Identification of Marine Debris and Its Distribution Using Unmanned Aerial Vehicle (UAV) on the Cirebon Coastal Area, Indonesia

Marine debris can be a significant problem when it enters the ocean. One of the areas, which has a marine debris problem is Cirebon Coast. Such a problem occurs due to the high human population and activities in this particular coastal area. An effective cleaning method is required to prevent this problem. However, to determine the cleaning method, comprehensive information about the debris condition is required. Therefore, this study aims to identify the dominant types of marine debris and analyze the effect of tides on the characteristics and distribution of debris on the Cirebon Coast. This study carried out marine debris identification by orthophoto obtained from a DJI Phantom 4 Pro Unmanned Aerial Vehicle (UAV)/drone. The dominant types of marine debris on the Cirebon Coast are plastic and styrofoam. Based on the aerial imagery validation results, plastic and styrofoam larger than Ground Sample Distance (GSD) are easily detected. Visually, debris in Karang Anom more than in Rawa Urip. The change in tidal height can affect debris not visible on the orthophoto at the maximum water level. In addition, the tides can also move marine debris varying from 10 to 50 cm from its previous position. The debris area at Rawa Urip Beach when slack before flood tide (55.53 m2) is larger than the area when slack before ebb tide (52.71 m2). The debris area at Karang Anom Beach at low tide (129.89 m2) is larger than when slack before ebb tide (75.79 m2). This study revelaed that the factors affecting debris area on the Cirebon Coast comprise tidal height, seawater visibility, and the beach structure (slope and coast components).

An Automated Method for Mapping Giant Kelp Canopy Dynamics from UAV

Satellite and aerial imagery have been used extensively for mapping the abundance and distribution of giant kelp (Macrocystis pyrifera) in southern California. There is now great potential for using unoccupied aerial vehicles (UAVs) to map kelp canopy at very high resolutions. However, tides and currents have been shown to affect the amount of floating kelp canopy on the water surface, and the impacts of these processes on remotely sensed kelp estimates in this region have not been fully quantified. UAVs were used to map fine-scale changes in canopy area due to tidal height and current speed at kelp forests off the coast of Palos Verdes, CA and Santa Barbara, CA. An automated method for detecting kelp canopy was developed that was 67% accurate using red-green-blue (RGB) UAV imagery and 93% accurate using multispectral UAV imagery across a range of weather, ocean, and illumination conditions. Increases in tidal height of 1 m reduced the amount of floating kelp canopy by 15% in Santa Barbara and by over 30% in Palos Verdes. The effect of current speed on visible kelp canopy was inconclusive, but there was a trend towards lower canopy area with increased current speed. Therefore, while tidal height and current speed can introduce significant variability to estimates of kelp abundance, the magnitude of this variability is site specific. Still, UAVs are a valuable tool for mapping of kelp canopy and can provide greater spatial resolution and temporal coverage than is possible from many satellite sensors. This data can provide insight into the patterns and drivers of high frequency fluctuations in kelp abundance.

Turbidity Estimation from GOCI Satellite Data in the Turbid Estuaries of China’s Coast

Knowledge of the distribution and variation of water turbidity directly represent important information related to the marine ecology and multiple biogeochemical processes, including sediment transport and resuspension and heat transfer in the upper water layer. In this study, a neural network (NN) approach was applied to derive the water turbidity using the geostationary ocean color imager (GOCI) data in turbid estuaries of the Yellow River and the Yangtze River. The results showed a good agreement between the GOCI-derived turbidity and in situ measured data with a determination coefficient (R2) of 0.84, root mean squared error (RMSE) of 58.8 nephelometric turbidity unit (NTU), mean absolute error of 25.1 NTU, and mean relative error of 34.4%, showing a better performance than existing empirical algorithms. The hourly spatial distributions of water turbidity in April 2018 suggested that high turbidity regions were distributed in the Yellow River estuary, Yangtze River estuary, Hangzhou Bay, and coastal waters of Zhejiang Province. Furthermore, the relationship between water turbidity and tide were estimated. A defined turbid zone was defined to evaluate the diurnal variations of turbidity, which has subtle changes at different times. Our results showed an inverse relationship between turbidity and tide over six selected stations, i.e., when the value of turbidity is high, then the corresponding tidal height is usually low, and vice versa. The combined effects of tidal height and tidal currents could explain the phenomena, and other factors such as winds also contribute to the turbidity distributions.

