Đánh giá việc sử dụng ảnh vệ tinh Landsat 8 - 9 trong giám sát tổng chất rắn lơ lửng (TSS) trong nước biển – Nghiên cứu ở vùng biển Đà Nẵng
Abstract
The study was conducted to assess the capability of using Landsat 8-9 satellite images in monitoring the quality of seawater during seabed sediment dumping activities in the Da Nang Sea area. Satellite image data used in the study were Landsat 8-9 OLI/TIRS C2 L2 images at path 124, row 049 with a resolution of 30m x 30m, acquired in May 2023. These images, obtained near the survey dates (3/5/2023, 10/5/2023, and 31/5/2023), were used in the research. All images used had cloud cover below 10% in the research area and were adjusted using ArcMap software. The use of ArcMap software in analyzing Landsat 8-9 images calculated the Suspended Sediment Concentration Index (NSMI) based on spectral reflectance in the visible spectrum channels, including blue, green, and red channels of the images, with values ranging from 0.004 to 1; 0.17 to 0.99; and 0.12 to 1, respectively. Additionally, regression equations were developed based on linear and quadratic functions, with R2 = 0.7618 for the quadratic equation. It was found to be consistent with the distribution of NSMI values ranging from -0.25 to 0.84. The quadratic equation (y = 23.32x2 + 17.94x + 4.1162) was used to predict the Total Suspended Solids (TSS) values (dependent variable) based on NSMI values (independent variable), explaining 76.18% of the variance in the TSS variable. The research results indicate that the monitoring method for TSS concentration in coastal seawater is entirely applicable during sediment dumping activities in the Da Nang Sea area. Combining satellite monitoring with laboratory sampling and analysis allows for accurate assessment of the causes, enabling timely and effective treatment measures.
