Shoreline changes at Mantanani Besar Island, Kota Belud, Sabah Malaysia

Russel Felix Koiting (2016) Shoreline changes at Mantanani Besar Island, Kota Belud, Sabah Malaysia. Masters thesis, Universiti Malaysia Sabah.

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Mantanani Besar Island is located about 30 km from the nearest point of Kota Belud mainland. Increasing development and usage of its beach has proven that the island is very important to the local community and has a high potential for a tourism destination. However, communities have stated that the island experienced beach erosion especially during the peak northeast monsoon (NEM) and southwest monsoon (SWM). Limitation of baseline data regarding shoreline changes and beach erosion at the island leads to the objectives of this study which are to determine the long-term shoreline changes, evaluate beach morphologies (beach profile, width, angle, slope condition and beach sediment volume) and sediment characteristics at different seasonal monsoons and as well as identification of erosion based on the communities observation and opinions. The island was divided into four zones and five sampling stations (st) based on the cardinal direction. Zone 1 located at the west (st 1), zone 2 at southern (st 2), zone 3 at eastern (st 3 and 4) and zone 4 at northern (st 5) part of the island. Aerial photos (1986, 1990, 2001 and 2013) and satellite images (2010) of Mantanani Besar Island were used to detect long-term changes by overlapping the images in ArcGIS 9.3 software. Field trips for beach profile and sediments collection were done twice to represent NEM and SWM in 2013, 2014 and 2015. The beach morphologies calculations were based on beach profiles data while collected sediment undergoes sand sieve analysis to calculate the sediment mean, sorting, skewness and kurtosis. Interviews with the community were done based on a structured questionnaire to assess the beach erosion. Results show that the size of Mantanani Besar Island was decreased with estimated total land loss of 170, 838 m² since 1986. The highest land loss is located in zone 2 with 71, 590 m2 (43%) while zone 3 was the most dynamic area based on the obvious changes on the maps and the highest occurrence of beach erosion and accretion (16 identified beach changes). The total average value of beach morphologies was higher at the NEM than the SWM indicating accretion during NEM and erosion during SWM. Mantanani Besar Island beaches dominated with medium sand size with the excess of finer sediment whereas the exposures of environmental forces were medium with slightly higher in SWM. The sediment sorting was achieved through cross-shore (NEM) and longshore transport (SWM). Communities observation and opinions were in line with the results of long-term shoreline changes where Mantanani Besar Island experienced beach erosion since the past 20 years and it occurs at all zones (highest land loss at zone 2). Beach erosion has affected the residential areas in terms of properties destruction including personal and public properties with few uprooted trees. The local communities are aware of the continuous shoreline erosion and preferred to wait for the government actions to protect the island. The findings of this study provide baseline data (erosion and accretion area with beach dynamic during seasonal monsoon) and can be utilized by community, tourist operators and government as a guideline for future developments and integrated management plan of the island.

Item Type: Thesis (Masters)
Keyword: shoreline changes, beach morphologies, sediment characteristics, seasonal monsoons, erosion
Subjects: G Geography. Anthropology. Recreation > GB Physical geography
Department: INSTITUTE > Borneo Marine Research Institute
Date Deposited: 27 Oct 2017 15:42
Last Modified: 27 Oct 2017 15:42

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