하구및 연안생태Coastal management 2015 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

History Geologically young < 5000yr Sea level maximum after LGM (15k yr) Human population have flourished ; 하구지역을 이용함으로서.. Tabascan lowland of mexico Nile valley Tigris-euphrates Yellow river Indus river

연안 하구 물질 순환의 주요 요소

Estuarine environment Estuaries are transition zones :differ from both in abiotic and biotic conditions. Temperature, salinity, and turbidity fluctuate on a daily basis and reach more extremes in estuarine waters than they do at sea or in rivers.  estuaries are highly productive ecosystems: coral reefs and mangrove swamps. An elevated productivity is maintained because of high nutrient levels in both sediment and water column.

Estuary for biologist Vital feeding areas for many species of birds, especially waders and wildfowl locations of coastal fisheries as fascinating areas present challenges to our understanding of how animals and plants adapt to their environment. the most productive natural habitats in the world

Estuary settings An estuary is a partially enclosed body of water formed where freshwater from rivers and streams flows into the oceans, mixing with the seawater. Although influenced by tides, estuaries are protected from the full force of the ocean waves, winds and storms by reefs, barrier islands or fingers of land, mud, and sand Can be bays, lagoons, harbors, and inlets or sounds.

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.