proposed standard for automatic calculation of rainfall erosivity
TRANSCRIPT
Proposed Standard for Automatic Calculation of Rainfall
Erosivity
Manuel Reyes, Hiroshi Suda, Mark Brooks, and Ryan Boyles
21st Century Watershed Technology: Improving Water Quality and the Environment
EARTH University, Costa Rica February 21-24, 2010
Hiroshi SudaNorth Carolina Agricultural and Technical State University
Mark BrooksState Climate Office of North Carolina
Ryan BoylesState Climate Office of North Carolina
Proposed Standard for Automatic Calculation of Rainfall Erosivity
• Accepted for publication in the
Applied Engineering in Agriculture journal of the American Society of Agricultural and Biological
Engineers May and June 2010 issue (tentative)
Outline• Objectives• What is rainfall intensity percentage (RIP)?
• What is automatic calculation of rainfall erosivity (ACRE)?
• Methodology for web access
• Recommendation
• Discussion
Objective
• To describe how daily erosivity values are automatically calculated from the State
Climate Office of North Carolina climate stations
• To propose that this methodology be adopted as a standard method of calculating daily
rainfall erosivity
Outline• Objectives• What is rainfall intensity percentage (RIP)?
• What is automatic calculation of rainfall erosivity (ACRE)?
• Methodology for Website access
• Recommendation
• Discussion
Rainfall Intensity Percentage RIP
– Idea came from the thesis of Dr. Norman Hudson (read his thesis in Silsoe)
–Developed by Reyes (1989) as Master of Philosophy thesis in Silsoe
College,
Cranfield
University, United Kingdom
–Applied to Baton Rouge, Louisiana rainfall as a special topics problem in a
meteorology class at Louisiana State University in 1990
Published in TRANSACTIONS of the ASAE 1993
Rainfall Intensity Percentage RIP
– A measure of the intensity distribution of daily rainfall
– Quantifies the distribution of daily rainfall amount by class
RIP
• Calculated using:
where
RIPk
= rainfall intensity percentage in rainfall intensity class k
(By
)k
= rainfall amount of event y in rainfall intensity class k
P = total daily rainfall
zk
= daily number of events in class k. An event is defined as
a rainfall depth accumulated in a fixed‐time‐base interval,
and is extracted from autographic rainfall records
Example RIP CalculationSummation of 1 minute rainfall amounts into 5
minute intervals (June 3, 2009 rainfall, NCA&T weather station)
Time Rainfall Amount (mm) 5 Minute Rainfall Amount17:26 4.06417:27 2.03217:28 1.77817:29 3.55617:30 2.032 13.46217:31 1.2717:32 0.76217:33 1.2717:34 2.79417:35 2.54 8.636
Example RIP Calculation
Time5 minute
rainfall (mm)
Duration
(min)
intensity
(mm/h)
Time
(cont.)
5 minute
rainfall
(mm)
Duration
(min)
intensity
(mm/h)
16:55 ‐ ‐ ‐ 18:10 2.79 5 33.5317:00 0.51 5 6.10 18:15 0.25 5 3.0517:20 0.00 20 0.00 18:20 0.76 5 9.1417:25 2.54 5 30.48 18:25 0.76 5 9.1417:30 13.46 5 161.54 18:30 0.25 5 3.0517:35 8.64 5 103.63 18:35 4.57 5 54.8617:40 10.16 5 121.92 18:40 2.03 5 24.3817:45 8.89 5 106.68 18:45 0.25 5 3.0517:50 4.83 5 57.91 20:15 0.00 90 0.0017:55 4.57 5 54.86 20:20 0.25 5 3.0518:00 3.30 5 39.62 20:45 0.00 25 0.0018:05 4.32 5 51.82 20:50 0.25 5 3.05
Total Rain (mm)73.41
Intensity class = 0 – 20 mm/h
Time5 minute
rainfall (mm)
Duration
(min)
intensity
(mm/h)
Time
(cont.)
