Upload
sudharsananprs
View
222
Download
0
Embed Size (px)
Citation preview
8/2/2019 Travel Time Calculation
1/21
Travel Time Calculation
Dr. T. Brikowski, Geosciences Dept., UTD
Spring 2007
Introduction
o Introduction
o Velocity Method
o Graphical Velocity Method
o Upland Velocity Method
o Sheetflow Observations
o Kinematic Wave Equationo Empirical Formulas
o SCS Lag Formula
o Kirpich Method
Runoff Curves
o SCS Runoff Curve Numbers
o Infiltration-Soil Groups
o Textural Criteria for Hydrologic Soil Groups
o Runoff Curve Numbero Part II: Runoff Curve Number
o Part III: Runoff Curve Number
o Antecedent Moisture Condition
o Antecedent Rainfall Limits
o Composite CN Curves
o Connected Impervious Area Graphical Composite CN
o Unconnected Impervious Areas
o Unconnected Impervious Area Graphical Composite CN
Bibliography
About this document ...
Introduction
http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Introduction.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Introduction.html#SECTION0001100000000000000000http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Velocity_Method.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Graphical_Velocity_Method.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Upland_Velocity_Method.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Sheetflow_Observations.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Kinematic_Wave_Equation.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Empirical_Formulas.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/SCS_Lag_Formula.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Kirpich_Method.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Runoff_Curves.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/SCS_Runoff_Curve.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Infiltration_Soil_Groups.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Textural_Criteria_Hydrologi.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Runoff_Curve_Number.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Part_II_Runoff.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Part_III_Runoff.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Antecedent_Moisture_Conditi.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Antecedent_Rainfall_Limits.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Composite_CN_Curves.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Connected_Impervious_Area.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Unconnected_Impervious_Area.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Unconnected_Impervious_Area.html#SECTION00021200000000000000000http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Bibliography.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/About_this_document.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/About_this_document.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/footnode.html#foot85http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Introduction.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Introduction.html#SECTION0001100000000000000000http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Velocity_Method.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Graphical_Velocity_Method.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Upland_Velocity_Method.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Sheetflow_Observations.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Kinematic_Wave_Equation.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Empirical_Formulas.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/SCS_Lag_Formula.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Kirpich_Method.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Runoff_Curves.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/SCS_Runoff_Curve.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Infiltration_Soil_Groups.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Textural_Criteria_Hydrologi.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Runoff_Curve_Number.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Part_II_Runoff.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Part_III_Runoff.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Antecedent_Moisture_Conditi.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Antecedent_Rainfall_Limits.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Composite_CN_Curves.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Connected_Impervious_Area.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Unconnected_Impervious_Area.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Unconnected_Impervious_Area.html#SECTION00021200000000000000000http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Bibliography.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/About_this_document.html8/2/2019 Travel Time Calculation
2/21
Flood hazard often depends on the time distribution of runoff, i.e. a given amount
of precipitation can yield a large flood over urban areas, or a minimal flood over
agricultural areas
This time distribution is characterized by estimates oftravel time, usually given as
time of concentration
Time of concentration is defined as the time required for water to travel from thefarthest point of the watershed to its outlet
Typically Manning Equation or ``Velocity Method'' are used to obtain , with
different parameters for each flow regime (sheet flow, concentrated flow, channel
and pipe flow, seesummary table)
Velocity Method
Noting that velocity = , solve for time:
Velocity is usually determined using the Manning Equation
(1)
Note that the factor of ` 1.49'' is for length measured in feet, use 1.0 for metric
length. For multiple flow segments, add up the times:
Graphical Velocity Method
for convenience assume there is a relationship between roughness and hydraulicradius , then (1) can be simplified to
(3)
then is a function of land cover (for sheet flow)
http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Watershed_Dynamics/Time_Parameter_Classificati.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Watershed_Dynamics/Time_Parameter_Classificati.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Velocity_Method.html#e-Manninghttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Watershed_Dynamics/Time_Parameter_Classificati.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Velocity_Method.html#e-Manning8/2/2019 Travel Time Calculation
3/21
by fitting to observations, lines of velocity vs. slope can be plotted for various land
covers, and used to graphically estimate velocity
this is termed the ``Upland Method'' (Fig.1), and is really just a simplification ofthe Manning Equation
Upland Velocity Method
http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Upland_Velocity_Method.html#f-uplandhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Upland_Velocity_Method.html#f-uplandhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Upland_Velocity_Method.html#f-upland8/2/2019 Travel Time Calculation
4/21
8/2/2019 Travel Time Calculation
5/21
Figure 1: Upland method, graphical velocity estimation (McCuen, 2004).
