Reconstruction of the Background Air Temperature Record in Japan (1916–2023): Implications for Climate Change and Urbanisation Bias in the 20th CenturyGenki Katata; Ryusei Nakayama; Fumiaki Fujibe; Shigeya Maeda, Last, ABSTRACT
Long‐term and contiguous records from the rural weather stations are necessary to estimate the rate of global warming without urbanisation bias. This study reconstructed the trends of the annual mean temperatures in rural Japan using digitised monthly maximum and minimum temperature data recorded from 1916 to 2023. Monthly temperature data from 1926 to 1940 were recently digitised from the printed materials of the Japan Meteorological Agency (JMA). While the reconstructed annual mean temperatures over Japan are in good agreement with those from previous studies for rural stations in Japan (population density < 100 people km
−2), the linear rate of increase in the annual temperature averaged for 15 monitoring stations of the JMA showed a linear trend of + 0.15°C decade
−1 for 1916–2023 higher than that averaged for our rural stations (+ 0.11°C decade
−1) due to the urbanisation bias. Interestingly, when the urbanisation biases were subtracted, a significant decreasing trend (i.e., a climatic jump) was detected in the rural temperature record during the 1960s. Comparing our rural temperature trend with those in other regions of the Northern Hemisphere and sea surface temperatures around the Japan region, the urbanisation bias likely partially masked the importance of natural variations such as PDO and solar variability., Wiley
International Journal of Climatology, 06 Oct. 2025,
[Reviewed] 〔Major achievements〕A Novel Application of Deep Learning–Based Estimation of Fish Abundance and Temporal Patterns in Agricultural Drainage Canals for Sustainable Ecosystem MonitoringShigeya Maeda; Tatsuru Akiba, Lead, Agricultural drainage canals provide critical habitats for fish species that are highly sensitive to agricultural practices. However, conventional monitoring methods such as capture surveys are invasive and labor-intensive, which means they can disturb fish populations and hinder long-term ecological assessment. Therefore, there is a strong need for effective and non-invasive monitoring techniques. In this study, we developed a practical method using the YOLOv8n deep learning model to automatically detect and quantify fish occurrence in underwater images from a canal in Ibaraki Prefecture, Japan. The model showed high performance in validation (F1-score = 91.6%, Precision = 95.1%, Recall = 88.4%) but exhibited reduced performance under real field conditions (F1-score = 61.6%) due to turbidity, variable lighting, and sediment resuspension. By correcting for detection errors, we estimated that approximately 7300 individuals of Pseudorasbora parva and 80 individuals of Cyprinus carpio passed through the observation site during a seven-hour monitoring period. These findings demonstrate the feasibility of deep learning-based monitoring to capture temporal patterns of fish occurrence in agricultural drainage canals. This approach provides a promising tool for sustainable aquatic ecosystem management in agricultural landscapes and emphasizes the need for further improvements in recall under turbid and low-visibility conditions., MDPI AG
Sustainability, 24 Sep. 2025,
[Reviewed] Water quality characteristics of rivers in volcanic areas affected by discharge from hydroelectric power plant
Lin, X.; Shinozaki, M.; Maeda, S.; Kuroda, H.
