A Concept of Time Domain Management for Resilient Rice Production　　　　　　　　　　　　　　　
Kotera; A., 筆頭著者
ICSEA2022 INTERNATIONAL CONFERENCE ON SUSTAINABILITY IN ENVIRONMENT AND AGRICULTURE 2022. Vietnam Japan University, Hanoi, Vietnam, 2022年11月, ［査読有り］

Determination of patterns of rainfall history creating situations for accurate classification of rain-fed paddy fields with SAR backscatter coefficients
Keisuke Hoshikawa; Kazuo Watanabe; Takanori Nagano; Akihiko Kotera; Yoichi Fujihara, © 2017 Elsevier B.V. It is worthwhile to classify paddy fields based on the long-term frequency of ponding, which strongly determines the yield of rice. However, the direct measurement of the frequency requires a large number of backscatter images from synthetic aperture radar (SAR). Another approach is the indirect estimation of the relative frequency of ponding from differences in ponding frequency with the same rainfall history. Any combination of backscatter coefficients with such rainfall history should result in a high accuracy of classification of paddy fields based on the relative frequency of ponding. This study aims to establish methodologies for the classification of rain-fed paddy fields into two categories: ‘wet’ and ‘dry’ fields, based on ponding frequency using a small number of time-series SAR backscatter coefficients that depend on the flood situation and soil water content of the land surface. By analyzing 21 images acquired by the ALOS-PALSAR during 2007–2011, patterns of rainfall history with obvious large differences between the two categories of paddy fields were determined. Through supervised classifications using a random forest classifier, it was evident that the backscatter coefficients onset of rainy seasons for years with an above average precipitation, would be suitable as variables for accurate classification. In years where the precipitation (1379 mm/year) neared the average (1330 mm/year), the supplementary use of a quartile deviation of the backscatter coefficient within each plot, that indicated a degree of partial ponding, increased the classification accuracy. It was also evident that the effective rainfall index, which registers a rough estimate of rainwater acculturation in the soil, was useful in the determination of periods of significantly large variations in the backscatter coefficient between categories of rice fields.
Remote Sensing Applications: Society and Environment, 2018年01月

Assessing the degree of flood damage to rice crops in the Chao Phraya delta, Thailand, using MODIS satellite imaging
Akihiko Kotera; Takanori Nagano; Patinya Hanittinan; Sucharit Koontanakulvong, The Chao Phraya delta in Thailand is a major rice production area. It is often subject to large flooding events, which may result in widespread crop failures, as most recently recorded in 2011 and 2006. The extent of flood damage in such areas is commonly assessed by field surveys. In this study, we investigate the spatial extent of flood damage to rice production in the Chao Phraya delta from 2000 to 2011 using moderate resolution imaging spectroradiometer satellite images. We examine the temporal relationship between the harvest time, estimated from the time-series enhanced vegetation index (EVI), and the onset of inundation, estimated from the time-series land surface-water index and EVI. The total area of rice damage throughout nine provinces in the Chao Phraya delta during the severe flood in 2011 was estimated to be 79,189 ha, of which 41,410 ha was estimated as total damage. The damage in 2011 was particularly severe on the eastern side of the Chao Phraya River, and we found that most of the paddy fields that experienced flood damage in 2006 did not experience similar damage in 2011, despite the longer inundation period. Analysis over this 12-year period showed that there were few areas that were repeatedly subjected to damage, highlighting successful adaptations to avoid damage. This novel approach to agronomic flood-damage assessment using high temporal resolution imaging proposed in this study proved to be a promising tool for agronomic flood-damage assessments, which enable quick investigations providing valuable findings from wide area and long-term perspectives., SPRINGER HEIDELBERG
PADDY AND WATER ENVIRONMENT, 2016年01月, ［査読有り］

A global dataset of noiseless time-series vegetation and water indices for farmland analysis
Akihiko Kotera; Takanori Nagano; Suha Berberoglu; Mehmet Ali Cullu, Time-series vegetation and water indices derived from remote sensing images are crucial materials for farmland analysis based on crop phenology and monitoring such as classification of cropping patterns and monitoring of crop growth and productivities. However, the optical remote-sensing images often contain problematic pixels, such as those affected by thick clouds and its shadows, resulting a noisy time-series data which is inadequate to use for farmland analysis. Lack of the high quality noiseless time-series data products have been a bottleneck for many studies on farmland analysis using remote-sensing data in both of global and local scales. Hence we aims in this study to produce remote-sensing data archives containing noiseless smoothed time-series Normalized Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), Land Surface Water Index (LSWI), and RGB composite (true color) image, covering global wide with the adequately downscaled 250-m resolution in 8-days interval from the period of 2000 to 2014 and up-to-date, derived from based on the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor images. The processing system for generating the global noiseless time-series data in this study is consist of four modules; image acquisition, preprocessing, noise reduction, and data archiving, implemented in Interactive Data Language (IDL) with PDP (Parallel Distributed Processing). Data products are derived from two sets of Terra/MODIS surface-reflectance 8-day composite data (MOD09Q1 v005 (250-m resolution) and MOD09A1 v005 (500-m resolution)) acquired from LP DAAC (Land Processes Distributed Active Archive Center, USGS) on a regular basis automatically to update the latest products. To generate noiseless and smooth time-series data, we applied following well-established procedure: 1) Eliminate cloud and sensor noise pixels by referring the image quality information: 2) Reconstruct daily time-series data by referring the actual date of observation for each pixels: 3) Synthesize daily time-series Terra and Aqua: 4) Interpolate eliminated pixel value on time-series axis by liner interpolation method: 5) Apply the Savitzky-Golay filtering to time-series data to produce smoothed time-series data. Denoised true color image can be used for visually checking the quality of noise reduction. Data products are mapped by MODIS Sinusoidal Tiling System, and archived with Hierarchical Data Format-Earth Observing System (HDF-EOS) format containing various meta-information, which are the standard archive format for MODIS Land products distributed by USGS, so that users can use existing favorite tools such the MODIS Reprojection Tool (MRT) for handling the archives. The advanced noiseless time-series vegetation and water indices data archives produced in this study would contribute significantly to advanced analysis and monitoring of the crop production., IEEE
2015 FOURTH INTERNATIONAL CONFERENCE ON AGRO-GEOINFORMATICS, 2015年, ［査読有り］