Sheetflow Observations
http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Bibliography.html#McCuen-2004http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Bibliography.html#McCuen-20048/2/2019 Travel Time Calculation
6/21
Figure 2: Raindrop impact erosion and sheetflow on bare soil (Dunne and Leopold, 1978).
Note transition to channel flow at edge of field (foreground). Other examples include USGS
Everglades Factsheet .
http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Bibliography.html#Dunne-Leopold-1978http://pubs.usgs.gov/fs/2004/3123http://pubs.usgs.gov/fs/2004/3123http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Bibliography.html#Dunne-Leopold-1978http://pubs.usgs.gov/fs/2004/3123http://pubs.usgs.gov/fs/2004/31238/2/2019 Travel Time Calculation
7/21
Kinematic Wave Equation
for sheet flow (Fig. 2) can often assume that hydraulic radius equals product of
rainfall intensity and travel time, then
substitute that into Manning Equation (1) and solve for travel time (in minutes),
using length in feet:
(4)
this equation is solved iteratively, since is needed only for the time of
concentration
note the equation assumes no local inflow (precip. is only water source), noponding or backwater effects, no storage effects, and that discharge is only a
function of depth.
These assumptions are only true for sheet-flow in the most distal parts of awatershed.
Generally it is better to use the Manning instead
Empirical Formulas
a variety of empirical formulas have been developed to predict for specific
watershed types, most are specialized forms of Manning equation
o FAA equation: developed from airfield drainage data, 1970
o Espey-Winslow equation, developed in 1974 predicting time to peak flow
for overland+channel flow, Houston area was main data source
o SCS lag formula (see next page), estimates time from center of mass of
excess rainfall to the peak discharge. (the lag time, where )
Many other methods exist, e.g.McCuen (1998, sec. 3.6.5)
in many wase these are obsolete with the advent of computers, but are important for
comparison purposes to older results
http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Sheetflow_Observations.html#f-sheet_flow_photohttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Velocity_Method.html#e-Manninghttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Bibliography.html#McCuen-1998http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Bibliography.html#McCuen-1998http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Sheetflow_Observations.html#f-sheet_flow_photohttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Velocity_Method.html#e-Manninghttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Bibliography.html#McCuen-19988/2/2019 Travel Time Calculation
8/21
SCS Lag Formula
used for small watersheds ( acres) where overland flow dominates
built into the SCS TR-55 and TR-25 urban watershed models
the formula is (where is watershed length in ft, slope , and is the SCS
runoff curve number):
(5)
Kirpich Method
One important empirical method (at least in WMS) is the Kirpich Method (Kirpich, 1940).
These are simply formulas that depend only on basin length and slope, and hencecan be calculated directly from WMS-computed basin parameters:
(6)
(7)
where is channel length in ft and is channel slope ( )
Equation (6) is for small watersheds in Pennsylvania. (7) was developed for
watersheds from 1-112 acres, slope 3-10% in Tennessee.