PAWEES 2024, Oct. 2024, [Reviewed]
Development of energy-saving irrigation and drainage systems for huge paddies rice field
Kuroda, H.; Yokoi, S.; Lin, X.; Maeda, S., Last
PAWEES 2024, Oct. 2024, [Reviewed]
Impact of nest size on deposition of detached filamentous algae within fish nests in an agricultural drainage canal: application of a 3D hydrodynamic model
Maeda, S.; Lin, X.; Kuroda, H., Lead
Proceedings of 15th International Symposium on Ecohydraulics and Fish Passage 2024, May 2024, [Reviewed]
Water depth and flow velocity characteristics of a portable fishway unit for salmon
Takahashi; N.; Nakata; K.; Sonoda; T.; Maeda; S., Last, International Society of Paddy and Water Environment Engineering
Proceedings of 2023 Conference of International Society of Paddy and Water Environment Engineering, 23 Oct. 2023, [Reviewed]
Numerical experiment on the deposition process of detached filamentous algae on artificial fish nests introduced to an agricultural drainage canal
Maeda; S.; Miyashita; S.; Lin; X.; Kuroda; H., Lead, PAWEES
Proceedings of 2023 Conference of International Society of Paddy and Water Environment Engineering, 23 Oct. 2023, [Reviewed]
環境配慮工が導入された農業用水路と河川における流れの数値計算
吉成香貫花・前田滋哉・福田信二・黒田久雄, Corresponding, 農業農村工学会水文・水環境研究部会
応用水文, 28 Mar. 2023
〔Major achievements〕流れ・路床変動モデルを用いた魚巣における泥上げ効率の評価手法
前田滋哉・黒田久雄, Lead
土木学会論文集B1（水工学）, 01 Sep. 2022, [Reviewed]
曲がり桝における3次元流れの数値解析
姫野敦行・皆川明子・前田滋哉, Last, 農業農村工学会 水文・水環境研究部会
応用水文, 28 Mar. 2022
付着藻類を考慮した魚巣・魚溜のある農業用排水路における路床変動の数値実験
前田滋哉・皆川明子・黒田久雄, Lead, 農業農村工学会水文・水環境研究部会
応用水文, 27 Mar. 2021
農業用排水路の急傾斜部に設置した可搬魚道における流れの数値計算
吉成香貫花・須藤真弥・前田滋哉・高橋直己, Corresponding, 農業農村工学会水文・水環境研究部会
応用水文, 27 Mar. 2021
水路急傾斜部に設置した可搬魚道における魚類遡上の調査
須藤真弥・前田滋哉・高橋直己, Corresponding, 農業農村工学会水文・水環境研究部会
応用水文, 27 Mar. 2020
タイ東北部農業主体地域を対象とした水資源・窒素負荷量推定モデルの構築
寺家谷勇希; 吉田貢士; Sritumboon SUPRANEE; Srisutham MALLIKA; 前田滋哉; 黒田久雄
農業農村工学論文集, 14 Nov. 2019, [Reviewed]
熱帯湿地における排水路水位の制御に伴うCO2放出量および火災リスクの低減効果
吉田貢士; 大澤和敏; 鈴木遥; 水野広祐; 前田滋哉; 黒田久雄
土木学会論文集B1(水工学), 06 Nov. 2019, [Reviewed]
Field observation and numerical simulation of bed evolution in agricultural drainage canal with eco-friendly physical structures
Takagi; S.; Maeda; S.; Yoshida; K.; Kuroda; H., Corresponding
Proceedings of 38th IAHR Congress, 01 Sep. 2019, [Reviewed]
温度変数に着目した水田・湿地の窒素除去速度推定方法の改良
林暁嵐; 瀬田千夏; 吉田貢士; 前田滋哉; 黒田久雄
農業農村工学論文集, 08 Aug. 2019, [Reviewed]
Ecohydraulic assessment of water abstraction for hydroelectric power generation in the Anegawa river, Japan
Maeda; S.; Ishizaki; S.; Minagawa; A.; Kobayashi; H.; Yoshida; K. and Kuroda; H., Lead
Journal of Rainwater Catchment Systems, 01 Jul. 2019, [Reviewed]
Fish habitat evaluation in river section affected by agricultural water withdrawal
前田滋哉; 小林佳奈; 皆川明子; 小林 久; 吉田貢士; 黒田久雄, Lead
Applied Hydrology, 22 Mar. 2019, [Reviewed]
サトウキビ栽培における渇水対策としての浅層地下水利用と生産ポテンシャル評価
吉田貢士; Desell Suanburi; 牧雅康; 前田滋哉; 黒田久雄, 土木学会
土木学会論文集G(環境), 2019, [Reviewed]
Canal bed evolution and current velocity distribution in artificially-created nest and pool habitats in rural area
Maeda; S.; Takagi; S.; Yoshida; K.; Kuroda; H., Lead
Proceedings of 12th International Symposium on Ecohydraulics, 19 Aug. 2018, [Reviewed]
Effect of upstream discharge regulation on fish habitat in the Ane River, Japan
Ishizaki; S.; Maeda; S.; Minagawa; A.; Noda; K.; Kobayashi; H.; Yoshida; K.; Kuroda; H.
Proceedings of the 37th IHAR World Congress, 13 Aug. 2017, [Reviewed]
急激な土地利用変化がジャカルタの大規模洪水リスクに及ぼす影響
吉田貢士; 前田滋哉; 黒田久雄
農業農村工学会 水文・水環境研究部会, 24 Mar. 2017, [Reviewed]
UAVによる高解像度熱画と水塊・植生2層熱収支モデルを用いた水田内湛水深の空間分布推定
吉田貢士; 本間香貴; 牧雅康; 前田滋哉; 黒田久雄
応用水門, 2017, [Reviewed]
Turbulence and energetic characteristics of water regions created by eco-friendly physical structures in an agricultural drainage canal
Maeda; S.; Iida; M.; Yoshida; K.; Kuroda; H.
