Assessment of the Water Area in the Lowland Region of the Mekong River Using MODIS EVI Time Series

Abstract

This paper presents an application of reconstructing Moderate-Resolution Imaging Spectroradiometer (MODIS) Enhanced Vegetation Index (EVI) time series to extract the water area in the lowland region of the Mekong River. Firstly, MODIS13A1 EVI time series with land surface reflectance 16-day and 500 m spatial resolution is collected from 2000 to 2017, resulting total of 411 images. Then, these images are used for reconstructing EVI time-series by using the Whittaker smoother method on the Google Earth Engine. Next, the water area in each image is computed based on the smooth EVI value. The results showed that the extracting water areas in year 2000 was in line with the observed water elevation at Tan Chau station (for the Mekong Delta) and at Phnom Penh station (for the Cambodian region). The correlation coefficient between the extracting water area and water elevation equals to 0.885 for the Mekong Delta while its value is 0.924 for the Cambodian region. The extracting water area from MODIS13A1 EVI for the lowland region of the Mekong River can be used for assessment of inundated area resulting from different flow conditions as well as for studying inundation processes in the lowland region of the Mekong River when using hydrodynamic models.