하구및 연안생태Coastal management 2015 년 가을학기

Estuarine geomorphology and physical oceanography Circulation patterns Stratification Mixing and flushing Time scale; when hydrodynamic changes occur quickly relative to biological, geological and chemical transformations Dominant controlling factors for estuarine ecological processes Organizing of estuary Classification of estuary Physical characteristics of estuary

Glaciation cycles LGM; 15,000 yr Current level in 5000 yr Estuaries are common in broader coast line: 80~90% east coast of US; 10~20 % in west coast. During glaciation period, estuaries are rare !! Because sea level is in continental shelf During last 1 My, only 10~20% of the time presented in current conditions current estuaries  filled with sediment  quickly disappear; for geological point of view “extremely short !” In current condition. Takes 9,500 yr to fill up Fill-up didn’t happen, because, sea level rise + erosion of sediment

From lagoons to deltas Geological development of estuary Glaciation cycling Sediment supply Climate variability Regional and local geology Marine energy input; wave + tides Lagoons : marine wave actions; behind barrier island; sand sized sediments; S. Texas Deltas: produced by river processes Protrude into a receiving basin Fine grained silt sediments Estuarine lagoon, estuaries, estuarine deltas ;wave energy + river input combinations

From lagoons to deltas Davis (1973) continuum of estuarine types : from lagoons to delta. Lagoons : marine wave actions; behind barrier island; sand sized sediments; S. Texas Deltas: produced by river processes Protrude into a receiving basin Fine grained silt sediments Estuarine lagoon, estuaries, estuarine deltas ;wave energy + river input combinations

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.

A new defnition (Day et al.1987) An estuarine system is a coastal indentation that has a restricted connection to the ocean and remains open at least intermittently. tidal river zone mixing zone Near shore turbid zone; between mixing zone and the seaward edge of the tidal plume at full ebb tide  included adjacent coastal waters

Dynamic boundaries Boundaries change position continuously Tidal cycles; spring neap tides Annual cycles Geologic time scale Freshwater discharge some estuaries does nto have all the zones Cancun bay; no tidal river Amazon river; no mixing zone