Combined with the Pinghaiwan Bay sea area planning, and through the investigation of geological features , bathymetry, sediment sampling and analysis on the bay beaches, test and data analysis of marine hydrology and sediment, the application of sea sediment movement analysis and other comprehensive means like the comparative analysis of the old and new maps and documents, the research results showed that; no larger rivers or creeks flow into the Pinghai Bay; the land area and the sea area only get a small amount of sand input; sediment activities are modest in the waters and on the beaches. Hydrodynamic conditions in the bay are relatively weak, seabed sediments are mainly composed of clayey silt, and the northeastern part of shallow coastal waters to the Pinghai village nearshore at the bay mouth are composed of coarse sand and sandy silt sediment. Beaches within the bay as a whole is in a basically stable state, but the inner bay tidal flats and the northern and eastern shore beaches of the inner bay are in a weak siltation state; net volume of wave sediment transport to bay head is 5. 37 × 10 m /a, while the west side and southwest beach is in a weak erosion state, and net volume of wave sediment transport from Shanbing village southward to out-bay is 1. 97 × 104m3/a. But the overall coastal retrogradation rate is quite slow. In the 37 years from 1970 to 2007, the inner bay belt within 5m depth of sea water displayed a weak siltation trend, with a siltation rate of only 0. 018 m/a.%结合平海湾海域规划,通过对平海湾岸滩地质地貌考察、水深测量、底质采样与分析、海域水文泥沙测验与资料分析、海域泥沙运动分析计算和新老图件对比分析等综合手段研究,结果表明:平海湾区周边无大河、溪注入,陆域和海域来沙量小,海域和沿岸泥沙活动不大.湾内水动力条件相对较弱,海底沉积物以粘土质粉砂为主,湾东北侧沿岸浅水区至湾口区的平海村近岸以较粗的砂和砂质粉砂沉积物为主.湾内岸滩总体属于基本稳定状态,但其内湾潮滩、内湾的北部和东部岸滩处于弱淤积状态,波浪输沙往湾顶岱前段净输沙量为5.37×104 m3/a,而西侧和西南岸滩处于弱的冲刷状态,山柄村向南往湾外净输沙量为1.97×104 m3/a,但总体而言,海岸蚀退的速度相当缓慢.平海湾自1970 ～2007年的37a来,在平海湾海域水深5m以浅的内湾海域呈弱的淤积趋势,淤积速率仅为0.018 m/a.
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