5 minute
rainfall
(mm)
Duration
(min)
intensity
(mm/h)
16:55 ‐ ‐ ‐ 18:10 2.79 5 33.5317:00 0.51 5 6.10 18:15 0.25 5 3.0517:20 0.00 20 0.00 18:20 0.76 5 9.1417:25 2.54 5 30.48 18:25 0.76 5 9.1417:30 13.46 5 161.54 18:30 0.25 5 3.0517:35 8.64 5 103.63 18:35 4.57 5 54.8617:40 10.16 5 121.92 18:40 2.03 5 24.3817:45 8.89 5 106.68 18:45 0.25 5 3.0517:50 4.83 5 57.91 20:15 0.00 90 0.0017:55 4.57 5 54.86 20:20 0.25 5 3.0518:00 3.30 5 39.62 20:45 0.00 25 0.0018:05 4.32 5 51.82 20:50 0.25 5 3.05
Total Rain (mm)73.41
Example RIP Calculation
Using
RIP0‐20
= * 100
RIP0‐20
= 4%
.51 + .25 + .76 + .76 + .25 + .25 + .25 + .25
73.41
Intensity class = 20 – 40 mm/h
Time5 minute
rainfall (mm)
Duration
(min)
intensity
(mm/h)
Time
(cont.)
5 minute
rainfall
(mm)
Duration
(min)
intensity
(mm/h)
16:55 ‐ ‐ ‐ 18:10 2.79 5 33.5317:00 0.51 5 6.10 18:15 0.25 5 3.0517:20 0.00 20 0.00 18:20 0.76 5 9.1417:25 2.54 5 30.48 18:25 0.76 5 9.1417:30 13.46 5 161.54 18:30 0.25 5 3.0517:35 8.64 5 103.63 18:35 4.57 5 54.8617:40 10.16 5 121.92 18:40 2.03 5 24.3817:45 8.89 5 106.68 18:45 0.25 5 3.0517:50 4.83 5 57.91 20:15 0.00 90 0.0017:55 4.57 5 54.86 20:20 0.25 5 3.0518:00 3.30 5 39.62 20:45 0.00 25 0.0018:05 4.32 5 51.82 20:50 0.25 5 3.05
Total Rain (mm)73.41
Example RIP Calculation
Using
RIP20‐40
= * 100
RIP20‐40
= 15%
2.54 + 3.30 + 2.79 + 2.03
73.41
Example RIP Calculation
By repeating this calculation we get the following table:
RIP RIP RIP RIP RIP RIP(0 ‐
20 mm/h) (20‐40 mm/h) (40 ‐60 mm/h) (60 ‐80 mm/h) (80 ‐100 mm/h) (>100 mm/h)
4% 15% 25% 0% 0% 56%
Outline• Objectives• What is rainfall intensity percentage (RIP)?
• What is automatic calculation of rainfall erosivity (ACRE)?