A New MODIS Global Product Noiseless Time-series Vegetation & Water Indices for Farmland Analysis　　　　　　　　　　　　　　　
Akihiko KOTERA; Takanori NAGANO; Süha Berberoğlu; Mehmet Ali Çullu, Agrogeoinformatics
Proceedings of 4th International Agro-Geoinformatics 2015 Conference, 2015年

Classification of crop fields in northeast Thailand based on hydrological characteristics detected by L-band SAR backscatter data
Keisuke Hoshikawa; Takanori Nagano; Akihiko Kotera; Kazuo Watanabe; Yoichi Fujihara; Osamu Kozan, Synthetic aperture radar (SAR) backscatter amplitude image data have proven useful in estimating soil moisture levels and in approximating areas of water inundation over large regions. Based on the pattern of seasonal change in the backscatter coefficient at each image pixel, this study classified a variety of crop fields in Northeast Thailand according to their hydrological characteristics. L-band horizontal-transmit horizontal-receive (HH) polarization images from advanced land observing satellite phased array type L-band synthetic aperture radar (ALOS-PALSAR) at six dates from January to December over the rainy season (May to November) in 2007 were used. Fifteen clusters of pixels were generated using the k-means method, with five variables obtained by taking the difference between the backscatter coefficient for the dry season (January) and the other five dates, effectively removing effects of soil surface roughness. As a result, a detailed spatial distribution of hydrological characteristics that accurately reflected topographical features and hydrological conditions was obtained., TAYLOR & FRANCIS LTD
REMOTE SENSING LETTERS, 2014年04月

ベトナム・メコンデルタの河川水位変動とその要因
藤原 洋一; 星川 圭介; 藤井 秀人; 小寺 昭彦; 長野 宇規; 横山 繁樹, ベトナム・メコンデルタは、洪水の増加、海面上昇などの影響を大きく受けることが懸念されている。近年、デルタ内における河川水位上昇が報告されているが、その原因については必ずしも明らかになっていない。そこで、本研究では、河川水位の上昇の原因として、（1）海面上昇、（2）地盤沈下、（3）洪水の大規模化、（4）輪中堤防の増設による氾濫原減少に伴う洪水緩和機能の低下、の4つを考え、デルタにおける水位変動の解析を行った。
解析にはメコン河委員会が管理している24地点の水位データ（1987年から2006年の20年間）を利用した。まず、年間の水位差（年間の最高水位と年間の最低水位の差）と日水位差の年平均を利用して、流況特性から見てデルタを分類した。さらに、観測日平均水位データを利用して、年最高水位、年最低水位を抽出し、それぞれのトレンドを求めた。土地利用変化に関しては、輪中堤防が増設されたエリアは水稲3期作、氾濫原は水稲2期作エリアと考えることができる。そこで、それぞれの面積を算定するためにMODIS/TerraのプロダクトであるMOD13Q1 のNDVI（空間解像度：250m、時間解像度：16日）を利用した。
まず、流況からみたデルタの分類図を見たところ、河口に近い4地点は、潮位の影響の方が季節変動より大きく、海面上昇の影響を大きく受けやすいことがわかった。さらに、Can Tho、My Thoといった河口から数十キロ内陸に入った地点であっても、上流からの洪水よりも潮位変動を大きく受けることが注目された。なお、河口から120キロ以上内陸（デルタ北部）では、潮位よりも上流からの流量の影響を受けていることがわかった。年最高水位、最低水位に関しては、デルタ中部から河口において、最高水位、最低水位が有意に増加トレンドであった。土地利用変化の推定結果によると、堤防で囲まれた3期作エリアが急速に拡大しており、とくに、カンボジアとの国境付近のアンジャン省、ドンタップ省における面積の拡大が顕著であった。これらの結果を重ね合わせたところ、最高水位の上昇とダイク拡大地域はあまり一致していない、最低水位の上昇と最高水位の上昇が見られるゾーンは、季節的な洪水の影響より潮位の影響が大きいゾーンであることから、最高水位の上昇には、相対的な海面水位の上昇の影響が大きいと考えられた。, 水文・水資源学会
水文・水資源学会研究発表会要旨集, 2014年

Recent trend of drought conciliation and agricultural water use in Japan　　　　　　　　　　　　　　　
Nagano T; Kotera Akihiko, ICID
Proceedings of the first World Irrigation Forum, 2013年10月