E-proceedings of 12th International Conference on Hydroscience & Engineering, 06 Nov. 2016, [Reviewed]
NITROGEN LOAD INFLOW TO LARGE SCALE RESERVOIRS IN THE CITARUM RIVER BASIN, INDONESIA
Yuki Jikeya; Koshi Yoshida; Shigeya Maeda; Hisao Kuroda
Proceedings of the 16th World Lake Conference, Nov. 2016, [Reviewed]
メコン川流域における栄養塩排出原単位および河川水中の栄養塩濃度の推定田中 健二; 吉田 貢士; 前田 滋哉; 黒田 久雄, In Mekong river basin, population increase and economic growth may cause the water pollution problem in the future. This study aimed to assess spatial water quality environment in main stream and tributaries of Mekong river. For that purpose, liner regression model to estimate unit of nutrient pollution loading and water circulation model to estimate river discharge were developed, and then river nutrient concentration was also calculated. As a result, estimated unit of nutrient pollution loading expressed the characteristics of wastewater treatment process and agricultural level in Mekong river basin. Calculated river discharge and annual average river nutrient concentration were good agreement with observed data., Japan Society of Civil Engineers
土木学会論文集G（環境）, 2014,
[Reviewed] Fuzzy comprehensive evaluation of water quality at monitoring points –Application to Lake Biwa-Maeda; S.; Fujita; T. and Kawachi; T., Lead, A method for comprehensively evaluating water quality at various points in a water body has been developed based on the fuzzy reasoning. Vagueness in borders of conventional water quality classes formed for each water quality index is quantified by introducing fuzzy sets associated with the classes and nonlinear membership functions. Mamdani method (or min-max-center of gravity method) is employed in the fuzzy reasoning in order to synthesize concentration data on multiple water quality indices. The evaluation method developed in this study can represent the state of water quality at each points with a real number ranging from 0 to 100. The applicability of the method is demonstrated with the series of monthly observed data from April 1980 to March 2010 at 49 monitoring points in Lake Biwa, Japan. Temporal and spatial variations of the synthesized water quality scores at the monitoring points are presented. The application of the fuzzy comprehensive evaluation method would lead to more rational comparison of synthesized water quality at MPs in the lake and to producing useful information in decision-making on water quality management in the water body., Japan Rainwater Catchment Systems Association
Journal of Rainwater Catchment Systems, 2013,
[Reviewed] Optimization of block placement for ecohydraulic design of fish habitat in canal
Maeda; S., Lead
Proceedings of 9th international Symposium on Ecohydraulics 2012, 2012, [Reviewed]
A Hydro-environmental Model Considering Nitrogen Dynamics in Surface Zone for Analysis of Groundwater Nitrate-nitrogen ContaminationImagawa, I; Takeuchi, J; Kawachi, T; Chono, S; Buma, N; Maeda, S, A cell-based distributed hydro-environmental model is developed which enables to analyze groundwater nitrate-nitrogen (N-N) contamination in rural areas, with well-coordinated incorporation of the water quality tank submodel for surface zone and the nitrate-nitrogen transport submodel for unconfined groundwater aquifer into the previously developed hydrologic model (Takeuchi et al., 2010). Cell-based building of all component submodels allows us to mesh the problem domain with unstructured cells of triangular shape, and therefore renders it possible to reflect in a refined fashion a variety of land-use practices in an analysis of the problem. The solutions based on reality, associated with groundwater flow and quality, can thus be obtained at a high (or field-plot-scale) resolution. It is also of great advantage that quantities of the hydro-environmental components of interest, such as surface water discharge, ground-water recharge, surface nitrogen discharge, and N-N leaching, can be obtained cell by cell or land-use by land-use. Application of the model to a real rural area having diverse terrains testifies to its satisfactory performance in a global sense. The simulated N-N concentrations of the groundwater vary in the ranges of the observed concentrations. The model also well reproduces the observed realities that the N-N concentration is high in upland areas such as alluvial fan and river terrace, while low in the lowland areas such as delta and valley floor, and is lowered in the irrigation season. It is thus considered that the model presently developed is useful for simulating and assessing the process and geographic distribution of groundwater N-N contamination in rural areas where fertilizing-induced groundwater contamination is a special concern., Japan Rainwater Catchment Systems Association
雨水資源化システム学会誌, Jan. 2011,
