Dry weather or dry season, normally creates a crust on river beds and wet winters would increase the discharge. The results of hydrograph readings would determine the design of a storm drainage

In analyzing the graphs above, we could say that the height of rise of water in the river was faster that when the water subsided. A sudden rise of water in rivers occurs after a rainstorm. This is the time when there is accumulation of water in the river. Another incidence of a sudden rise of water in rivers is when there is a down pour of rain upstream. It may not fall on the exact location of the rise in water height, it could come from the accumulation of water somewhere in the upstream of the river.

In the study done in Cynon river, there was a steady flow of water on the first 42 hours. At the start of the 43rd hour, water began to rise. The rise of water in a hydrograph is called the rising limb. The water reached its peak flow at its52nd hour. The time of the peak flow is known to be the basin lag time. As the water starts to fall down, the term given to the falling down of the height of water is recession limb. After the falling down of water discharge, the water height starts to normalize. The storm flow is called the total of the overland flow, and the through flow. The overland flow, is the flow at which the water rises above the through flow and the through is termed as the water that rises above the base flow.

In the computations of the design of the open channel and the river, or the water source for a reservoir. or a water impounding area, there are factors or conditions to be taken into account. First, we must set conditions for the design criteria. Next, the elevation where the pump is to be placed or would it be feasible to have the pump in that certain location. If a pump is needed, how much force will the pump require in order to draw water from a river to a location higher that the river elevation.

Computations of the Channel design

With the given data below, it is required that we get the value of breadth b of an open channel using the Manning's Formula. After we achieve the value for the depth, it is also stated that we solve for the value of the width of the river where in, the river is the proposed water source of a nearby reservoir

Given Data

Q = 1.0 m3/s

n = 0.020

S = 1/3000 = 0.0003

d = 0.5

Formula to be used

V = where: v = velocity

Q = Av R = Hydraulic Radius

Q = A S = slope

A = bd n = Manning's coefficient

R = Q = discharge

Solutions to the required unknown

A = db

= 0.5(b)

Q = A

R =

1.0 = 0.5b

1.0(0.020) = 0.5b

0.0200 = 0.5b

= 0.5

1.1695 = 0.5

=

2.339 =

(2.339)3 = b3

12.7964 =

12.7964 =

12.7964(1.0 + 2b + b2) = 0.25b5

12.7964 + 25.5928b + 12.7964b2 = 0.25b5

12.7964 + 25.5
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