海口湾海滩冲淤遥感分析

Analysis of the coastal erosion and accretion in Haikou Bay by remote sensing

卫星遥感水边线分析海滩冲淤比现场观测方便、快速,而且资料源更多,但是海口湾海滩缺乏这种研究.本文建立了四种水体指数遥感水边线方法,通过观测检验发现,NDWI指数更适合海口湾.对1994—2013年的15景Landsat卫星遥感影像提取了水边线,利用这些水边线推算了高潮位和低潮位之间的海滩坡度演变,海滩坡度基本稳定,其值为3.7~4.2°.利用遥感水边线的位置变化及其推算的海滩坡度,分析了海滩冲淤演变特征：海口湾各段海滩的冲淤规律并不一致,其中西秀海滩和假日海滩发生冲刷,高潮位附近的冲刷厚度为0.36 m、冲刷速率为1.9cm/a,低潮位附近的冲刷厚度为0.30 m、冲刷速率为1.8 cm/a.

The analysis of coastal erosion and accretion,based on the remote sensing water line,is better than that using field observations because of its convenience,quickness and more data. However,this method hasn＇t been applied to Haikou Bay. Four types of water index for extracting waterline from Landsat sensing image are checked by observations in Haikou Bay,in which the water index of NDWI is proved to be the best. The waterlines of 15 Landsat sensing images in 1994—2013 are extracted by NDWI,with which the evolution of the beach slope between high tidal level and low tidal level is analyzed. And the results show that the beach slope is basically stable with the value of 3. 7 ~ 4. 2°.Then the coastal erosion and accretion are analyzed using the extracted waterlines and the beach slope. The character of erosion and accretion isn＇t uniform in the beach. Xixiu Beach and Jiari Beach have been eroded,and the eroded depth is 0. 36 m near the high tidal level and 0. 30 m near the low tidal level,the eroded speed is 1. 9 cm / a near the high tidal level and 1. 8 cm / a near the low tidal level.