Masahiro Tamai

The authors showed that cold nocturnal darainage flows break out in the northern part of Osaka Plain, can lower temperature of the part by 2℃ and have velocity profiles similar to those of gravity density currents on inclined plains. In the present study, numerical simulation using the WRF was conducted to examine structures and generation mechanisms of the flows. The accuracy of the calculation was checked by comparison with some existing meteorological data. The simulation results showed that the drainage flow which the authors have been studying is generated by outflow of cold air mass which accumulates in the Tada basin into Osaka Plain and there are other nocturnal drainages which flow on flood plains of the Akutagawa and Aigawa Rivers in the part.

A new method by the concept of entropy has been used to classify sediment color distribution. We objectively characterized the distribution profile and clarified the relationship between the geology and sediment characteristics. Sediment colors were defined by L*a*b* instead of RGB, and of the following four indexes, lightness, hue, saturation and chromaticity, lightness was the optimal index. In order to determine the optimal number of groups, a C-H criterion, Rs statistic and the skewness of the third moment on sediment color distribution were used. The sediment colors could be divided into 7 groups. Kagoshima Pref. has geology of the Shirasu plateaus, but the sediment color could be grouped by white minerals such as quartz and feldspar contained in granite and pyrophorite and colored minerals such magnetite contained in mafic volcanic rock, and therefore, they can be related to geology. In addition, it could be possible to make sediment transport path clear by focusing on a specific mineral such as olives.

Purposes of the present study are to obtain quantitatively color characteristics of sands which were collected in the mainland beaches in Kagoshima Pref., Japan and to examine relationships between the color characteristics and geological features of the surrounding area of the beaches. Some relationships between the two are clarified, such as that a lot of the beaches have sand colors of medium dark brown under the influence of late Pleistocene non-alkaline pyroclastic flow volcanic rocks, Holocene non-alkaline pyroclastic flow volcanic rocks and non-alkaline pyroclastic mafic volcanic rocks make beach sand color dark gray, and dark blown sands of some east coasts in Osumi Peninsula originate in middle Miocene to late Miocene granodiorite.

The final goal of this research is to develop a simple risk evaluation method for SO₂ erupted from a Mt. Aso, Kyushu Discricts, Japan. As the first step for that, influences of meteorological conditions on behavior of SO₂ were examined by analyzing high SO₂ concentration events that hourly concentration is over 50ppb. The high SO₂ concentration events occurred under the condition that speed of eastern geostrophic wind is about 30m/s and, solar radiation is relatively small or potential temperature gradient is relatively large, or under the condition that eastern geostrophic wind speed is about 5-20m/s with relatively large solar radiation.

In order to develop a simple risk evaluation method for SO₂ erupted from Mt. Aso in Kyushu district, west Japan, relationships between SO₂ concentration variations observed at a point 20km east from the crater of the mount and some meteorological observation data were examined. By using cluster analysis, days when observed SO₂ concentration were relatively high, were selected from the target period and the meteorological data of the days were analyzed. Some typical meteorological patterns which can cause high SO₂ concentrations were clarified.

Purposes of the present study are to obtain quantitatively color characteristics of sands which were collected in 41 beaches in Niigata Pref., Japan and to examine relationships between the color characteristics and geological features of river drainage areas which are adjacent to the beaches or of area within 5km distance from the beaches. The geological features drastically changes because of some tectonic lines, the Fossa Magna and so on and accordingly beach sands have a variety of colors. Some relationships between sand colors and geological features are clarified, such as that the beaches in the east side of Agano River have bright color sands owing to felsic plutonic rocks of the late Cretaceous and that those in the Fossa Magna area have dark color sands under the influence of non-alkaline mafic volcanic rocks and sedimentary rocks in the Niigata Oil Field.

