Monitoring Seawater Quality in the Kali Porong Estuary as an Area for Lapindo Mud Disposal leveraging Google Earth Engine

Abstract

The hot mudflow released by Lapindo Mud Volcano periodically requires a large storage space. It is resulting the change in the main function of Kali Porong which is the channel for mud to the river mouth. This causes changes in water quality at Kali Porong estuary. The purpose of this study was to monitor water quality at Kali Porong estuary using Sentinel 2 image data with Total Suspended Solid (TSS) and chlorophyll-a analysis. Cloud computing technology can process image data into useful information. One of the open source cloud computing platforms is Google Earth Engine (GEE). In this platform, there is a database for storing satellite image data, including Sentinel-2. In addition to storing remote sensing data, GEE can process images quickly using the Java scripting language. In this study, monitoring was carried out in February-June 2021. The results show the average value of chlorophyll-a each month from February to June was 2.78 μg/m3, 2.76 μg/m3, 2.74 μg/m3, 2.98 μg/m3, and 3.2 mg/l. The average monthly TSS values from February to June were 16.11 μg/m3, 15.91 μg/m3, 15.76 μg/m3, 17.45 μg/m3, and 19.86 μg/m3, respectively. The correlation test result for chlorophyll-a estimation is 0.654. In the other hand, the correlation test result for the estimated TSS is 0.652. The trophic status of the waters at Kali Porong estuary is in the eutrophic class or has been polluted. The results show a tendency for the area with polluted trophic status to increase from February to June.