The Quaternary stratigraphy on subsurface geology of the Osaka Plain has been mainly built up with drilling cores sampled by 13 deep drilling investigations for ground subsidence countermeasures and the analysis of activity on Quaternary faults. Meanwhile, seismic reflection surveys in the Osaka Plain have been carried out along 13 lines. Depth sections of the seismic surveys provided much additional information on the subsurface geological structure. But, the correlation between the depth section and the litho-stratigraphy of the Quaternary formation in the Osaka Plain was not complete. The upper part of the Quaternary formation in the Osaka plain intercalates 21 marine clay beds. The depth distribution of these marine clay horizons can be explained with a linear relation with the standard probability curve on base depth distribution at the OD-1 drilling site. This linear relation is used for the correlation between the reflectors in the depth section of the seismic survey and the base horizon of the each marine clay bed. The result of the correlation can be applied for the mapping on subsurface geologic structure in the Osaka Plain. The author tried to make geologic structure contour map of the horizons of the main marine clay beds. These Quaternary marine clay beds have been correlated with the oxygen isotope record from deep sea cores. Therefore, those geologic structure maps of the Osaka Plain are available for not only the geo-technical utilization but also the estimation of the historical basin activity.

View full abstract

There are many researches concerning the deforestation but in fact are not comprehensive enough to understand the interactions between the its causes in particular socio-economic and historical conditions of the country, especially in the mountainous areas. This study attempts, therefore, to use the cartographic approach to focus on the interaction between the deforestation and the needs of subsistence of local people, namely the food production, in the Na Hang district, Tuyen Quang province of the region of Northern Uplands of Vietnam. The spatial scale of analysis is the national, regional and communal. The temporal scale is about 100 years for Vietnam, about 40 years for the district and the commune. The multiscaling analysis in this research is useful to understand deeply the effect of socio-economic forces on the complex process as the deforestation. This approach is proved to be effective to clarify the spatial distribution of the forest, agricultural land and food production in space and time. Furthermore, all statistical data such as demographic data, ethnic groups, agricultural lands, sown areas of food cultures, other socio-economic data and forest statistics have been represented on the basis of administrative limits of commune in order to find out the relations between these phenomena. By this way, the whole picture of study area has been reconstructed in its historical evolution in the integration with the principle policies related to the land use and development issues.

View full abstract

The Central Highlands of Vietnam characterized by popular distribution of soils originated from weathered basalts, which occupies 1,455,200 ha. Due to high fertility these soils are considered suitable for many crops, especially such cash crops like coffee, rubber, pepper. Recently extensive planting of some crops, such as coffee, tea, fruit-tree, etc., and expanse of cultivated land of migrant farmers have made large scale irregular floods, long drought, lowered water table brings adverse effects on crop yields. To meet appropriate and economic agricultural planning on basalt soils at the Central Highlands the Land and land use information system was established.
Land and land use information system on basalt soils at Central Highlands is web-based and specifically designed for generating readily accessible and transferable information on physical land resources and socio-economics in both map and tabular formats, which are used for agricultural resource management and development planning. This information system includes information on soils, land use and other pertinent socioeconomics of agricultural production data.

View full abstract

Mountainous area in Vietnam is mostly dominated by ethnic groups which rely on various agricultural activities composed of lowland and upland cultivation. The upland cultivation is one of traditional methods of how local people use the land. This activity, however, has great impact on environment due to forest cutting, exploitation of vegetation cover for household usage such as fuel consumption, house building material etc. One of the way for monitoring shifting cultivation including distribution of upland crop is usage of multitemporal remote sensing images. To facilitate better change analysis, the single date remote sensing data should be analyzed by consistent methodology so that classification results of different times can be comparable to the other. In this study, the author proposes a so called knowledge based classification approach for land use/cover mapping. In this research, the SPOT image is segmented at first into bare and vegetated land (mask image). The bare land is further divided into upland and lowland areas by using hydrographical network. This model is based on the fact that all lowland is situated along rivers or streams. Because lowland is limited to valley areas that have been long time exploited so we could assume that there is no change. By subtraction of lowland crop from the mask image we could generate upland cultivated areas that is important for monitoring mountainous environment as well as vegetation degradation rate. By using land use model typical for ethnic people in the study area we can further extract mosaick /orchard from the classified image. The final land use/cover map that is featured by classes: forest, bush land, grassland, upland crop, lowland crop, mosaick, water body and bare land (transition and built up) is used as input for subsequent change analysis.

View full abstract

It is quite difficult to model soil erosion and sediment transport at regional scales using coarser grid size (1 km) due to slope averaging and land-use averaging effects. To cater the problem, a process-based soil erosion and sediment transport modeling strategy has been developed to estimate the soil erosion, deposition, transport and sediment yield at regional scale. The catchment's spatial variability is modeled as a regular square grid system with canopy interception, infiltration, depression storage, one-dimensional overland flow and sediment transport in the steepest descent direction. The overland flow is modeled as the equivalent channels, which may represent the cumulative width of all rills and gullies in each grid. The fraction of the ponded surface is determined on the basis of the flow accumulation value of the each grid, grid size and its land use type. The soil erosion processes are modeled as the detachment of soil by the raindrop impact over the entire grid and detachment of soil due to overland flow only within the equivalent channels, whereas sediment is routed to the forward grid considering the transport capacity of the flow and the existing sediment load. The slope averaging effect is taken care by adapting a Fractal analysis approach. The model has been calibrated for Nan river basin (N.13A) and applied to the Yom river basin (Y.6) and Nam Mae Klang river basin (P.24A) of Thailand, simulated results show good agreements with the observed sediment discharge data.

