FLOOD06289 - Laserfiche WebLink

Home Browse Search

ing during their 15- to 50-year life span. Even so, they are more cost-effective than large structures, such as groin fields or segmented offshore breakwaters. These structures can also build or increase beach width as well as provide protection, but erosion can occur downdrift if they are not properly designed. Structures like seawalls, bulkheads, and revetments protect development, but are not intended to renourish or \".iden the beach. Erosion can occur in front of them because the natural movement of the shoreline has been affected. Such structures as breakwaters and jetties, which are designed to protect harbors and navigation channels from wave action or to stabilize inlets, can also cause erosion on the downdrift side if they do not include a sand- bypassing system. Because of their high cost, few shoreline protection projects have been built without federal assistance, although most coastal states and many com- munities have participated in various ways. Some states, notably North Caro- lina, have adopted policies against new structural shoreline protection projects, opting to allow the shoreline to retreat naturally. Others, such as Connecticut, discourage construction of new structural projects, but do not specifically pro- hibit them. Still others, such as New Jersey, have active structural protection programs. Some states have empowered localities to establish beach protection districts with the authority to collect taxes to fund long-term maintenance programs. Private landowners also use various techniques to forestall erosion and reduce damages. These measures are necessarily low-cost and small-scale: vegetation plantings, beach fill, breabvaters, groins, revetments, bulkheads, and seawalls. Land Treatment Measures Land treatment measures reduce overland runoff from agricultural lands to streams or other waters by improving infiltration of rainfall into the soil, slowing and minimizing runoff, and reducing the sedimentation that can clog stream channels or storage reservoirs. These techniques are most com- monly used in agricultural areas. They include maintaining trees, shrubbery, and vegetative cover; terracing; slope stabilization; using grass waterways; con- tour plowing; conservation tillage; and strip farming. Some measures involve building structures to retain or redirect runoff. Several land treatment meas- ures involve little additional cos: 0 the fanner, and some, such as no till or minimum tillage, actually red Ace costs. Technical and financial assistance for the more expensive techniques is often provided through public sources, par- ticularly programs of the U.S. Department of Agriculture. Although the impact of an individual measure is limited, extensive land treatment pro- grams can effectively reduce flooding in small headwater areas. ADJUSTING TO A RETREATING SHORELINE rVhtre relative sea level rise is accelerating, coastal Jlooding and erosion will also acceleTau, plLuing bil- lions oj dollars worth oj additional coastal properl)' at risk. The nation will thus haDe the options qf retreating from the shoreline, armoring it with pro- Uctive measures, or providing beach nourishmRnt. TIu lv'ational Park St!rvue's poluy is to allow natu- ral ]orces to cut on tlu shoreline rather than trying to prevent eroswn with structural devues. Tk state if lvorth CaroliT/.a has tnken a similar starue. Some federal agencus have limited the use oj structural measures on federal lands, but wkn it is ecorwmi- call.yjustifinhle and erwironmental?;' acceptable, the;' will still construct projects to protect existing coasltll develofrmeni. Likewise, many states limit stnu:tures in undeveloped OT lightly deveWped cOaJtal areas, but continue [.0 permit structural projects to protect exist- ing development. The COaJtal Barrier Resources Act excluded tlu use of federal funds in "undeveloped" coastal regums. ... / Rtsroralio/1 0/ beach vegtli11ion. is one means 'if slowing bUKh (lrmon. and transport Be(lt;h gran planting by volun./m"s ro prt.fffl/f Ja,ld dunes, ,Vnvl.l1<1)'porl, A1asmchusdls - 39