Damming Tropical Island Streams: Problems, Solutions, and Alternatives

H uman population growth and increased water usage are placing greater demands on the world's freshwater supplies Despite their geographic isolation, tropical islands are not immune to this global phenomenon In fact, islands, which frequently have less access to freshwater and less land area for potential expansion of human populations, often have more challenging water resource problems than do continental areas. Because of high demand for freshwater, governments on tropical islands are frequently under immense pressure to allow increasing exploitation of freshwater resources. The groundwater resources of many tropical islands are not sufficient to meet demand and are in danger of being irrevocably lost because of overpumping and subsequent saltwater intrusion (e.g., Hunter and Arbona 1995). Consequently, governments increasingly turn to surface water, primarily rivers and streams, for their freshwater supplies. The effects of hydrologic alterations of rivers and streams from dams, reservoirs, and water withdrawals are well documented for continental streams, with most of the literature coming from temperate locations (e.g., Tropical continental streams have also received some recent attention (e.g., In contrast, very little research has been done on the effects of dams on tropical island streams. Furthermore, alternatives to damming and to increased water withdrawal are often not considered when making water resource management decisions.