12:00 PM - 12:15 PM
[AHW24-12] Simulating the historical human engineering waterworks in Tone River
Keywords:Tone River Eastward Diversion Project, H08 hydrological model, Historical maps reconstruction, Low flows, Navigable paths
The Tone River was flowing towards Tokyo Bay more than 400 years ago when engineers diverted it towards the Pacific Ocean, where the new river mouth was dislocated for cca 100 kilometers. One hypothesis of historians from the 19th century is that the main reason for the diversion was the defense of Tokyo (then Edo) from floods. Takashi Okuma, Haku Koide, and others proposed the other, which is raising low river water levels for easier navigation on new river routes from the Pacific Ocean to Tokyo. We traced the latter hypothesis for the main reason for conducting the Tone River Diversion Project using the H08 hydrological model.
We successfully reconstructed the hydrological cycle of the Tone-Ara-Edo Rivers, supporting the latter historical claim by demonstrating the substantial increase in channel connectivity. Because of this increase, the possibilities of uninterrupted navigation of boats through the river waterways of the Pacific Ocean to Tokyo have been significantly improved. This study presents the first distributed hydrological simulation confirming the claims that the Tone River Eastward Diversion Project in Japan was conducted 4 centuries ago to increase low flows and subsequent travelling possibilities surrounding the Capitol Edo using inland navigation.
We reconstructed 6 historical river maps and indirectly validated simulations with reachable ancient river ports via increased low-flow water levels. The results of present-day simulations using uncalibrated and calibrated parameters with bifurcation functions at the Tone Ozeki Weir, where some water is diverted to the Ara River, and at the Sekiyado Dam, which controls the water that flows toward the Edo River. For historical simulation, we applied the same modeling configurations as for the present-day simulation, but with different operational functions of the bifurcation toward the Edo River, to determine the constant diversion rates by varying the percentages of river discharge flowing toward the Edo and Tone Rivers.
The Tone River Diversion Project is used as proof that pre-modern human engineering waterworks can greatly improve people's life quality without excessive destruction of natural flows. Learning from history should become important factor in challenging climate change.
We believe that our approach will encourage the broader scientific audience to engage in transdisciplinary hydrological and related studies by providing insights into historical engineering and scientific knowledge. There are a lot of present-day scientific efforts focused on the projection, prediction, and forecasting of near-future or far-future scenarios, yet historical studies are often sidelined. If only the scientific community realizes that, sometimes at tipping points of climate, we can learn from the past more than from the future, then we believe that the historical cross-disciplinary insights will create abundant new approaches.
Reference: Trošelj J. and Hanasaki N. Simulating the Tone River eastward diversion project in Japan carried out 4 centuries ago; Hydrology and Earth System Sciences 29 (3), 753-766, doi.org/10.5194/hess-29-753-2025, 2025.
We successfully reconstructed the hydrological cycle of the Tone-Ara-Edo Rivers, supporting the latter historical claim by demonstrating the substantial increase in channel connectivity. Because of this increase, the possibilities of uninterrupted navigation of boats through the river waterways of the Pacific Ocean to Tokyo have been significantly improved. This study presents the first distributed hydrological simulation confirming the claims that the Tone River Eastward Diversion Project in Japan was conducted 4 centuries ago to increase low flows and subsequent travelling possibilities surrounding the Capitol Edo using inland navigation.
We reconstructed 6 historical river maps and indirectly validated simulations with reachable ancient river ports via increased low-flow water levels. The results of present-day simulations using uncalibrated and calibrated parameters with bifurcation functions at the Tone Ozeki Weir, where some water is diverted to the Ara River, and at the Sekiyado Dam, which controls the water that flows toward the Edo River. For historical simulation, we applied the same modeling configurations as for the present-day simulation, but with different operational functions of the bifurcation toward the Edo River, to determine the constant diversion rates by varying the percentages of river discharge flowing toward the Edo and Tone Rivers.
The Tone River Diversion Project is used as proof that pre-modern human engineering waterworks can greatly improve people's life quality without excessive destruction of natural flows. Learning from history should become important factor in challenging climate change.
We believe that our approach will encourage the broader scientific audience to engage in transdisciplinary hydrological and related studies by providing insights into historical engineering and scientific knowledge. There are a lot of present-day scientific efforts focused on the projection, prediction, and forecasting of near-future or far-future scenarios, yet historical studies are often sidelined. If only the scientific community realizes that, sometimes at tipping points of climate, we can learn from the past more than from the future, then we believe that the historical cross-disciplinary insights will create abundant new approaches.
Reference: Trošelj J. and Hanasaki N. Simulating the Tone River eastward diversion project in Japan carried out 4 centuries ago; Hydrology and Earth System Sciences 29 (3), 753-766, doi.org/10.5194/hess-29-753-2025, 2025.