研究等業績 - その他 - 河合　隆行

GNSS受信機を利用した広域土壌水分測定の可能性検討

門田直哉, 齊藤忠臣, 河合隆行, 藤巻晴行, 猪迫耕二, 登尾浩助, 森也寸志

農業農村工学会中国四国支部講演会講演要旨集   75th   2021年

J-GLOBAL

Cropland expansion outweighs the monetary effect of declining natural vegetation on ecosystem services in sub-Saharan Africa

Ayele Almaw Fenta, Atsushi Tsunekawa, Nigussie Haregeweyn, Mitsuru Tsubo, Hiroshi Yasuda, Katsuyuki Shimizu, Takayuki Kawai, Kindiye Ebabu, Mulatu Liyew Berihun, Dagnenet Sultan, Ashebir Sewale Belay, Jian Sun

ECOSYSTEM SERVICES ( ELSEVIER )  45   2020年10月

Changes in land cover and land degradation alter natural ecosystems, thereby affecting the services these ecosystems provide. However, there have been few attempts to estimate the effects of land cover change and land degradation on ecosystem services at large spatial scales and under the strong influence of human activities. Here, we used the European Space Agency Climate Change Initiative land cover maps (1992-2015) and the value transfer valuation method to estimate the changes in ecosystem services value (ESV) in response to land cover change in sub-Saharan Africa (SSA). Moreover, we estimated the loss of ESV due to land degradation by using the long-term (1992-2015) trend in the annual normalized difference vegetation index as a proxy for longterm biomass productivity decline. Our results revealed that, between 1992 and 2015, cropland increased by about 20 million ha, largely at the expense of forest and shrubland. The total estimated ESV of SSA was about US $9 trillion year(-1), of which 55% was derived from cropland and deciduous forest, with comparable contributions. Land cover change resulted in a net increase in the total ESV by US$125 billion year(-1) (1992-2015), albeit with an ESV loss of US$60 billion year -1 from the conversion of evergreen forest and shrubland. Overall, cropland expansion accounted for about 60% of the increase in the total ESV (US$125 billion year(-1)), thereby outweighing the decrease in ESV due to the decline in natural vegetation. Land degradation hotspots covered about 5% of SSA, resulting in a total ESV loss of about US$56 billion year(-1), of which nearly 65% was due to the degradation of forests and croplands. Changes in ESV varied across sub-regions, climate zones, and countries, depending on the dominant land cover change and the extent of land degradation. Our results provide useful insights for making informed decisions towards sustainable use and management of ecosystems.

DOI

Electrical Conductivity, pH, Minerals, and Sensory Evaluation of Airag (Fermented Mare's Milk)

Ryouta Tsuchiya, Takayuki Kawai, Tserenpurev Bat-Oyun, Masato Shinoda, Yuki Morinaga

FOODS ( MDPI )  9 ( 3 )   2020年03月

Traditional airag (fermented mare's milk) is a sour, slightly alcoholic drink handmade by Mongolian nomads. As airag is not heated after production, the fermentation continues to proceed and the taste changes rapidly. The objective of this study was to investigate the association of the sensory taste evaluation of airag with some properties-electrical conductivity (EC), pH and concentrations of macro minerals (calcium (Ca), phosphorous (P), sulfur (S), magnesium (Mg), potassium (K), and sodium (Na))-of airag. We held an airag contest in Mogod county, one of the most famous airag production areas, in order to collect samples of airag for the analysis of airag properties and to conduct an airag taste evaluation by Mongolian people. The results of the statistical analysis indicated that the EC-value was related to the evaluation score of airag. Except for EC, no statistically significant relationship between the taste score and the other properties was found in this study. It was concluded that the EC-value would be a simple measurement indicator for evaluating the quality of airag on site.

DOI

Land susceptibility to water and wind erosion risks in the East Africa region

Fenta A. A, Tsunekawa A, Haregeweyn N, Poesen J, Tsubo M, Borrelli P, Panagos P, Vanmaercke M, Broeckx J, Yasuda H, Kawai T, Kurosaki Y