Improving Stage–Discharge Relation in The Mekong River Estuary by Remotely Sensed Long-Period Ocean Tides

Ocean tidal backwater reshapes the stage–discharge relation in the fluvial-to-marine transition zone at estuaries, rendering the cautious use of these data for hydrological studies. While a qualitative explanation is traditionally provided by examining a scatter plot of water discharge against water level, a quantitative assessment of long-period ocean tidal effect on the stage–discharge relation has been rarely investigated. This study analyzes the relationship among water level, water discharge, and ocean tidal height via their standardized forms in the Mekong Delta. We found that semiannual and annual components of ocean tides contribute significantly to the discrepancy between standardized water level and standardized water discharge time series. This reveals that the long-period ocean tides are the significant factors influencing the stage–discharge relation in the river delta, implying a potential of improving the relation as long as proper long-period ocean tidal components are taken into consideration. By isolating the short-period signals (i.e., less than 15 days) from land surface hydrology and ocean tides, better consistent stage–discharge relations are obtained, in terms of improving the Pearson correlation coefficient (PCC) from ~0.4 to ~0.8 and from ~0.6 to ~0.9 for the stations closest to the estuary and at the Mekong Delta entrance, respectively. By incorporating the long-period ocean tidal height time series generated from a remotely sensed global ocean tide model into the stage–discharge relation, further refined stage–discharge relations are obtained with the PCC higher than 0.9 for all employed stations, suggesting the improvement of daily averaged water level and water discharge while ignoring the short-period intratidal variability. The remotely sensed global ocean tide model, OSU12, which contains annual and semiannual ocean tide components, is capable of generating accurate tidal height time series necessary for the partial recovery of the stage–discharge relation.

TIPOLOGI BANGUNAN DI PERMUKIMAN BANTARAN SUNGAI BERDASARKAN LOKASI DAN JENIS KONSTRUKSI (STUDI KASUS: PERMUKIMAN BANTARAN SUNGAI KAHAYAN, PALANGKARAYA)

Rumah yang berada di permukiman bantaran Sungai memiliki keunikan dan karakter tersendiri, hal ini dikarenakan fisik bangunan rumah menyesuaikan dengan kondisi dan lingkungan di daerah bantaran sungai. Pulau Kalimantan dibelah oleh sungai – sungai besar yang memiliki keunikan dan kondisi lingkungan yang berbeda satu dan yang lain, misalnya Sungai Kahayan yang membelah kota Palangkaraya memiliki kondisi dimana ketinggian pasang surut air sungai yang sangat tinggi dan terdapat permukiman awal terbentuknya Kota Palangkaraya. Bangunan rumah di permukiman yang berada di bantara Sungai Kahayan memiliki 3 segmen, yaitu 1) bangunan rumah yang bearda di atas air (apung/lanting), 2) bangunan rumah yang berada di bantaran/transisi antara air dan daratan (panggung), 3) bangunan rumah yang berada di darat. Metode yang di gunakan adalah metode kualitatif deskriptif, metode ini bertujuan untuk mengambarkan dan mendeskripsikan tipologi berdasarkan jenis struktur dan ruang pada bangunan di permukiman ini. Tujuan Penulisan artikel ini untuk mengetahui tipologi bangunan rumah di bantaran Sungai Kahayan yang terdiri dari segmen bangunan di atas air, panggung, dan bangunan yang di darat, berdasarkan konfigurasi bentuk dan ruang (spatial structure). Hasil dari penulisan paper ini adalah lokasi rumah dan perkembangan permukiman ini mempengaruhi tipologi yang terbentuk.BUILDINGS TYPOLOGY IN RIVERFRONT SETTLEMENTS BASED ON LOCATION AND TYPE OF CONSTRUCTION (CASE STUDY: KAHAYAN RIVER SIDE SETTLEMENTS, PALANGKARAYA)Houses in riverbank settlements have their uniqueness and character, and this is because the physical building of the house adapts to the conditions and environment in the riverbanks. Borneo is divided by large rivers that have unique and different environmental conditions; for example, the Kahayan River, which divides the city of Palangkaraya has a condition where the tidal height of the river is very high, and early settlements forming the City of Palangkaraya. Houses in settlements located on the riverbanks of the Kahayan have 3 segments, 1) Houses that are built on water (floating/lanting), 2) Houses that are located on the banks/transitions between water and land (stage), 3) house building in the land. The method used is a descriptive qualitative method; this method aims to describe and describe typologies based on the type of structure and space in buildings in this settlement. Purpose The writing of this paper seeks to find out the typology of house buildings on the banks of the Kahayan river, which consists of building segments on water, stage buildings, and buildings on the land, based on their spatial structure configurations. The results of this paper are the location of the house and the development of this settlement affect the typology that is formed.