하구및 연안생태Coastal management 2016 년 가을학기

Estuary Where river meets ocean Birth place of human culture places of navigation locations on their banks for towns and cities repositories for the effluent of industrial processes and domestic waste, or as Prime sites for land-claim to create sites for industry or urban development

연안 하구 물질 순환의 주요 요소

Major Estuaries Amazon Nile Mississippi Plume: history of water biotic richness greenish brown: more river input, broad shelf area

Estaurine history 5000 년 이내; Holocene; sea level peak after LGM; 이 시기 문명의 발달. 하구 덕분에? Sea level maximum after LGM (15k yr) “Cradle of civilization”; Rich biota + flooding cycles : bottomland soils and readily available freshwater Tabascan Mexico, Tigris-euphrates Nile, Yellow river China, Indus river

Estuarine survey at 1000 m 상류: 좁음 하류:넓고, 습지 Barrier islands Pass : 외부로 가면 1 km 정도에서 해수 색이 바뀜 내부에는 갯벌발달

하구의 특징 Complex Dynamic Biologically rich Dominated by physical forces  need knowledge in geology, hydrology, chemistry, physics and biology

Estuary definition “estuary” is of sixteenth century origin, derived from the Latin word aestuarium meaning marsh or channel. An estuary is a semienclosed coastal body of water that has free connection with the open sea and within which seawater is measurably diluted with freshwater derived from land drainage (Pritchard 1963). 연안 환경에 속하는 수역으로 강물이 바다로 유입하고 강의 어귀는 만의 형태를 이루어 해수가 조석작용에 의해 혼합 희석됨으로써 광염성 생물 종들이 서식할 수 있는 곳.

Estuary definition Fairbridge (1980) an estuary is an inlet of the sea reaching into a river valley as far as the upper limit of tidal rise, usually being divisible into three sectors: a) a marine or lower estuary, in free connections with the open sea; b) a middle estuary subject to strong salt and freshwater mixing; and c) an upper or fluvial estuary, characterized by freshwater but subject to strong tidal action. The limits between these sectors are variable and subject to constant changes in the river discharges

Pritchard (1963) and Fairbridge (1980) For Pritchard it is the upstream limit of salt penetration for Fairbridge it is the upstream limit of tidal penetration, which in an un-modified estuary will always be further inland.

Driving force determining salinity gradient in an estuary The salinity: seawater(35) coastal seas (33) tropical waters (37). salinity of estuarine waters: between 0.5 and 35; brackish, The balance between tide and freshwater determines salinity gradient twice-daily rhythm of the tides. The seawater that enters the estuary is then measurably diluted with freshwater flowing into the estuary from rivers.