Science of The Total Environment ( ELSEVIER )  703   135016   2020年02月

Land degradation by water and wind erosion is a serious problem worldwide. Despite the significant amount of research on this topic, quantifying these processes at large- or regional-scale remains difficult. Furthermore, very few studies provide integrated assessments of land susceptibility to both water and wind erosion. Therefore, this study investigated the spatial patterns of water and wind erosion risks, first separately and then combined, in the drought-prone region of East Africa using the best available datasets. As to water erosion, we adopted the spatially distributed version of the Revised Universal Soil Loss Equation and compared our estimates with plot-scale measurements and watershed sediment yield (SY) data. The order of magnitude of our soil loss estimates by water erosion is within the range of measured plot-scale data. Moreover, despite the fact that SY integrates different soil erosion and sediment deposition processes within watersheds, we observed a strong correlation of SY with our estimated soil loss rates (r(2) = 0.4). For wind erosion, we developed a wind erosion index by integrating five relevant factors using fuzzy logic technique. We compared this index with estimates of the frequency of dust storms, derived from long-term Sea-Viewing Wide Field-of-View Sensor Level-3 daily data. This comparison revealed an overall accuracy of 70%. According to our estimates, mean annual gross soil loss by water erosion amounts to 4 billion t, with a mean soil loss rate of 6.3 t ha(-1) yr(-1), of which ca. 50% was found to originate in Ethiopia. In terms of land cover, ca. 50% of the soil loss by water erosion originates from crop-land (with a mean soil loss rate of 18.4 t ha(-1) yr(-1)), which covers ca. 15% of the total area in the study region. Model results showed that nearly 10% of the East Africa region is subject to moderate or elevated water erosion risks (>10 t ha(-1) yr(-1)). With respect to wind erosion, we estimated that around 25% of the study area is experiencing moderate or elevated wind erosion risks (equivalent to a frequency of dust storms >45 days yr(-1)), of which Sudan and Somalia (which are dominated by bare/sparse vegetation cover) have the largest share (ca. 90%). In total, an estimated 8 million ha is exposed to moderate or elevated risks of soil erosion by both water and wind. The results of this study provide new insights on the spatial patterns of water and wind erosion risks in East Africa and can be used to prioritize areas where further investigations are needed and where remedial actions should be implemented. (C) 2019 The Author(s). Published by Elsevier B.V.

DOI

GPSのマルチパス信号を利用した土壌水分推定の可能性検討

齊藤忠臣, 足立望, 河合隆行, 藤巻晴行, 猪迫耕二, 登尾浩助, 森也寸志

農業農村工学会大会講演会講演要旨集(CD-ROM)   2020   2020年

J-GLOBAL

Prediction of summer rainfall over the source region of the Blue Nile by using teleconnections based on sea surface temperatures

Alhamshry Asmaa, Fenta Ayele Almaw, Yasuda Hiroshi, Shimizu Katsuyuki, Kawai Takayuki

THEORETICAL AND APPLIED CLIMATOLOGY   137 ( 3-4 ) 3077 - 3087   2019年08月

DOI

鳥取県におけるモミの分布

前田雄一, 河合隆行, 矢部 浩, 小山 敢, 土屋竜太

樹木医学研究   23 ( 1 ) 40 - 41   2019年01月

強度の枝打ち後に発生したヒノキ林の立ち枯れ被害

前田雄一, 河合隆行, 土屋竜太, 中村徳和, 小山 敢, 矢部 浩

樹木医学研究   23 ( 1 ) 14 - 21   2019年

Evaluation of satellite rainfall estimates over the Lake Tana basin at the source region of the Blue Nile River

Ayele Almaw Fenta, Hiroshi Yasuda, Katsuyuki Shimizu, Yasuomi Ibaraki, Nigussie Haregeweyn, Takayuki Kawai, Ashebir Sewale Belay, Dagnenet Sultan, Kindiye Ebabu

Atmospheric Research ( Elsevier Ltd )  212   43 - 53   2018年11月

Satellite rainfall estimates (SREs) have become alternative sources of rainfall data for several applications. However, the accuracy of the SREs is likely to vary from region to region and must be evaluated on a local basis. This study evaluated the accuracy of three SREs for the Lake Tana basin in northwestern Ethiopia. This basin is characterized by complex topography comprising both lowlands and highlands. The three SREs were the Tropical Applications of Meteorology using SATellite data and ground-based observations (TAMSAT), the Climate Hazard Infrared Precipitation with Stations (CHIRPS), and the Africa Rainfall Climatology (ARC). The SREs were compared with gauge measurements in lowland and highland regions during the period 1995–2010 on a point-to-pixel basis at daily, dekadal (10 days), monthly, and seasonal periodicities. The results show that the three SREs underestimated rainy events, but TAMSAT captured rainfall occurrence relatively well in both regions. ARC better estimated light rain rates (1–5 mm d−1) than did TAMSAT and CHIRPS
however, all the SREs markedly underestimated moderate and heavier rain rates (≥10 mm d−1). TAMSAT and CHIRPS estimated the amount of rainfall reasonably well (high efficiency, low random errors, and bias &lt
10%) at daily, dekadal, and monthly time scales, whereas ARC did not perform satisfactorily (high random errors, low efficiency, and bias &gt
20%) at any time scale. On a seasonal scale, CHIRPS estimated the secondary rainy season (March–May) rainfall better than did ARC and TAMSAT, whereas TAMSAT outperformed both CHIRPS and ARC during the primary rainy season (June–September). Overall, the rainfall detection capabilities and rainfall amount estimates of the SREs were better over the lowlands, and the cumulative rainfall estimates tended to improve with increasing integration time (i.e., from daily to seasonal totals).

DOI

Teleconnection of rainfall time series in the central Nile Basin with sea surface temperature

Yasuda H, S. N, Pandaa, Mohamed, A. M. Abd Elbasitc, T. Kawai, T. Elgamrie, A. A. Fenta, H. Nawata

Paddy and Water Environment   16   805 - 821   2018年08月

都市部の人を森林へ誘うための試み

前田雄一, 矢部 浩, 小山 敢, 中村徳和, 河合隆行, 土屋竜太

樹木医学研究   22 ( 2 ) 113 - 114   2018年04月

Spatial distribution and temporal trends of rainfall and erosivity in the Eastern Africa region

Ayele Almaw Fenta, Hiroshi Yasuda, Katsuyuki Shimizu, Nigussie Haregeweyn, Takayuki Kawai, Dagnenet Sultan, Kindiye Ebabu, Ashebir Sewale Belay

HYDROLOGICAL PROCESSES ( WILEY )  31 ( 25 ) 4555 - 4567   2017年12月

Soil erosion by water is one of the main environmental concerns in the drought-prone Eastern Africa region. Understanding factors such as rainfall and erosivity is therefore of utmost importance for soil erosion risk assessment and soil and water conservation planning. In this study, we evaluated the spatial distribution and temporal trends of rainfall and erosivity for the Eastern Africa region during the period 1981-2016. The precipitation concentration index, seasonality index, and modified Fournier index have been analysed using 5x5-km resolution multisource rainfall product (Climate Hazards Group InfraRed Precipitation with Stations). The mean annual rainfall of the region was 810mm ranging from less than 300mm in the lowland areas to over 1,200mm in the highlands being influenced by orography of the Eastern Africa region. The precipitation concentration index and seasonality index revealed a spatial pattern of rainfall seasonality dependent on latitude, with a more pronounced seasonality as we go far from the equator. The modified Fournier index showed high spatial variability with about 55% of the region subject to high to very high rainfall erosivity. The mean annual R-factor in the study region was calculated at 3,246 +/- 1,895MJ mm ha(-1)h(-1)yr(-1), implying a potentially high water erosion risk in the region. Moreover, both increasing and decreasing trends of annual rainfall and erosivity were observed but spatial variability of these trends was high. This study offers useful information for better soil erosion prediction as well as can support policy development to achieve sustainable regional environmental planning and management of soil and water resources.

DOI

鳥取市の広葉樹緑化木に発生していた日焼け被害

前田雄一, 河合隆行, 土屋竜太, 小山 敢, 矢部 浩

樹木医学研究 ( 樹木医学会 )  21 ( 4 ) 201 - 208   2017年09月

CiNii Research

強度の枝打ち後に発生したヒノキ林の立ち枯れ被害_速報

前田雄一, 河合隆行, 土屋竜太, 中村徳和, 矢部 浩, 小山 敢

樹木医学研究   21 ( 1 ) 20 - 21   2017年04月

広葉樹緑化木に発生していた日焼け被害

前田雄一, 河合隆行, 土屋竜太, 小山 敢, 矢部 浩

樹木医学研究   20 ( 3 ) 138   2017年01月

The effects of ocean SST dipole on Mongolian summer rainfall

Hiroshi Yasuda, Banzragch Nandintsetseg, Ronny Berndtsson, Ganbat Amgalan, Masato Shinoda, Takayuki Kawai

GEOFIZIKA ( UNIV ZAGREB , ANDRIJA MOHOROVICIC GEOPHYS INST )  34 ( 1 ) 199 - 218   2017年

Cross-correlations between inter-annual summer rainfall time series (June to August: JJA) for arid Mongolia and global sea surface temperatures (GSST) were calculated for prediction purposes. Prediction of summer rainfall for four vegetation zones, Desert Steppe (DS), Steppe (ST), Forest Steppe (FS), and High Mountain (HM) using GSSTs for time lags of 5, 6, and 7 months prior to JJA rainfall was evaluated. Mongolian summer rainfall is correlated with global SSTs. In particular, the summer rainfall of FS and HM displayed high and statistically significant correlations with SST in specific parts of the oceans. SST dipoles (pairs of positively and negatively correlated areas) were identified, and correlation for time series of the SST differences between SST dipoles (positive - negative) with the summer rainfall time series was larger than the original correlations. To predict the summer rainfall from SST, an artificial neural network (ANN) model was used. Time series of the SST difference that represents the strength of the dipole were used as input to the ANN model, and Mongolian summer rainfall was predicted 5, 6, and 7 months ahead in time. The predicted summer rainfall compared reasonably well with the observed rainfall in the four different vegetation zones. This implies that the model can be used to predict summer rainfall for the four main Mongolian vegetation zones with good accuracy.

DOI