Morphodynamics of a sandy beach during a one-year cycle at Sandbukt, Breivika, Troms, northern Norway

Abstract

Six cross-shore beach profiles were monitored in a monthly interval at Sandbukt Beach at Breivikeidet, from October 2014 to October 2015, in order to study impact of storms on the beach profile and understand monthly, seasonal, and annual changes in the beach profile. Change in beach volume showed erosion and decrease in beach width on the southern part of the beach during the winter season, while there was a slight accretion on the northern part. There was an increase in the beach volume at every profile during the summer season, while during the winter season the beach volume decreased at the southern part of the beach, while small increase was observed at the northern end. The profile data at Profile A showed onshore transport of a sandbar, and subsequent welding of said sandbar onto the beach. The welding of sandbars could play a major role in berm and beach ridge building at Sandbukt. The effect of storms were minimal when the wind direction during the storms was from the south, while erosion occurred during storms from the north, eroding large portions of the beach profile. Erosion caused by northern storms was possibly decreased when a thick cover of snow and ice was present on the berm. Textural characteristics and sub-surface architecture of the beach during the summer season in 2015 were studied as well. The beach was dominated by medium sand, with both fine sand and fine gravel present as well. The beach shows a variation in grain size, with grain size decrease from north to south, indicating longshore transport of sediments from the north to the south.