Transcript RainExcess1.ppt

Rainfall Excess Method
For
Deranged Networks
With
Depressions
Harry Downing
SWFWMD
July 19, 2007
Surface Runoff Networks
Current Method of Rainfall Excess
Determination
NRCS Method TR-55
And
National Engineering Handbook-4
Curve Number Method
Soil and Land Cover Overlay with Table LU
Soils
Hydrologic
Group
Land Cover
Table
Catchments'
CN - DCIA
CN Formula
• S=1000/CN – 10
• Q=(P-Ia)2/(P-Ia+S);
• S = maximum potential retention
• P = the cumulated storm rainfall depth
• Ia = initial abstraction, where Ia = 0.2*S
Definition of Hydrologic Soil Groupings
• Group A – Low runoff potential when thoroughly wet, 90% or greater
sand or gravel and less than 10% clays, saturated hydraulic
conductivities for all soil layers exceed 5.67 inches/hour, depth to
impermeable layer greater than 20 inches, and depth to water table
greater than 24 inches from surface.
• Group B – Moderately low runoff; 10-20% clays can have 50-90
percent sands, with loamy sand or sandy loam textures; saturated
hydraulic conductivities range between 1.42 and 5.67 inches/hour;
depth to impermeable layer greater than 20 inches, and depth to
water table greater than 24 inches from surface.
• Group C – Moderately high runoff potential, 20-40% clays with less
than 50 percent sands with loam and silt loams, saturated hydraulic
conductivities range between 0.14 and 1.42 inches/hour, depth to
impermeable layer greater than 20 inches, and depth to water table
greater than 24-inches.
• Group D – High runoff potential, have greater than 40% clays and
less than 50% sands, depth to impermeable layer less than 20
inches, and water table within 24 inches of the surface. Higher
organic content.
Need for Alternative Method
 Florida watersheds were not considered in the analysis that
produced the CN array.
 The SCS methodology excludes time as a variable, and therefore
rainfall intensity.
 Limited comparisons elsewhere have suggested significant
departures between handbook and data-defined CNs. In addition,
the primary reference for the CN method, NEH-4 suggest that the
soils-based table values are but guides, and that local values should
be used if possible.
• The CN procedure does not work well in karst topography areas.
This is because a large portion of the flow is subsurface rather than
direct runoff.
• Typically runoff generated from CN procedures do not match rainfallrunoff data for local watersheds, and the 0.2S for initial abstraction
(Ia) was not corroborated by linear regression techniques.
Runoff Process and Soil
Characterization
Types of Rainfall Excess
• Infiltration excess overland flow-This occurs when the rate of
rainfall on a surface exceeds the rate at which water can infiltrate
the ground, and any depression storage has already been filled.
This is called infiltration excess overland flow, Hortonian overland
flow (after Robert E. Horton), or unsaturated overland flow.
• Saturation excess overland flow-When the soil is saturated and
the depression storage filled, and rain continues to fall, the rainfall
will immediately produce surface runoff. The level of antecedent soil
moisture is one factor affecting the time until soil becomes
saturated. This runoff is saturation excess overland flow or
saturated overland flow (after Thomas R. Dunne).
• Subsurface return flow-After water infiltrates the soil on an upslope portion of a hill, the water may flow laterally through the soil,
and exfiltrate (flow out of the soil) closer to a channel. This is called
subsurface return flow or interflow.
Simple Soil Properties
Silt Loam
5%
Vs Solids
29%
47%
Va Air
Vm Water
Organic Matter
19%
Characterization Soil Infiltration and Runoff Excess
• Infiltration is a function:
 Soil Suction (ψ) = attraction of water to soil particles through electrostatic
forces between the polar bonds of water and the particle surfaces
 Gravity (z)
 Soil Hydraulic Conductivity (K)
• One-Dimensional Richard’s Equation:
 ∂θ/∂t = ∂/∂z (K dΨ/dθ ∂θ/∂z + K)
• Horton’s Equation: f(t) = fc + (f 0 - f c) e –kt
• Green and Ampt Method:
• f(t) = K(Ψ∆θ / F(t) + 1); infiltration rate
• F(t) = Kt + Ψ∆θ ln (1+F(t)/ Ψ∆θ ); amount infiltrated - solved by
successive substitution, etc.
