Exploratory Sampling of Submarine Groundwater Discharge in Taiwan

that alkalinity generated on the continental shelves may be as important as those generated in the global open oceans. SGD may be an important source of alkalinity and carbon to the conti-nental shelves but the current biogeochemical models (e.g. Chen and Wang, 1999) do not prop-erly include contributions from SGD because of the lack of data. In fact, SGD has not been measured in most coastal areas of the world. No such data have been published in Southeast Asia where rainfall is abundant and SGD is to be expected. The subtropical island of Taiwan enjoys a high rainfall (av. 2,515 mm or 90×109m3a year between 1949 and 1990 for the island of 35,873 km2 in size). However, the areas of steep moun-tain terrain above 1,000 m elevation cover 32 % of the island and 156 peaks stand taller than 3,000 m. Further, hills and terraces between 100 and 1,000 m elevation comprise 31 % of the is-land. Because of the rough topography, rivers are short and most rainwater reaches the oceans within a very short time. As a result, rivers supply only one third of the total water consumption on Taiwan. As reservoirs are all small, combined together they account for only one fourth of the water supply. The major source of freshwater turns out to be groundwater. The usage of ground-water started in 1923 when the Taiwan Sugar Co. drew water in the Pingtung Plain in south