scholarly journals ESTIMATION OF FLOOD CONTROL CAPABILITY OF MULTIPLE DRY DAMS CONSTRUCTED IN SERIES BASED ON CASCADE METHOD

2015 ◽  
Vol 71 (4) ◽  
pp. I_1417-I_1422
Author(s):  
Hideo OSHIKAWA ◽  
Toshimitsu KOMATSU
Keyword(s):  
Flood Control ◽  
In Series ◽  
Control Capability ◽  
Cascade Method

An Experimental Study on Flood Control Capability of Dry Dams Constructed in a Series

2015 ◽  
Vol 10 (3) ◽  
pp. 467-474 ◽  
Author(s):  
Hideo Oshikawa ◽  
◽  
Yuka Mito ◽  
Toshimitsu Komatsu ◽  
◽  
...  
Keyword(s):  
Experimental Study ◽  
Flood Control ◽  
Laboratory Experiments ◽  
Slide Gate ◽  
Reservoir Capacity ◽  
Control Effect ◽  
Flood Disasters ◽  
Control Capability ◽  
Cascade Method ◽  
Large Dam

The new Cascade concept of flood control is demonstrated in laboratory experiments in which upstream dams in a series of dams constructed along a river overflow from emergency spillways while the final downstream dam is required only to use its normal spillway and never do its emergency spillway. Multiple small dry dams lacking a slide gate in a normal spillway should be constructed in a series rather than as a single large dam to prevent flood disasters and to preserve the natural environment. Dry dams for flood control have recently been reviewed, planned, and built at sites in Japan. In this paper, we compare the Cascade method to conventional flood control in laboratory experiments conducted based on the condition that dams all have the same reservoir capacity. Results have shown that the Cascade method using multiple dry dams was considerably more effective than conventional flood control. Furthermore, the additional flood control effect of a dry dam equipped with closable and openable gate in its regular spillway was experimentally confirmed although there is no such kind of the gate on an ordinary dry dam. This new dry dam should be constructed in the river’s upper reaches away from the existing downstream storage dam needing still more its capacity for water utilization, thus ensuring the amount of water available by closing the regular spillway after the dry dam is filled to capacity. The flood control capacity of dams including the new dry dam is stronger than that of an ordinary storage dam thanks to the dry dam’s storage function.

Flood Control Mechanism of Multiple Dams Constructed in a Series Based on Cascade Method

2015 ◽  
Vol 10 (3) ◽  
pp. 475-485
Author(s):  
Hideo Oshikawa ◽  
◽  
Toshimitsu Komatsu ◽  
Keyword(s):  
Conventional Method ◽  
Flood Control ◽  
Control Mechanism ◽  
Water Discharge ◽  
High Water ◽  
Control Approach ◽  
Flood Peak ◽  
Control Concept ◽  
Control Capability ◽  
Cascade Method

Using numerical simulation, we clarified the mechanism that the flood control capability is dramatically strengthened by using multiple serial dams efficiently, based on a new flood control concept that let dams overflow through emergency spillways. Numerical analysis results for a group of dry dams were used to quantitatively evaluate this effect and to derive an empirical formula. The conventional flood control approach sets the design high water discharge of individual dams, even when dams are constructed serially, ensuring that no overflows occurs in any of the dams, here called the “conventional” method. By comparing the group of dry dams based on the conventional method and a method on the same scale but set based on a new concept that we called Cascade method, we found that when the flood peak is cut in conventional control, the latter half of the cutoff flood peak must be cut again, making flood control redundant. The Cascade method avoids this redundancy in storage use and cuts the flood peak efficiently and linearly.

scholarly journals Study of Flood Control Capability and Advanced Application of Multiple Dams Constructed in Series

2013 ◽  
Vol 8 (3) ◽  
pp. 447-455 ◽  
Author(s):  
Hideo Oshikawa ◽  
◽  
Yuka Mito ◽  
Toshimitsu Komatsu ◽  
Keyword(s):  
Flood Control ◽  
Large Scale ◽  
Control Method ◽  
Upstream Region ◽  
Small Scale ◽  
Water Utilization ◽  
In Series ◽  
New Type ◽  
Cascade Method ◽  
Cascade Type

The new concept for flood control called ‘Cascade’ method which permits dams to overflow around an upstream region with a sequence of dams constructed in a river is proposed. Multiple small scale dry dams should be constructed in series instead of a large scale dam in order to prevent flood disaster and preserve the natural environment. Recently a flood control dam with a bottom outlet hole as its regular spillway, known as ‘dry dam’, has been reviewed, planned and built in some sites in Japan. Under a condition of a common reservoir capacity, the Cascade type flood control permitting upstream dams to overflow except for the most downstream dam in a river is compared with a conventional one not to overflow each dam in a numerical simulation. As a result, it is made clear that the Cascade method using multiple dry dams is much more effective than the conventional one. In this connection, the Cascade type flood control method permitting upstream dams to overflow from emergency spillways except for the most downstream dam can be applied to normal storage dams with slide gates operated conventionally. Therefore, it could become an effective adaptation method for the global warming problem since it is performed by only changing how to operate slide gates in existing storage dams constructed in series. In addition, we also propose a new type of dry dam that has a closable and openable gate for its regular spillway primarily to retain the water for the water utilization. The new type of dry dam, which should be constructed in the upper reach away from the existing downstream storage dam needing still more its capacity for water utilization, ensures the amount of water available for the use by closing the regular spillway after the new dry dam is at full capacity, and the flood control capacity of the dams including the new dry dam is stronger than that of the normal dams owing to the storage function with the new dry dam. The new dry dams may improve the water utilization, the flood control, and environmentfriendliness under the current condition in Thailand damaged by the severe flood in 2011.