Infiltration into Soil Column for Green-Ampt Model
Wet Soil
Advantages of the Green-Ampt Method
• Parameters Based Upon Published Soil Properties
Provided by the NRCS and IFAS
• Allows Direct Comparison of Rainfall Intensities to Soil
Infiltration Capacity on a Real Time Basis
• Allows Comparison of Cumulative Rainfall Infiltrated to
Estimated Soil Storage Above Water Table
• Applies to Most Soil Types and Conditions (Multi-Layer)
Soil Parameters
• NRCS - ‘Soil Survey’ and Soil Survey Geographical (SSURGO)
Database
• IFAS - ‘Site Specific Soil Characterization’
• Site Specific Characteristics from ERP Applications
• Table Information from Other Studies (Text Books)
ERP Information
Reference Information
NRCS Soil Water Table Depths (Feet) - SSURGO
NUM
MUNAME
HYD
TEX
WTL
WTH
1
ARREDONDO FINE SAND/0 TO 5 PERCENT SLOPES
A
2
ARREDONDO FINE SAND/5 TO 8 PERCENT SLOPES
3
ACRES
FS
6
6
15,706.63
A
FS
6
6
2,385.86
ASTATULA FINE SAND/0 TO 8 PERCENT SLOPES
A
FS
6
6
865.46
4
CANDLER FINE SAND/0 TO 5 PERCENT SLOPES
A
FS
6
6
87,802.46
5
CANDLER FINE SAND/5 TO 8 PERCENT SLOPES
A
FS
6
6
12,988.30
6
CANDLER-URBAN LAND COMPLEX
A
FS
6
6
1,430.45
7
KENDRICK FINE SAND/0 TO 5 PERCENT SLOPES
A
FS
6
6
8,537.66
8
LAKE FINE SAND/0 TO 5 PERCENT SLOPES
A
FS
6
6
5,931.11
9
MASARYK VERY FINE SAND/0 TO 5 PERCENT SLOPES
A
VFS
3.5
6
4,653.66
10
PAOLA FINE SAND/0 TO 8 PERCENT SLOPES
A
FS
6
6
3,043.09
11
QUARTZIPSAMMENTS/SHAPED/0 TO 5 PERCENT
A
FS
2
8
260.50
12
TAVARES FINE SAND/0 TO 5 PERCENT SLOPES
A
FS
3.5
6
5,984.23
149,589.41
NRCS Soil Water Table Depths (Feet) - SSURGO
NUM
MUNAME
HYD
TEX
WTL
WTH
ACRES
24
ADAMSVILLE FINE SAND
C
FS
2
3.5
285.06
25
ARENTS-URBAN LAND COMPLEX
C
GR-S
2
3
566.66
26
ARIPEKA FINE SAND
C
FS
1.5
2.5
1,005.96
27
ARIPEKA-OKEELANTA-LAUDERHILL ASSOCIATION
C
FS
1.5
2.5
13,847.89
28
ELECTRA VARIANT FINE SAND/0 TO 5 PERCENT SLOPES
C
FS
1.5
2.5
1,150.16
29
MICANOPY LOAMY FINE SAND/0 TO 2 PERCENT SLOPES
C
LFS
1.5
2.5
1,365.41
30
MICANOPY LOAMY FINE SAND/2 TO 5 PERCENT SLOPES
C
LFS
1.5
2.5
7,931.00
31
NOBLETON FINE SAND/0 TO 5 PERCENT SLOPES
C
FS
1.5
3.5
16,387.16
32
PITS
C
VAR
0
0
729.87
33
PITS-DUMPS COMPLEX
C
VAR
6
6
7,241.45
34
POMELLO FINE SAND/0 TO 5 PERCENT SLOPES
C
FS
2
3.5
1,253.92
35
SPARR FINE SAND/0 TO 5 PERCENT SLOPES
C
FS
1.5
3.5
11,688.53
36
SPARR FINE SAND/5 TO 8 PERCENT SLOPES
C
FS
1.5
3.5
1,625.19
37
