Land Use Effect on Water Resources of Ternate Island and Its Management Strategy

The high urbanization rate of Ternate Island, a small volcanic island located in North Maluku Province, Indonesia, has dramatically changed the land-use patterns of the island in the last twenty years. This paper will analyze how these changes, especially forest land and agricultural land being transformed into built-up spaces, affect the recharge capacity of the groundwater and the sustainability of the water resources in general. On the basis of multi-temporal satellite images (Landsat 7 and 8 of 2009-2023), GIS-based spatial analysis, hydrological modeling, and SWOT analysis, the study indicates that the areas under built-up hindrances grew by 943.3 ha in 2009 to over 2,000 ha in 2023, whereas forest cover refers to the decline of about 24 percent. Although the slopes of Mount Gamalama have fairly high potential for natural infiltration, the rising impervious surfaces have decreased the effective groundwater recharge and the risk of flooding during heavy rainfall. Despite having registered a surplus of 38.9 million m3 of water in 2018, the current plans to keep converting land unless the situation is controlled pose a threat to long-term water security. The proposed study is an integrated management framework that incorporates the concept of green infrastructure (retention ponds, biopores), mandatory green open space regulations, and reforestation targets, as well as digital monitoring systems. Contrary to earlier studies wherein the majority of the research concentrated on mainland or larger islands, this study is the first to carry out a comprehensive spatial-hydrological evaluation with specific reference to small volcanic islands with high levels of demographic pressure within eastern Indonesia that can be transferred to other island-like situations of the world.