[Reviewed] Infiltration Process in Rainfed Rice Field Soil of Ghanaian Inland ValleyUNAMI Koichi; IZUMI Tomoki; IMAGAWA Chie; KAWACHI Toshihiko; MAEDA Shigeya; TAKEUCHI Junichiro, Soils of rainfed rice fields have unique characteristics. Inland valleys are extensively found in West African savannas, and their hydromorphic valley bottoms are intensively used for rainfed rice-culture during rainy seasons when become wetlands. Data of rainfall and soil moisture are perennially collected in a study site located in Northern Region of Ghana. The soil of the site is classified as Dystric Planosols. The soil moisture retention curve at a depth of the soil is identified from observed volumetric water content and matric head. Since the soil is variably saturated, it is important to clarify abruptly changing hydraulic properties of the soil near saturation. A bimodal model including eight empirical parameters turns out to be suitable for this purpose. The vertically one-dimensional Richards equation is considered to reproduce infiltration process of rainwater into the soil. The saturated water content, one of the empirical parameters, and saturated hydraulic conductivity are assumed to be functions of the depth of soil. Then, the finite element method is applied for solving the Richards equation to simulate the process. The simulation results are in good accordance with actually observed data. The physically-based model serves as a tool for comprehending formulation process of the wetlands at early stages of rainy seasons., Japan Rainwater Catchment Systems Association
J Rainwater Catchment Syst, Jan. 2010,
[Reviewed] Optimal allocation of maximum allowable discharged total nitrogen load among field plots in agricultural watershedMaeda, S; Yoshikawa, K; Takeuchi, J; Kawachi, T; Chono, S; Unami, K, Lead, A multiobjective optimization model is developed for controlling TN (Total Nitrogen) load discharged from field plots in an agricultural watershed. In optimization, maximizations of allowable TN discharge per unit area and total yield of rice are intended while complying with an effluent limitation standard prescribed for river water quality management. The discharge from a field plot is separated into two components, i.e., direct runoff and baseflow. As discharged TN from a plot travels with these components toward an outlet of the watershed, the amount of TN is assumed to decrease due to distance-related self-purification occurring in subsurface zone, drainage canal and river. Locations of field plots and traveling routes of TN are identified or predicted by a GIS (Geographic Information System) with a digital elevation model and by field surveys. The model developed is applied to an agricultural watershed bordering with Lake Biwa in Shiga Prefecture, Japan. The result demonstrates that the optimal allocation of maximum allowable discharged TN load among field plots is helpful in prioritizing plots where fertilization should be reduced., The Japanese Society of Irrigation, Drainage and Rural Engineering
Transactions of the Japanese Society of Irrigation, Drainage and Rural Engineering, 2010,
[Reviewed] Dynamics of Nonpoint Source Pollutant Loadings from Agricultural Watershed : A Case Study in Paddy-farming Area with 122 Drainage Water Outfalls Exactly IdentifiableChono Shunsuke; Maeda Shigeya; Kawachi Toshihiko; Unami Koichi; Takeuchi Junichiro, Paddy farming is the cause of water pollution in many parts of the Asian monsoon district. As a primary study for strategically managing river water quality on a watershed scale, the dynamics of nonpoint source pollutant loadings from paddy farming area are examined for a selected agricultural watershed where a river runs through and rice paddies take greater part of the farmland. A total of 122 outfalls at which drainage (irrigation runoff) waters enter the river are exactly identifiable along the whole course of the river. Results of the detailed surveys of drainage waters, conducted at typical stages in an indigenous calendar of paddy farming practice (CPFP) in an irrigation season as well as at a few stages in the off-season, are analyzed. Major findings are as follows. (1) Any of the COD_<Mn>, NO_3-N, T-N and T-P loadings totalized over all the outfalls is maximized in puddling and transplanting with basal fertilizer application. (2) The concentrations of NO_3-N and T-N, averaged over all the outfalls, are rather low during the irrigation period of mid April to early September. Nevertheless the loading amounts of them remain high during the same period, relatively closely correlating with the amount of outfall discharge. (3) Topdressing the paddies in the booting stage of rice causes a distinguishable extra load of NO_3-N. (4) The dynamics of the COD_<Mn> and T-P loadings are totally different from those of the NO_3-N and T-N loadings, taking straightforward declines from their maximums or being significantly restricted by their concentrations rather than by outfall discharges., 日本雨水資源化システム学会
Journal of Rainwater Catchment Systems, 2009,