The geological features in singing sandy beaches can be devied into three types. These are the dynamic equilibrium becch, indicating the domination of pocket beaches it the area. The prominent sand color in singing sandy beaches was brawn. The major chemical elements are as follows; Si, Al, Ca, Fe, Na, K and Mg. There is little difference between singing sandy beaches and general sandy beaches on chemical elements. However, Ohyama beach in Yamaguchi Prefecuter is rich in Ca. The 1^st peack frequency of singing sand sound is related to sand grain size, 2^nd the sorting coefficient.

Mountain winds are recognized to drop air temperatures at the foots of mountains in nighttime. If we try to use the winds as countermeasures for nocturnal heat-island phenomena, such informations as flow structures, occurrence mechanisms and etc. of the winds have to be obtained before that. The author indicated that cool air winds occur and drop air temperature by about 1 degree in the Eastern part of the Osaka Plain. The purpose of the present study is to clarify flow structures of the cool air winds by pilot balloon observations and meteolorogical data analyses. It is shown that the winds are mountain winds which are generated in surrounding mountains of the Osaka Plain and that layer thichnesses of the mountain winds are about 100m and maximum velocities of the winds are 2-3m/s.

Sand samples along the shorelines and in the rivers of Tottori Prefecture were assayed for chemical elements using energy dispersive X-ray spectrometer. Samples contained more than 60 wt% Si, Al, Ca, Fe, Na and Mg less than 10 wt%. It was found by EOF analysis that Si, Al, Ca and Fe were the significant chemical elements. The spatial variations of first mode of Si are related to sediment dynamic behavior. The transport regime is net accretion when the first mode value of Si is increasing, and net erosion when being decreasing.

The WBGT index is commonly used to indicate heatstroke disease risk but the index does not always expect the risk in night time correctly. The puopose of the present study is to examine whether daily fluctuation patterns of surface wind directions can be a indicator which appropriately expresses the night time risk. It is shown that fluctuation characteristics of the WBGT vary by the daily fluctuation patterns. A new index Y(T) which is calculated by time integrations of the WBGT and can take past records of sultry environments into consideration is proposed and it is also shown that fluctuation characteristics of Y(T) differ by the patterns. It is indicated that night time averages of Y(T) for each pattern correlate closely with nocturnal heatstroke desease risks and the pattern W which means that west wind blows all day long has the highest risk for nocturnal heatstrokes. From the above results, we concluded the daily fluctuation patterns of surface wind directions can be utilized as a indicator to expect heatstroke disease risks in the night time.

Using digital images of sand grain with a scanner, the training data set on minerals; quartz, feldspar, shale silicified stone and chart was made. The data set could be divided into five regions using the CIEL*a*b* color space methods. Especially color brightness and satulation are important to identity mienrals. Shapes of quartzs and feldspars are more rounder than other minerals. Filed observations were carruied out in Awaji Island and 17 samples of beach sand and 51 river were colleceted. The optimiation method was applied to estimate the impact rate from rivers toward beaches with a distance among a beach and a river. The estimated results are corresponding to the existing knowledge.

Beach sand were collected in selected 27 beaches in the Biwa Lake shore and in 14 rivers which flow into the Lake, to examine supply sources of the beach sand. Sand colors were analyzed using the simple color analyzing method proposed in our preceding papers. Rrelationships between the sand colors and geological stratums around the lake were investigated and it is comfirmed that sand colors of the beaches were obviously depend on the geological stratums. Color relationships between the beach sand and the river sand were examined using a simple optimization analysis.

The Osaka Plain faces with the Hokusetsu and Rokko Mounts on the north. The purpose of the present study is to clarify flow structures of nocturnal drainages which break out on the south-facing slopes of the mounts and flow into the north part of the Osaka plain. Vertical profiles of horizontal wind velocity and turbulence properties on the ground are observed by the pilot balloon observation and a ultra-sonic anemometer. And such meteorological data as AMeDAS data were analyzed to examine horizontal flow extent. Vertical profiles of a north-south component of horizontal wind velocity of the nocturnal drainages are quite similar to those of gravity density currents which flow on inclined planes. The nocturnal dranages caused suddenly temperature drops when heads of the nocturnal drainages arrive at the observation point but doesn't contribute to suppress vertical turbulent temperature transport.