UDALFIC ARENTS-URBAN LAND COMPLEX
C
GR-S
2
3
882.88
38
WILLISTON LOAMY FINE SAND/2 TO 5 PERCENT SLOPES
C
LFS
6
6
754.83
39
WILLISTON VARIANT LOAMY FINE SAND/0 TO 5 PERCENT SLOPES
C
LFS
6
6
1,097.78
67,813.74
NRCS Soil Water Table Depths (Feet) - SSURGO
NUM
MUNAME
HYD
TEX
WTL
WTH
13
BASINGER FINE SAND
B/D
14
EAUGALLIE FINE SAND
15
ACRES
FS
0
1
1,940.06
B/D
FS
0.5
1.5
4,118.45
FLORIDANA VARIANT LOAMY FINE SAND
B/D
FS
0
0
2,423.08
16
KANAPAHA FINE SAND
B/D
FS
0.5
1.5
962.82
17
MYAKKA FINE SAND
B/D
FS
0.5
1.5
6,506.61
18
OKEELANTA-TERRA CEIA ASSOCIATION
B/D
MUCK
0
0
12,629.23
19
PINEDA FINE SAND
B/D
FS
0
1
234.51
20
POMPANO FINE SAND
B/D
FS
0
0.5
308.34
21
SAMSULA MUCK
B/D
MUCK
0
0
303.60
22
WABASSO FINE SAND
B/D
FS
0.5
1.5
3,205.08
23
WAUCHULA FINE SAND/0 TO 5 PERCENT SLOPES
B/D
FS
0.5
1.5
6,786.90
39,418.68
NRCS Soil Water Table Depths (Feet) - SSURGO
NUM
WT
L
WT
H
MUNAME
HYD
TEX
ACRES
40
ANCLOTE FINE SAND
D
FS
0
0
1,318.59
41
BASINGER FINE SAND/DEPRESSIONAL
D
FS
0
0
5,239.56
42
BLICHTON LOAMY FINE SAND/0 TO 2 PERCENT SLOPES
D
LFS
0.5
1.5
1,751.05
43
BLICHTON LOAMY FINE SAND/2 TO 5 PERCENT SLOPES
D
LFS
0.5
1.5
9,453.58
44
BLICHTON LOAMY FINE SAND/5 TO 8 PERCENT SLOPES
D
LFS
0.5
1.5
2,206.65
45
DELRAY FINE SAND/DEPRESSIONAL
D
FS
0
0
1,428.72
46
FLEMINGTON FINE SANDY LOAM/0 TO 2 PERCENT SLOPES
D
FSL
1
1.5
1,328.54
47
FLEMINGTON FINE SANDY LOAM/2 TO 5 PERCENT SLOPES
D
FSL
1
1.5
7,854.58
48
FLEMINGTON FINE SANDY LOAM/8 TO 12 PERCENT SLOPES
D
FSL
1
1.5
715.37
49
FLORIDANA FINE SAND
D
FS
0
0
2,955.54
50
FLORIDANA-BASINGER ASSOCIATION/OCCASIONALLY FLOODED
D
FS
0
0.5
777.19
51
HOMOSASSA MUCKY FINE SANDY LOAM
D
MK-FSL
0
0.5
4,118.29
52
HYDRAQUENTS
D
SIC
0
0
3,103.15
53
LACOOCHEE FINE SANDY LOAM
D
FSL
0
0.5
1,328.94
54
PAISLEY FINE SAND
D
FS
1
1.5
2,498.40
55
WEEKIWACHEE MUCK
D
MUCK
0
0.5
3,475.76
56
WEEKIWACHEE-HOMOSASSA ASSOCIATION
D
MUCK
0
0.5
937.86
57
WATER
W
0
0
4,462.84
58
WATER
W
0
0
10.79
54,965.41
NRCS Soil Hydraulic Permeability (In/Hr) – Soil Survey
MUNAME
HYD
LP1
HP1
LP2
HP2
LP3
HP3
ARREDONDO FINE SAND/0 TO 5 PERCENT SLOPES
A
6
20
2
6
0.6
6
ARREDONDO FINE SAND/5 TO 8 PERCENT SLOPES
A
6
20
2
6
0.6
6
ASTATULA FINE SAND/0 TO 8 PERCENT SLOPES
A
20
20
CANDLER FINE SAND/0 TO 5 PERCENT SLOPES
A
20
20
6
20
CANDLER FINE SAND/5 TO 8 PERCENT SLOPES
A
20
20
6
20
CANDLER-URBAN LAND COMPLEX
A
20
20
6
20
KENDRICK FINE SAND/0 TO 5 PERCENT SLOPES
