Seasonal effect of agricultural pollutants on coastline environment: a case study of the southern estuarine water ecosystem of the boseong county Korea

The untreated disposal of wastewater in the coastal environment leads to growth of harmful algal blooms which risks the coastal ecology and human health. The harmful algal bloom can destroy aquatic natural life by reducing dissolved oxygen concentration. This study aimed to evaluate the eutrophication status at the Boseong county, Beolgyo village estuary, considering different water quality parameters. Furthermore, this study also investigated the effect of land use activates the estuarine water environment. The date of the acquisition for the Landsat 8 high-resolution satellite images were four different events i.e., 11th March, 2019, 15th June, 2019, 19th September, 2019, and 8 th December, 2019 in four different seasons such as Spring, Summer, Fall, and Winter respectively for selected study region. Land use and land cover were extracted on the basis of accuracy’s percentage and the Kappa coefficient. Concentrations of water quality parameters such as Chlorophyll-a (Chla), Total Phosphorous (TP), Transparency of Sechi Depth (TSD) were extracted using Carlson Trophic State Index (CTSI). The study found that the overall value of the CTSI is classified under the medium eutrophication state in summer and autumn season (CTSI~60-70). While it falls in the light eutrophic state in winter and spring seasons (CTSI~50-60). The value of TSI for all studied nutrients is the higher nearby cropping area as well as land settlements. The spatial variation of the trophic index in the study region aided strong evidence to be detected over the area’s adjutant to agrarian farming and urban habitats. The study concludes that the TSI could be used as a simple management tool to classify individual water ecosystems into broad classification that represent their water quality health.