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大学院国際資源学研究科 |
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Improving satellite-based global rainfall erosivity estimates through merging with gauge data
Fenta A.A.
Journal of Hydrology ( Journal of Hydrology ) 620 2023年05月
研究論文（学術雑誌）
Rainfall erosivity is a key factor that influences soil erosion by water. Rain-gauge measurements are commonly used to estimate rainfall erosivity. However, long-term gauge records with sub-hourly resolutions are lacking in large parts of the world. Satellite observations provide spatially continuous estimates of rainfall, but they are subject to biases that affect estimates of rainfall erosivity. We employed a novel approach to map global rainfall erosivity based on a high-temporal-resolution (30-min), long-term (2001–2020) satellite-based precipitation product—the Integrated Multi-satellitE Retrievals for Global Precipitation Measurement (GPM-IMERG)—and mean annual rainfall erosivity from the Global Rainfall Erosivity Database (GloREDa) stations (n = 3286). We used a residual-based merging scheme to integrate GPM-IMERG-based rainfall erosivity with GloREDa using Geographically Weighted Regression (GWR). The accuracy of the GWR-based merging scheme was evaluated with a 10-fold cross-validation against GloREDa stations. Based on GPM-IMERG-only, the global mean annual rainfall erosivity was estimated to be 1173 MJ mm ha−1 h−1 yr−1 with a standard deviation of 1736 MJ mm ha−1 h−1 yr−1. The mean value estimated via GPM-IMERG merged with GloREDa was 2020 MJ mm ha−1 h−1 yr−1 with a standard deviation of 3415 MJ mm ha−1 h−1 yr−1. Overall, GPM-IMERG-only estimates underestimated rainfall erosivity. The underestimations were greatest in areas of high rainfall erosivity. The accuracy of rainfall erosivity estimates from GPM-IMERG merged with GloREDa substantially improved (Nash-Sutcliffe efficiency = 0.83, percent bias = −2.4%, and root mean square error = 1122 MJ mm ha−1 h−1 yr−1) compared to estimates by GPM-IMERG-only (Nash-Sutcliffe efficiency = 0.51, percent bias = 27.8%, and root mean square error = 1730 MJ mm ha−1 h−1 yr−1). Improving satellite-based global rainfall erosivity estimates through integrating with gauge data is relevant as it can contribute to enhancing soil erosion modeling and, in turn, support land degradation neutrality programs.
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Occurrence of wet and dry spells of rainfall in Bagan, Myanmar
Yasuda H.
Journal of Earth System Science ( Journal of Earth System Science ) 132 ( 1 ) 2023年03月
研究論文（学術雑誌）
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Yasuda H.
Journal of Great Lakes Research ( Journal of Great Lakes Research ) 48 ( 2 ) 468 - 477 2022年04月 [査読有り]
研究論文（学術雑誌） 国際共著
Water level change of Lake Tana, the source of the Blue Nile was analyzed. Correlations between the water level change and global sea surface temperature (GSST) were calculated and teleconnections were found. Prediction of water level was performed using a recurrent artificial neural network model. First, the seasonal change of water level was divided into three phases, the rising, recession 1, and recession 2 phases. The water level increased during the rising phase, decreased rapidly during the recession 1 phase, and decreased at a uniform rate during the recession 2 phase. To find teleconnections of the water level change in the rising phase with GSST, correlations between the level change and GSST were calculated. Sea regions on the Pacific Ocean indicated significant correlations with the level change at lag 0–1 month and lag 6–7 months. There was a strongly correlated sea zone over the western Pacific Ocean at time lags of 6–7 months. To predict water level change, SST time series of the correlated zone was applied to a recurrent neural network model. Predictions of changes of the rise of the water level of Lake Tana during the rainy season from teleconnections with SSTs via the neural network model simulated the observed changes well (r = 0.795). Prediction of the changes of Lake Tana's water level with a lead time of 6–7 months can greatly facilitate management of the lake's water resources.
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Teleconnection of rainfall time series in the central Nile Basin with sea surface temperature
Yasuda H.
Paddy and Water Environment ( Paddy and Water Environment ) 16 ( 4 ) 805 - 821 2018年10月 [査読有り]
研究論文（学術雑誌） 国際共著
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An integrated modeling approach for estimating monthly global rainfall erosivity
Fenta A.A.
Scientific Reports ( Scientific Reports ) 14 ( 1 ) 2024年12月
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An integrated framework for improving watershed management planning
Fenta A.A.
Environmental Research ( Environmental Research ) 236 2023年11月
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Construction of Virtual Reality Space of the Tottori Sand Dunes using UAVs
SAITO Tadaomi, KAWAI Takayuki, OKASHITA Kisumi, INOSAKO Koji
沙漠研究 ( 日本沙漠学会 ) 32 ( S ) 187 - 191 2022年12月
<p>The Tottori Sand Dunes, located along Japan’s Sanin Coast, are a UNESCO Global Geopark and a popular tourist attraction with millions of annual visitors. However, the tourism opportunities offered by them are hampered by such problems as severe meteorological conditions and vast, undulating landscapes. Constructing a virtual reality (VR) space might be one solution to these problems. Recently, a technique that combined unmanned aerial vehicles (UAVs or drones) and structure from motion (SfM) photogrammetry has been attracting attention for generating 3D models. The main objective of this paper is to construct a VR space of the Tottori Sand Dunes using 3D models generated from UAVs. Another objective is to examine optimal photography conditions and model generation conditions to create beautiful but small 3D models for the construction of a VR space. Two types of UAVs were used to acquire the image data. Metashape (Agisoft) was used as the SfM software for data processing. A cross-platform game engine called Unity (Unity Software Inc.) was used to construct the VR spaces. VIVE Cosmos (HTC) was employed as a head-mounted display (HMD) with controllers for the VR system. As the results, the VR space was successfully constructed in Unity using a 3D model generated by a combination of UAV techniques and SfM photogrammetry. The optimal photography and model generation conditions were determined and used to generate beautiful 3D models for the construction of a VR space.</p>
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Yasuda H.
