Study on Outflow Control Effect of on-Site Storage and Soil Improvement for Small Watershed

Itsukushima, Rei; Iwanaga, Yuki; Ideta, Kazufumi; Sato, Tatsuro; Shimatani, Yukihiro

doi:10.2208/jscejhe.72.49

Cited by 5 publications

(2 citation statements)

References 14 publications

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“…Details of the development of the runoff calculation model and the setting of the rainfall pattern have already been reported in a previous study [40]; therefore, only an outline is described below.…”

Section: Methodsmentioning

confidence: 99%

“…Due to the anthropogenic impact and natural phenomena mentioned above, surface runoff is caused by a low rainfall rate in urban areas. The authors have developed technologies for strengthening the infiltration capacity of soils using bamboo charcoal, humus, and bamboo chips and evaluated the infiltration and retention capacity of soils mixing these materials [39,40]. This study reports the calculated runoff reduction effects for different scales of outflow control facilities (including soil infiltration improvement materials and rainwater tanks) adopted in small watersheds belonging to densely populated areas.…”

Section: Introductionmentioning

confidence: 99%

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Investigating the Influence of Various Stormwater Runoff Control Facilities on Runoff Control Efficiency in a Small Catchment Area

Itsukushima

Ogahara

Iwanaga³

et al. 2018

Sustainability

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Abstract:Urbanization causes an increase in the flood discharge because of the infiltration capacity. Furthermore, extreme precipitation events have been an increasing concern for many regions worldwide. This study aimed to investigate the influence of different outflow control facilities on runoff reduction in a small watershed. We focused on the soil-improvement technology and rainwater tanks as outflow control facilities and conducted a runoff calculation using a rainfall event of a magnitude that is likely to occur once in a hundred years. The calculation showed that the soil-improvement technology reduced runoff during long-term continuous rainfall, whereas in a concentrated short-term rainfall event, a significant difference in the runoff reduction effect between rainfall tanks of various volumes was observed. Since effective countermeasures for runoff reduction differ depending on the rainfall distribution pattern, we suggested both facilities for storing initial rainfall and initiating countermeasures for penetration improvement over the long term.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Investigating the Influence of Various Stormwater Runoff Control Facilities on Runoff Control Efficiency in a Small Catchment Area

Itsukushima

Ogahara

Iwanaga³

et al. 2018

Sustainability

Self Cite

View full text Add to dashboard Cite

show abstract

Relationship between compaction and infiltration capacity of amended soil for urban flood damage mitigation

Itsukushima

Ideta

Takata

2021

Soil Use and Management

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To mitigate urban flooding, conserving pervious areas and securing the infiltration capacity are important. The infiltration capacity of an area can be significantly reduced by compaction; thus, we attempted to build a runoff reduction technology that can ensure the infiltration capacity even after compaction to mitigate urban flooding.Herein, we revealed the relationship between the degree of compaction and infiltration capacity of amended soils using humus and bamboo chips. We performed a watering infiltration experiment, which initially demonstrated the nonoccurrence of surface runoff in all experimental materials for rainfall intensities of 60 and 120 mm hr −1 , without compaction. However, as the degree of compaction increased, humus mixed with soil exhibited behaviour similar to that of unimproved soil and the surface runoff exceeded seepage drainage. In contrast, in the case of bamboo chips mixed with soil, the surface runoff remained small even at high degrees of compaction. Consequently, when the rainfall intensity was 120 mm hr −1 and compaction was 3 kg cm −2 , the surface runoff per unit time for bamboo chips mixed with soil was 2.4 times less than that for humus mixed with soil and 2.2 times less than that for unimproved soil. Moreover, such differences were observed in the infiltration capacity with respect to compaction because of the void structure owing to soil improvement. Thus, we conclude that soil improvement using bamboo chips can be considered an effective technology to mitigate urban flooding.

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Collaborative Development of Green Infrastructure: Urban Flood Control Measures on Small-Scale Private Lands

Taura¹,

Ohme²,

Shimatani³

2021

JDR

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Focusing on green infrastructure (GI), which utilizes nature’s diverse resources, we developed urban flood control measures on three small-scale private tracts in Tokyo and Fukuoka in Japan, experiencing high rainfall. In addition, we implemented these measures and verified the possibility of introduction. Using a target rainfall of 100 mm/h and previous rainfall data, we set our goal of reducing runoff from each site below the capacity of a public sewage pipe. Implementation was conducted by assessing the soil infiltration rate and developing and installing rain gardens and storage layers using crushed stones. These measures satisfied the initially set goals, drastically reducing runoff at all three sites. The target installation cost was set at 100,000 yen per cubic meter of runoff reduction. The target costs were met in the two Fukuoka sites but not at the Tokyo site. The key reasons were the high costs of removing non-permeable surfaces or improving the soil of compacted surfaces, which called for a process to balance the runoff reduction and cost to determine the most effective plan for implementing GI in urban areas. The development and implementation processes were conducted in collaboration with the house owners and concerned parties; the workshops produced constructive ideas being unconstrained by conventional thinking. Visitors highly appreciated ideas related to using water because the techniques were derived from the Japanese culture of lifestyle. Thus, introducing attractive and effective GI may be possible through collaboration. Additionally, sharing experiences led to the formation of new community ties, supporting post-implementation site maintenance.

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Study on Outflow Control Effect of on-Site Storage and Soil Improvement for Small Watershed

Cited by 5 publications

References 14 publications

Investigating the Influence of Various Stormwater Runoff Control Facilities on Runoff Control Efficiency in a Small Catchment Area

Investigating the Influence of Various Stormwater Runoff Control Facilities on Runoff Control Efficiency in a Small Catchment Area

Relationship between compaction and infiltration capacity of amended soil for urban flood damage mitigation

Collaborative Development of Green Infrastructure: Urban Flood Control Measures on Small-Scale Private Lands

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