OKUBO Takuya




Campus Career 【 display / non-display

  • University of Shiga Prefecture  School of Environmental Science  Department of Biological Resources Management  Professor   2015.04 - Now

Field of expertise (Grants-in-aid for Scientific Research classification) 【 display / non-display

  • Environmental dynamic analysis

  • Modeling and technologies for environmental conservation and remediation

  • Environmental engineering and reduction of environmental burden

  • Environmental and ecological symbiosis

  • Rural environmental engineering/Planning

Qualification acquired 【 display / non-display

  • Fundamental Information Engineer/Information Processing Engineer, Class 2

  • Pollution Prevention Manager


Papers 【 display / non-display

  • Estimation of Phosphorus Transport Influenced by Climate Change in a Rice Paddy Catchment Using SWAT

    Wang K., Onodera S.i., Saito M., Okuda N., Okubo T.

    International Journal of Environmental Research  International Journal of Environmental Research  15 (4)   759 - 772  2021.08

    10.1007/s41742-021-00350-0  Joint Work  


    Phosphorus is an essential nutrient for maintaining and increasing crop production. Owing to frequent human activities, phosphorus resources cause serious environmental pollution. Simulating phosphorus transport with a hydrological model could help understand the phosphorus loss processes at catchment scale. However, in previous modeling studies, phosphorus calibration and validation usually run in monthly time steps, it is difficult to correctly simulate the phosphorus transport peak. Additionally, most previous studies have disregarded the form of phosphorus in transported processes and only considered the total phosphorus, which cannot accurately assist in understanding the specific process of phosphorus transport. Rice is an important agricultural product, widely planted in Asia, and the particulate inorganic phosphorus loss in rice paddies is generally high. Previous studies could not fully simulate the transport of different phosphorus forms in rice paddy catchments. We analyzed the impact of climate change on phosphorus transport under different fertilization scenarios using the Soil and Water Assessment Tool. We compared mineral phosphorus flux with the sum of particulate phosphorus and dissolved orthophosphate during the calibration and validation processes. The Nash–Sutcliffe efficiencies of mineral and total phosphorus in both the calibration and validation periods were higher than 0.65. Rice paddies are the major source of phosphorus loss from the catchment, amounting to 5.4 kg/ha, and particulate inorganic phosphorus accounted for 53% of total phosphorus loss. The average annual phosphorus export was 30 tons/yr; the maximum value was nine times higher than the minimum value. Precipitation had a clear impact on phosphorus transport. Graphic Abstract: [Figure not available: see fulltext.]

  • Juvenile migration of Japanese dace Pseudaspius hakonensis revealed in a tributary of Lake Biwa with seasonal changes in abundance and stable isotope ratios

    Ishizaki D., Nagata T., Kikko T., Mizuno T., Ida C., Okubo T., Fujioka Y., Yodo T.

    Ichthyological Research  Ichthyological Research    2021.01

    10.1007/s10228-021-00804-7  Joint Work  


    Migration patterns of Japanese dace Pseudaspius hakonensis in and around Lake Biwa, Japan are unknown, although fluvial–lacustrine life history has been known in most tributaries, the many mature individuals migrating upstream into tributaries in early spring. Field surveys and stable isotope analyses were used to clarify the migratory history of Japanese dace in the Ishida River, inflowing to Lake Biwa. In the field surveys, the number of young of the year (YOY) individuals caught per unit effort (CPUE) by hand net and casting net in the tributary and lake-shore area was calculated. The CPUE peaked from May to July, after the spawning season, thereafter decreasing rapidly, suggesting that YOY Japanese dace migrated downstream to Lake Biwa immediately after emerging, possibly due to the abundant food resources there. From September to November, the CPUE of YOY individuals increased in the lower reaches of the stream, although their stable nitrogen isotope values were variable, in some cases being similar to those recorded in the upper reaches and the lake-shore area. This suggests that some YOY individuals migrate upstream from the lake in autumn. In the present study, the juvenile migration pattern of fluvial–lacustrine Japanese dace in Lake Biwa was described using a CPUE survey and δ N and δ C analyses. 15 13

  • Water quality issues due to the constructions of estuary barrages in Japan

    Okubo, T and Kim, J

     The 2011 KEI International Water Symposium, 19th July 2011, Seoul, Republic of Korea.    2011

    Joint Work  Joint(The main charge)

  • Performance of Ponds for Control of Nutrient Loadings into Lake Biwa

    Okubo, T.

     Proceedings of 8th International Conference on Diffuse Nonpoint Pollution (CD-ROM).    2004

    Single Work  

  • Effects of environmental conditions on removal of pollutant loading in Ekai Lagoon, Japan

    Okubo, T.

     Proceedings in 9th International Conference on the Conservation and Management of Lakes  3G-P05   388 - 391  2001

    Single Work  

  • Knowledge-based decision support system for selecting small-scale wastewater treatment

    Okubo, T., Kubo, K., Hosomi, M. and Murakami, A.

     Water Science and Technology  30 (2)   175 - 184  1994

    Joint Work  Joint(The main charge)

  • Purification of grey water in small channels

    Okubo, T., Kudo, N., Tanabe, T., Okada, M. and Murakami, A.

     Proceedings of IAWPRC Conference in Kyoto on Water Pollution Research and Control   731 - 734  1990

    Joint Work  Joint(The main charge)

  • Influence of daily variation of flow and pollution load on the performance of submerged anaerobic/aerobic biofilm system

    Okubo, T., Okada, M., Murakami, A. and Inamori, Y.

     Water Science and Technology  22 (3-4)   153 - 160  1990

    Joint Work  Joint(The main charge)

Books 【 display / non-display

  • Issues for Reduction of Pollution Loads from Point and Non-point Sources, in Lake Biwa 2nd edition (Kawanabe, H., Nishino, M., & Maehata, M. Eds.)

    Okubo, T., Sato, Y

    Springer Science & Business Media  2020.08

    Scholarly Book  Joint Work

  • Issues for reduction of pollution loads from point and non-point sources, In: Lake Biwa: Interactions between Nature and People

    Takuya Okubo (eds., Kawanabe, H., Nishino, M., and Maehata, M.)

    Springer  2012

    Scholarly Book  Contributor

  • Special measures for the preservation of lake water quality and it’s effect, In: Water Pollution Policy and Management -The Japanese Experience-

    Okubo, T. (eds., Okada, M. and Peterson, S. A.)

    GYOSEI  2000

    Scholarly Book  Contributor

  • Lake Biwa, In: Water Pollution Policy and Management -The Japanese Experience-

    Okubo, T. (eds., Okada, M. and Peterson, S. A.)

    GYOSEI  2000

    Scholarly Book  Contributor

  • Use of water temperature-ecological model to simulate global warming effects on a lake ecosystem, In: Climate Change and Plants in East Asia

    Hosomi, M., Saegusa, T., Okubo, T. and Murakami, A. (eds. By Omasa, K et al.)

    Springer  1996

    Scholarly Book  Joint Work

  • Effects of sewage works on the flow rate and water quality in Nogawa River, Tokyo, In: RIVER BASIN MANAGEMENT-V

    Okubo, T., Okada, M. and Murakami, A. (ed. by Laikari, H.)


    Scholarly Book  Joint Work