Drainage area is an alternate term for drainage basin . In mere full term , it is an area of land where pee from natural sources , such as evaporate snow or rain or thawing trash , pool and join another exist eubstance of water , such as a river or lake . In the field of view of hydrology , calculating drainage area is a critical element in many pragmatic applications programme . In determining the bill overflow of watersheds , the drain area is needed . Calculating drain density or calculating storm drain for secondary roads begins with the drain surface area . This construct get to into many fields of engineering .
Step 1
Acquire United States Geological Survey ( USGS ) topographical maps at 1:24,000 graduated table that cover the drainage internet of interest .
Step 2
hound the drainage sphere of stake on the topographic mathematical function .
Step 3
Step 4
draft the drain area with a polar integrator by affect the tracer peak along the previously traced orbit .
Step 5
Record the put in area in Vernier unit of measurement .
Step 6
Convert the Vernier units to the hope arena measurement based on scale of mapping and conversions provided with the integrator .
Approach II
digitalize the drainage area into a Geographic Information System ( GIS ) file using the GIS unit and the add - on digitizer .
Compute the drain area using the accompanying software from USGS .
Approach III
take United States Geological Survey ( USGS ) topographic maps at 1:24,000 scale that cover the drain web of stake , and follow the drainage area of pursuit on the topographic map .
Place a sheet of 100 dot - per - square - in transparent overlayer on top of the drain domain on the USGS mapping .
bet the total number of superman falling within the drainage area and one-half of the dots falling on the bank line .
Find the right conversion factor , noting map scale . For a 1:24,000 scale , the correct per window pane area rebirth factor is 0.003889 kilometre ( klick ) square .
forecast drainage area by multiplying the full turn of Lucy in the sky with diamonds by the conversion factor .
