Chesapeake Bay Program Modeling
Sediment Land Calibration:
Status and Decision Rules
Chesapeake Bay Program Modeling
Land-River Connection in HSPF
BMP Factor
Land Acre FactorDelivery Factor
Edge of Field
Edge of Stream
Chesapeake Bay Program Modeling
Corresponding to model structure, calibration strategies break into…
• Land calibration
• River Calibration
Chesapeake Bay Program Modeling
Land Sediment Simulation
J1= KSER * RO *(RO + Water Storage)
Detached Sediment
Soil Matrix(unlimited)
Wash off
Det
achm
ent
Att
achm
ent
= (1-cover) * KRER* (Rain) J2
= AFFIX * (Detached sediment)
= NVSI lb/day
Input
Chesapeake Bay Program Modeling
• Calibrate Edge of Field to targets
• Split into major land uses
Land Calibration
Chesapeake Bay Program Modeling
13 Land use categories for sediment:
Group 2 –
• Harvested Forest• Natural grass• Extractive• Barren• Pervious Urban• Impervious Urban• water
Group 1 –
• Forest• Pasture• Hay • High till with manure• High till without
manure• Low till with manure
Chesapeake Bay Program Modeling
EOF Targets
• For each land use in group 1: EOF targets available at county level
RUSLE supplied by NRI
• For each land use in group 2: Single EOF target obtained from
literature
Chesapeake Bay Program Modeling
Land EOF calibration
• For each land use in group 1, reach EOF
targets county by county
Total = 6 land use X 308 counties
= 1848
• For each land use in group 2, reach single
target for the entire watershed
Chesapeake Bay Program Modeling
Iterative Calibration• Wrote computer programs to automatically
calibrate EOF for all land use and all counties
• Started with parameter set from manual calibration
• Developed rules for adjusting parameter values based on model outputs
Chesapeake Bay Program Modeling
Decision Rules for Four Key land Parameters:
• Rule1 – detached sed reach 90% of max sediment in 30 days
AFFIX = 0.07673
Detached Sediment
Att
achm
ent
= AFFIX * (Detached sediment)
)1( *tAFFIXeAFFIX
NVSIS
SAFFIXNVSIdt
dS*
Chesapeake Bay Program Modeling
• Rule2 – Vertical Input high enough for hysteresis
NVSI (lb/acre/day)= a * target load (lb/acre/yr) a - changeable parameter Assumed a =0.5
for hvf grs pur … NVSI 0.93 9.32 4.11 3.01 …
Detached Sediment= NVSI lb/day
Input
Chesapeake Bay Program Modeling
• Rule 3 - Zero Detached Sed after Large Storms
Adjust KRER and KSER to ensure
- No build-up after most big storms
- Reach to targets
Ratio of KSER:KRER = b (changeable)
Enforced minimum and maximum values
Chesapeake Bay Program Modeling
Decision Rules
PARAMETERS
for hvf grs pas hay hom hwm lwm pur ext bar
AFFIX, 0.07673
NVSI, 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5
KS-KR, 2 2 2 2 2 2 2 2 2 2 2
*** min and max allowed by user and by HSPF
KRER, 0.01 50. 0.0 100.
KSER, 0.01 100. 0.0 200.
Chesapeake Bay Program Modeling
Expected results:
• Land segment A42033
0
0.5
1
1.5
2
2.5
12/20/83 09/15/86 06/11/89 03/07/92 12/02/94 08/28/97 05/24/00
SURO
DETS
WSSD
0
0.2
0.4
0.6
0.8
1
1.2
0 50 100 150 200 250 300
SURO
DETS
WSSD
Chesapeake Bay Program Modeling
Eight Scenarios tested
Scenarios a (NVSI/Target) KSER:KRER 1 0.5 2 2 0.6 2 3 0.7 2 4 0.8 2 5 0.5 2.5 6 0.5 3 7 0.6 2.5 8 0.6 3
Chesapeake Bay Program Modeling
Scenarios with same KSER:KRER ratioKSER:KRER =2
0
1
2
3
4
5
6
7
0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85
NVSI /Target
Avera
ge d
ets
(to
ns)
for
hvf
grs
pas
hay
hom
hwm
lwm
pur
ext
bar
KSER:KRER =2
05
1015202530354045
0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85
NVSI/Target
Ave
rag
e K
SE
R
for
hvf
grs
pas
hay
hom
hwm
lwm
pur
ext
bar
Chesapeake Bay Program Modeling
Scenarios with same NVSI/Target ratio
NVSI/Target =0.5
0
12
3
45
6
1.5 2 2.5 3 3.5
KSER:KRER
Avera
ge D
ets
(to
ns)
for
hvf
grs
pas
hay
hom
hwm
lwm
pur
ext
bar
NVSI/Target =0.5
0
10
20
30
40
50
1.5 2 2.5 3 3.5
KSER:KRER
Avera
ge K
SE
R
for
hvf
grs
pas
hay
hom
hwm
lwm
pur
ext
bar
Chesapeake Bay Program Modeling
Status and expected steps
• Computer programs ready
• EOF calibration can be done in 2~3 days
once final land use and hydrology
parameters available
Chesapeake Bay Program Modeling
Land-River Connection
BMP Factor
Land Acre FactorDelivery Factor
Edge of Field
Edge of Stream
Chesapeake Bay Program Modeling
River Calibration…
• Have started manual calibration
• Calibrate to three sediment rating curves, statistics…
• Hope to develop iterative calibration based on manual practice
Chesapeake Bay Program Modeling