Oregon Inlet, North Carolina—A History of Coastal Change

OREGON INLET, NORTH CAROLINA— A HISTORY OF COASTAL CHANGE Robert Dolan and Robert Glassen* INTRODUCTION. Th e co ntinu ed inv estig atio n o f sand y inlets alo ng b arrier island s is o f fu nd am ental im p o rtance to g eo m o rp ho lo gists, g eo l­ o gists, and co astal eng ineers. Th e sed im entary d ep o sits asso ciated w ith the m ig ratio n and clo sure o f co astal inlets rep resent a sig nificant seg­ m ent o f the g eo lo g ic histo ry o f b arrier island s, and the u nstable nature o f these featu res has b een a challeng e to eng ineers fo r d ecad es. Fo r this stud y , a ty p ical u nstable inlet alo ng th e O u ter Banks o f N o rth C aro lina has b een iso lated . T h e p u rp o se is to d escrib e th e tem p o ral resp o nses o f the inlet to fo rces o n a hig h energ y co ast, and to co u p le these resp o nses to the m ajo r inlet-shap ing p ro cesses in o rd er to d em o nstrate ho w their in teractio n results in sp ecific in let co nfig uratio ns. THE INLET. O reg o n In let, sep arating Bo d ie Island fro m Pea Island o n N o rth C aro lin a’s O u ter Banks (Fig u re 1), w as first reco rd ed in 1585. This inlet’s histo ry has b een o ne o f m ig ratio n and p erio d ic clo sure. Th e p resent d ay in let w as re-o p ened b y a sto rm o n Sep tem b er 8, 1846, and nam ed fo r o ne o f th e first b o ats to p ass thro ug h it, the steam er “O reg o n.” (1) To d ay , the inlet’s unco ntro lled m ig ratio n is threatening a fixed -sp an hig hw ay b rid g e as w ell as recreatio nal d ev elo p m ents o n the ad jacent sho res. Rap id sho aling is ano ther p ro blem w hich ham p ers use o f the inlet. T h e A rm y C o rp s o f Eng ineers stated that, . . . the existing p ro ject channel d ep th o f 14 feet acro ss the o cean b ar at O reg o n In le t is n o t d eep eno ugh no r stab le eno ug h fo r safe nav ig atio n by th e o p erato rs o f co m m ercial fishingv essels . . . co m m ercial fishing -v essel insu rance und erw riters d o n o t co nsid er O reg o n In let an ap p ro v ed w ater co urse. (2) T h e in let is “no t reco m m end ed to strang ers” and “requ ires co ntinuo us d red g ing .” (3) O p erato rs o f sp o rt fishing b o ats m ust nav ig ate aro und larg e sho als in o rd er to reach the sea. M any bo atm en hav e blam ed the recen t d ev elo p m ent o f these sho als o n the co nstru ctio n in 1964 o f the Bo nn er H ig hw ay Brid g e (Fig u re 2). THE BARRIER ISLAND-INLET SYSTEM. C o astal inlets p ro v id e the co nnectio n betw een th e o cean and the lag o o...