• Methodology for website access
• Recommendation
• Discussion
Automatic Calculation of Rainfall Erosivity
ACRE• A method of automatically calculating
erosivity using rainfall events measured by dataloggers
ACRE paper published in TRANSACTIONS of
the ASAE 1995
ACRE Erosivity Index
• The Daily Erosivity Index (DEI30
) is calculated using the
equation:
where
DEI30
= the daily erosivity index
Ed
= estimated daily rainfall kinetic energy
(I30
)d
= maximum daily 30‐minute intensity
Daily Rainfall Kinetic Energy
• The estimated daily rainfall kinetic energy is calculated using
the equation (Reyes 1989):
where
Ed
= estimated daily rainfall kinetic energy
P = total rainfall amount
UKEk
= unit kinetic energy using the mean of the RIP kth
intensity class
interval as I
RIPk
= rainfall intensity percentage in a rainfall intensity class k
Unit Kinetic Energy• Unit kinetic energy is calculated using the
equation:;
if k ≥
76 mm/h, UKEk
= 28.3 J / m2
mm
where
UKEk
= metric form of unit kinetic energy from Wischmeier
and Smith’s (1978) equation in J m‐2
mm‐1
I = rainfall intensity (mm/h)
ACRE Erosivity Index
• The Daily Erosivity Index (DEI30
) is calculated using the
equation:
where
DEI30
= the daily erosivity index
Ed
= estimated daily rainfall kinetic energy
(I30
)d
= maximum daily 30‐minute intensity
Calculating (I30
)dTime
5 Minute Rainfall
Amount (mm)
30 Minute Rainfall
Amount
30 Minute Rainfall
Intensity
16:55 0 0 017:00 0.51 0.51 1.017:05 0 0.51 1.017:10 0 0.51 1.017:15 0 0.51 1.017:20 0 0.51 1.017:25 2.5 3.0 6.117:30 13.5 16.0 32.017:35 8.6 24.6 49.317:40 10.2 34. 8 69.617:45 8.9 43.7 87.417:50 4.8 48.5 97.117:55 4.6 50.5 101.118:00 3.3 40.4 80.818:05 4.3 36.1 72.118:10 2.8 28.7 57.418:15 0.25 20.1 40.1
Calculating (I30
)dTime
5 Minute Rainfall
Amount (mm)
30 Minute Rainfall
Amount
30 Minute Rainfall
Intensity
16:55 0 0 017:00 0.51 0.51 1.017:05 0 0.51 1.017:10 0 0.51 1.017:15 0 0.51 1.017:20 0 0.51 1.017:25 2.5 3.0 6.117:30 13.5 16.0 32.017:35 8.6 24.6 49.317:40 10.2 34. 8 69.617:45 8.9 43.7 87.417:50 4.8 48.5 97.117:55 4.6 50.5 101.118:00 3.3 40.4 80.818:05 4.3 36.1 72.118:10 2.8 28.7 57.418:15 0.25 20.1 40.1
Calculating (I30
)dTime
5 Minute Rainfall
Amount (mm)
30 Minute Rainfall
Amount
30 Minute Rainfall
Intensity
16:55 0 0 017:00 0.51 0.51 1.017:05 0 0.51 1.017:10 0 0.51 1.017:15 0 0.51 1.017:20 0 0.51 1.017:25 2.5 3.0 6.117:30 13.5 16.0 32.017:35 8.6 24.6 49.317:40 10.2 34. 8 69.617:45 8.9 43.7 87.417:50 4.8 48.5 97.117:55 4.6 50.5 101.118:00 3.3 40.4 80.818:05 4.3 36.1 72.118:10 2.8 28.7 57.418:15 0.25 20.1 40.1
Example Erosivity Calculation
From the example above:
Where (I30
)d
= 101.1 mm/h and
Given P=total rainfall = 73.41mm
Example Erosivity Calculation
UKE10
= 11.9+8.7 log10
(10) = 20.6 J/ m2
mm
UKE30
= 11.9+8.7 log10
(30) = 24.8 J/ m2
mm
UKE50
= 11.9+8.7 log10
(50) = 26.7 J/ m2
mm
UKE70
= 11.9+8.7 log10
(70) = 28.0 J/ m2
mm
UKE90
= 28.3 J / m2
mm (since K ≥
76 mm/h)
UKE100
= 28.3 J / m2
mm (since K ≥
76 mm/h)
Example ACRE Erosivity Calculation
Therefore
Ed
= 73.41
= 1987 J / m2
And
DEI30
= Ed
(I30
)d
= 1987 J / m2
(101.1 mm / h)
DEI30
= 200886 J mm m‐2h‐1
20.6 J/ m2
mm(4%) + 24.8 J/ m2
mm(15%) + 26.7 J/ m2
mm(25%) + 28.3 J / m2
mm(56%)
100
Outline• Objectives• What is rainfall intensity percentage (RIP)?
