Hiromu Okazawa

EVALUATION OF IMPACT OF EARTHQUAKE ON AGRICULTURE IN NEPAL BASED ON REMOTE SENSING

The big earthquake happening in April 2015 killed over 9000 people in Nepal. The effect of earthquake affected not only safety of local people but also agricultural field. Agricultural economy dominates in income of local people. Therefore, restoration of agricultural areas is required for improving life of locals. However, lack of information about agricultural areas is the main problem for local government to assess and restore damaged agricultural areas. Remote sensing was applied to access damaged agricultural field due to its advantages in observing responds of environment without temporal and spatial restriction. Accordingly, the objective of the study is to evaluate disaster risks based on data from questionnaire survey, remote sensing and geographic information system (GIS) in agricultural areas of Nepal. Firstly, we conducted questionnaire survey about thirty indicators of agriculture-related issues. Moreover, based on USLE (Universal Soil Loss Equation), soil erosion risk was compared between before and after the earthquake. To clarify the relation between soil erosion risk and land-use, land-use map was created based on Worldview-3. Finally, statistical analysis was conducted based on the collected data. From the results of field survey and analysis, it turned out that there was little damage on agricultural areas but huge damage on houses and barns in the villages in the research site. It is attributed to the vulnerable house materials. Soil erosion risk, that has been little observed in agricultural area, decreased in forest area and increased in residential area compared to the pre-earthquake time. From the statistical analysis, multi regression analysis was applied and age of house and elevation was computed as dominant factors of building damage in the research site. It is suggested that it is important to improve house materials in the villages and increase vegetation cover to prevent from further soil erosion in the research site.

RELIABILITY OF BASE-COURSE THICKNESS DESIGN CURVES FOR CONCRETE PAVEMENTS IN JAPAN

本研究では，（独）土木研究所の舗装走行実験場に施工した実大コンクリート舗装試験区，実大路盤試験区での路床，路盤の支持力調査結果および既往の研究事例に基づき，路盤厚設計曲線の信頼性に関する検討を行った．その結果，クラッシャラン，粒度調整砕石の設計曲線の信頼度はそれぞれ80％，70％であること，セメント安定処理路盤の設計曲線は路盤厚によって信頼度が異なっていることがわかった．また，これらの結果に基づき，本研究では信頼度に応じた各路盤材料の設計曲線を提案した．