DETECTION OF SHORELINE CHANGES IN THE NORTHERN DISTRICT OF BUENAVENTURA USING REMOTE SENSING

Abstract

This study focuses on detecting the magnitude of shoreline changes of the northern District of
Buenaventura, in the Colombian Pacific, over a 30-year period, on a coast where the geomorphology
includes beaches, cliffs, estuaries, deltas and salt marshes. Satellite imagery (Landsat MSS, ETM + and
OLI TIRS) were used to detect historical positions of the shoreline in order to identify the processes of
change, in terms of erosion and accretion, from 1986 to 2015. Statistical analysis of changes was carried
out to estimate distances and shoreline change rates, using a tool developed by the United States Geological
Survey (USGS): Digital Shoreline Analysis System (DSAS). The statistics on Net Shoreline Movement
(NSM) and End Point Rate (EPR), provided information about the magnitude and trends of changes in the
shoreline. The results indicate that areas with more advanced processes of accretion correspond to sectors
in Boca San Juan, Puerto España and near to La Concepción beach in the Department of Valle del Cauca
and in the south of Chavica, in the Department of Chocó; all these sectors are located in the northern part
of the study area. Also in the same sectors, particularly around Chavica, the most advanced processes of
erosion were found, along with El Choncho beach and a small sector in the Malaga bay. Some sectors of
the shoreline remained mostly stable, such as Malaga and Buenaventura Bays. Average shoreline change
rate of (-) 0.21m per year was found, reflecting its erosive tendency with maximum EPR values 26.92m
of accretion and (-) 21.01m for coastal erosion. Natural processes such as the influence of river discharge
and El Niño phenomenon, have contributed to these shoreline changes. The identified erosion and accretion
processes can be recognized as priority areas of coastal management in the Colombian Pacific.