Geofizika ( Geofizika ) 39 ( 1 ) 1 - 20 2022年
In the central dry zone of Myanmar, the mean annual rainfall is less than 1000 mm. Although rainfed agriculture is commonly practiced there, the feasibi?? lity of rainfed farming is compromised by the large fluctuations of rainfall and the frequent occurrence of dry years. The monthly distribution of rainfall follows a bimodal pattern. The intensity of the monsoonal rainfall from May to October is characterized by two peaks, an early peak (May???June) and a late peak ( August??? October), separated by the inter ??monsoon (July). The return times of dry and wet years make management of rainfed agriculture problematic. There is very little correlation between the early and late monsoonal rainfall (r = ???0.257). However, monsoonal rainfall is teleconnected to sea surface temperatures (SSTs) in certain areas of the Pacific Ocean in real time. Furthermore, at lag times of 6???9 months, there are teleconnections between the early monsoonal, inter ??monsoonal, and late monsoonal rainfall and SSTs in certain areas of the Indian Ocean and Atlantic Ocean. We used an Elman artificial neural network model to predict early monsoonal, inter ??monsoonal, and late monsoonal rainfall based on teleconnections with SSTs in the Indian and Atlantic oceans 6???9 months before the rainfall occurred. The correlation coefficient between the predicted and observed rainfall exceeded 0.7 in all three cases.
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UAVを用いた鳥取砂丘のバーチャルリアリティ空間の構築【JST・京大機械翻訳】
SAITO Tadaomi, KAWAI Takayuki, OKASHITA Kisumi, INOSAKO Koji
沙漠研究 32 ( S ) 2022年
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科研費（文科省・学振）獲得実績 【 表示 ／ 非表示 】
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複合的物理探査による農業用施設及び地盤中の流体・物質移動の高速可視化技術の開発
基盤研究(A)
研究期間: 2016年04月 - 2019年03月 代表者: 黒田 清一郎, 河合 隆行, 森井 俊廣, 佐藤 源之, 塩谷 智基, 斎藤 広隆, 藤巻 晴行
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複合的物理探査による農業用施設及び地盤中の流体・物質移動の高速可視化技術の開発
基盤研究(A)
研究期間: 2016年04月 - 2019年03月 代表者: 黒田 清一郎, 河合 隆行, 森井 俊廣, 佐藤 源之, 塩谷 智基, 斎藤 広隆, 藤巻 晴行
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モンゴルのアイラグ（発酵馬乳）の製造法の地理学的・生態学的検証
基盤研究(B)
研究期間: 2015年04月 - 2019年03月 代表者: 森永 由紀, 高槻 成紀, 尾崎 孝宏, 河合 隆行, 石井 智美, 田村 憲司, 上村 明, 多田 泰之, 伊藤 健彦, 小宮山 博, 篠田 雅人, ツエレンプレブ バトユン, 土屋 竜太, 浅野 眞希, 竹内 菜穂子
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モンゴルのアイラグ（発酵馬乳）の製造法の地理学的・生態学的検証
基盤研究(B)
研究期間: 2015年04月 - 2019年03月 代表者: 森永 由紀, 高槻 成紀, 尾崎 孝宏, 河合 隆行, 石井 智美, 田村 憲司, 上村 明, 多田 泰之, 伊藤 健彦, 小宮山 博, 篠田 雅人, ツエレンプレブ バトユン, 土屋 竜太, 浅野 眞希, 竹内 菜穂子
学会等発表 【 表示 ／ 非表示 】
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Influence of polacrylamede application on structure stability of Ethiopian soils
Fujimaki H, Kawai T, Mamedov A.L
10th International congress on the Soil resources and environment conservation 2018年10月 - 2018年10月
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Aerial photogrammetry and three-dimensional modeling of the Tottori sand dune using UAV
Saito, T, Kawai, T, Inosako, K, Yasuda, H
Desert Technology 13 International Conference 2018年03月 - 2018年03月
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Estimation of hydrogeological structure combining groundwater-aeration-sound, ground-penetrating- radar and resistivity tomography in semi-arid area
Takayuki Kawai, Motoyuki Sato, Yasuyuki Tada, Ryota Tsuchiya, Yuki Morinaga, Masato Shinoda, Seiichirou Kuroda, Hiroshi Yasuda
Desert Technology 13 International Conference 2018年03月 - 2018年03月
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NMR and GPR sounding to characterize groundwater aquifer in sand dunes area
Chisato Konishi, Kunio Aoike, Takayuki Kawai, Seiichiro Kuroda
Symposium on the Application of Geophysics to Engineering and Environmental Problems 2017 2017年03月 - 2017年03月