The meteorological scenario days are representative samples of a variety of daily meteorological conditions which occur during risk estimation period. In the present study, we proposed a simple method using meteorological data of the meteorological scenario days and the Trajectory-puff model, to get long-term averaged concentrations of air pollutants which are discharged instantaneously. Assuming that air pollutants were discharged instantaneously at a point of the Fukusima first nuclear power plant, seasonal long-term averaged concentrations are calculated. Applicability of the method was examined by comparing this seasonal mean concentrations by using the meteorological data with those by using meteorological data of whole three months. Inaddition, ausage of the method was investigated by comparing with monitoring date of radioactive materials.

Sand samples were collected in selected 18 beaches and in rivers which are supposed to supply sand to the beaches in order to examine supply sources of sand of the beaches in the Awaji Island. Sand colors were analyzed using the simple color analyzing method proposed in our preceding papers and relationships between sand colors and geological features of drainage areas of the rivers were investigated. Color differences of the sands collected in the rivers were relatively obvious owing to distinctive colors of geological stratums of the Awaji Island. Those of the beach sands were unclear because of weathering, artificial nourishment or sand transport by coastal current.

The Osaka Plain faces with the Ikoma and Kongo Mounts on the east and south. Our preceding study confirmed using 3 dimensional numerical simulations that nocturnal drainages break out on the west-facing slopes of the mounts and flow into the east part of the plain. Purposes of the present study are to examine their occurrence conditions and influences on nocturnal temperature distributions of the part by analyzing such observational data as the AMeDAS data. In addition, occurrence relationships between the nocturnal drainages of the east part and those of the north part and influences of the two on heatisland phenomena in the Osaka Plain are investigated. The result shows that the nocturnal drainages in the east part tend to occur in the condition that daily solar radiation is relatively large and both north-south and east-west components of geostrophic wind are about 5.0m/s.

Beach sand color is one of important components of coastal landscape. But color information has not been used to coastal engineering. Color determination of sand grains collected in 164 coastal sand beaches was performed with a scanner and the relative frequency of sand color was calculated based on RGB color palette. The principle component analysis and cluster analysis were applied to the relative frequency of sand color. The sand beaches were classified into two general groups; gray and brown. The artificial beach is consisted of many colored grains. Tan and brown colored grains are seen at singing sand beaches. Sand color changes are confirmed before and after the tsunami which has attacked the beach in Japan last year.

Although sand colors have influences on a variety of functions, such as coastal landscapes and beach ecological systems, they have never been research subjects in the coastal engineering area. The purposes of the present study are to clarify color characteristics of sands which were collected at 23 beaches in Japan and to examine relationships between the color characteristics and geological features of river drainage areas which are adjacent to the beaches. PCA ordinations showed that the 23 beach sands colors can be well ordinated in a coordinate plane which has axes of brightness and of black to brown. It was confirmed that the brightness of the sand is well explained by area ratios of the felsic rock and of mafic rock, by examining the relationships between the beach sand colors and the igneous rocks.

Artificial sandy beach profiles and the vertical distributions of sediment grain size were measured monthly along one cross-shore line in Azure Maiko Beach for two years. All the measured profiles and vertical distributions are approximated using the quadratic profiles. In order to interpret the temporal variations of the quadratic profiles, six parameters are introduced. The principle component analysis was applied to evolutions of the six parameters to detect major variation modes. The relationships between the detected modes and the external forces, wave height and tidal level, are expressed using the multiple linear regression analysis. The first mode is found to be caused by tidal oscillations and the second by the energetic wave motions. Long term prediction of the modes is examined using these regression results.

Manning's roughness coefficient is influenced by roughness condition of perimeter, shapes of longitudinal and cross sections, flow conditions represented by parameters such as the Reynolds Number and so on. There are few preceding studies dealing with relationship between the roughness coefficient and other factors than the roughness condition. The purpose of this study is to examine relationship between the Manning's overall roughness coefficient and configurations of river channels which have different roughness perimeters by numerical simulation. Characteristics of variations in the Manning's coefficient according to water depth and applicability of composite roughness coefficient are discussed.

