Estimation of Chlorophyll-a Phytoplankton in the Coastal Waters of Semarang and Jepara for Monitoring the EutrophicationProcess using MODIS-Aqua Imagery and Conventional Methods

This study investigates the concentration of chlorophyll-a (chl-a) using the data of field observation and MODISAqua‎imagery. The field observation data were retrieved by using a conventional method and processed using‎spectrometric analysis. This study covers the coastal and near land areas which have different levels of anthropogenic‎activity. The results showed that the coastal waters of Semarang with a high level of anthropogenic activity‎persistently show a concentration of chlorophyll a (chl-a) twice as large as Jepara coastal waters. This comparison‎value is obtained based on imagery and field data. Meanwhile, the ratio of chl-a field data in each region shows‎a value of ±5 times greater than the MODIS data. Field observation data shows a higher value than the MODISAqua‎imagery data. The use of imagery data can be employed as a method of monitoring the eutrophication‎process on the coast. On the basis of the chlorophyll a classification and field observations, the coastal water of‎Semarang are classified as eutropic waters and Jepara is categorized as mesotropic category. The classification‎results will be different if monitoring is carried out using the image data with a location far from the mainland, the‎Semarang waters are included in the mesotropic category (> 2 mg·m-3) and Jepara is included in the oligotropic‎water category (< 2 mg·m-3).