Abstract
In Ibusuki port coast, a coastal improvement project is in progress applying the idea of integrated shore protection system combining jetties, offshore breakwaters, seawalls and beach nourishment. In the project, the local groundwater environment named “natural sand-steaming hot spring” should be carefully conserved, because that is an important tourism resource in the region. With the aim of evaluating the impact of the beach nourishment on the hot spring groundwater, this study develops a basic model to analyze the flow and temperature variations of the hot spring groundwater in this site. The developed model is found to reproduce well both the steady groundwater levels in the land region and the time varying ones with tidal level fluctuations in the coastal region. The developed model also describes the coastal temperature fields well in the following aspects; in the upper layer, the temperature drops rapidly by cooling of the seawater during flood tides and it grows hotter as the tidal level decreases; in the lower layer, the temperature variations with tide becomes less with decrease of the influence of in-filtering seawater flows.
