In the flood management planning of the river in which weir(s) is/are placed or operation of tipping weir, weir hydraulics should be considered from various directions. But most of the previous studies exclusively directed towards discharge evaluation, and evaluation of the water level just upstream of the weir, which is particularly important for water flood management of the river in which weir(s) is/are set, is extremely rare. Also, as far as we searched for, there exist no study evaluating weir height which is required to suppress upstream water level at desired value under the designated discharge. In this paper, we derived the equations for each of the discharge, upstream water level and weir height of the submerged flow over sharp-crested weirs, from downstream water level plus two quantities other than itself. The calculation showed good agreement with the results of the previous experiments carried out precisely and systematically.

 Hydrodynamic analysis was carried out to investigate performance of a rubble mound weir in controlling water level and discharge, impounding water, generating flow force, dissipating fluid momentum and energy and purifying water. A solid impermeable weir with the same dimension and scale was assumed as a reference case. Time-dependent behaviors of depth and discharge during a single-peaked flood event suggested that the rubble mound weir decreased the water level during the rising stage more than the impermeable weir. By analyzing momentum and energy balances, performances as a flow force controller and as an energy dissipater were compared between the rubble mound and impermeable weirs. Additionally, the pollutant removal rate was analyzed by assuming a primary reaction in the course of infiltration through the porous body.

 In this study, we investigated various approaches to assess the advisability on the day before marine construction works, which is based on error characteristics derived from the disparity between forecasted and observed wave variables. We applied these approaches to the Akita Port and the Hitachinaka Port, representing the Japan Sea and the Pacific Ocean, respectively. The simplest and most straightforward method involved calculating the root mean square (RMS) of the error. The RMS was added to the forecasted wave height and the resulting value was checked whether it falls below the permissible wave height for construction work. However, it was determined that this method tends to be overly cautious in its judgment. As an alternative, we proposed the application of the safety factor method, which is a conventional approach in civil engineering design. We found that the safety factor method yielded a safety margin comparable to that obtained from the error probability distribution.

 Landslide can occur on slopes in snow covered areas because of snowmelt water and rainfall during the snowmelt season. In this study, the effect of snow accumulation on slope stability was examined for the purpose of more accurately evaluating the risk of such snowmelt disasters. In this study, hydraulic properties and strength characteristics of snow were determined through laboratory tests. In addition, precipitation experiments were conducted on a snow-covered embankment model to observe the moisture response and deformation of the embankment. And Finite Element Method of saturated and unsaturated seepage flow and slope stability analysis were also conducted on the snow-covered embankment model. As a result, it was confirmed that the snow accumulation has the effect of slightly inhibiting the infiltration of water into the embankment and slightly improving the slope stability by restraining the surface layer of embankment slope with high water content.

 In this research, the triaxial compression tests are carried out to grasp the strength and deformation properties of improved sand by chemical grout. In this paper, examinations were performed to confirm the effect of strain rate and back pressure on the deformation properties as a first step. From the results, an upper yield point of triaxial compression tests were shown in around the unconfined compression strength and failure strain of them, and the deviator stress became to the maximum according to the strain hardening behavior thereafter. Although upper yield stress increased as increasing the strain rate, the maximum deviator stress decreased as increasing the strain rate irrespective drainage condition. In addition, upper yield stress decreased as increasing the back pressure, but the maximum deviator stress increased as increasing the negative pressure provided with increasing the back pressure in undrained conditions.

 After the COVID-19 pandemic, people were expected to disperse to rural areas through development of telework and other means. In reality, however, the dispersion to the suburbs of metropolitan areas is more pronounced. In order to implement effective local residential policies, it is important to quantitatively understand the actual situation of the intention to move to the rural and suburban areas that occurred during the epidemic (hereafter, "dispersal-type" intention to move). For this study, we examined the occurrence of "dispersed" relocation intention in the three metropolitan areas under the COVID-19 epidemic, and then quantitatively compared the factors that cause the intention to move to rural areas with the intention to move to the suburbs. Results show that it was found that the higher the frequency of telework, the more likely "dispersal-type" relocation intention tends to occur, but the destination tends to be the suburbs compared to rural areas, and this newly clarified the issues of the rural residence policy centering on telework.

 This paper aims to clear land use changes in disaster risk areas, including flood inundation risk areas, sediment disaster risk areas, and tsunami inundation risk areas, from 1976 to 2016 in the whole of Japan, with land use subdivision mesh data. As results, density-built land use shows an increasing trend in every disaster risk area, at the less degree of increasing in the whole land use of Japan. On the other hand, paddy-field land use shows a decreasing trend at the same degree of decreasing in the whole land use of Japan. In addition, with respect to the land use changes from natural or agricultural land use to urban land use, density-build areas were increased by mainly paddy-field in flood inundation risk areas, paddy-field and forest in sediment disaster risk areas, and paddy-field and non-paddy farm in tsunami inundation risk areas. These results imply a necessity of preferential treatments of agricultural and natural land-use in response to the type of hazards.

 The purpose of this study was to clarify the characteristics of “intrinsic value” and the issues of protection regulations for important cultural landscapes, including those listed in the selection criteria 6, by analyzing plans and other documents related to the conservation and utilization of important cultural landscapes and interviewing local government officials in charge of such landscapes.

 As a result, a table was created to list the descriptions of “intrinsic value, ” the types of “important components” and their specific requirements, policies for preservation and utilization, and landscape formation standards set forth in the landscape plan, and its usefulness as a reference material was demonstrated. It was pointed out that the “intrinsic value” of important cultural landscapes should be considered as the total history of the landscape, including continuity and change, even for elements that do not appear to be related to people’s daily lives and livelihoods. The paper clarified that policies and standards based on qualitative descriptions in protection regulations are subject to differences in interpretation and recognition among the parties concerned, and discussed measures to deal with these issues.