[Reviewed] An Inverse Method to Estimate Soil Hydraulic Properties in Saturated-unsaturated Groundwater Flow ModelIZUMI Tomoki; TAKEUCHI Junichiro; KAWACHI Toshihiko; UNAMI Koichi; MAEDA Shigeya, An alternative approach to the inverse problems encountered prior to the computations of saturated-unsaturated groundwater flow is addressed. The soil hydraulic properties (i.e., the relative hydraulic conductivity K_r and the volumetric water content θ) which are the a priori unknown parameters in the Richards equation governing the flow are interpolated by an assembly of the piecewise cubic spline functions expressed in terms of the pressure head. This free-form parameterization approach provides high flexibility and degrees of freedom in identifying the functional form of the parameters, compared with the conventional approaches in that the functions are of specific shape as in the van Genuchten model of a fixed functional form. In addition, the approach is field-oriented in a point that the solution of the inverse problem can be achieved having only recourse to the observed time-series data of pressure head which are relatively easily in situ available. To find the shapes of such spline functions best expressing head-dependency of the soil hydraulic properties, a simulation-optimization algorithm with the aid of the Levenberg-Marquardt method is developed which serves to iteratively solve an optimization problem of minimizing errors between the observed (or measured) and computed values of the pressure head, in combination with the embedded simulation module for solving forward problems. Validity of the approach is examined with its application to different two soil types which are characterized by less and more sensitive changes of the relative hydraulic conductivity near saturation, respectively. The results show that the approach developed could be a viable alternative to the conventional fixed functional form approaches., Japan Rainwater Catchment Systems Association
J Rainwater Catchment Syst, Jan. 2008,
[Reviewed] Model-based Optimal Design of Land Use Arrangement for Environmentally Sound Watershed ManagementTakeuchi Junichiro; Izumi Tomoki; Kawachi Toshihiko; Unami Koichi; Maeda Shigeya, In Japan, more and more paddy fields, left fallow mainly by nationwide rice production control policy, have recently been changed to upland crop fields or artificial wetlands. Since such change or diversification of land use probably has an impact on the water quality environment of the whole neighborhood, it must strategically be implemented in the context of land use arrangement for environmentally sound watershed management. Of great importance is then to make effective use of self-purification functions fulfilled by paddy fields or wetlands. The present study is associated with development of a simulation-optimization model for designing an optimal land use on a watershed scale. The model is composed of a hydro-environmental subsurface watershed simulation model, represented by coupled 3-D Richards and advection-dispersion equations, and a GA (Genetic Algorithm)-aided optimization part. An optimization problem is formulated which, with the most use of self-purification, minimizes the objective function expressed in terms of a weighted total of discharged nutrient from a watershed and residual nutrient within the watershed, taking the location of paddy fields in fallow, changed to upland crop fields or wetlands, as a decision variable. An example problem for a small watershed of an irrigation tank is solved that requires deciding the optimal locations of paddy fields that can be changed to other land use categories. The results show that the model developed could be a powerful tool for making tactics to combat the environmental impact resulting from land use diversification., 日本雨水資源化システム学会
Journal of Rainwater Catchment Systems, 2008,
[Reviewed] Fuzzy optimization model for allocating allowable discharged T-N load to point and nonpoint sources
Maeda; S. and Kawachi; T., Lead
Proceedings of 32nd IAHR Congress, 2007, [Reviewed]
Optimal management of agricultural wastewaters for improving river water quality
Maeda; S. and Kawachi; T., Lead
Proceedings of Pawees 2005 International Conference, 2005, [Reviewed]
Evaluation of river water quality management level based on COD-loads optimally allocated to point and nonpoint sources
Maeda; S. and Kawachi; T., Lead
Proceedings of XXXI IAHR Congress, 2005, [Reviewed]
Integrated management of river water quality under uncertainty using optimization model
Maeda; S. and Kawachi; T., Lead
Proceedings of XXX IAHR Congress, THEME B, 2003, [Reviewed]
Management of water quality environment under uncertainty – Mathematical modeling and computational optimization -
Kawachi; T.; Unami; K.; Maeda; S. and Takeuchi; J.
Proceedings of the International Conference on Water and Environment (WE-2003), 2003, [Reviewed]
Decision support model for managing river water quality under uncertainty
Maeda; S.; Kawachi; T. and Okumura; H., Lead
Proceedings of 4th International Conference on Hydroinformatics, 2000, [Reviewed]