While there are a lot of preceding studies dealing with relationships between urban heat islands and sea-breezes in the daytime, there only a few studies of those between nocturnal heat islands and sea and land breezes. The purpose of the present study is to clarify the influences of wind field structures on nocturnal temperature or nocturnal heat islands in the Osaka bay area in the summer season by analyzing some observational data including the doppler soda observational data. It is found that sea surface temperature contributes to increase daily minimum temperature in the Osaka bay area and that penetration of nocturnal land breeze or of nocturnal cool air mass into the area is important to lower nocturnal temperature.

The purpose of this study is to clarify relations between sea-surface temperature and air temperature of an urbanized bay area in summer seasons by observational data analysis and numerical simulation. The observational data analysis using the AMeDAS and the Meteorological Objective Data showed that the sea-surface temperature has great influences on the air temperature of the bay area and sea breeze in night time contributes to raise the air temperature. The numerical simulation with the HOTMAC represents that a control of sea-surface temperature may be an effective method of lowering the air temperature of the bay area in summer night time

The Reinan area is the western part of Fukui Prefecture and bounded on the north by the Wakasa Bay and on the south by the Nosaka mountains. Valleys in the area connect Wakasa Bay and Lake Biwa areas and wind through the valleys plays important roles in heat and pollutants transports between the two area. Field observation was carried out in Sept., 2004 using a Doppler sodar velocitimeter to investigate structures of mountain and valley winds in one of the valleys. The results were examined in relation to macro- and meso- scale wind fields using the AMeDAS data and the objective analysis data by the JMA.

Structures of sea and land breeze over the Osaka Bay area are complex because of westerly general wind flow and complex topographical conditions. The purpose of this study is to simulate three dimensional structures of realized sea and land breeze over the area by introducing the objective analysis data. Vertical profiles of wind velocity were measured by a Doppler sodar anemometer at the Osaka Nanko area in the 2003 summer. Numerical model simulations were carried out to produce weather conditions which occurred during the measurement. Simulated vertical profiles of horizontal wind velocity vectors agreed quite well with the observed one. However vertical velocity couldn't be simulated accurately. Some modification will be needed for the numerical model to calculate behavior of atmospheric pollutants emitted in the bay area.

Aquatic insects were surveyed to evaluate a biotope of Aono dam fishway ecologically. The Aono dam is located on the Aono river, a tributary of the Muko river which flows through Hyogo Prefecture, Japan. The fishway consists of pool-type fishway, riffle and pool sequences and etc. Aquatic insects were sampled by picking up surface bed materials in about 0.09m₂ quadrat and washing adhered materials out. Sampled aquatic insects were identified to genera and individual numbers were counted for each genus. The genera and their individual numbers were examined in relation to hydraulic and bed conditions. EPT, Shannon Diversity Index and etc. were calculated for each sample. Most sampled insects belongs to genera which have tolerance to organic pollutions and usually live in lower reaches. Algae and mud which are supposed to come from the dam reservoir strongly influence spatial distribution of the genera of insects.

Environmental risk assessments will be necessary in the near future when every facility that may exhaust pollutants such as a chemical plant or a waste disposal plant is constructed. The puff-plume model is commonly used for the environmental assessments of atmospheric pollutions in Japan. Although the puff-plume model is applicable to calculating pollutants concentration in relatively simple wind fields, we have to examine whether it satisfies requirements of the risk assessment model. The aim of this study is to verify the model using common weather conditions simulated by a three dimensional atmospheric model. Pollutants concentrations were calculated by the puff-plume model and compared to those by three-dimensional simulations. The puff-plume model doesn't calculate pollutants concentrations accurately in the bay area under a weather condition that sea and land breeze is rising.