Computed is multiplied by 0.4 for overland flow path that are concrete or
asphalt, and by 0.2 where the channel is concrete lined
Runoff Curves
http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/SCS_Runoff_Curve.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Bibliography.html#Kirpich-1940http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Kirpich_Method.html#e-Kirpich_Penns.%23e-Kirpich_Penns.http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Kirpich_Method.html#e-Kirpich_Tenn%23e-Kirpich_Tennhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/SCS_Runoff_Curve.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Bibliography.html#Kirpich-1940http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Kirpich_Method.html#e-Kirpich_Penns.%23e-Kirpich_Penns.http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Kirpich_Method.html#e-Kirpich_Tenn%23e-Kirpich_Tenn8/2/2019 Travel Time Calculation
9/21
Subsections
SCS Runoff Curve Numbers
Infiltration-Soil Groups
Textural Criteria for Hydrologic Soil Groups
Runoff Curve Number Part II: Runoff Curve Number
Part III: Runoff Curve Number Antecedent Moisture Condition
Antecedent Rainfall Limits
Composite CN Curves
Connected Impervious Area Graphical Composite CN
Unconnected Impervious Areas
Unconnected Impervious Area Graphical Composite CN
SCS Runoff Curve Numbers
the Soil Conservation Service developed curve number ( ) as an index
combining hydrologic soil group and land use factors (cover and condition)
Soil Group (Figs. 3-4) best identified using SCS County soil conservation surveys
o really represents typical infiltration rate
o modern access usually via USGS STATSGO database, land-use data also
included
earlier applications used Curve Number tables (Figs. 5-7)
Infiltration-Soil Groups
http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/SCS_Runoff_Curve.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Infiltration_Soil_Groups.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Textural_Criteria_Hydrologi.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Runoff_Curve_Number.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Part_II_Runoff.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Part_III_Runoff.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Antecedent_Moisture_Conditi.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Antecedent_Rainfall_Limits.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Composite_CN_Curves.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Connected_Impervious_Area.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Unconnected_Impervious_Area.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Unconnected_Impervious_Area.html#SECTION00021200000000000000000http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Infiltration_Soil_Groups.html#f-soil_groups_infilthttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Textural_Criteria_Hydrologi.html#f-soil_groups_texturehttp://water.usgs.gov/GIS/metadata/usgswrd/XML/ussoils.xmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Runoff_Curve_Number.html#f-cn1http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Part_III_Runoff.html#f-cn3http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/SCS_Runoff_Curve.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Infiltration_Soil_Groups.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Textural_Criteria_Hydrologi.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Runoff_Curve_Number.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Part_II_Runoff.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Part_III_Runoff.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Antecedent_Moisture_Conditi.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Antecedent_Rainfall_Limits.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Composite_CN_Curves.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Connected_Impervious_Area.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Unconnected_Impervious_Area.htmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Unconnected_Impervious_Area.html#SECTION00021200000000000000000http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Infiltration_Soil_Groups.html#f-soil_groups_infilthttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Textural_Criteria_Hydrologi.html#f-soil_groups_texturehttp://water.usgs.gov/GIS/metadata/usgswrd/XML/ussoils.xmlhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Runoff_Curve_Number.html#f-cn1http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Part_III_Runoff.html#f-cn38/2/2019 Travel Time Calculation
10/21
Figure 3: Infiltration rate criteria for SCS Hydrologic Soil Groups (McCuen, 2004).
Textural Criteria for Hydrologic Soil
Groups
http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Bibliography.html#McCuen-2004http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Bibliography.html#McCuen-20048/2/2019 Travel Time Calculation
11/21
Figure 4: Textural Criteria for SCS Hydrologic Soil Groups (McCuen, 2004).
Runoff Curve Number
http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Bibliography.html#McCuen-2004http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Bibliography.html#McCuen-20048/2/2019 Travel Time Calculation
12/21
8/2/2019 Travel Time Calculation
13/21
Figure 5: Runoff curve numbers for typical land use types (McCuen, 2004).
Part III: Runoff Curve Number
http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Bibliography.html#McCuen-2004http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Bibliography.html#McCuen-20048/2/2019 Travel Time Calculation
14/21
Figure 7: Runoff curve numbers for typical land use types (cont.) (McCuen, 2004).
