A stationary front activated by Typhoon 4 in 1998 dropped a record breaking rainfall on the east side of the Nasu Mountains of more than 1200 mm over six days which caused flood disasters in the upper and middle reaches of the Abukuma River basin. Results of field surveys of the areas and those of a runoff analysis are reported. Besides the heavy rainfall, the analysis shows a high runoff efficiency of 0.73.
The middle reaches of the basin were secured through improvement in countermeasures based on experiences in the 1986 flood. The upper reaches which in the past had a low frequency of flooding and therefore did not have improved preventative measures, suffered serious damage by sudden huge floods accompanied landslides, driftwood and sedimentation.

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Heavy rainfall over a wide area of northern Japan from August 26 to 31, 1998, triggered many landslides which caused serious damage to human lives as well as houses and civil engineering structures, particularly in Fukushima Prefecture. We report preliminary finding of a hydro-geological study of two landslide sites, Nishigo and Taishin, Fukushima. When the stability of slopes during a rainstorm is discussed, both the thickness and hydraulic conductivity of the surface soil must be taken into account, in addition to the rainfall intensity and cumulative rainfall. These hydro-geological factors are important, in particular for the prediction of the time of slope failure. In certain cases, the hydro-geological structure of the surface soils can be used as a diagnostic factor for slope stability. For example, an impermeable zone can obstruct the outflow of seepage water from a slope, so that a kind of underground dam is accidentally constructed in situ. In such a case, a site investigation, in which much attention is paid to the hydro-geological structure, is crucial for the discussion of slope stability.

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Based on data compiled during the period 1600-1999, 105 tsunami have occurred in Indonesia. Ninety-five events (90%) of them were caused by earthquakes in a shallow region at subduction and plate boundaries, 9 (8%) by volcanic eruption, and one (1%) by a landslide. To clarify the regional characteristics of tsunami, we defined 6 zones; West and East Sunda, Banda, Makassar, Molucca and Irian Jaya, and made the histograms of earthquakes and tsunami by region by decade from 1600 to 1999. Seismic activities were found in East Sunda, Banda and Makassar are high and tsunami activities in West Sunda, Banda, and Molucca. An interval of about 100 years was found for high earthquake and tsunami activities in the period 1800-1999. The percentages of earthquakes accompanied by tsunami to all earthquakes in Banda and Molucca exceed 50%. In terms of human loss due to tsunami, West Sunda is the worst zone because of the devastating damage done by the 1883 Karakatau volcanic eruption. The tsunami potentials in Banda and Molucca in terms of both frequency and damage are very high. Tsunami activity in Banda since 1960 has been remarkably high.

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HEIFE (HEIhe River Field Experiment) was planned as one of the Sino-Japan joint projects of WCRP (World Climate Research Program). The HEIFE project investigated energy exchange between the atmosphere and surface of a dry desert region. Several important results were obtained, and some peculiar effects observed in the Hexi Corridor area of Northwestern China. This project is the first integrated study on experiment of physical processes between the atmosphere and land surface.

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