Rainfall is measured by rain gauges whose collection opening is horizontal. Therefore, roof area needs to be horizontal. You need to multiply the roof area in the video by the cosine of the roof angle (in his sketch, cos (45deg) = 0.71. If you are looking at draining your yard "swamp", multiply the roof area by two other factors: Gutter Clog Factor (my gutters are perpetually clogged, so I use 1.0); Applicability Factor (my roof has two dormers, the applicable area is the area between the two dormers, roughly half the roof, so I use 0.5). Then add the area of the yard "swamp" to be drained.
Can you please help me. My neighbor installed a wider and thicker concrete driveway to accommodate RV now Mt yard is under water because his runoff that naturally went into ground can't because of concrete. I can't do math and I want to know how much runoff I'm getting from his yard
do we need to calculate a flow rate of rainfall from wall of building. I am calculating The storm water runoff for a landscape area which is beside a building 140 meter height and 80 meter length. The wall is glass. Please advise me. Thank in advance.
You’re probably just gonna have to use a hose. Maybe dig a hole at the bottom of the hill or whatever your collections on his line it with a cheap tarp or piece of plastic and then either run one or two hoses from your house at the top of the hill or wherever the most rain typically falls or fill up a wheelbarrow and dump it. I have pretty dense clay and I legitimately have about 65% to 70% runoff during more than 2 1/2 inches of rain per hour rain events. If the rain is falling less than approximately 2 in./h it all seems to go into the ground fine. There are other ways to do this calculation like the leech field test, but I personally find the leech field test in accurate, because safer instance your house sits on 10 feet of dense clay and then somewhere between let’s say 8 feet and 30 feet underground is a large rock that is a quarter-mile wide in both directions. The water will drain out of the Leitchfield very easily and very quickly and show that you can drain a couple hundred gallons in 30 minutes and are safe to build a septic tank, but when the ground water become saturated from a local river or something else flooding, then the system will no longer work. So the leechfield test Will not differentiate between seepage along the ground water plane to the left and right or down to the depths of the earth, which imo is not a good test especially for places with rising groundwater in spring
I paused the video. However, you can also Google the NOAA website for the chart. (It's in a research paper from 1961. I wonder if they've taken into account Global Warming/Polar Vortex?)
@@danharty7517 they don’t take anything into account except individual insurance claims for flooding every 10 years. That is what drives most of the map changes. Otherwise we would have to accurately map the elevation of the United States from drones or satellites which would be difficult, Especially because rivers and large salons are nearing projects will change the natural course of water
why use the rational method? you want to calculate volume. the scs curve number gives it directly and more accurately. with the rational method you're calculating peak discharge, so by multiplying with time you're overestimating volume!!
Because homeowners and unlicensed landscape installers will often be doing these small application calcs and they don't need to be using SCS when the simple rational method will work just fine. It it overestimates, the additional factor of safety won't hurt and will offer some additional capacity when clogs inevitably occur.
Dear sir or madam, I Am a civil engineer from the United Kingdom, I am planning to undertake some work from ( 4271 N High School Road Indianapolis IN 46254 ) I am looking for the drainage guidance where I can follow design my drainage system, such as 1) Rainfall intensity 2) Rain Map 3) Guidance documents can anybody help m to send me Rainfull intensity map, please ?
3:12 You actually said "The square footage for one HALF of the roof of the house shown here is 40' x 20' '" AND you drew that dimension. Then why would the square footage be 800 sqft my bald friend? If HALF of the A frame roof that you drew is 800 sqft then the TOTAL should be 1600 sqft. COME ON! And you call yourself a doctor! You'd expect bullshit calculations like that from your nurse not you. Doctor Drainage. Step in to my office, cause you're fucking fired! And take your nurse with you!
OIC: At 4:06 he says, "this portion of the roof." The question should be, "Does the 20' length horizontal or sloped (as it is drawn)?" If it is horizontal then "this portion of the roof" would be 800 sf. If it is sloped then the question is, "what is the roof slope?"
The drawing is misleading. To be clear, the area you should care about for this task is parallel to the ground, not along the slope of the roof. So it should be calculated as horizontal width x horizontal length and the fact that it's sloped should be ignored.
I thought so, too at first. But, the entire area of the roof is exposed to and collecting rain water, regardless of the slope (excepting 90 degrees, parallel to rain fall). Now, if we wanted to figure the aerodynamic drag of the roof flying through the air, then slope would be very important. Look-out, Toto! 🙂
The roof total would be 1,600 ft², (Assuming the other half is a mirror image.) He only drew a dimensions for the half of the roof he was working with. A dimension showing both halves of the roof would be the distance between the end points of the roof & wouldn't account for the extra distance created by the slope. Since the roof on the house drawn doesn't appear to have any over hangs it makes it easy to explain. The 40' dimension would be correct, but other dimension would have been across the front of the house. That dimension would be less than the 40' you'd get from adding the 2 20' halves of the roof together. So he only showed dimension for the half of the roof he was working on. Had he measured the bottom corners of the house then taken half of that for the roof area it wouldn't have accounted for all the area of the half of the roof he was working with.
