Get this from a library! Freeboard allowances for waves in inland reservoirs. [ Thorndike Saville; Elmo W McClendon; Albert L Cochran]. Derive simple wave prediction methods for British inland reservoirs taking account of E W, & Cochran A L, () Freeboard allowances for waves in Inland. overtopping due to wind-generated waves and reservoir setup. • Relationships in “Freeboard Allowances for Waves in Inland Reservoirs.

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Determining the wave run-up height. Journal of Engineering and Technology. When a wave meets a vertical face, the part of the energy transported by the former is dissipated in the form of turbulence whereas the remaining energy is transformed into potential energy thus causing an upsurge in the water level due to wave run-up.

Freeboard Allowances for Wave in Inland Reservoirs

The significant height Hs calculated previously is defined as the average height of waves situated in the upper third. Characteristics of wave spectrum. An average depth of 30m has been retained in the ensuing calculations. Distance to the dam – reservoir and the calculation of the effective fetch. The waves generated by the wind under the hypothesis of great depth do not have the same height. In order to expose a larger part of the reservoir, we suppose that the longest stretch of water is the direction perpendicular to the dam.

These latter considerations will take into account the following different parameters.

Freeboard Allowances for Wave in Inland Reservoirs

The maximum elevation of the water level at the neighborhood of the upstream face is defined by the following formula:. The submersion of an embankment due to waves could affect its lifespan and unland is thus necessary to verify the height of the crest of the dam in a way that would protect it against a maximum increase of the water level. We consequently conclude that the crest of the structure is sufficiently high to resist any risk resulting from allowanes run-up of waves on the crest.


The latter is defined as the sum of the wind set-up S and the wave run-up R for a given wave height H.

A model of the phenomenon caused by wind. This length is called the effective fetch and denoted Fe. This increase in the height of the waves is called wave run-up. The fetch represents the distance which separates the dam from the shore where the wind is blowing.

Our article is interested in water rise due to wind set-up and wave run-up with respect to the crest of the dam. When the waves hit the upstream face of the dam, we assist in an upsurge of the water level due to the fact that the kinetic energy in the waves is transformed into potential energy.

Freeboard Allowances for Waves in Inland Reservoirs

Freebooard paper has as purpose to show the calculations done to determine the upstream freeboard the difference in height between the highest level of water upstream and the crest of the embankment for the Lom pangar dam in Cameroon.

For each of the configurations considered, the criteria for expected minimum freeboard in table 1 are respected for all the dams considered. The RCC dam — Calculation of freeboard. The objective of evaluating the freeboard is to provide needed assurance against freboard resulting from the following: Transition embankment at 1. The value of the rise in water level is calculated freeborad applying the Zuider Zee formula Fell et al.


Historically, we usually work with the significant height. The average of rise in water level is a result of the blowing of the wind.

Freeboard Allowances for Waves in Inland Reservoirs

The development objective of the Lom Pangar Hydropower Project for Cameroon is to increase hydropower generation capacity and reduce seasonal variability of water flow in the Sanaga River and to increase access to electricity [ 78 ]. H is defined as the average height of waves over the percentage of the highest waves. Freeboard would however carry out a study on the sensitivity of the speed of wind. For the continuity of our calculations we would suppose that the waves have had enough time to attain their maximum height and that the condition of the wave height supported is always verified for periods of wind superior to one hour.

Once the significant height has been calculated, it is possible to determine the frequency of occurrence for a given wave height [ 3 ]. The method used here to determine the effective fetch is based on recommendations from USACE [ 56 ].

Laterite Embankment fill at 3. The freeboard f is defined as the difference between the height of the dam freebooard and the maximum elevation attained by the waves on the upstream face of the dam. The notion of effective fetch has been introduced to take into account the following phenomena:. reserfoirs

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