Coastal Dynamic Products Monitoring: Ratioing Strength and Weakness Analysis, ENVI Based Modelling

Abstract

Studies on coastal area changes have attracted more studies over time. Monitoring highly dynamic coastal areas is effective using raster-to-vector modeling methods. This study aimed to demonstrate the ratioing method and evaluate other image-processing in simple raster analysis methods to analyze shoreline changes as coastal dynamics products. The most commonly used methods are change detection analysis, color mapping: density slice, Region of Interest (ROI), and ratioing. However, the existing methods are distinctive in assumptions, which reflect their suitability and effectiveness as the primary method for monitoring the coastal dynamics. As part of simple raster analysis, ratioing is deemed the most accurate in determining shoreline change. It shows clear pixel values with binary codes, i.e., “0” and “1” as sea or water body, and land or non-water, respectively. The lowest initial percentage of Digital Number at the first decline of the histogram is the key to minimize the error value in band ratio. This study thereby employed it to process the Landsat 8 OLI/TIRS and Landsat 5 TM images from 2011 until 2021 and identify the coastal dynamic in Kendal Regency, Central Java Province, Indonesia. The results showed that throughout ten years’ sedimentation occurred dynamically in Kendal estuary from 0.84 km to 1.19 km, with average LRR of 6.99 m and 111.77 m for the highest rate.