• What is automatic calculation of rainfall erosivity (ACRE)?
• Methodology for Website access
• Recommendation
• Discussion
Proposed ACRE Web Accessible Method to be published in TRANSACTIONS of ASABE
Weather Stations• There are currently 14 weather stations with
daily erosivity available online (the only weather stations applying ACRE method in the world)
• Horticultural Crops Research Station (CAST)• Horticultural Crops Research Station (CLIN)• Upper Mountain Research Station (LAUR)• Lake Wheeler Rd Field Lab (LAKE)• Central Crops Research Station (CLAY)• NC A&T SU Research Farm (NCAT)• Buckland Elementary (BUCK)• NC Electric Cooperative Anson Peaking Plant (LILE)• Hamlet Tower (HAML)• Mount Mitchell State Park (MITC)• Williamsdale
Field Lab (WILD)• Taylorsville Tower (TAYL)• North Durham Water Reclamation Facility (DURH)• Burnsville Tower (BURN)
Weather station on a mountain in North Carolina
The automatic calculation of rainfall erosivity available from the State Climate Office of North Caroline is the only system of its kind on the world.
Weather Stations• There are currently 14 weather stations with
daily erosivity available online (the only weather stations applying ACRE method in the world)
• Horticultural Crops Research Station (CAST)• Horticultural Crops Research Station (CLIN)• Upper Mountain Research Station (LAUR)• Lake Wheeler Rd Field Lab (LAKE)• Central Crops Research Station (CLAY)
• NC A&T SU Research Farm (NCAT)• Buckland Elementary (BUCK)• NC Electric Cooperative Anson Peaking Plant (LILE)• Hamlet Tower (HAML)• Mount Mitchell State Park (MITC)• Williamsdale
Field Lab (WILD)• Taylorsville Tower (TAYL)• North Durham Water Reclamation Facility (DURH)• Burnsville Tower (BURN)
NC A&T Weather Station
Retrieving Data
• To retrieve the erosivity data, first go to the NC Climate Office CRONOS website
(http://www.nc‐climate.ncsu.edu/cronos)
• From here, type the name of the station you wish to view the data for, or use the four
letter code given on the previous slide
Retrieving Data
Type station name
or 4 letter code
here
Retrieving Data
• If a list of stations appears, click on the name of the desired station to navigate to its data
retrieval page
• From the data retrieval page, click on the “daily”
tab
Click here
Retrieving Data
• Immediately below the Daily tab you may select the number of days you
wish to retrieve data for.
• Scroll down to “Daily Moisture Parameters”
and click the checkbox for
daily erosivity. You may also select any other desired parameters.
Check this box
Retrieving Data
• Scroll down to the bottom of the page and click the “RETRIEVE DATA”
button
Click here to
retrieve data
Use this to change the
output format (Web
page, Excel spreadsheet,
or text file)
Retrieving Data
• If you select webpage format, the data will be given as shown below.
RIP RIP RIP RIP RIP RIP(0 ‐
20 mm/h) (20‐40 mm/h) (40 ‐60 mm/h) (60 ‐80 mm/h) (80 ‐100 mm/h) (>100 mm/h)
4% 15% 25% 0% 0% 56%
DEI30 = 200886 J mm m-2h-1(I30)d = 101.1 mm/h
Outline• Objectives• What is rainfall intensity percentage (RIP)?
• What is automatic calculation of rainfall erosivity (ACRE)?
• Methodology for web access
• Recommendation
• Discussion
Recommendation
The ACRE method of: (1) summarizing short duration rainfall intensities and (2) calculating
of daily rainfall erosivity be adopted as a standard method.
Outline• Objectives• What is rainfall intensity percentage (RIP)?
• What is automatic calculation of rainfall erosivity (ACRE)?
• Methodology for web access
• Recommendation
• Discussion and Questions
Discussion and questions
I will take notes: