The Application of Remote Sensing and Geographical Information Systems to Change Detection for Integrated Coastal Management.

The coastal zone of the South Pacific Islands represents varied and highly productive ecosystems such as mangroves, coral reefs and sea grasses. It is necessary to protect these coastal ecosystems to ensure sustainable development because they are found to be mostly degraded and polluted.

Location of the Study Site in Fiji

This requires information on habitats, landforms, coastal processes, water quality and natural hazards on a repetitive basis. Reliable and timely information is required in order to monitor and manage the remaining mangrove resources, coastline changes and rural development areas.

Overlay of 1994 (blue) with 1978 (pink)

The area chosen for this research was the Sigatoka Coral Coast in Fiji. The main aim of this thesis is to investigate how changes in the past can be documented and analysed utilising remote sensing data and GIS tools. The GIS technique corrects and analyses the aerial photographs of 1967, 1978, 1986 and 1994. The aerial photographs were available with good spatial resolution once scanned and rectified. IKONOS satellite image was also used providing reference for correcting aerial photos.

These aerial photographs were rectified using ERDAS Imagine software and

Multi-temporal image – putting together of 1978, 1986 and 1994 coloured image to show changes in mangrove and rural development areas.

data for analysis, mangroves, coastline and rural development areas were drawn and analysed in the Map Info Environment. Change detection maps were created through overlay of layers in different time periods, and visualising through multi-temporal images.

The results showed that coastlines have moved inland 0.54 m/yr to 2.18 m/yr during the studied period from 1967 to 1994. The mangrove analysis showed 1.3% regrowth in some areas like Naevuevu and 11.6% regrowth in other areas like Korotogo from 1986 to 1994. On the other hand there was a 1.4% decrease in mangrove in Naevuevu from 1967 to 1978 and 10.7% removal of mangroves along the Sigatoka River from 1967 to 1994. The rural development analysis showed an increase in the number of houses in the studied areas from 1967 to 1994 and at the same time more deforestation.