Proceedings of the General Meeting of the Association of Japanese Geographers

Recently, many local goverments have made the floods hazard maps because of the flood prevention law revision. How does people feel these flood hazard map and does they change the awareness of the land which they live? We made questionnaire survey about the people's awareness of hazard map at the Shinminato district on Imizu city, Toyama Prefecture.
The perception rate of hazard maps are not high, 60%. The ratio is not different between dangerous area of flood disaster and safety area.

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Acidity and magnetic susceptibility of acid sulfate soils were investigated in the central plain of Thailand. Soil pH (H₂O) and pH (H₂O₂) of samples collected from surfaces of various landforms were measured in the laboratory. Magnetic susceptibilities were measured at each sampling point. On the basis of the combination of pH (H₂O) and pH (H₂O₂), two classification of acid sulfate soils were made: AASS, actual acid sulfate soils, pH (H₂O) <4.0 and pH (H₂O₂) <3.0; PASS, potential acid sulfate soils, pH (H₂O) >4.0 and pH (H₂O₂) <3.0. AASS is mostly distributed along the paleo-shoreline of the Holocene transgression at 7 - 8 cal kyr BP. Furthermore, the AASS develops on landforms of relatively low altitudes such as back marshes and deltas. Oxidation of pyrite derived from mangrove vegetation at the paleo shoreline and periodic wetting and drying at these landforms involves acidity in soils.

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The city before the modernization was a scale of an extremely small range among a castle wall and the castle towns. In the investigation for the Asia Metropolis, after modernization in approximately 150 years before, a range of the city area began to enlarge it by increase of the population and the urban infrastructure. Metropolis enlarged toward each direction although there was limitation of the topography such as the river and hill part. It is important to decide a setting range so that aging compares these as from a topographical map to GIS data or statistics document.
Especially Bangkok is suited for analysis about the relationship between urbanization and hydrological environment. Bangkok is located at the lower delta of Chao Phraya. The Thailand dynasty has replaced its capital to downstream along the river. In the latter half of 18c, Bangkok became the capital of the Kingdom. There was transportation network with river and canal which called klong in Thailand. As the road network has constructed, the klong system also has effected on urban function. After the period of growth, Bangkok has extended to outer BMA (Bangkok Metropolitan Administration) with industrial urbanization. They have caused traffic jam. Because many workers live on suburb and factories are located on periphery of the city. As same as other developing countries, Bangkok has been judged the primate city for the rest cities. Recently, new railroad system (Bangkok Transit System and subway) has constructed in Bangkok. Under the suburbanization, shipping service has remained. In addition to that, the major facilities (e.g. temples which called Wat in Thailand) are concerned with the klong network. Its location has been regulated with water (re)use and the transportation system.
So, one of human impacts can be analyzed by the urban hydrological environment.

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Bangladesh is one of the most densely populated countries in the world. Its population is exceeding 150 million, while the land area is only 40 % compared with that of Japan. Bangladesh is located in the heart of the South Asian monsoon region where copious rainfall is concentrated in summer monsoon season. Moreover, it is located in the juxtaposition where two major rivers; the Ganges and Burahmaputra murge together, and where another river; the Meghna whose drainage basin includes the most rainiest region of the world; the Meghalaya Plateau also murges together with these rivers within its country. Thus, this country is prone to big flood disasters. In addition, Cyclones from the Bay of Bengal also caise serious damages. When accompanied with the large storm surges, the number of death sometimes exceeded 100,000. Most parts of Bangladesh are less than 10 metres above the sea level, and it is feared if the sea level were to rise by global warming, its submersing area wold increase more and more. The recent situations of flood and cyclone disasters in Bangladesh will be presented.

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