Fundamental Researches on the Unit Hydrograph Method and Its Application

Ishihara, Tojiro; Takasao, Takuma

doi:10.2208/jscej1949.1959.d1

Cited by 6 publications

(5 citation statements)

References 4 publications

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“…(3') is rewritten as (3") and therefore, the characteristic representation of Eq. (3") becomes ( 5 ) Eqs. (5) signifiy that on a straight characteristic line of constant slope U, as illustrated in Fig.…”

Section: Discussion On the Conventional Formulas For Storm Run-off In Sewersmentioning

confidence: 99%

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Run-Off Estimation in Storm Sewer System Using Equivalent Roughness

Sueishi

1963

Transactions of the Japan Society of Civil Engineers

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The rational method has been often used to estimate the storm water run-off in combined sewerage system. But rigorously, this method still remains unreasonable hydraulically because the motion of flow is usually not taken into account correctly. Therefore, in this paper, the fundamental factors concerning the process of calculation are revised by the method of characteristic curves introducing the equivalent roughness of drainage area. The inlet time must be taken equal with the time which is needed for the standard characteristic curve to cover the distance from the upstream end of drainage area to its downstream end and also the flowdown period with the shortest time required for the curve in sewer samely, while, especially, the former must be related to the width of the area and the equivalent roughness. When the drainage area is comparatively larger and the retardation occurs, the maximum rate of run-off decreases proportionally with the equivalent roughness, so that the run-off coefficient may better be represented by the equivalent roughness. Moreover, it was pointed out theoretically that the maximum rate of run-off could become larger value if retardation occured, according to the type of rainfall intensity curve. The characteristics of the equivalent roughness can be explained in relation to the width of drainage area and the density of sewer net, and it may become very small value in the street area in which side gutters or sewers are fully equipped, but may become larger in the suburban undeveloped district. If the sewerage system consists of circular pipes the overall equivalent roughness in the whole drainage area can be calculated approximately by only the roughness in the smallest end area and accordingly the run off analysis can be made without the assumption of pipe diameters.

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Section: Discussion On the Conventional Formulas For Storm Run-off In Sewersmentioning

confidence: 99%

“…(3") becomes ( 5 ) Eqs. (5) signifiy that on a straight characteristic line of constant slope U, as illustrated in Fig. 2, the relation, dAldt=qs, exists.…”

Section: Discussion On the Conventional Formulas For Storm Run-off In Sewersmentioning

confidence: 99%

Run-Off Estimation in Storm Sewer System Using Equivalent Roughness

Sueishi

1963

Transactions of the Japan Society of Civil Engineers

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“…The flood concentration time T given by Ishihara and Takasao (1959) As data indicating the outflow situation of a river, we know that changes in water stage for every hour are publicized on the Internet. However, since it is actually difficult to convert the water stage into the flow rate, we cannot obtain the peak outflow coefficient f. It may be possible to investigate a formula that converts the water stage into the flow rate to some degree on each river using a roughness coefficient of Manning or the like.…”

Section: Figmentioning

confidence: 99%

Experiential relationship between the farming rate of riverside land and flood concentration time factor

Kajisa

Ermolin

Masaaki

2005

Paddy Water Environ

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In order to prove a reduction function concerning flood damage according to land use, we have to compare evaluation indices, such as flood concentration times. These can be derived from the calculation of the outflows from two basins where rainfall, geology, geographical conditions, etc. are the same and only the land use is different. However, it is very difficult to obtain comparable data from large basins under the above mentioned conditions. An elaborate observation for a long period is required to obtain such data. In this paper, we aim to establish a calculation process that offers consideration factors from a viewpoint that is different from a conventional research where elaborate observation is essential. Therefore, first we use easily obtainable data of many basins, such as the information on the Internet, or data from official documents or the like, which are difficult to deal with in hydrology. Then, we obtain several evaluation indices, which are coefficients close to the flood concentration times in this paper, on each basin in which various kinds of land uses are mixed. We then perform the statistical analysis with a land use ratio. In order to use various data on several basins, we evaluate the difference in the land use ratio in the basin by using of a length of a riverside instead of an area in the basin. Moreover, since a river-mouth is at the end of the riverside and a water stage observation point is not at the river-mouth, an error arises. Although there are several problems in accuracy as mentioned above, the evaluation of the reduction function concerning the flood damage according to land use will be feasible, automatically and efficiently, if the calculation process is established.

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“…By applying the kinematic wave flow model for surface flow on mountaneous slopes, Ishihara and Takasao 1) developed the theory of surface runoff and initiated modern physically-based hydrology. In their theory, the discharge of surface flow is assumed to be expressed by the power-law funcion of the depth of the flow.…”

Section: Introductionmentioning

confidence: 99%

Kinematic Wave Flow Models for River Basin Runoff Simulation

Shiiba

Tachikawa

Ichikawa

2008

PROCEEDINGS OF HYDRAULIC ENGINEERING

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Kinematic wave flow models for simulating river basin runoff are reviewd. After the baic equations of kinematic wave flow are derived, some modified kimematic wave flows which are devised for treating surface-subsurface flow on watersheds are introduced. Then, the routing of kinematic wave flows on digital terrain models are inroduced. Finally, lumping methods of kinemtatic wave flows for watershed runoff are shown.

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Fundamental Researches on the Unit Hydrograph Method and Its Application

Cited by 6 publications

References 4 publications

Run-Off Estimation in Storm Sewer System Using Equivalent Roughness

Run-Off Estimation in Storm Sewer System Using Equivalent Roughness

Experiential relationship between the farming rate of riverside land and flood concentration time factor

Kinematic Wave Flow Models for River Basin Runoff Simulation

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