Estudo da variação da linha de costa nos bairros de Malaua, Quichanga e Macuacuane no distrito de Pebane

Abstract

Changing the coastline is a problem that has been observed in most points in the coastal zone. This evolution can happen due to the processes of deposition or erosion. When it comes to deposition it has just contributed to the reduction of the depth of the channel, whereas if for erosion it contributes to the decrease of the terrestrial part. In the Pebane district, the biggest negative impact is the erosion process that is threatened by the local Aerodrome, an INAHINA Lighthouse Station. In order to evaluate the speed of the erosion process, two satellite images (2005 and 2015) of this region were compared and an extension was determined that was eroded during the period under analysis. In addition, data on precipitation, seas, sea currents and waves were obtained to identify the main causative agent of erosion in the region. In addition, the local community was consulted on the causes of erosion through an inquiry. Results found indicate that in the region near the port, the coastline is subject to a setback of 2884 mm / year; in the area where the Logde Pebane Fish is located the coastline is static (erosion equals deposition); in the region in front of the Aerodrome, the advance (erosion) of the coast line is recorded at a speed of 5191mm / year. The erosion observed in front of the Aerodrome is caused by the pluviometry discharges, whereas the deposition verified in the port side and the sedimentary balance verified in the log is related to the waves and currents. If no mitigation measures are taken the runway of the Aerodrome will be reached in 2024. It is suggested that drainage ditches be created along the eroding zone to direct rainwater in order to decrease in the erosion process and to be constructed schemes and structures for the dissipation of energy and for the reduction of wave energy and the tidal current.