Hiro Ikemi

GIS-Based Computational Method for Simulating the Components of 3D Dynamic Ground Subsidence during the Process of Undermining

Most research has focused on using the subsidence prediction method to calculate final movement at the center line above mining operations and assess the surface structural damage without taking into account the dynamic extraction process. Nevertheless, the occurrence of subsidence caused by underground mining has three-dimensional (3D) time-dependent components of movement in which each of these components has a different effect on the types of structures subject to subsidence. In this paper, a new computational method is proposed to calculate 3D dynamic subsidence during the process of undermining by combining the stochastic theory, the Knothe model, and the Geographic Information System (GIS). A case of 3D dynamic modeling was simulated for a rapid undermining scenario to demonstrate the effect of different advancing mining faces on the development of traveling strain. In addition, an application of the GIS-based method to actual field conditions in coal-mining subsidence in China is presented in this ...

Effect of Precipitation Timescale Selection on Tempo-spatial Assessment of Paddy Water Demand in Chikugo-Saga Plain, Japan

For the purpose of fully understanding tempo-spatial water circulation in the rice growing region of Chikugo-Saga, Japan, an assessment model of paddy water demand at daily/monthly time and one-kilometer space scales was established by using agro-statistic data, land use and meteorological data under GIS environment. Then, the daily and monthly precipitation data were, respectively, imported into the model to assess the tempo-spatial distribution of paddy water demand. Through the comparison between the two estimated results, it is shown that the selection of precipitation timescale has significant influence on the assessment of paddy water requirements during non-drought seasons while hardly effects the paddy water demand estimated for drought seasons. Furthermore, the daily-time-series analysis of the paddy water demand assessment was performed. It is found that the timescale-induced difference in the paddy water demand has a direct relation to the frequency and the amount of the concentrated heavy rainfall. From the investigation, it can be concluded that the proposed GIS-based model is suitable to be used to quantitatively carry out the tempo-spatial assessment of paddy water demand, and the daily precipitation data are more reasonably adopted to estimate paddy water requirements in non-drought seasons than the monthly precipitation data are done.

Estimation of RUSLE EI 30 based on 10 min interval rainfall data and GIS-based development of rainfall erosivity maps for Hitotsuse basin in Kyushu Japan

Land erosion is regarded as one of the most important phenomenon causes land degradation. In revised universal soil loss equation (RUSLE) erosion model, rainfall erosivity factor (R) is one of the important parameters. Ideally, the calculation of EI30 (R factor) uses breakpoint rainfall intensity data which is calculated manually from graphical charts that are generated by continuously recording rain gauges. However, due to limited availability of breakpoint rainfall data, many simple methods for estimating EI30 have been developed by using yearly, monthly and daily rainfall data. In this research, due to limited data availability, pluviograph data at 10 minute interval from eight stations in Hitotsuse basin were used to compute EI30 (R factor) for RUSLE. The approach used in this research is based on storm rainfall and duration data from 1990 to 2009. This method is based on the calculation of rainfall energy per unit depth of rainfall, total storm kinetic energy (E), rainfall intensity for a particular increment of a rainfall, and maximum 30 minute rainfall intensity. Furthermore, EI30 were computed, and then GIS method was used to create rainfall erosivity maps. The annual rainfall erosivity values prediction model was developed based on MFI values.

Process-Based Topographic Analysis and Hydrological Properties in Temperate Mountainous Catchments

How much is known about the relationship between topography and sediment dynamic in mountainous catchments? A previous numerical process-based study, with a high-resolution digital terrain model (DTM), reported a quantitative relationship between annual precipitation and river incision. However, the ability to predict sediment transport within mountainous streams is still needed in order to integrate sediment management in rivers. In this study, we focus on the relationship between topography and hydrologic properties in temperate mountainous catchments as a fundamental study to connect topography and sediment movement. The studied mountain catchments located in northern Kyushu, Japan, are composed mainly of Mesozoic granitic rocks. In the catchments, three terrain parameters were determined with topographic analysis using a process-based model and airborne LiDAR survey data. Hydrological measurements such as electric conductivity and water discharges were also carried out on the streams. One of the studied terrain parameters, D/K, shows a bimodal distribution indicating a few groups in our study area. The values also show a relationship with water discharges. These results show that the basin topography would have been formed through similar surface processes and correlate with the current hydrological environment. This process-based modeling could be an effective tool to quantitatively analyze short-term impacts of climate on topography.