Rainfall is measured by rain gauges whose collection opening is horizontal. Therefore, roof area needs to be horizontal. You need to multiply the roof area in the video by the cosine of the roof angle (in his sketch, cos (45deg) = 0.71. If you are looking at draining your yard "swamp", multiply the roof area by two other factors: Gutter Clog Factor (my gutters are perpetually clogged, so I use 1.0); Applicability Factor (my roof has two dormers, the applicable area is the area between the two dormers, roughly half the roof, so I use 0.5). Then add the area of the yard "swamp" to be drained.
Can you please help me. My neighbor installed a wider and thicker concrete driveway to accommodate RV now Mt yard is under water because his runoff that naturally went into ground can't because of concrete. I can't do math and I want to know how much runoff I'm getting from his yard
do we need to calculate a flow rate of rainfall from wall of building. I am calculating The storm water runoff for a landscape area which is beside a building 140 meter height and 80 meter length. The wall is glass. Please advise me. Thank in advance.
You do not have to consider the wall for this type of calculation.
How to calculate rainfall vs infiltration into the soil/ground....? please tell me with example....
You’re probably just gonna have to use a hose. Maybe dig a hole at the bottom of the hill or whatever your collections on his line it with a cheap tarp or piece of plastic and then either run one or two hoses from your house at the top of the hill or wherever the most rain typically falls or fill up a wheelbarrow and dump it. I have pretty dense clay and I legitimately have about 65% to 70% runoff during more than 2 1/2 inches of rain per hour rain events. If the rain is falling less than approximately 2 in./h it all seems to go into the ground fine.
There are other ways to do this calculation like the leech field test, but I personally find the leech field test in accurate, because safer instance your house sits on 10 feet of dense clay and then somewhere between let’s say 8 feet and 30 feet underground is a large rock that is a quarter-mile wide in both directions. The water will drain out of the Leitchfield very easily and very quickly and show that you can drain a couple hundred gallons in 30 minutes and are safe to build a septic tank, but when the ground water become saturated from a local river or something else flooding, then the system will no longer work. So the leechfield test Will not differentiate between seepage along the ground water plane to the left and right or down to the depths of the earth, which imo is not a good test especially for places with rising groundwater in spring
Where to find the 100 year flood maps?
I paused the video. However, you can also Google the NOAA website for the chart. (It's in a research paper from 1961. I wonder if they've taken into account Global Warming/Polar Vortex?)
@@danharty7517 they don’t take anything into account except individual insurance claims for flooding every 10 years. That is what drives most of the map changes.
Otherwise we would have to accurately map the elevation of the United States from drones or satellites which would be difficult, Especially because rivers and large salons are nearing projects will change the natural course of water
Those rain fall tables might want to be updated for 6 to 7 inch per hour rain events
InstaBlaster
why use the rational method? you want to calculate volume. the scs curve number gives it directly and more accurately. with the rational method you're calculating peak discharge, so by multiplying with time you're overestimating volume!!
Because homeowners and unlicensed landscape installers will often be doing these small application calcs and they don't need to be using SCS when the simple rational method will work just fine. It it overestimates, the additional factor of safety won't hurt and will offer some additional capacity when clogs inevitably occur.
my brain hurts!
Victor Sp
Are you really a doctor?
So dumb, but I admit I laughed.
Dear sir or madam,
I Am a civil engineer from the United Kingdom,
I am planning to undertake some work from ( 4271 N High School Road Indianapolis IN 46254 )
I am looking for the drainage guidance where I can follow design my drainage system, such as
1) Rainfall intensity
2) Rain Map
3) Guidance documents
can anybody help m to send me Rainfull intensity map, please ?
3:12 You actually said "The square footage for one HALF of the roof of the house shown here is 40' x 20' '" AND you drew that dimension. Then why would the square footage be 800 sqft my bald friend? If HALF of the A frame roof that you drew is 800 sqft then the TOTAL should be 1600 sqft. COME ON! And you call yourself a doctor! You'd expect bullshit calculations like that from your nurse not you. Doctor Drainage.
Step in to my office, cause you're fucking fired! And take your nurse with you!
OIC:
At 4:06 he says, "this portion of the roof."
The question should be, "Does the 20' length horizontal or sloped (as it is drawn)?" If it is horizontal then "this portion of the roof" would be 800 sf. If it is sloped then the question is, "what is the roof slope?"
The drawing is misleading. To be clear, the area you should care about for this task is parallel to the ground, not along the slope of the roof. So it should be calculated as horizontal width x horizontal length and the fact that it's sloped should be ignored.
I thought so, too at first. But, the entire area of the roof is exposed to and collecting rain water, regardless of the slope (excepting 90 degrees, parallel to rain fall). Now, if we wanted to figure the aerodynamic drag of the roof flying through the air, then slope would be very important. Look-out, Toto! 🙂
The roof total would be 1,600 ft², (Assuming the other half is a mirror image.) He only drew a dimensions for the half of the roof he was working with.
A dimension showing both halves of the roof would be the distance between the end points of the roof & wouldn't account for the extra distance created by the slope. Since the roof on the house drawn doesn't appear to have any over hangs it makes it easy to explain. The 40' dimension would be correct, but other dimension would have been across the front of the house. That dimension would be less than the 40' you'd get from adding the 2 20' halves of the roof together.
So he only showed dimension for the half of the roof he was working on. Had he measured the bottom corners of the house then taken half of that for the roof area it wouldn't have accounted for all the area of the half of the roof he was working with.