Shoreline Change Analysis in Demak, Indonesia

Abstract

Demak Regency is located in Central Java Province Indonesia bordering the Java Sea. Intense activities in the coastal area of Demak have caused changes in the shoreline. This paper aimed to determine the shoreline change for 25 years and to identify the major factors that influenced those changes in the coastal area of Demak. A shoreline change analysis was conducted based on Multitemporal Landsat satellite imagery with sensors of Thematic Mapper (TM), Enhanced Thematic Mapper plus (ETM+), and Operational Land Imager (OLI). This study used the data from multitemporal Landsat imagery of year 1990, 1994, 1999, 2002, 2008, 2011, and 2015. Identification of the shoreline was performed through band ratio, histogram threshold, and composite band 457 methods. An erosion and accretion analysis has been done using the wind data via the processing of Wind Rose Plot (WRPLOT), wave prediction using Sverdrup Munk Bretschneider (SMB) method, tide data processing to know the value of Mean High Water Level (MHWL), Mean Sea Level (MSL), Mean Low Water Level (MLWL), and Lowest Low Water Level (LLWL), as well as currents data processing that has been implemented to achieve the goal. The research results showed that the shoreline change in Demak Regency was quite distinct compared to several previous years due to erosion and accretion processes. The greatest shoreline change happened in Sayung District and Wedung District. Sayung District was likely to experience erosion process while Wedung District tended to show accretion process. Several physical factors that became the major influence on these changes were the wind, waves, currents, and tides.