scholarly journals Correlation between LID Flood Control Capability and Runoff Coefficient

2020 ◽  
Vol 20 (5) ◽  
pp. 339-351
Author(s):  
Yonggil Jeong ◽  
Jongpyo Park ◽  
Hyunsuk Sin
Keyword(s):  
Flood Control ◽  
Low Impact Development ◽  
Qualitative Evaluation ◽  
Development Projects ◽  
Runoff Coefficient ◽  
Evaluation Procedures ◽  
Runoff Reduction ◽  
Control Capability ◽  
The Impact ◽  
The Relationship

Short-term heavy rains caused by global warming could lead to urban flooding as well as damage to both people and property. Although Korea is taking active measures to reduce the impact of flood-related disasters through disaster impact assessments, these assessments mainly consist of qualitative evaluation procedures for urban inundation when designating districts for development projects. The recently developed “inundation determination and detention site size calculation program” has made it possible to review urban inundation hydraulic calculations, even when designating districts for development projects. However, there is still a limit to the hydraulic review and the utilization of Low Impact Development (LID) facilities due to the lack of linkage between the use of such facilities and the inundation determination program. Accordingly, it is necessary to develop a technique to utilize runoff coefficients in applying the LID in the flood determination program. Therefore, in this study, the flood control capacity of stormwater runoff reduction facilities at each LID facility was reviewed and the relationship with runoff coefficient was analyzed.

scholarly journals Analysis of the specific water level of flood control and the threshold value of rainfall warning for small and medium rivers

2020 ◽  
Vol 383 ◽  
pp. 201-211
Author(s):  
Yuzhong Hu ◽  
Zhaoxia Wang ◽  
Bin Zhou ◽  
Shiqi Jiang
Keyword(s):  
Flood Control ◽  
Flash Flood ◽  
Threshold Value ◽  
Rainfall Threshold ◽  
Threshold Values ◽  
Study Region ◽  
Flood Warning ◽  
Variable Characteristic ◽  
Control Capability ◽  
The Relationship

Abstract. In order to fully use the newly-built hydrologic stations in small and medium rivers for flood warning and prevention, based on the technical line of the investigation and evaluation of flash flood disasters, different historical flood information of the warning river section was investigated, while the elevations of riverain houses were measured. The relationship between the stations and affected population has been established for the study region. According to integrated flood control capability of riverside residents, the characteristic water levers and rainfall threshold values were determined in this case. The results indicate that the warning and safety levels are 54.0 and 55.3 m, respectively. The analysis results show that the warning should be issued when the net rainfall intensity is 70 mm h−1 or 110 mm for 6 h condition. And considering the effectiveness of disaster avoidance, variable characteristic water levers of the hydrologic station for flood warning in different village were determined on the basis of the flood control capability of each village. The relationship between hydrologic numerical value and inundating influence was established in a one-to-n way.

scholarly journals Numerical Investigation of the Combined Slot Effect on the Erosion Pattern Around a Combination of Spur Dikes in Series

2021 ◽  
Author(s):  
Khosrow Hosseini ◽  
Shahab Nayyer ◽  
Mehran Kheirkhahan ◽  
Sayed-Farhad Mousavi
Keyword(s):  
Flood Control ◽  
Effective Area ◽  
The Body ◽  
Scour Depth ◽  
Spur Dike ◽  
Bed Erosion ◽  
Geometrical Shapes ◽  
In Series ◽  
Spur Dikes ◽  
The Web

Abstract Modifying the river course for flood control, prevention of bed erosion, bank protection, and the regulation of river width are among the goals of spur dikes incorporation. The common spur dikes have simple (I), L and T geometrical shapes. The present research has been conducted to reduce the scour depth in front of the spurs dikes and improve the sedimentation conditions for the LTT combination of spur dikes in series by investigating different combinations of slots in the body of the spur dike; using numerical methods. The slot dimension was taken equal to 10% of the effective area of the spur dike body. Finally, the (LS-W-Wi, TS-W, TS-W-Wi) combination contained the slots in the web and wing of the first and third spur dike also the slot at the web of the middle spur dike was found as the best combination of slots. This combination conducted to reduce the scour depth about 6.8% and increase the deposition about 52% comparing by the spurs dikes without slots. Reducing the scour depth and increasing the sedimentation rate of materials between the spurs dikes. Also, the maximum scour depth decreases up to 20%. The results revealed that the presence of slots in spur dike structures and their different positions have complicated and considerable influences on the form and morphology of the erodible bed which could be the topic for further researches.

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