A modeling approach for assessing rice cropping cycle affected by flooding, salinity intrusion and monsoon rains in the Mekong Delta, Vietnam
Kotera, A; N. D. Khang; T. Sakamoto; T. Iizumi; M. Yokozawa, We developed a crop scheduling model for rice cultivation in the Vietnam Mekong Delta (VMD), focusing on the adaptive behavior of crop planning to various water resource constraints. In addition, we also examined the effects of environmental change on rice cultivation in the last decade. In the VMD, multiple rice cropping is practiced under a variety of adverse water conditions, including flooding, salinity intrusion, and irregular monsoon rains. These environmental changes influence the durations of growing seasons and the number of crops per year, resulting in changes in productivity. To validate the performance of the model, we compared model estimates for the heading date and changes in leaf area index at nine sites with estimates of these parameters derived from MODIS satellite time series data for the period 2002-2006. The root mean square errors of heading date between the modeled and satellite data in the upper, middle, and coastal regions of the delta were 17.6, 11.2, and 13.0 days, respectively. Based on the model, we examined case studies to assess the changes in cropping cycles and crop failures in the VMD due to extreme flooding in 2000 and salinity intrusion in 2004 by applying evaluation indices defined by available period for cultivation (APC) and safe margin for cropping (SMC) which is defined as the marginal time between APC and the period required for cultivation. Findings of case studies suggested that a small difference in the SMC of the cropping pattern is critical to the stability and productive capacity of the rice crop. © 2013 Springer Japan.
Paddy and Water Environment, 2013年07月, ［査読有り］

Statistical downscaling with Bayesian inference: Estimating global solar radiation from reanalysis and limited observed data
Iizumi, T; M. Nishimori; M. Yokozawa; A. Kotera; N. D. Khang, Daily global solar radiation (SR) is one of essential weather inputs for crop, hydrological, and other simulation models to calculate biomass production and potential evapotranspiration. The availability of long-term observed SR data is, however, limited, especially in developing countries. This hinders climate applications in various sectors in these countries. To overcome this difficulty, we here propose a method to infer the reasonable daily SR condition for past decades from global reanalysis and limited observed SR data. The method consists of the regression-based statistical downscaling method and two empirical models for estimating the SR condition (i.e. the S-model and the DTR/RH-model). These empirical models were independent in terms of the variables explaining the SR condition. The regression models were trained on the basis of the SR conditions estimated by the S-model and the DTR/RH-model instead of the observed SR data. The Markov Chain Monte Carlo (MCMC) technique was applied to determine the parameter values of these models that guide the models to provide SR conditions that are close in value to each other at both the site and domain-mean scales. After that, we computed the SR condition over the 30 years from 1978 through 2007 at 17 sites in the Vietnam Mekong Delta area using the determined parameter values. The inferred SR condition was close in value to the corresponding observations available from the literature. This suggests that the proposed method yielded a reasonable inference of the SR condition at the sites despite the limited availability of observed SR data. The provided estimates of the daily SR condition over the past 30 years are useful for climate applications in agricultural, hydrological, and other sectors in this area. © 2011 Royal Meteorological Society.
International Journal of Climatology, 2012年, ［査読有り］

農業参入企業の持続的経営と地域貢献の関係
多田 ひかり; 長野 宇規; 小寺 昭彦, 企業の農業参入に関する既存研究より考察した参入企業の持続性に重要である条件に則し事例分析を行った。その結果,事例企業において持続的な経営と地域貢献の相乗的な繋がりが明らかになった。企業は地域の人的資源を活かすことで持続的な経営を可能としている。また,そのような働きかけが地域に新たな資源を提供し,地域への貢献に繋がっている。地域のルールを守りながら共同作業やコミュニケーションの機会に参加することが,地域の文脈を知り,地域の実状に合わせて経営を行い,地域の人的資源を活かすことに繋がっている。, 農村計画学会
農村計画学会誌 = Journal of Rural Planning Association, 2011年11月, ［査読有り］

Agro-ecological interpretation of rice cropping systems in flood-prone areas using MODIS imagery
Toshihiro Sakamoto; Toshihiro Sakamoto; Phung Van Cao; Nhan Van Nguyen; Akihiko Kotera; Masayuki Yokozawa, This study attempts a new approach using Moderate Resolution Imaging Spectroradiometer (modis) time-series imagery to evaluate the agro-ecological interpretation of rice-cropping systems in flood-prone areas. A series of wavelet-based methodologies were applied to reveal the dynamic relationships among annual flood inundation, rice phenology, and land-use change in the Vietnamese Mekong Delta (vmd). The rice-heading dates of multi- cropping areas were estimated by detecting the local maximal points in smoothed Enhanced Vegetation Index (evi) profiles, using the Wavelet-based Filter for determining Crop Phenology (wfcp) and Wavelet-based Filter for evaluating the spatial distribution of Cropping Systems (wfcs) methods. The temporal information for annual flood intensity was determined for the six annual flood seasons over the period from 2000 to 2005 by the Wavelet- based Filter for detecting spatio-temporal changes in the Flood Inundation (wffi) method. Analysis using remote sensing techniques revealed an interaction between the regional environment and agricultural activity in the vmd. First, comparing the estimated heading date of the winter- spring rice with the end date of flood inundation showed that the cropping season for the winter-spring rice in the flood-prone area fluctuates depending on the annual change in flood scale. This result implied that the onset of winter-spring rice is spatially and temporally linked to the variable flood-recession season, and hence the annual change in flood scale. Secondly, the field survey study of the yearly change in the rice-cropping system in the An Giang province from 2000 to 2006 showed that the triple rice-cropped area in the An Giang province expanded from 2000 to 2005, because the construction of a ring-dyke system and water-resource infrastructure allowed an additional rice crop to be sustained during the flood season. However, the area of the third rice crop in the An Giang province decreased drastically in 2006 as a result of the management of pest outbreaks. Although the regional water-resource environment was gradually transformed by the construction of water-resource infrastructure, in order to achieve favorable conditions for a third rice crop during the flood season, the rapid change in land-use for agricultural activity may complicate the spatio-temporal configuration of the agricultural environment in the vmd. This case study used modis time-series imagery to help understand the functions of the macro-scale ecosystem, including annual flood regimes and human activity. © 2009 American Society for Photogrammetry and Remote Sensing.
Photogrammetric Engineering and Remote Sensing, 2009年04月

