A Study on the Subsurface Runoff and Itseffects on Runoff Process

Ishihara, Tojiro; Takasao, Takuma

doi:10.2208/jscej1949.1962.79_15

Cited by 9 publications

(2 citation statements)

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“…are derived, and also the relationship between the sectinoal area of flow A, mean velocity U and rate of flow Q becomes (11) Here, an, denotes the correction factor of momentum, h the water depth, g the gravity acceleration, is the Manning's coefficient of roughness of sewer, R the hydraulic radius of sewer, and e is (RIA)1(dRIdA). Calculation of run-off at the lower end of the reach will be made as was described concerning the rational method, but the equation of the characteristic curves in Eqs.…”

Section: (•@ 5'•@)mentioning

confidence: 99%

“…The theoretical basis is the approximate analytical method using the characteristic curves derived by Dr. Iwagaki 7),8), and modifying this method for the run off analysis of mountain district the author already published the practical procedure in which the concept of equivalent roughness of equivalent drainage basin and logarithmic representation of the standard characteristic curves were introduced 9). Subsequently, many researchers studied the factors on above mentioned procedure in relation with the various basin characteristics 10), 11) In the present investigation, several discussions are made on the usual formulas for storm run off calculation in sewers, then so-called rational method is intended to revise using above mentioned procedure, which is considered more profitable for the artificial street area, especially, it is emphasized to clarify the hydraulic significances of several important factors, inlet time, flow-down period, run-off coefficient, rainfall duration.…”

Section: Introductionmentioning

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: (•@ 5'•@)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%