Yodo river park, the first government-managed river park in Japan, has annual visitors of about 5 million and has become one of the most important parks in Osaka and its neighboring prefectures. The park also plays a role to protect or preserve natural river environment and is composed of four types ofareas according to purposes. The actural condition of various functions and utilization of the park has never been investigated sufficiently since the park was open to the public. The purpose of this study is to evaluate the utilization of the park economically using a questionnaire survey result and visitors number data by the park administrator. A relation between characteristics of the areas and the benefit of the utilization is investigated. Annual benefit of the park is over 2.7 billion yen.

Local climate change with urbanization in Kobe City area was investigated by using a turbulence closure model. Wind and temperature fields in air were computed with respect to the present ground conditions in the city and those of about fifty years ago when the city area was less extended. Parameters of ground surface such as albedo, geometrical roughness and water content of the old age were estimated from correlation between land use and categories of governmental districts. The analysis showed that urbanization in the last fifty years brings local warming such air temperature increases of about 0.5 degree in daytime and 0.3 degree in nighttime at the maximum. Intensification of sea-land breezes by the urbanization is also confirmed.

Air pollution is getting serious in urban areas by increase of automobile traffic. A variety of methods to control the traffic have been proposed, but efficiency of the methods has not been examined quantitatively yet. It's important to develop a system to simulate a series of pollution processes from an occurrence of automobile traffic to diffusion and deposition of pollutants. In this study, in order to simulate SPM originated from automobiles, we constructed an integrated model composed of a mesoscale meteorological simulation model (HOTMAC), a random-puff model to calculate transport process of pollutants (RAPTAD), a photochemical reaction model (CBM-IV), SPM generation model proposed by Japan Environmental Agency and an automobile pollutant emission model. We calculated behavior of secondary SPM originated from automobiles in Osaka Prefectural area under various meteorological conditions to examine validity of the simulation model.

The region of Hiroshima is a coast position, which faces the Hiroshima bay. The diffusion of the air pollution material from the car traffic and the factory exhaust is a problem in this area. Air pollution in the coast regions strongly influenced about the sea breeze. A numerical model expressing the appropriate wind profile is necessary for a good pollution forecast. The characteristics of wind filed and the transport of heat at fine day in summer were examined by using AMeDAS data The relation between the sea breeze and the temperature was examined, at Hiroshima and Kabe. The simulation used HOTMAC was carried out for Hiroshima area, and The simulation products the good wind velocity and direction.

Field measurements of surface flows on a river by using a helicopter were carried out. Image Velocimetry (IV) is applied for measurement of surface flow of the river. The images are taken by a video camera which is built in the helicopter. For tracers of surface river flows, the “Senbei” is selected because of its decomposable in natural situation.

A wind field over the Lake Biwa is very complex and variable since the wind field is influenced by sea and land breezes from Osaka, Ise and Wakasa Bays, and the Lake Biwa is surrounded by mountains. In this study, we conducted a three-dimensional numerical simulation of the wind field with HOTMAC of a mesoscale meteorological simulation model. And we verified the numerical simulation method by making a comparison between calculated result and some preceding observational data and examined a relationship between the wind field and the extended sea breeze. The simulation result show that a northwest wind which is the most dominant wind system is caused by the sea breeze from the the Wakasa Bay and that the lake breese is strongly influenced by the extended sea breese.

Field measurements of surface flow on a river were carried out by using a helicopter on June 11^th, 2001. The images were taken by a standard camera and an infra-red camera.

Heat-island phenomenon is commonly observed around megalopolises. As most of the megalopolises locat near coastal lines in Japan, the heat-island is closely influenced by the see breeze. Recently some researchers indicate that the characteristics of the see breeze has changes due to the influence of the heat-island in some area. In this study, we examined the AMeDAS temperature data set and carried out the numerical simulation using the three dimensional model (HOTMAC) to discuss the heat transport and the interaction between the heat-island and the see breeze in the Osaka Plain.