Regional Consequences of Seawater Intrusion on Rice Productivity and Land Use in Coastal Area of the Mekong River Delta
Akihiko Kotera; Toshihiro Sakamoto; Duy Khang Nguyen; Masayuki Yokozawa, This study investigates rice productivity in the coastal area of the Mekong River Delta, Vietnam focusing on relationships with the influences of seawater intrusion and recent changes in the land use at regional scale. We examined the statistical data on rice production at 30 districts of 4 provinces in the coastal area for the years 2003-2005, together with the average salinity concentration observed at 48 points in canals and rivers during the dry season. As an index of the extent of seawater intrusion to be compared with rice statistical data in each district, average salinity of each district was derived by using spatial interpolation from the data in the observation points. It was shown that seawater intrusion was the major factor leading to regional differences in rice cropping systems and land use patterns in the region. Rice cropping intensities, which is defined as the ratio of planted area to district area, decreased with increasing salinity level in canal water, but rice yields averaged over the district are independent of the salinity level. To avoid salinity stress to rice growth, rice cultivation in the coastal area is mainly undertaken during the period when seawater intrusion is weakened by the seasonal decrease in salinity in the rainy season. Specifically, in districts with high salinity, the salinity-free duration required for rice cultivation is short. There, rice cropping intensities are potentially limited by the salinity. In addition, recently, the area of paddy fields in the coastal area has been decreased through land use conversion to aquaculture, especially shrimp farms. Intensity of aquaculture, which requires brackish water, was also limited by seawater intrusion. Thus., rice production in the coastal area of the Mekong Delta was limited by the interrelationship between seawater intrusion and land-use diversification., JAPAN INT RESEARCH CENTER AGRICULTURAL SCIENCES
JARQ-JAPAN AGRICULTURAL RESEARCH QUARTERLY, 2008年10月

Determining the Spatial Pattern of Rice Cropping Schedules using Time-Series Satellite Imagery of the Red River Delta, Vietnam　　　　　　　　　　　　　　　
Kotera; A.; Sakamoto; T.; and Yokozawa; M.
International Journal of Geoinformatics, 2007年12月, ［査読有り］

Detecting temporal changes in the extent of annual flooding within the Cambodia and the Vietnamese Mekong Delta from MODIS time-series imagery
Toshihiro Sakamoto; Nhan Van Nguyen; Akihiko Kotera; Hiroyuki Ohno; Naoki Ishitsuka; Masayuki Yokozawa, This paper presents the methodology used to detect temporal changes in the extent of annual flooding within the Cambodia and the Vietnamese Mekong Delta (VMD) based on MODIS time-series imagery (Wavelet-based Filter for detecting spatio-temporal changes in Flood Inundation; WFFI). This methodology involves the use of a wavelet-based filter to interpolate missing information and reduce the noise component in the time-series data, as proposed in a previous study. The smoothed time profiles of Enhanced Vegetation Index (EVI), Land Surface Water Index (LSWI), and the Difference Value between EVI and LSWI (DVEL) are obtained from MOD09 8-day composite time-series data (resolution: 500 m; time period: 2000-2005). The proposed algorithm was applied to produce time-series inundation maps (WFFI products) for the five annual flood seasons over the period from 2000 to 2004. The WFFI products were validated via comparisons with Landsat-derived results and inundation maps based on RADARSAT images, hydrological data, and digital elevation model data. Compared with the RADARSAT-derived inundation maps at the province level, the obtained RMSE range from 364 to 443 km2 and the determination coefficients [R2] range from 0.89 to 0.92. Compared with Landsat-derived results at the 10-km grid level, the obtained RMSE range from 6.8 to 15.2 km2 and the determination coefficients [R2] range from 0.77 to 0.97. The inundated area of flooded forests/marsh to the northeast of Tonle Sap Lake were underestimated, probably because of extensive vegetation cover in this area. The spatial characteristics of the estimated start dates, end dates, and duration of inundation cycles were also determined for the period from 2000 to 2004. There are clear contrasts in the distribution of the estimated end dates and duration of inundation cycles between large-scale floods (2000-2002) and medium- and small-scale floods (2003 and 2004). At the regional scale, the estimated start dates for the southern part of An Giang Province during 2003 and 2004 was distinctly later than that for surrounding areas. The results indicate that these triple-cropping areas enclosed by dikes increased in extent from 2003 to 2004. In contrast, the estimated end dates of inundation at the Co Do and Song Hau State Farms were clearly earlier than those for surrounding areas, although the estimated start dates were similar. Temporal changes in the inundation area of Flood pixels in the Dong Thap and Long An Provinces are in excellent agreement with daily water-level data recorded at Tan Chau Station. The estimated area of Long-term water body increased in size from 2000 to 2004, especially in coastal areas of the Ca Mau and Bac Lieu Provinces. Statistical data for Vietnam indicate that this trend may reflect the expansion of shrimp-farming areas. The WFFI products enable an understanding of seasonal and annual changes in the water distribution and environment of the Cambodia and the VMD from a global viewpoint. © 2007 Elsevier Inc. All rights reserved.
Remote Sensing of Environment, 2007年08月

Role of plant height in the submergence tolerance of rice: A simulation analysis using an empirical model
Akihiko Kotera; Eiji Nawata, This study explored how plant height increment as a measure of growth affected the interaction between submergence tolerance and hydrographic conditions, and also examined which growth stages were the most sensitive and the most tolerant to flash floods using an empirical simulation model. The factors affecting submergence yield losses in the model were assumed to be the start date, the duration, and the depth of submergence. The duration and depth of submergence were calculated from simple hydrographic factors and plant height. The increment of plant height affected both submergence avoidance and the duration of submergence. It appeared that the yield losses of rice plants that were submerged in the early vegetative phase exceeded the losses of plants submerged in the reproductive phase under almost all hydrographic conditions. The results indicate that plants submerged at the end of the vegetative phase had robustness to yield losses, and that the growth stage immediately following transplanting was the most sensitive. (c) 2007 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
AGRICULTURAL WATER MANAGEMENT, 2007年04月

Influence of Flooding on Rice and Its Risk Mitigation in the Red River Delta, Vietnam　　　　　　　　　　　　　　　
Kotera Akihiko, 筆頭著者
Doctoral thesis, Kyoto Univ., 2005年11月, ［査読有り］

Application of wavelet analysis to the multi-temporal modis data for detecting the rice phenology
Toshihiro Sakamoto; Akihiko Kotera; Naoki Ishitsuka; Hiroyuki Ohno; Nhan Van Nguyen; Masayuki Yokozawa, We examined the spatial pattern of rice phenology in the Red River Delta (RRD) by using time-series MODIS data in 2003. We applied the Wavelet based Filter for determining Crop Phenology (WFCP) to assess the seasonal change of EVI data reflecting from the crop status. Time courses of smoothed EVI derived by WFCP showed two peaks on April-March and August-September, indicating that double rice cropping is mainly being performed in RRD. It was also shown that there are winter-spring rice cropping areas in eastern RRD (Hai Duong province, Hai Phong province and Thai Binh province) where cultivation period is about two weeks earlier than the other provinces. Furthermore, spatially heterogeneous distribution of heading dates for rainy season rice was detected by the spatio-temporal EVI. MODIS EVI with WFCP enable us to grasp the geographical characteristics of agricultural activity in RRD i.e. spatial pattern of rice cropping system, phenology and its recent changing trend with high accuracy.
Asian Association on Remote Sensing - 26th Asian Conference on Remote Sensing and 2nd Asian Space Conference, ACRS 2005, 2005年

Effect of Submergence on Rice Yield in the Red River Delta, Vietnam
Kotera,A; Nawata,E; Thao,L.V; Vuong,N.V; Sakuratani,T, ベトナム紅河デルタ地域における水稲の冠水抵抗性が, 高収量性品種の導入前後でどのように変化したのかを検証するために, 高収量性品種導入以前に広く栽培されていた在来品種Moc Tuyenおよび, 高収量性品種CR203, Tap Giao4の3品種を用いて, 分げつ初期から登熟期の4つの生育段階において5日間の完全冠水処理試験を行い乾物生産量, 収量を比較した.冠水に対して最も減収する品種は冠水した生育段階によって異なったが, Moc Tuyenは分げつ期を除いて3品種の中で最も低収であった.これらの結果と実際の洪水発生パターンを考慮した結果, これら2つの高収量性品種が導入されたことにより紅河デルタの洪水被害が大きくなる可能性は低いことが示唆された.次に, 冠水被害が拡大する冠水条件を明らかにするために, CR203を用いて, 異なる生育段階に対して2, 5, 8日間の冠水期間, 草丈の3/4の水深および完全冠水を組み合わせた冠水試験を行った.分げつ期においては3/4水深処理区の収量は冠水期間が8日間でもほとんど減少せず, 完全冠水処理区では5, 8日間の冠水で収量が大きく減少したことから, CR203の分げつ期における冠水では, 完全冠水期間が2日以下であれば, 収量への影響が最小限に抑えられる可能性が示唆された., Japanese Society for Tropical Agriculture
Jpn. J. Trop. Agr., 2005年01月, ［査読有り］

A model for phenological development of Vietnamese rice influenced by transplanting shock
A Kotera; E Nawata; P Van Chuong; NN Giao; T Sakuratani, Phasic development of rice is influenced by various climatic conditions and the nursery duration. As a step toward the analysis of yield potential and yield loss in the Red River Delta, Vietnam, we conducted field trials with different nursery durations and transplanting times to develop a model for estimating heading times of a non-photosensitive cultivar CR203 in the Red River Delta. Days from seedling emergence to heading varied from 73 to 106 d, the rainy season crops having a shorter duration than the winter-spring season crops. The heading time could generally be estimated by the function of air temperature, but the delay in heading due to transplanting (transplanting shock), defined as the difference in the days from emergence to heading between transplanted and direct-seeded rice, ranged from 1 to 9 d and caused a substantial error in the heading time estimation. This variation in the delay of heading was explained as a function of the seedling age at the transplanting time. The model considering the transplanting shock estimated the heading dates in the independent data sets obtained at fields of local farmers with root mean square deviation (RMSD) of 2.15, while the model not considering the transplanting shock estimated those with a RMSD of 3.34. We conclude that this simple transplanting shock model was applicable for estimating the rice phasic development in the Red River Delta., CROP SCIENCE SOC JAPAN
PLANT PRODUCTION SCIENCE, 2004年03月, ［査読有り］

