Analysis of Water Quality Dynamics of Sentarum Lake, Indonesia, with Water Index Application and Water Parameter Algorithm Methods Using Google Earth Engine

Abstract

Water quality is one of the main issues with lake degradation in Indonesia. Limited water quality data due to a lack of funding makes lake management in Indonesia difficult. The use of remote sensing technology has enormous potential as a source of data provision to obtain water quality information. We monitored Sentarum Lake in West Kalimantan, Indonesia, from 2019 to 2024 using open-access Sentinel-2 remote sensing data on the Google Earth Engine cloud computing platform. In this study, we combined Sentinel-2 Harmonized with the cloud score+ algorithm to produce cloud-free images of the study location. This paper used the Application Water Index and water parameter algorithms to analyze water quality. Using the Modified Normalized Difference Water Index (MNDWI), water area segmentation enhances open water features while efficiently suppressing and eliminating non-water area information. To estimate chlorophyll-a (Chl-a), we proposed the Normalized Difference Chlorophyll Index (NDCI) and an algorithm. Calculate total suspended solids (TSS) concentration using the Normalized Difference Texture Index (NDTI) and an algorithm. The study’s findings show that Sentarum Lake’s water quality is generally in excellent condition, with yearly averages of Chl-a and TSS fluctuating. This lake categorizes the lake as seasonal based on its stable condition. This estimate will provide lake managers and policymakers with critical information.