A
6
20
0.6
2
0.6
2
LAKE FINE SAND/0 TO 5 PERCENT SLOPES
A
6
20
MASARYK VERY FINE SAND/0 TO 5 PERCENT SLOPES
A
6
20
0.2
2
PAOLA FINE SAND/0 TO 8 PERCENT SLOPES
A
20
20
20
20
QUARTZIPSAMMENTS/SHAPED/0 TO 5 PERCENT
A
20
20
TAVARES FINE SAND/0 TO 5 PERCENT SLOPES
A
20
20
LP4
0.6
HP4
2
LP5
HP5
NRCS Soil Hydraulic Permeability (In/Hr) – Soil Survey
MUNAME
HYD
LP1
HP1
LP2
HP2
ADAMSVILLE FINE SAND
C
6
20
6
20
ARENTS-URBAN LAND COMPLEX
C
0.1
2
0.6
2
ARIPEKA FINE SAND
C
6
20
2
6
ARIPEKA-OKEELANTA-LAUDERHILL ASSOCIATION
C
6
20
2
6
ELECTRA VARIANT FINE SAND/0 TO 5 PERCENT
SLOPES
C
6
20
0.6
MICANOPY LOAMY FINE SAND/0 TO 2 PERCENT SLOPES
C
6
20
MICANOPY LOAMY FINE SAND/2 TO 5 PERCENT SLOPES
C
6
NOBLETON FINE SAND/0 TO 5 PERCENT SLOPES
C
PITS
C
PITS-DUMPS COMPLEX
C
POMELLO FINE SAND/0 TO 5 PERCENT SLOPES
LP3
HP3
2
6
2
6
20
0.6
2
0.1
0.2
20
0.6
2
0.1
0.2
6
20
0.2
2
0.2
0.6
C
20
20
2
6
6
20
SPARR FINE SAND/0 TO 5 PERCENT SLOPES
C
6
20
0.6
2
0.6
2
SPARR FINE SAND/5 TO 8 PERCENT SLOPES
C
6
20
0.6
2
0.6
2
UDALFIC ARENTS-URBAN LAND COMPLEX
C
0.1
2
2
6
0.6
2
WILLISTON LOAMY FINE SAND/2 TO 5 PERCENT SLOPES
C
6
20
0.6
2
0.2
0.6
WILLISTON VARIANT LOAMY FINE SAND/0 TO 5
PERCENT SLOPES
C
6
20
0.2
0.6
LP4
HP4
LP5
HP5
0.6
6
6
20
0.2
2
0.2
6
NRCS Soil Hydraulic Permeability (In/Hr) – Soil Survey
MUNAME
HYD
LP1
HP1
LP2
HP2
LP3
HP3
LP4
HP4
LP5
BASINGER FINE SAND
B/D
20
20
EAUGALLIE FINE SAND
B/D
6
20
0.6
6
6
20
0.6
6
FLORIDANA VARIANT LOAMY FINE SAND
B/D
6
20
6
20
0.6
6
2
6
KANAPAHA FINE SAND
B/D
6
20
0.6
2
0.2
0.6
MYAKKA FINE SAND
B/D
6
20
0.6
6
6
20
OKEELANTA-TERRA CEIA ASSOCIATION
B/D
6
20
6
20
6
20
PINEDA FINE SAND
B/D
6
20
2
6
POMPANO FINE SAND
B/D
20
20
SAMSULA MUCK
B/D
6
20
6
20
WABASSO FINE SAND
B/D
6
20
0.6
2
6
20
0.6
2
WAUCHULA FINE SAND/0 TO 5 PERCENT
SLOPES
B/D
6
20
6
20
0.6
6
6
20
HP5
0.1
0.2
0.6
6
NRCS Soil Hydraulic Permeability (In/Hr)
MUNAME
HYD
LP1
HP1
ANCLOTE FINE SAND
D
6
20
BASINGER FINE SAND/DEPRESSIONAL
D
20
20
BLICHTON LOAMY FINE SAND/0 TO 2 PERCENT
SLOPES
D
6
BLICHTON LOAMY FINE SAND/2 TO 5 PERCENT
SLOPES
D
BLICHTON LOAMY FINE SAND/5 TO 8 PERCENT
SLOPES
LP2
HP2
LP3
HP3
LP4
HP4
6
20
20
2
6
0.6
2
0.2
0.6
6
20
2
6
0.6
2
0.2
0.6
D
6
20
2
6
0.6
2
0.2
0.6
DELRAY FINE SAND/DEPRESSIONAL
D
6
20
6
20
0.6
6
FLEMINGTON FINE SANDY LOAM/0 TO 2 PERCENT
SLOPES
D
2
20
0.1
0.1
0.1
0.1
0.1
0.1
FLEMINGTON FINE SANDY LOAM/2 TO 5 PERCENT
