查看更多>>摘要：Journal of Hydroscience and Hydraulic Engineering, JHHE, was first issued in April, 1983. The English journal has been edited by the editorial committee organized under the committee on Hydroscience and Hydraulic Engineering, Japan Society of Civil Engineers, JSCE. It has been issued twice a year for 30 years as one of the JSCE official English journals. The total number of papers published amounts to 505.
查看更多>>摘要：We introduce a new "disaster immunity" concept in place of conventional "disaster management capacity" that reflects dynamic transitions in society and nature more accurately than the fixed conventional "disaster management capacity" concept. Because awareness deeply impacts on disaster management, the new concept captures disaster dynamics and could play an important role in disaster reduction. Since global warming involves disaster hazard intensification, it is not enough to simply strengthen existing measures. As an example, Japan responds to particular temperate zone patterns through long-term disaster management infrastructures. Society and nature in Japan have disaster management capacity matching typical temperate zone hazards. A rapid transition to subtropical climate patterns within the next several decades to a century is expected to generate large gaps between disaster hazards and disaster management capacity of human society and nature, leading to an imbalance. Under unstable conditions, society and nature have become increasingly vulnerable due to decreased "immunity." Increasing "disaster immunity" is thus an urgent and important issue.
查看更多>>摘要：Bed degradation has been increasing rapidly in the upper part of the Ishikari River, owing to exposed bedrock erosion caused by bedload on the bedrock. In order to estimate the erosion velocity of bedrock, we performed an experiment by using a circular flume with artificial bedrock made of gypsum. This study also proposes a numerical model which can simulate the bed deformation process of rivers with bedrock to reproduce the bedrock channels induced by bedload. We incorporated the erosion velocity equation of bedrock and a bedload layer model into the plane two-dimensional morphodynamic model. The computational results show that the proposed model can simulate the development of bedrock channels by a concentration of bedload, and channel patterns in the simulation are similar to the channels which are generally observed on bedrock in real rivers. It was found that bed degradation progresses by erosion which is caused by sediment transport itself.
查看更多>>摘要：In August 2009, Typhoon Morakot struck Taiwan, producing an extraordinary amount of rainfall. The heavy rainfall caused a large number of floods and sediment-related disasters across the island. In Shaolin Village, Kaohsiung County, a huge landslide, about 1,200 m long, 500 m wide, and 80 m deep, occurred around 6:00 on August 9th, destroying the village and killing more than 500 people. After the landslide, we visited the landslide site and investigated the landslide scour to collect information about factors affecting landslide occurrence such as exposed bedrock and soil layer conditions. Geographic information system (GIS) analysis using digital elevation model data was also conducted to determine the sliding domain. On the basis of the site investigation and GIS analysis, rainwater infiltration and slope stability analyses were conducted. The simulated landslide occurred at the lower part of the slope, in contrast to the actual landslide. Although the exact process of the huge landslide in Shaolin Village is unknown, a multi-phase collapse was a possibility and the simulated landslide may represent the first step in this process.
查看更多>>摘要：The diurnal rainfall variation in Matsuyama plain was analyzed by using datasets from AMeDAS, MLIT (Ministry of Land, Infrastructure, Transport and Tourism), and the local government. The late afternoon peak of precipitation is particularly noticeable around the top of alluvial fan, especially in the warm season. The absolute humidity observations indicate that the sea breeze transports the moist air along the river toward the inland regions, and thus contributes to an increase in the water vapor content around the top of alluvial fan. This is one of the reasons for the intense precipitation around the top of alluvial fan.
查看更多>>摘要：Prediction methods of flow resistance and bed-load transport rate in alluvial streams with sedimentary dunes under lower flow regime are proposed in this study. At first, a skin friction equation is derived by integrating the grain-roughness shear stress distribution equation on the dune surface. Next, an equation of flow resistance based on equations of skin friction and form drag is proposed. The flow resistance equation is verified by estimating the mean depth of flow over dunes. An equation of effective tractive force is also proposed, and then the difference between the skin friction and the effective tractive force is discussed. The reach averaged bed-load transport rate can be calculated reasonably by the Meyer Peter & Mtiller's equation by using the proposed effective tractive force equation and estimated mean flow depth. The proposed method can predict the mean flow depth, mean length and height of dunes, as well as bed-load transport rate by providing water discharge, bed slope and grain size as input variables. The method which we propose also clarifies that the ratio of the form drag and the skin friction to the total shear stress is different in uniform and non-uniform sediment beds.
查看更多>>摘要：The purpose of this study is to investigate the vertical structure of a river bed which is composed of an extremely wide range of sediment grain size in the state of static equilibrium. Several series of experiments were conducted under the conditions which were set systematically. The bed materials were modeled as three grain size groups of sediment: the larger particle of stone or gravel which cannot move at all, the medium particles of gravel which moves as bed load and the finer particle of sand or silt which can move as suspended load. As a result, it was found that a vertical grain sorting occurs clearly in the void of bed which was surrounded by the larger stones. The structure of such bed results from the hiding effect by the larger stones. The characteristics of this structure were evaluated in this paper.
查看更多>>摘要：This study deals with traffic problems in the Kyoto urban area due to inundations caused by heavy rainfall. First, under normal conditions, a "time-of-day" user equilibrium traffic assignment is performed and traffic conditions on the network are computed. Next, assuming a heavy rainfall, an inundation flow analysis by means of unstructured meshes is made to obtain the water depth distribution. A similar traffic analysis is performed under inundation conditions, by changing the travel speed and traffic capacity based on the computed water depth of each link. Then, the degree of congestion and the travel time between major ODs are compared and discussed for normal conditions and when inundations occur. We found that the inundations at the southwest of the studied area including the underpass of JR line has an effect on the traffic network all over the city, and that traffic difficulties change with the beginning of rainfall, namely, the temporal change of inundation.
查看更多>>摘要：I am pleased to have this opportunity to give a remark about the Journal of Hydrosciece and Hydraulic Engineering (JHHE). Since 1983 the JHHE has been contributing to internationalization of the Japan Society of Civil Engineers (JSCE) by introducing Japanese research activities in hydraulics and related fields to the world and advancement of academic information exchange by calling for papers internationally.
查看更多>>摘要：The objectives of publication of the Journal of Hydroscience and Hydraulic Engineering is to introduce Japanese research activities in hydraulics and related fields to the world and to advance the international exchange of academic information by calling for papers internationally in future.
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