HomeMy WebLinkAboutCDP 99-04; Day Residence; Hydrology Study; 2000-01-25REYNOLDS CIVIL
INC.
ENGINEERING
PLANNERS ENGINEERS SURVEYORS
1
0JI
477 LEXINGTON CIRCLE OCEANSIDE, CA 92O57 TEL: (76O) 966-1466
EMAIL: rce@nctimes.net
76O) 966-1467
INTENSITY-DURATION DESIGN CHART
TTr~T~[Tf|Ti Mii nil 11"1'
'I Equation:I = 7.44 P. D
I- = Intensity (In./Hr.)
= 6 Hr. Precipitation (In.)
D = Duration (Min.)
10 15 20
Minutes
30 40 50 1
Duration
5 6
Directions for Application:
1) From precipitation naps determine 6 hr. and
24 hr. amounts for the selected frequency.
These maps are printed in the County Hydrology
Manual (10, 50 and 100 yr. maps included in the
Design and Procedure Manual).
2) Adjust 6 hr. precipitation (if necessary) so
that it is within the range of 45% to 65% of
the 24 hr. precipitation. (Not applicable
to Desert)
3) Plot 6 hr. precipitation on the right side
of the chart.
4) Draw a line through the point parallel to the
plotted lines.
5) This line is the intensity-duration curve for
the location being analyzed.
Application Form:
0) Selected Frequency yr.
., P24=
2) Adjusted *Pg= ^1
3) t = "^ • o min.
4) I = C^^r in/hr.
^i=<
P24
in.
*Not Applicable to Desert Region
Revised 1/85 APPENDIX XI-A
RUNOFF COEFFICIENTS (RATIONAL METHOD)
LAND USE Coefficient. C
Soil Group (1)
A jj C D
Undeveloped .50 .35 .40 .45
Residential:
Rural .50 .55 .40 .45
Single Family .40 .45 .50
Multi-Units .45 .50 .60 .70
Mobile Homes (2) .45 .50 .55 .65
Commercial (2) .70 .75 .80 .35
80% Impervious
Industrial (2) .SO .85 .90
90% Impervious
NOTES:
(1) Obtain soil group from maps on file with the Department of Sanitation
and Flood Control.
(2) Where actual conditions deviate significantly from the tabulated
imperviousness values of 80% or 90%, the values given for coefficient
C, may be revised by multiplying 80% or 90% by the ratio of actual
imperviousness to the tabulated imperviousness. However, in no case
shall the final coefficient be less than 0.50. For example: Consider
commercial property on D soil group.
Actual imperviousness = 50%
Tabulated imperviousness = 80%
Revised C = £ X 0.85 = 0.55
APPENDIX IX
COUNTY OF SAN DIEGO
DEPARTMENT OF SANITATION
FLOOD CONTROL
33°
100-YEAR 8-K001 PRECIPITATION
-21U ISOPLUVIALS
PRECIPITATION III
OF 100-YEAR 6-HOUR
EMTHS Or AN lUCSI
U.S. DEPARTMEN
NATIONAL OCEANIC AND AT!
SPECIAL STUDIES BRANCH. OFFICE OF II
W^7
>SI>|IERIC ADMINISTRATION
IKOLOGY. NATIONAL WEATHER SERVICE
30' 15' 116°
Revised 1/85 APPF-NDIX XI-K
COUNTY OF SAN DIEGO
DEPARTMENT OF SANITATION
FLOOD CONTROL
33'
30'
15
100-YEAR 24-IIQlJR PRECIPITATION
-2(MSOPLUVIALS OF 100 -YEAR 24-HOUR
PRECIPITATION IN ^EMTHS OF AN INCH
U.S. DEPARTMEN
NATIONAL OCKAMC AND
SPECIAL STUDIES bKANCll. OhKICli OK II
30'
n ir
Obl'lltKIC ADMINISTRATION
UKOLOCY, NATIONAL WCATIIEK StHVlCE
30'117''•'•' in1
Revised 1/85
116-
Al'PENDIX XI-M