Scientific information on coral reef habitat changes of Morotai island is very limited to none. This study aimed to detect the change of coral reef habitats between 1996 and 2013, using -14.1%, -14.9%, and -16.6%, respectively. In 2002-2013, mixed-habitat, sand ABSTRAKInformasi ilmiah terkait perubahan habitat terumbu karang di pulau Morotai sangat terbatas bahkan belum ada sampai saat ini. Penelitian ini bertujuan untuk mendeteksi perubahan habitat terumbu karang dalam kurun waktu 17 tahun (1996-2013) menggunakan seri citra Landsat yang diintegrasikan dengan data pengamatan lapangan tahun 2012. Penelitian ini dilaksanakan di kawasan terumbu karang pulau Morotai Propinsi Maluku Utara menggunakan data Landsat 5TM (1996), Landsat 7ETM+ (2002) dan Landsat 8 OLI (2013). Analisis deteksi perubahan menggunakan teknik klasifikasi terbimbing dan normalisasi band transformasi depth invariant index (DII) untuk lima kelas habitat yaitu kelas campuran, karang hidup, lamun, pasir, dan pecahan karang. Deteksi perubahan dideskripsikan berdasarkan perubahan habitat antar waktu maupun perubahan luas habitat antara tahun 1996-2002 dan 2002-2013. Analisis deteksi perubahan menunjukan bahwa dalam kurun waktu 1996-2002 luas kelas campuran dan pecahan karang meningkat sebesar 11,3% dan 32,5%, luas kelas pasir, lamun, dan karang hidup berkurang masing-masing sebesar -14,1%, -14,9% dan -16,6%. Sedangkan tahun 2002-2013, luas kelas campuran, pasir, dan lamun meningkat masing-masing sebesar 1,1%, 13,3% dan 24,7%, luas kelas pecahan karang dan karang hidup berkurang sebesar -22,7% dan -27,0%. Dalam kurun waktu 17 tahun, kematian terumbu karang sekitar 43,6%. Hal ini mungkin disebabkan peningkatan suhu air laut dan meningkatnya intensitas kegiatan manusia.

ABSTRACT Scientific information on coral reef habitat changes of Morotai island is very limited to none. This study aimed to detect the change of coral reef habitats between 1996 and 2013, using Landsat imagery integrated with field data in 2012. The research was conducted in the coral reef ecosystem of Morotai Island in North Maluku province. Change detection analyses were conducted using supervised classifications and transformation depth invariant index (DII), with five habitat classes i.e., mixed-habitat, coral, seagrass, sand, and rubble. The result showed that in 1996-2002 there was a significant increase in the mix-habitat and rubble classes (11.3% and 32.5%), however,  there  was  a siginifcant decrease in the sand, seagrass, and coral classes of -14.1%, -14.9%, and -16.6%, respectively. In 2002-2013, mixed-habitat, sand, and seagrass classes were increase by 1.1%, 13.3%, and 24.78%, respectively.  Meanwhile, coral and rubble classes were decrease by -22.7% and -27.0%, respectively. Within the period of 1996-2013, there was about 43.6% loss of coral reef of Morotai island.  This was probably caused by the increase of seas surface temperature nad and the increase of human activities in the region. Keywords: coral reef habitats, Landsat, change detection, Morotai Island

Increase of human activities on coastal area in Central Weda Sub-District has caused degradation of coastal ecosystems. Even though coastal ecosystems have an essential role in marine ecology, such as coral reefs and mangrove forests, they are sometimes undermined by economic or commercial interests. This study aimed to determine density and cover percentage of mangrove forests and coral reefs in Central Weda Sub-district, North Maluku. Data collection on coral reef ecosystem components was carried out by applying georeferenced photo-transect and line transect quadrat techniques. While for mangroves, data collection included species diversity and tree/canopy cover percentage. Study result showed that based on lifeform percentage of coral reefs, most of the study areas were in a good category with 23.95% coverage, moderate condition 39,5%, and poor condition 36.6%. The coral reefs in good and moderate conditions were found at location having relatively low human activities. Whereas percentage of mangrove cover from all stations ranged from 78,39 to 78,76% with Important Value Index ranging from 106,79% to 158,32%.

Floods that occurred in Central Halmahera district had given a significant impact on environmental damage. This study aims to assess the risk level of flood and calculate vulnerability in study areas. The vulnerability will calculate based on social, economic and environmental aspects. Furthermore, the flood risk will be shown on risk map that refers to hazard index, and vulnerability index. The hazard index parameter was based on the high, the duration and the frequency of the flood. The vulnerability index parameter was based on the number of peoples, the sex ratio, vulnerability peoples, poverty ratio, number of facilities, and natural resources. Those parameters were analyzed by using guidelines for disaster risk assessment authorized by the National Disaster Management Agency. The result shows that the total vulnerability index found six villages at a high category and nine villages at the moderate category. Meanwhile, the risk map displays that almost all the village areas have a flood risk level varies from low to high risk. Low-risk areas are generally located in high altitudes. While high-risk areas are dominated on village areas.

The objectives of this study are to mapping the hazard-prone area and to analyse the flood vulnerability index in Kobe Watershed, Central Halmahera District. In order to determine the optimal selection of weights for the factors that contribute to flood risk, GIS and multi-criteria decision analysis (MCDA) were used in conjunction with the application of the analytical hierarchy process (AHP) method to create the flood hazard map. The flood hazard map was generated by using selected hazard factors including land use, topography, slope, and rainfall pattern. The result shows that the Kobe River basin is a flood-prone area, with 77.46 percent of its land classified as less prone to flooding and 21.41 percent classified as flood-prone. However, only 21.41 percent of its land is classified as flood-prone. Only 1.13 percent of the land is protected from the danger of floods, compared to the whole country. The altitude factor is the most important element influencing flood susceptibility in Weda District, where the majority of the land (16.34 percent) is located at or below sea level, making it particularly vulnerable to flooding.