We evaluate an economic effect of potential flood risk which is defined by height difference between high water level and ground level with the two-regional residential location model. The model describes residential behavior of households which choose one of the two regions to maximize their utilities. First we get a parameter in a utility curve which shows a preference rate of the risk. Second we examine the risk-mitigation benefit under a variety of condition. Finally we discuss that a relationship of beneficiaries or a total benefit depends on an extent of influence which we set.

Air pollution is getting serious in urban areas by increase of automobile traffic. A variety of methods to control the traffic have been proposed, but efficiency of the methods has not been examined quantitatively yet. It's important to develop a system to simulate a series of processes from an occurrence of automobiletraffic to reaction and deposition of pollutants. In this study, we are trying to construct such a system with HOTMAC of a mesoscale meteorological simulation model and RAPTAD, a sort of random walk model to calculate transport process of pollutants in an urban area. And the mobile source emissions are estimated by using road traffic census data and emission function in RAS-W. Here we simulate behavior of SPM (Suspended Particulate Matter) which is ejected by automobiles in Osaka area under a various meteorological conditions to examine a validity of thesystem.

We investigate environmental ethics of river engineers who have many problems about conflicts river improvement works and nature-conservation movements with questionnaire. In this paper, we report a variety of troubles related to the conflicts which most of the engineers who answered the questionnaire. We classify the described concrete troubles into some categories (Negotiation and decision making, Construction cost, Evaluation method of nature and etc.) and show you some typical examples of the troubles. Finally we discuss what we have to do to find out a solution of the conflicts.

Movements against public works to save natural environments are now in fashion and a sort of environmental problem such as that observed in the Isahaya Bay reclamation project will repeatedly occur. We think that understanding their environmental thought which supports the movements will contribute to solution of friction between public works and actions to protect the natural environments. In this paper, we analyze a lot of objections to the Isahaya Bay reclamation project published in the three major newspapers from the viewpoint of the environmental thought by ethicists and philosophers in order to know the level of environmental ethics of general public.

The development of geographic information system (GIS) has significantly changed the way we acquire and use spatial data and introduced the potential for increasing the use for planning drainage and determining the physical watershed characteristics in hydrologic modeling.<BR>In this paper, we describe the attempts that further incorporates the spatial analysis capabilities of GIS into the sewerage management and planning. We construct a distributed model in which the spatial distribution of landuse is taken into consideration and propose a new index for the danger of inundation of each sewerage pipe that is acquired by the difference between the distributed and lumped models.

The importance of ethics education for engineers is emphasized in these days. The reason is that the way to look at social responsibility of engineers is now changing under the influence of global environmental problems. New ethics education requests that engineers have a sense of responsibility not only for activities in their fields but also for every social problem which the activitiesinduce in the future. In this paper, we describe the social responsibility of the engineers and professionalethics which civil engineers should reconsider, and conclude that the civil engineers should take responsibility for the ethics education of their own.

In this study, we evaluated the economic effects of potential flood risk in the Neya River basin with the hedonic approach which relates land price to a variety of environment factors. We introduced height difference between land elevation, high water level, distance from the river, land subsidence of ground, and etc. as environmental factors into a hedonic price function. We found out that the land price is closely influenced by the height difference in the region relatively near the Neya River and that the subsidence, improvement of sewerage system and flood experience has influence on the land price in the region relatively far from the river.

Groundwater contaminations by VOCs (Volatile Organic compounds) are searched in many sites. These contamination are spread in both saturated zone and unsaturated zone. In these cases, mass transport is very important between these two zones, because the volatilization of VOCs from groundwater and the subsequence process are same mechanism on groundwater contamination.<BR>In this paper, the mechanism of VOCs transport in subsurface and these processes are discussed. Two types of experiments are carried out. One is the evaluation of the transport of VOCs in saturatedunsaturated zone under a soil moisture profile. Other is the estimation of the transport of VOCs under the oscillating water table condition. And a numerical model, considered with mass transfer on the interface, is applied to both saturated zone and unsaturated zone. This simulation agrees qualitatively with experimental results.