乾燥地域における長期作物判別・塩害挙動監視システムの開発
LIU Haochen; 長野宇規; 小寺昭彦; 田中賢治
農業農村工学会大会講演会講演要旨集(CD-ROM), 2023年

乾燥地域における長期作物判別・塩害挙動監視システムの開発
LIU Haochen; 長野宇規; 小寺昭彦
農業農村工学会京都支部研究発表会講演要旨集, 2022年

中解像度衛星画像を用いた毎筆作付判別
長野宇規; 浅野剛; 小寺昭彦; 藤原洋一; 吉川夏樹
農業農村工学会大会講演会講演要旨集(CD-ROM), 2017年

合成開口レーダを用いた天水田分類に適した状況をもたらす降雨履歴の特定
星川圭介; 渡辺一生; 小寺昭彦; 長野宇規; 藤原洋一
農業農村工学会大会講演会講演要旨集(CD-ROM), 2017年

水土里情報システムを活用した農用地作付の自動判別
浅野剛; 長野宇規; 吉川夏樹; 小寺昭彦; 藤原洋一
農業農村工学会京都支部研究発表会講演要旨集, 2016年

参加型学習における立体地理情報表示システムの活用
小寺昭彦; 加藤久明; RAMPISERA Dorotea Agnes; BUDIASA I Wayan; 窪田順平
農業農村工学会大会講演会講演要旨集(CD-ROM), 2016年

分布型降雨流出・氾濫モデルによるメコン川流域大規模洪水の再現
井上将徳; 小林健一郎; 小寺昭彦; 長野宇規
土木学会年次学術講演会講演概要集(CD-ROM), 2015年

Quasi-real-time satellite monitoring for assessing agronomic flood damage
Akihiko KOTERA; Yuta YAMAMURA; Takanori NAGANO
Proceedings of THA2015 International conference on "Climate change and Water & Environmental management in Monsoon Asia", 2015年01月

Detection of paddy fields at sub-state level by combined use of MODIS and Landsat imagery
Takanori NAGANO; Yumiko ONO; Akihiko KOTERA; Ranvir SINGH
Proceedings of THA2015 International conference on "Climate change and Water & Environmental management in Monsoon Asia", 2015年01月

海外レポート 世界潅漑農業アトラスが可視化する水と農業の関係
長野 宇規; 小寺 昭彦
土地改良 : 大地にきざむ農の文化, 2014年04月

トルコ南東部の灌漑農地におけるタイムアライメント補正画像を用いた作目判別
小寺昭彦; 山村祐太; SATIR Onur; BILGILI Ali Volkan; CULLU Mehmet Ali; 長野宇規
日本リモートセンシング学会学術講演会論文集, 2014年

セルオートマトンを用いた未来遺産運動による影響推定
東健斗; 松本文子; 小寺昭彦; 長野宇規
農業農村工学会京都支部研究発表会講演要旨集, 2014年

綿花葉面の近赤外線ハイパースペクトル分光反射率を用いた塩害の測定
長野宇規; 宮嶋崇志; 小寺昭彦; BILGILI Ali Volkan; CULLU Mehmet Ali
農業農村工学会大会講演会講演要旨集(CD-ROM), 2014年

ベトナム・メコンデルタにおける輪中農業のレジリアンスと脆弱性
小寺 昭彦; 長野 宇規
ARDEC : world agriculture now, 2013年03月, ［招待有り］
筆頭著者

時系列衛星データによる水稲冠水被害の判別
小寺昭彦; 長野宇規
農業農村工学会大会講演会講演要旨集, 2013年

里山棚田地域のため池環境とトンボの多様性の関係
長野宇規; 武内涼子; 小寺昭彦; 松本文子
農業農村工学会大会講演会講演要旨集, 2013年

モンスーン地域における時系列衛星画像の雲ノイズ処理の信頼性評価
中嶋和成; 小寺昭彦; 長野宇規
農業農村工学会大会講演会講演要旨集, 2012年

水利権市場下における農家の渇水対策の分析
小野由美子; 小寺昭彦; 長野宇規
農業農村工学会大会講演会講演要旨集, 2012年

世界灌漑農業アトラスの開発
長野宇規; 小寺昭彦; 鼎信次郎
農業農村工学会大会講演会講演要旨集, 2012年

MODIS画像のミクセル分解による作物分布の高解像度化
藤田藍斗; 小寺昭彦; 長野宇規
農業農村工学会大会講演会講演要旨集, 2012年

時系列衛星データから見た過去11年間における灌漑農地利用の変化
小寺昭彦; 長野宇規
農業農村工学会大会講演会講演要旨集, 2012年

世界灌漑農業アトラスの作成と利用
小寺昭彦; 大森伸哉; 藤田藍斗; 中嶋和成; 長野宇規
環境科学会年会プログラム, 2011年

時系列衛星画像を用いたミクセル分解による作付暦推定
藤田藍斗; 小寺昭彦; 長野宇規
農業農村工学会大会講演会講演要旨集, 2011年

NDVI時系列解析によるメコン川下流域の農業土地利用形態の同定
大森伸哉; 小寺昭彦; 長野宇規
農業農村工学会大会講演会講演要旨集, 2011年

トルコ・ユーフラテス川上流域の河川流路網作成
松本嵩; 小寺昭彦; 長野宇規
農業農村工学会京都支部研究発表会講演要旨集, 2011年

ベトナム・メコンデルタにおける水稲作付暦の広域推定と水資源環境の変動による影響
小寺昭彦; KHANG N.D.; KHANG N.D.; 坂本利弘; 飯泉仁之直; 横沢正幸
熱帯農業研究, 2009年

ベトナム・メコンデルタの広域水環境と水稲生産の脆弱性
小寺昭彦; グエン ズイカン; 坂本利弘; 飯泉仁之直; 横沢正幸
農業環境工学関連学会合同大会講演要旨集(CD-ROM), 2009年

ベトナムメコンデルタにおける水資源環境変動による水稲生産の脆弱性
横沢正幸; 小寺昭彦; KHANG Nguyen Duy; 坂本利弘; 飯泉仁之直
日本農業気象学会全国大会講演要旨/Proceedings of International Symposium on Agricultural Meteorology, 2009年

MODIS時系列データを用いたメコンデルタにおけるファーミングシステムの変化把握
坂本利弘; PHUNG Cao V; 小寺昭彦; KHANG Nguyen D; 横沢正幸
日本リモートセンシング学会学術講演会論文集, 2008年

ベトナム・メコンデルタの塩水遡上による水稲生産の脆弱性
小寺昭彦; KHANG N.D.; 坂本利弘; 横沢正幸
熱帯農業研究, 2008年

P116 ベイズ推定と統計的ダウンスケーリングを併用したベトナム・メコンデルタ域の全天日射量の推定
飯泉 仁之直; 西森 基貴; 横沢 正幸; 小寺 昭彦; Khang Nguyen Duy
大会講演予講集, 2008年

ベトナム・メコンデルタにおける塩水遡上が水稲生産に及ぼしている影響
小寺昭彦; TOAN T. Q.; KHANG N. D.; 坂本利弘; 横沢正幸
熱帯農業, 2007年

時系列衛星データ解析による農業的土地利用変化把握
坂本利弘; 小寺昭彦; 大野宏之; 石塚直樹; 横沢正幸; VAN NHAN Nguyen
日本写真測量学会学術講演会発表論文集, 2007年

MODIS時系列解析によるメコンデルタ洪水の時空間変動特性把握
坂本利弘; NGUYEN Nhan Van; 小寺昭彦; 大野宏之; 石塚直樹; 横沢正幸
システム農学会シンポジウム要旨集, 2007年

TERC-RAMSを用いた温暖化時の気候極値/異常気象予測への取り組み
西森基貴; 横沢正幸; 小寺昭彦; 飯泉仁之直; 木村富士男
農業環境工学関連学会合同大会講演要旨集(CD-ROM), 2006年

ベトナム,メコンデルタ及び紅河デルタにおける水稲フェノロジー空間分布特性の把握
坂本利弘; 小寺昭彦; 石塚直樹; 大野宏之; NGUYEN Nhan Van; 横沢正幸
農業環境工学関連学会合同大会講演要旨集(CD-ROM), 2006年

TERC-RAMSを用いたアジア域における気候極値・異常気象の再現と予測
西森基貴; 木村富士男; 飯泉仁之直; 小寺昭彦; 横沢正幸
日本気象学会大会講演予稿集, 2006年

県平均水稲収量の推定モデル
横沢正幸; 飯泉仁之直; 小寺昭彦; 坂本利弘; 中川博視
農業環境工学関連学会合同大会講演要旨集(CD-ROM), 2006年

移植の影響を考慮した水稲生育過程のモデル化
小寺昭彦; 縄田栄治; 桜谷哲夫; CHUONG P V
熱帯農業, 2001年

冠水がベトナム水稲の収量に及ぼす影響の品種間差異について
小寺昭彦; 縄田栄治; THAO L V; DOANH L Q; 桜谷哲夫
熱帯農業, 2000年

1999年ベトナム中部地方における水稲の洪水被害について
小寺昭彦; TRUONG T M; DOANH L Q
熱帯農業, 2000年

紅河デルタの土地利用及び農業資源の評価 2. 稲作収量推定モデルの開発 2-ii) 移植による生育遅延を考慮した水稲発育過程モデル (文部省S)
小寺昭彦; 縄田栄治; 桜谷哲夫; THAO L V; DOANH L Q
紅河デルタの土地利用及び農業資源の評価 平成9-11年度 No.09041156, 2000年

紅河デルタの土地利用及び農業資源の評価 2. 稲作収量推定モデルの開発 2-i) 水稲冠水障害モデルの概要および水稲冠水試験について (文部省S)
小寺昭彦; 縄田栄治; 桜谷哲夫; CHUONG P V; DOANH L Q
紅河デルタの土地利用及び農業資源の評価 平成9-11年度 No.09041156, 2000年

ベトナム水稲の収量に冠水が及ぼす影響
小寺昭彦; 縄田栄治; THAO L V; DOANH L Q; 桜谷哲夫
熱帯農業, 1999年

〔主要な業績〕Interlocal Adaptations to Climate Change in East and Southeast Asia: Sharing Lessons of Agriculture, Disaster Risk Reduction, and Resource Management
Tetsuji Ito; Makoto Tamura; Akihiko Kotera; Yuki Ishikawa-Ishiwata (Editors), 共編者(共編著者)
Springer Nature, 2022年01月
9783030812065