View full abstract

Warning and preparedness are two key measures for flood disaster reduction. Flood warning with adequate lead-time greatly help in reducing loss of life and economic damage. Preparedness calls for estimating flood risk and taking action to mitigate flood damage through both structural and non-structural measures. In the present study we explore a comprehensive warning and risk assessment scheme in a two stage approach considering data availability and operational ease. In the first stage, river flow is forecasted with sufficient lead-time to warn of flows that could exceed the safe river capacity. The second stage takes the forecasted river flows at the city as input to a limited area model that covers the city and simulates the inundation extent incorporating embankment overtopping.
A distributed hydrological model, which simulates all the hydrological processes, is used in the system. In stage 1, where river flow is forecasted, dynamic wave model is used to solve for river network but inundation simulation is switched off to improve computational efficiency. In stage 2, diffusive wave implicit solution scheme for both inundation modeling and river network solution is used. The modeling domains for stage 1 and stage 2 are setup such that flooding from embankment overtopping would not occur upstream of the common boundary covered in stage 1. For river flow forecasting, the river network derived from the GTOPO30 global data set whereas for stage 2 model is setup using a high resolution local DEM. The results show that for the application in Yom River basin, lead times about 14 hours can be achieved with the dynamic equation for river discharge forecasts. The discharge hydrographs are successfully incorporated as inputs in inundation modeling and employing 50m or 100m horizontal resolution grids sizes help differentiate inundations resulting from different river inflows.

View full abstract

The GIS database of the Holocene sedimentary processes occurred in Balat River Mouth, its evolution and distribution in space and time. The remotely sensed satellite imageries including Landsat TM, Landsat 7 ETM are processed, visually interpreted in combination with GIS data to clarify the Holocene sedimentation, its facies conditions and characteristics. The relationships of Holocene deposits and the interpretation pattern recognition of satellite remotely sensed data are established. The database in GIS environment is created and GIS spatial and attribute data analysis is applied to draw the change of Holocene lithofacies in horizontal/vertical space directions and time in relation to the sedimentary evolution of the coastline. The relation between sedimentary evolution and global sea level change expressed the sedimentary rate and it also describes the process of Land-Ocean interaction in relation with present sea level change. Finally, the paper gives the picture of litho-dynamic characteristics and distribution of lithofacies of Balat river mouth in Holocene. The principal lithofacies are as follows: sandy ridge, mangrove swamp, delta's flood plain, tidal channel and tidal flats.

View full abstract

Soil erosion is one of the most serious environmental problems commonly in over the world, which is caused by both natural and human factors. GIS and remote sensing technique has recently become a powerful tool for investigations of natural resources and environmental situation. This research focuses on estimation of global soil erosion by the RUSLE model with the use of a comprehensive global dataset. The accuracy of the estimate mostly depends on the available information related to the study area. Presently available global datasets were used in this study. As the desired objective of estimating soil erosion by water at global scale, the application of RUSLE has shown its positive applicability on large-scale estimates. Global datasets of land cover, digital elevation, soil property and precipitation act as indispensable database in getting erosive parameters used in the RUSLE model. Data sources and data processing methods are carefully discussed in this paper. The study has provides a global estimate of water soil erosion potential with 0.5-degree grid resolution. Regional validations and evaluations have been carried out by different ways. The global mean of annual soil erosion by water was estimated as 1150 ton/ km², which agrees with several results obtained in different regions.

View full abstract

MRittmann is a petrological software package for identifying and calculating the normative minerals of volcanic, sub-plutonic, and carbonatite rocks from bulks chemical analyzes. The calibration of the software is built on the Rittmann norm calculation principles, and its calculating results include both hydrous and anhydrous minerals, rock name as well as petrological index such as tau (τ) and degree of oxidation (Ox⁰) of the analyzed samples. The norms obtained from MRittmann are in volume percentages. They are close to the modes and convenience for petrologist to use in graphical purposes in term of plotting the analyzed rock in QAPF double-triangle. The program is written in Delphi for PC and compatibles, and runs under Windows 9x, 2000, NT operating systems. The first version of MRittmann, MRittmann 1.0R was released by Duong The Hung and Dam Quang Minh at the Faculty of Geology, Hanoi University of Science, with all copyrights reserved.

View full abstract

WinASEAN 4.0 - Windows based Advanced System for Environment ANalysis with remote sensing data version 4.0 is the follow up product of WinASEAN 3.0 which was developed by the Department of Environmental Information Study and Analysis (EISA) and has been used for hands-on-training in the framework of the annual Regional seminar on Earth observation for tropical ecosystem management organized jointly by NASDA and UN ESCAP since 1993 to 2000. The WinASEAN runs on most of the latest MS window platforms like Windows 2000 and Windows XP. The WinASEAN 4.0 features new functions such as modeler: advanced inter channel and inter image analysis function using interactive input of computing model written in FORTRAN programming languag, Hyperspectral image visualization: new false color composite technique for image with more than 3 spectral channels, Image mosaicking: easy-to-use function for mosaicking geo-referenced images, virtual reality display: combination of image and DEM data to create virtual reality images. The WinASEAN 4.0 can handle 2 byte data processed by computers with different CPU systems and can be used for both practical usage and educational purpose.

View full abstract

A prototype online Spatial Information System for Geologic Modeling (SISGeM) has been developed. SISGeM has been successfully implemented by integrating the GIS and relational database management system (RDBMS) with the Internet. The spatial data management is carried out using Geographic Resource Analysis Support System (GRASS) GIS. Online access to GRASS functions has been enabled using the basic framework of GRASSLinks interface. Several additional modules were incorporated into web interface to tailor the system for its present needs. PostgreSQL RDBMS manage data that is recorded in a field outcrop or derived by digitizing hardcopy geologic maps. The system is capable of managing geologic data, generating 3-D geologic models and visualizing horizontal sections at user-defined depths.

View full abstract