本計晝整合六個子計晝進行東沙環礁水動力與海岸地形變遷之研究。有三個子計晝 使用演變型緩坡方程式EEMSE (evolution equation of mild-slope equation)，淺水坡方程 式 SWEs (Shallow water equations)及布斯尼斯尼 BE (Boussinesq equation)之數值模式模 擬颱風波浪及亞重力波（infragrativity waters)通過東沙環礁之變形，並計算環礁海域二 維平面波場。有二個子計晝分別以二維近岸流水動力模式、漂砂與海岸地形變化模式及 三維 POM (Prince Ocean Modelling)及 ECOMSED (3-D hydrodynamic and sediment transport model)模擬環礁海域之潮流、水位堆升、近岸流流場、海岸漂砂及海岸地形變 化。有二個子計晝分別進行環礁波之潮流、環礁演化及漂砂觀測。 量測成果可作為數值模擬結果之校驗，總計晝研究成果可了解東沙環礁海域波潮流 水動力、海岸漂砂運移及海岸地形變化機制，提供東沙環礁研擬海岸侵蝕防禦策略之依 據，促進東沙環礁海域環境經營。 The 3-year integral project includes 6 subprojects to study hydrodynamics of wave induced setup, nearshore current, tidal current, sediment transport and coastal morphological changes. The frame structure of the integral project consists of numerical simulations and in-situ measurements at Dongsha Atoll waters. Waves propagating Dongsha fringing reef are described by 3 developed models, i.e., 2-D EEMSE (evolution equation of mild-slope equation) model, 2-D SWEs (Shallow waters equations) model and 1-D/2-D BE (Boussinesq equation) model. Wave induced setup, nearshore current and tidal current are simulated by nearshore hydrodynamics model of NCM (nearshore current model). Sediment transport are estimated by the wave and nearshore current fields and ECOMSED (3-D hydrodynamic and sediment transport) model. Coastal topographical changes are calculated using CMCM (coastal morphological changes model) based on continuity equation of sediment. In-situ measurements are performed to observe waves, tidal currents, nearshore currents and sediment transport to explore topographical changes of Dongsha Atoll waters. Research results provide valuable information to investigate characteristics of nearshore dynamics and morphological changes around Dongsha fringing reef. Proper countermeasures are proposed to prevent coastal erosion and management of sustainable environment of Dongsha Atoll.