Marine debris characteristics in various coastal typologies in the Gunungkidul coastal area of Yogyakarta—Indonesia

Abstract Marine debris is one of the environmental issues that can be brought on by rapid human development and activity, including marine tourism, like what happened in the coastal area of Gunungkidul, Indonesia. The issue of marine debris might decrease the environmental quality and impact tourism in Gunungkidul. This study aims to identify the characteristics of coastal typologies in Gunungkidul and analyze their influence on the characteristics of marine debris. Google Earth images and the Digital Elevation Model were used to interpret and classify the typology across the study area based on their physical characteristics. Marine debris samples, either macro or meso-sized, were collected using the transect method for each beach. Based on the imagery interpretation combined with elevation data from DEMNAS, there are three typologies in the Gunungkidul coastal area, i.e., pocket, non-pocket, and cliff beaches. Cliff typology was eliminated and only pocket and non-pocket beaches were used as marine debris sample collection locations. Hence, four beaches were chosen as study areas, i.e., Seruni, Drini, Sepanjang, and Sedahan; each represents each coastal typology. About 193 macro-sized and 217 meso-sized debris were found in our research area, totaling 1380.31 g. Compared to non-pocket beaches, pocket beaches contain more marine debris. The higher slopes of the pocket beach typology will trap marine debris and make it challenging to reenter the water. On pocket beaches, oceanographic processes concentrate marine debris in one location. Still, on non-pocket beaches, marine debris can disperse and return to the sea more readily due to the cycling of currents near the coast.