved fr public release; distributin unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT 11. SPONSOR/MONITOR S REPORT NUMBER(S) 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT a. REPORT unclassified b. ABSTRACT unclassified c. THIS PAGE unclassified Same as Reprt (SAR) 18. NUMBER OF PAGES 18 19a. NAME OF RESPONSIBLE PERSON Standard Frm 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18

3 Definitins Crss-shre Transprt Vs. Alngshre Transprt Onshre migratin Where is the beach accreting? Adjacent beach r regin f nurishment Hw much is it accreting by? Shreline change r prfile vlume What is the lng-term fate f the material? Carser Finer

4 Large-scale Sediment Transprt Facility 0 LRB1, t = 60 min 36 LRB1, t = 60 min Nrmalized Red Intensity g 6 ~ «! '0 c: 8 8 c ~ 10 '0 a. :::) 12 ~ Q) g 14 «! (ij 0 :::- 16 > Alngshre Prcesses: Lngshre current-driven advectin Crss-shre Prcesses: Wave-driven diffusin acrss the surf zne X(m) Dr. Ernest Smith, CHL (Funded by LRB)

5 3-ft Wave Flume: Crss-shre Sediment Transprt March m l Om 16, l-----~, Par11clt Diameter lmm) Alngshre Prcesses: Lngshre current-driven advectin Crss-shre Prcesses: Wave-driven diffusin acrss the surf zne I Test 5 I Run 31 Meters -...,- 2.5 Tanya Beck, CHL (Funded by CHL-IRIP)

6 The Variatin f Placement Types Large, Designed Migratinal Placements Perdid Key (SAM) Shark River Inlet (NAN) Brunswick (SAS; DOER) Small Dispersive Placements Assateague Island, MD (NAB) Bensn Beach Beneficial Use Placement; Nrth and Suth Jetty Placements at MCR (NWP)

7 Research Supprted Mnitring Prjects in Cllabratin with SAJ & SAM Jan 2013 Cmplete

8 Native Berm Perdid Key Swash Zne Berm (Jan 2012) Westward Alngshre Spreading in Prfile Accreted Berm Pst-Debbie Placed Swash-zne Berm Sediment grades carser away frm inlet; fill is unifrm inlet material Fllwing placement, shreline erdes landward and shreface accretes Rapid migratin furthest frm the inlet; lwest ersin rates near the ebb shal Alngshre spreading thrugh the nearshre prfile Inlet shreline changes nt substantial; limited bayside mnitring

9 Perdid Key Swash Zne Berm (Jan 2012) Vlume Change <-0.01% +9% -18% 6 Mnth Vlume Calculatin Accurate means f determining sand vlume within and adjacent t the nurished area Quantitative methd t describe the mvement f material

10 Ft. Myers Nearshre Berm (Jun 2009) Fine sediment fund in trugh and ffshre fr 1st year; 2nd year nne in trugh, and carsening f berm/trugh t native grain size as migrating PreMarch 2012 April 2010 Cnstructin Berm migrated 150 ft/yr; characteristic f an asymmetric nshre migrating bar Gaps in berm migrated alngshre, but there was little alngshre spreading Little effect n shreline respnse (lw-wave energy) July 2012 Pst-Cnstructin September (June 2009) 2011 BUILDING STRONG Overall, predminantly mbile in the crss-shre, with mderate alngshre spreading

11 New Smyrna Nearshre Placement (Aug 2012) RADAR INLET OBSERVING SYSTEM: Remtely acquired waves, currents, and bathymetry RIOS sandbar swash Placement lcatins

12 New Smyrna Nearshre Placement (Aug 2012) Nearshre placement (depth and height abve bttm) rarely influences lcal wave field Little t n measureable increase in the bed elevatin due t placement activities N measurable indicatin f shreline r sandbar respnse (accretin r ersin) in prximity f placement

13 Desktp Planning Tl: Nearshre Berm Calculatr (NBC) Planning-Scping Tl Estimates placement depth (based n wave-limited crssshre transprt) Calculates psitin and design frm userdefined parameters and castal engineering design practices Autmated wave parameter extractin; user-defined beach prfile; draft depth and placement limitatins based n dredge

14 CMS Mdeling Validated 2DH Castal Mdel that simulates vertical variatin f hrizntal velcities and includes mixed sands 1D Castal Mdel validated fr ersin/accretin in the crss-shre fr bth East and West Cast Applicatins Surf Zne Prcesses: Undertw Stkes Drift Wave Asymmetry Separated Bed and Suspended Lad CShre

15 Gals fr Nearshre Berm R&D What are we ging t get ut f ur mnitring effrts? What d these tls prvide?

16 Summary A need exists fr imprved predictin f nearshre placement behavir, and a mre cmprehensive understanding fr guidance n placement types and the varius envirnmental factrs influencing lng-term perfrmance Basic design parameters exist [depth limits, gap spacing, end slpes], but are insufficient in predicting perfrmance Dcumentatin is very limited Labratry experiments islate varius parameters and analyze that part f sediment transprt and mrphlgy change Varius nearshre placement activities have been mnitred fr necessary dcumentatin, and t better define perfrmance metrics. Key Factrs include: Crss-shre transprt rates fr a given wave climate and ambient sediment transprt Alngshre spreading f placement material under varius envirnmental frcings Tempral incrpratin int natural castal mrphlgy (beach prfile) Displacement/migratin f cncentrated fines

17 Thank Yu Tanya M. Beck Phne: (601) Julie D. Rsati Phne: (251) Kelly R. Legault Phne: (904)

18 Questins t Discuss Are there studies with the perfrmance f material with different % fines in similar placement areas and wave climate, t determine what % fines wrks and what desn't? Hw d we knw what will happen if we place material alng a stretch f beach that has nt be mdeled r analyzed? Hw d we knw that what wrked in ne area (e.g. new Smyrna) will wrk in anther (e.g. Melburne)? Hw can we crrelate these?

19 Questins t Discuss Hw many O&M prjects in FL actually have viable quantities f exclusively nearshre cmpatible material per state standards? (ie beach quality, except fines between 10 & 20 %) If the majrity f material is beach quality, in rder t justify nearshre placement using small equipment such as the Currituck, quantify the ecnmic and eclgic benefit f utilizing small scale "strategic" dredging t hit just critical shals and expanding the interval between large scale dredging events at the prject (maybe g frm 3 t 5 years between large scale, traditinal dredging events with beach placement). Hw des this crrespnd t the funding envirnment the Crps currently faces, especially fr shallw draft nav prjects.