Part II: Runoff Curve Number
http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Bibliography.html#McCuen-2004http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Bibliography.html#McCuen-20048/2/2019 Travel Time Calculation
15/21
8/2/2019 Travel Time Calculation
16/21
8/2/2019 Travel Time Calculation
17/21
Figure 6: Runoff curve numbers for typical land use types (cont.) (McCuen, 2004).
GEOS 5313 Lecture Notes, Spring 2007
Dr. T. Brikowski, UTD. All rights reserved.
Antecedent Rainfall Limits
http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Bibliography.html#McCuen-2004http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Bibliography.html#McCuen-20048/2/2019 Travel Time Calculation
18/21
Figure 8: Seasonal rainfall limits (left) and CN adjustment (right) for antecedent moisture
conditions (McCuen, 2004).
Composite CN Curves
in urban areas, percent imperviousness highly variable
http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Bibliography.html#McCuen-2004http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Bibliography.html#McCuen-20048/2/2019 Travel Time Calculation
19/21
a weighted approach is used for transitional values of imperviousness not
shown in standard tables (Figs. 5-7)
can be computed mathematically, where is the fraction of impervious area, and
98 is the curve number of completely impervious material:
(8)
or use graphical method (Fig. 9)
Connected Impervious Area Graphical
Composite CN
Figure 9: Graphical computation of composite CN curves for all impervious surfacesconnected to storm drain (SCS, 1986, Fig. 2-3).
Unconnected Impervious Area Graphical
Composite CN
http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Runoff_Curve_Number.html#f-cn1http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Part_III_Runoff.html#f-cn3http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Connected_Impervious_Area.html#f-composite_CN_connectedhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Bibliography.html#SCS-TR55-1986http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Runoff_Curve_Number.html#f-cn1http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Part_III_Runoff.html#f-cn3http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Connected_Impervious_Area.html#f-composite_CN_connectedhttp://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Bibliography.html#SCS-TR55-19868/2/2019 Travel Time Calculation
20/21
Figure 10:Graphical computation of composite CN curves for impervious surfaces not connected tostorm drain (SCS, 1986, Fig. 2-4). To use, enter right half of diagram with unconnected fraction of total
impervious area (total ) and the ratio of total unconnected impervious area to total impervious area.
Then move left to the appropriate pervious CN and read down to find the composite CN.
Bibliography
T. Dunne and L. B. Leopold.
Water in Environmental Planning.W. H. Freeman, New York, 1978.
ISBN 0-7167-0079-4.Z. P. Kirpich.
Time of concentration in small agricultural watersheds.
Civil Engineering, 10 (6): 362-, 1940.
R. H. McCuen.Hydrologic Analysis and Design.
Prentice Hall, Upper Saddle River, New Jersey, 07458, 2nd edition, 1998.
ISBN 0-13-1345958-9.URLhttp://www.prenhall.com.
R. H. McCuen.Hydrologic Analysis and Design.Prentice Hall, Upper Saddle River, New Jersey, 07458, 3rd edition, 2004.
ISBN 0-13-142424-6.
URLhttp://www.prenhall.com.
SCS.
http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Bibliography.html#SCS-TR55-1986http://www.prenhall.com/http://www.prenhall.com/http://www.prenhall.com/http://www.prenhall.com/http://www.utdallas.edu/~brikowi/Teaching/Applied_Modeling/SurfaceWater/LectureNotes/Travel_Time/Bibliography.html#SCS-TR55-1986http://www.prenhall.com/http://www.prenhall.com/8/2/2019 Travel Time Calculation
21/21
Urban hydrology for small watersheds.
Technical Release TR-55, Soil Conservation Service, Hydrology Unit, June 1986.
URLhttp://www.wcc.nrcs.usda.gov/hydro/hydro-tools-models-tr55.html.
http://www.wcc.nrcs.usda.gov/hydro/hydro-tools-models-tr55.htmlhttp://www.wcc.nrcs.usda.gov/hydro/hydro-tools-models-tr55.htmlhttp://www.wcc.nrcs.usda.gov/hydro/hydro-tools-models-tr55.html