Study of Shoreline Change Using Geographic Information System

Abstract

ABSTRACT

        This study is to analyze the Shoreline Change from the aerial photo using the geographic information system. The  area of study is the coast of Pak-Panang ranging from Tha-Paya canal to the jetty of Baan Khone Thee. The total distance is approximately 45.8 kilometers. Another area is in the vicinity from the tip of Talumpook peninsula to the jetty of Baan Bor Khone Thee. The analysis of coastal alteration from the aerial photo is carried out based on the data of the area from the tip of Talumpook peninsula to the jetty of Baan Khone Thee by comparing the change between 2 periods, from 1995 to 1999 and from 1999 to 2002. 

        The study result revealed that wind wave in the NE monsoon is the crucial factor on the alteration of the natural shoreline.  The protection structures such as jetty at the mouth of canal, groin along the shore or at the outlet can impact on the change in the study area. They prevent the shallow of water channel and erosion.  They, however, also act to impede the sand movement by accelerating the erosion up end the structure or downstream direction and, subsequently, accelerating the deposition process at the down end of the structure which is the upstream direction.  From the comparison of aerial photo taken in 1995 and 1999, it is found that the construction of the jetty at the Ban Bor Khon Thee canal mouth in 1984 causes a severe erosion of the shore along the Pakpanang – Huatrai road up end the jetty for 400 meters at the rate of 7.89 meters per year.  From that point the Harbor Department constructed the protection structures for 4 kilometers long which compose of 19 T-groins and 4 I-groins. The construction was finished in 2000.  From the comparison of aerial photo taken in 1999 and 2000, it is found that at the up end of the last groin found the erosion of 2.6 kilometers long, or 118,450.70 m². The rate of erosion is 15.18 meters per years and the increasing rate is gradually.

        The protection measure for coastal erosion in particular area, therefore, must be performed in a whole picture. The movements of sand are interrelated that the construction of any structure will inevitably impact the vicinity areas thus requires cautions. The impact can last even in a very long term.