基于MODIS数据的淤泥质海岸水体指数比较与分析——以黄河三角洲海岸为例

Comparison and analysis of water indexes in muddy coasts based on MODIS data:A case study of the Yellow River Delta coast

淤泥质海岸地区具有独特且复杂的水体环境,深入分析水体指数在该区域的性能特点具有重要的科学意义。以黄河三角洲海岸为研究区,使用2008年、2009年和2015年的MODIS和Landsat遥感数据,从地表覆盖类型光谱特征的角度,比较分析6种水体指数(即NDWI,MNDWI,AWEI nsh ,AWEI sh ,TCW和WI 2015 )的水体提取性能。通过ROC曲线得到各水体指数的最佳阈值,研究水体指数在淤泥质海岸地区的水体提取精度和提取误差,分析不同地表覆盖因素对水体提取性能的影响。研究结果表明,AWEI nsh 的水体提取效果最佳,总体精度达97.29%,制图精度达96.84%,用户精度达97.69%。各水体指数提取海水的制图精度较高,均高于90%;陆地水体的提取效果一般,制图精度均低于80%;NDWI对潮滩水的识别能力较差,制图精度低于其他水体指数。各水体指数的陆地水体漏分率较高,海水和潮滩水体的漏分率较低,MNDWI的海水漏分率高于其他水体指数。潮滩土壤对水体提取性能的影响最大,其次为耕地土壤,稀疏植被、茂盛植被和建成区的影响最小。研究结果可为进一步开展淤泥质海岸水体变化监测与分析提供参考依据。

Muddy coastal areas have a unique and complex water environment. It is of great scientific significance to deeply analyze the water extraction efficiency of water index in this area. The authors took the Yellow River Delta coast as the study area and used the MODIS and Landsat remote sensing data of 2008, 2009 and 2015. The water extraction performance of 6 water index (NDWI, MNDWI, AWEI nsh , AWEI sh , TCW, WI 2015 ) were analyzed from spectral characteristics of land cover types. The best threshold of each water index was obtained through the ROC curve. The accuracy and extraction errors of water indexes in muddy coastal area were studied, and the influence of different land cover factors on water extraction was analyzed. The results show that the AWEI nsh have the best performance in extraction of water, with an overall accuracy of 97.29%, mapping accuracy of 96.84%, and user accuracy of 97.69%. The accuracy of seawater extraction by different water indexes is higher than 90%. The extraction accuracy of land water is at general level and the map precision is less than 80%. The capability of NDWI for identifying tidal flat water is poor, and the accuracy of mapping is lower than that of other water indexes. The different water indexes have high omission error of land water, and the omission errors of seawater and tidal flat water are low. The MNDWI has the highest omission error of seawater. The influence of the tidal flat soil on the water extraction is the greatest, followed by the cultivated soil. The sparse vegetation, luxuriant vegetation, and built-up area have the least impact. This study provides a reference for the further development of water extraction methods suitable for muddy coastal areas.