Problems on prevention of natural disasters discussed in relation with the developments of the regions are as follows : 1) Problems due to eruption of Mt. Fuji and debris supply from the Osawa-kuzure-Gully, near the crest of Mt. Fuji, through the Osawa-Valley and the Uruigawa River to Port of Tagonoura, newly excavated at the mouth of the Uruigawa River. 2) Problems related to rapid change of salinity of ground water in the vicinity of the port. 3) Problems due to deformation of coastal lines caused by the construction of such port facilities as wave breakers, port entrance etc. and change of shingle beds of the Fuji River resulted from the construction of dams, dykes, sand and gravel pits etc. 4) Problems due to the industrial development on the unconsolidated soft sediments, alternations of peat, clay, sands and gravels, and natural disasters due to their physical properties. For 1) precise observations and measurements are requested before concluding definitely. For 2) two possibilities to explain such phenomena are discussed. For 3) obvious changes are described. For 4) physical properties of unconsolidated sediments are analysed. Those studies have been carried out by the colleagues of the author. This is only an abstract of the papers prepared by the cooperators.