SLOPES
D
2
20
0.1
0.1
0.1
0.1
0.1
0.1
FLEMINGTON FINE SANDY LOAM/8 TO 12 PERCENT
SLOPES
D
2
20
0.1
0.1
0.1
0.1
0.1
0.1
FLORIDANA FINE SAND
D
6
20
6
20
0.6
2
FLORIDANA-BASINGER ASSOCIATION/OCCASIONALLY
FLOODED
D
6
20
6
20
0.6
2
HOMOSASSA MUCKY FINE SANDY LOAM
D
2
20
2
20
2
20
HYDRAQUENTS
D
0.1
0.1
LACOOCHEE FINE SANDY LOAM
D
0.6
2
2
6
PAISLEY FINE SAND
D
6
20
0.1
0.2
WEEKIWACHEE MUCK
D
2
6
2
6
WEEKIWACHEE-HOMOSASSA ASSOCIATION
D
2
6
2
6
LP5
HP5
Determination of Soil Storage
Soil Moisture Curve for Each Horizon (Gravity Water)
Depth Above Water Table
Land Surface
Each Horizon
Water Table
Moisture Content Percent
Height Above Water Table Centimeters
Soil Moisture for 200 cm Depth to WT
Soil Moisture
Saturation / Soil Porosity
Soil Moisture Content %
Soil Storage in Inches
Soil Storage vs. Depth to WT
Depth to WT Feet
Determination of Hydraulic Conductivity (K)
Divide by 2
Proposed Procedure
1.
Soil Parameterization (Green–Ampt)
•
•
•
•
•
Spatial extent (GIS)
Depth to water table
Soil Storage
Soil Hydraulic Conductivity
Soil Suction
Proposed Procedure (Cont’d)
2.
Land Cover Parameterization
•
•
•
•
•
•
Residential
Commercial
Impervious Area, DCIA
Industrial
Transportation
Agriculture (Citrus, Row Crops, Irrigation Method, Timing)
Natural - Uplands and Wetlands *
Proposed Procedure (Cont’d)
3.
Catchments
•
•
•
•
Delineation – Deranged Networks (Arc Hydro Tools)
Union of Soil and Land Cover Information
Identification of Percolation Areas (Depression and/or SMAs)
Determine Initial Conditions (Water Table, Ponds, and
Depressions) * - (Historical Data, Biological Indicators,
Structure Information)
Proposed Procedure (Cont’d)
4.
Rainfall Excess Hydrograph
•
•
•
•
•
For Each Unique Polygonal Area of Catchment
Use Design Storms for Area
Verification Storm Analysis
Determine runoff (Green-Ampt and DCIA)
Develop Composite Rainfall Excess Hydrographs
by summing the individual polygons hydrographs
Proposed Procedure (Cont’d)
5.
Percolation at DepressionsHydrograph
•
•
•
•
•
•
Identification of Expected Ponding Area for Initial Try
Rainfall Excess will be 100% over area - infiltration
Geotechnical Testing or Retrieval of ERP Data to Determine
Infiltration/Percolation Parameters (bulk densities, porosities,
KV, KH, and expected WT Conditions)
Develop initial inflow hydrographs
Perform Mounding Analysis
Remodel
Questions?