Breadth - Water Resources Flashcards
if pressure is measured from a vaccuum then what type of pressure is it?
absolute pressure
if pressure is measured from a gage then what type of pressure is it?
gage
how do you convert ftsq per sec to gpm?
multiple fps by 449
what is the equation for pressure head?
pressure / gamma
if you have a pump in a bernoulli’s equation problem what side of the equation should it go on?
the left side
if you have a turbine, valve loss, or friction losses, where should it go in the bernoulli’s equation?
it should be added to the right side of the equation
what is another name for the bernoulli’s equation?
energy grade line
what is the HGL?
it is the hydraUlic grade line and it depicts potential energy plus pressure head
how do you convert MGD to cfs?
you must multiply MGD by 1.55
how can you calculate friction losses?
you can use the darcy weishback or hazen williams equation
what does it mean to have turbulent flow?
it means that the velocity are so great that it cannot dampen out disturbances caused by surface roughness
what is laminar flow?
its a smooth flow in water with a relatively low velocity. surface area ofd the pipe is probably smooth as well
what are the steps to solving a darcy-weisbach problem?
first calculate velocity, then determine the reynold’s number and the flow type, then plug into equation and solve
can you convert head loss to pressure drop? if so what is the conversion?
yes you can. divide your head by 2.31 to get psi
1 psi = 2.31 ft
when calculating head loss in pipes what is important to remember?
always include the exit and entrance values when finding the minor head losses
when froude’s number is 1, what does that mean?
it means that the flow is critical and unstable
what is a hyteograph?
a hyteograph measures the rainfall intensity during a period of time
when using the average method in hydrology what is important to remember about the 1/n value?
n is equal to number of gauges minus the number of missing readings
what is IDF?
it is a curve that gives the duration and the intensity of a storm
what is a storm frequency?
it determines the probability of a certain storm occuring or not occuring
what is the reliability formula for rain storms?
reliability is the event of recurrence of it NOT occurring in N years
P(f) = (1/1/F)^n
what is effective rainfall?
effective rainfall is total rainfall - losses. aka the portion of rainfall that is available as overland supply
what is a hydrograph?
it is a graph showing runoff with respect to time for a given rainfall event
how do you find the direct runoff using the graph?
you need to find the area of the triangle so bh(1/2)
what is a unit hydrograph?
its a hydrograph of direct runoff observed due to 1 unit or 1 inch. values cannot exceed 1 in either
what does a higher curve number mean?
a higher curve number means more runoff per unit of rainfall
what is the abstraction/retention value S?
it is the maximum depth of water that can infiltrate under existing conditions
what is time of concentration?
its the amount of time it takes a particle of water to travel to the outflow location
what is the hydraulic path?
it is the most remote path that a water drop can travel
what is a shallow concentrated flow?
its a small rivulets of different flows
why does urbanization increase discharge?
urbanization has an increase in pavement which in turn increases flow, and theres nothing to absorb or reduce the flow such as soils and other natural materials
what is the purpose of stormwater management?
control peak rate of runoff, control the volume of runoff, improve water quality, decrease downstream channel erosion, and promote the recharge of stormwater
how do you determine the detention storage volume?
Vin - Vout
determine the water being detained from the water shed. find the surface area of the detention basin and subtract from there
direct runoff hydrograph is the result of what?
rainfall excess
when dealing with a bernoulli’s equation problem with a free flow jet at the end what value can be assumed as 0?
pressure is assumed to be 0. not velocity
what is the average water consumption a day?
100-125 gpcd. for problems use the maximum which is 125 gpcd
is a rushing erosion a stormwater erosion classification?
no it is not
what can reduce the chances of cavitation happening in pipes?
lowering the pump elevation and increasing the suction diameter
