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Purpose 1:
Derive coefficients for depth-duration-frequency curves from NOAA rainfall DDF data.

Purpose 2:
Use Atlas-14 DDF csv file to generate hyetographs.

Purpose 3:
Apply the curves to generate DDF, IDF and Hyetographs. These data can be used as input for hydrologic modeling softwares.

Steps:
1)	Depth-durtion data is available from dropdown list for many locations.
	Select one location to load data in text area 1.
	
	The data is in this format:
		Location Name
		yr, minutes, inch
		1, 5, .2
		1, 10, .4
		...
		5,5,.4
		5,10,.6
		5,15,.92
		...	
		5,28800,6.96
		5,43200,8.29
		5,64800,10.29

		This data can also be manually typed in.

2)	Click Coefficients button to perform logarithmic interpolation.
	This will give coefficients for DDF curve in the text area 2, like this: 
		yr, a0, a1
		1, 0.069278, 0.485421
		2, 0.081271, 0.488593
		5, 0.097149, 0.492840
		10, 0.109819, 0.496441
		25, 0.126893, 0.501882
		50, 0.140274, 0.505681
		100, 0.153617, 0.509930

	Where a0 and a1 are the coefficients for year yr
	in the equation:
		inch = a0 x (minutes ^ a1)

3)	Click Table.
	Each table contains 3 columns showing DDF, IDF and Hyetograph.
	You can adjust timesteps, duration, advancement coefficient and decimals.
	Rainfall Advancement Coefficient allows temporally position the maximum intensity of the hyetograph. 


4) Click Charts to plot data from the tables.

==============================================================================

For advanced usage, if there is no pre-loaded data available:

Method (A)

- Open NOAA site
- NOAA Site	http://hdsc.nws.noaa.gov/hdsc/pfds
	- Select raingauge site on map
	- Load data table
	- Download csv data using the dropdown and Submit button at the bottom of the table.  
		It says  "Estimates from the table in csv format. 
	- Save the csv file.

- Load this csv file into text area.
- Use browse or copy/paste it directly.
- Press Re-format button.
  It will output the tabular data in a different format.

Now continue to step (2) above.


Method (B) Obsolete
-	Get data from NOAA
		Open NOAA table from
		http://hdsc.nws.noaa.gov/hdsc/pfds

	-	Open firebug
	-	Load jquery using firebug
	-	Run script found in
			noaa_reader.js
			Copy the output data


			Output should be like

				yr, minutes, inch
				1, 5, .2
				1, 10, .4
				...
				5,5,.4
				5,10,.6
				5,15,.9

	-	Paste it into textarea 1


Notes
1)	Durations more than 24 hours are excluded from logarithmic interpolation.


Reference:
Rojiani, Programming in C, Chapter on Linear Regression, p924
Chow, V. T., Applied Hydrology, Alternate Block Method

Jun 2016 B. Shrestha 
Updated 2018 B. Shrestha


Sample NOAA file:

Point precipitation frequency estimates (inches)
NOAA Atlas 14 Volume 1 Version 5
Data type: Precipitation depth
Time series type: Partial duration
Project area: Southwest
Location name (ESRI Maps): Logan, Utah, USA
Station Name: LOGAN UTAH STATE UNIV
Latitude: 41.7456
Longitude: -111.8033
Elevation (USGS): 4790 ft


PRECIPITATION FREQUENCY ESTIMATES
by duration for ARI (years):, 1,2,5,10,25,50,100,200,500,1000
5-min:, 0.107,0.135,0.187,0.233,0.305,0.368,0.442,0.525,0.661,0.778
10-min:, 0.163,0.206,0.285,0.354,0.464,0.560,0.673,0.799,1.01,1.19
15-min:, 0.202,0.256,0.353,0.439,0.575,0.693,0.834,0.991,1.25,1.47
30-min:, 0.272,0.344,0.476,0.591,0.773,0.933,1.12,1.33,1.68,1.98
60-min:, 0.337,0.426,0.589,0.732,0.957,1.16,1.39,1.65,2.08,2.45
2-hr:, 0.447,0.559,0.736,0.897,1.14,1.37,1.61,1.90,2.35,2.75
3-hr:, 0.527,0.660,0.837,1.00,1.26,1.48,1.72,2.00,2.43,2.81
6-hr:, 0.722,0.898,1.12,1.32,1.61,1.85,2.12,2.41,2.85,3.23
12-hr:, 0.970,1.21,1.48,1.72,2.07,2.34,2.64,2.95,3.40,3.76
24-hr:, 1.26,1.55,1.89,2.17,2.57,2.89,3.22,3.56,4.04,4.41
2-day:, 1.47,1.81,2.19,2.52,2.97,3.33,3.71,4.10,4.65,5.08
3-day:, 1.62,1.99,2.42,2.78,3.28,3.67,4.09,4.53,5.12,5.60
4-day:, 1.77,2.17,2.64,3.03,3.59,4.02,4.48,4.96,5.60,6.12
7-day:, 2.14,2.64,3.22,3.70,4.37,4.89,5.43,6.00,6.77,7.37
10-day:, 2.43,3.00,3.66,4.19,4.92,5.48,6.07,6.66,7.46,8.08
20-day:, 3.19,3.94,4.74,5.37,6.19,6.81,7.43,8.03,8.81,9.39
30-day:, 3.89,4.79,5.74,6.50,7.51,8.27,9.03,9.78,10.8,11.5
45-day:, 4.85,5.96,7.08,7.93,9.04,9.84,10.6,11.4,12.3,13.0
60-day:, 5.75,7.06,8.31,9.26,10.4,11.3,12.1,12.9,13.8,14.5

Date/time (GMT):  Mon Aug 27 03:00:22 2018
pyRunTime:  0.101181030273