基于Landsat影像的惠州海岸线近30年动态变化监测

Dynamic monitoring of Huizhou coastline based on Landsat satellite data in the past 30 years

广东省惠州市海岸线是我国南海海岸线的重要组成部分,其近30年的动态变化尚不明确。基于Google Earth Engine平台和1990—2020年的Landsat系列影像,该研究获取了惠州沿海1990—2020年改进的归一化差异水体指数(Modified Normalized Difference Water Index, MNDWI)和土地利用分布,提取了惠州市1990—2020年的海岸线,并分析其变化趋势。结果表明:(1)惠州市1990、2000、2010和2020年的海岸线长度分别为240.11、242.36、260.90和282.83 km。1990—2020年间,惠州海岸线的长度增加了42.72 km,增加主要发生在2000年之后。(2)1990—2020年,惠州2020年海岸线5 km缓冲区内,面积减少最多的是农用地,减少面积为146.47 km^(2),这主要受“退耕还林”政策和城镇扩张的影响;建设用地面积从20.40 km^(2)增加到135.46 km^(2),增加面积为115.06 km^(2)。(3)2010—2020年间惠州沿海开始出现蚝场,蚝场面积大约为10.28 km^(2)。

Guangdong Province is an important coastal province in China, and the coastline line in Huizhou is an important part of Guangdong Province. However, the dynamics of Huizhou's coastline in the past 30 years are still uncertain. Here, based on the Google Earth Engine platform and the Landsat series of images from 1990 to 2020, this study obtained the MNDWI(Modified Normalized Difference Water Index) and land use distribution along the coast of Huizhou from 1990 to 2020, and further combined the method of visual interpretation to extract the coastline of Huizhou from 1990 to 2020. The results show that:(1)The coastline lengths of Huizhou in 1990, 2000, 2010 and 2020 were 240.11 km, 242.36 km, 260.90 km and 282.83 km, respectively. Between 1990 and 2020, the length of the Huizhou coastline increased by 42.72 km.(2)From 1990 to 2020, within the 5-kilometer buffer zone of Huizhou's coastline in 2020, the area of agricultural land decreased the most, with an area of 146.47 km^(2), which was mainly affected by the policy of “Returning Farmland to Forest”. The building area increased from 20.40 km^(2) to 135.46 km^(2), with an increase of 115.06 km^(2).(3)From 2010 to 2020, oyster farms began to appear along the coast of Huizhou, with an area of about 10.28 km^(2). The above results are helpful for the management of Huizhou marine ecology.