「情報ツールから始まる対話」,『水を分かつ－地域の未来可能性の共創－』　　　　　　　　　　　　　　　
窪田順平(編), 分担執筆
勉誠出版, 2016年03月
9784585230403

Climate Change and Disaster Risk Reduction in Urban and Coastal Areas, case studies of the Vietnamese Mekong Delta　　　　　　　　　　　　　　　
Nguyen Thi Thuy Hang; Nguyen Van Quang; Kotera, Akihiko
International Meeting on Land Cover/Land Use Change (LCLUC) in South/Southeast Asia and Synthesis. Hanoi, Vietnam, 2024年02月
202402, 202402

The Power of Dialogical Tools in Participatory Learning
KOTERA Akihiko
Beyond Interlocal Lessons Learnt on Climate Change: Mapping, Fertilizing and Social Permeating, 2021年09月
202109, 202109

Building Climate Security Index for Sustainable Development Strategies in the Coastal Area in Phan Thiet City, Vietnam
NGUYEN Thi Que; DOI Thi Loan*; NGUYEN Van Quang; NGUYEN Thi Thuy Hang; KOTERA Akihiko
Beyond Interlocal Lessons Learnt on Climate Change: Mapping, Fertilizing and Social Permeating, 2021年09月
202109, 202109

Image Processing for Creating Noiseless Global Time-Series Satellite Remote-Sensing Image Product and Its Practical Application　　　　　　　　　　　　　　　
The International Workshop on High Performance Computing (HPC) System and Applications, 2019年11月

ベトナム・メコンデルタの広域水環境と水稲生産の脆弱性　　　　　　　　　　　　　　　
小寺 昭彦
農業環境工学関連学会2009年合同大会オーガナイズドセッション, 2009年

ベトナム・メコンデルタにおける水稲作付暦の広域推定と水資源環境の変動による影響　　　　　　　　　　　　　　　
小寺 昭彦
日本熱帯農業学会第105回講演会, 2009年

ベトナム・メコンデルタの塩水遡上による水稲生産の脆弱性　　　　　　　　　　　　　　　
小寺 昭彦
日本熱帯農業学会第103回講演会, 2008年

ベトナム・メコンデルタにおける塩水遡上が水稲生産に及ぼしている影響　　　　　　　　　　　　　　　
小寺 昭彦
日本熱帯農業学会第101回講演会, 2007年

Salinity intrusion affecting rice production in the coastal area of the Mekong Delta　　　　　　　　　　　　　　　
小寺 昭彦
CLRRI-IRRI International Conference, CuuLong Delta Rice Research Institute, at Can Tho, Vietnam (Better Rice, Better Environment and Better Life), 2007年

ベトナム紅河デルタにおける水稲栽培時期の空間的把握　　　　　　　　　　　　　　　
小寺 昭彦
日本熱帯農業学会第99回講演会, 2006年

Detecting spatial pattern of rice cropping schedules using time-series satellite images in the Red River Delta, Vietnam　　　　　　　　　　　　　　　
小寺 昭彦
International Symposium on Geoinformatics for Spatial Infrastructure Development in Earth and Allied Sciences 2006, at Ho Chi Minh City, Vietnam (GIS-IDEAS), 2006年

ベトナム紅河デルタにおける高収量性水稲品種の導入と洪水被害　　　　　　　　　　　　　　　
小寺 昭彦
日本農業気象学会近畿支部大会, 2004年

移植の影響を考慮した水稲生育過程のモデル化　　　　　　　　　　　　　　　
小寺 昭彦
日本熱帯農業学会第91回講演会, 2001年

ベトナム水稲の収量に冠水が及ぼす影響の品種間差異について　　　　　　　　　　　　　　　
小寺 昭彦
日本熱帯農業学会第89回講演会, 2000年

1999年ベトナム中部地方における水稲の洪水被害について　　　　　　　　　　　　　　　
小寺 昭彦
日本熱帯農業学会第89回講演会, 2000年

ベトナム水稲の収量に冠水が及ぼす影響　　　　　　　　　　　　　　　
小寺 昭彦
日本熱帯農業学会第87回講演会, 1999年

収量推定モデルを用いたベトナム紅河デルタ地域の水稲生育環境の評価　　　　　　　　　　　　　　　
小寺 昭彦
日本熱帯農業学会第84回講演会, 1997年

2014年 - 現在, 日本リモートセンシング学会

2010年 - 現在, 農業農村工学会

日本農業気象学会

日本作物学会

日本熱帯農業学会

〔主要な業績〕失敗経験行動モデルによる稲作の多様な作付暦の成立過程と気候変動レジリエンスの,評価　　　　　　　　　　　　　　　
基盤研究(C)（一般）
2023年04月 - 2026年03月

東南アジア地域における農作物の洪水-干ばつ被害と統合的被害緩和策
基盤研究(C)
茨城大学
2017年04月 - 2021年03月

東南アジア地域における衛星リモセンによる農作物洪水被害の判別と適応策の再評価
基盤研究(C)
総合地球環境学研究所
2014年04月 - 2017年03月

大規模灌漑農地の総合塩害管理技術の開発
基盤研究(B)
神戸大学
2010年04月 - 2013年03月

メコンデルタにおける海面上昇に伴う水稲生産の脆弱性評価
基盤研究(B)
独立行政法人農業環境技術研究所
2007年04月 - 2010年03月

ベトナム・メコンデルタにおける水稲生産の気候変化影響予測　　　　　　　　　　　　　　　
2005年 - 2009年