Transcript Hydrologic Modeling Environmental Hydrology

Hydrologic Modeling
Environmental Hydrology
As scientists we are intrigued by the
possibility of assembling our knowledge into
a neat package to show that we do, after all,
understand our science and its complex
interrelated phenomena.
W. M. Kohler, 1969
Why model?
• To estimate conditions where measurements
are not available or possible.
• To test system understanding.
• To facilitate design.
The Modeling Process
Revise
perceptions
The Perceptual Model
- deciding on the processes
Revise
equations
The Conceptual Model
- deciding on the equations
Debug
Code
The Procedural Model
- getting the code to run on a computer
Revise
parameter values
Model Calibration
- getting values of parameters
Model Validation
- good idea but difficult in practice
no
Declare
success?
yes
from Beven, 2001. Rainfall-runoff modelling, The Primer.
Development of Hydrologic Models
• Mulvaney (1851) – Rational Method
Qp = c i A
Development of Hydrologic Models
• Mulvaney (1851) – Rational Method
• Ross (1921) – Time-Area method
Development of Hydrologic Models
• Mulvaney (1851) – Rational Method
• Ross (1921) – Time-Area method
• Sherman (1932) – Unit Hydrograph
Principle of superposition of unit hydrographs
Source: http://hydram.epfl.ch/VICAIRE/mod_1b/chapt_4/text.htm
Development of Hydrologic Models
• Mulvaney (1851) – Rational Method
• Ross (1921) – Time-Area method
• Sherman (1932) – Unit Hydrograph
• Mockus (1949)* – SCS Curve Number
* and McCuen (1982)
1000
S
 10
CN
(P  0.2S)2
Q
(P  0.8 S)
Development of Hydrologic Models
• Crawford & Linsley (1966) – Stanford
Watershed Model
• …. Later evolved into Hydrologic
Simulation Program (HSP-F)
The first in a series of explicit soil moisture accounting models (ESMA)
Development of Hydrologic Models
• Freeze and Harlan (1969) – “Blueprint for
a physically-based, digitally simulated
hydrologic response model.” Journal of
Hydrology 9: 237-258.
Freeze and Harlan, 1969
Development of Hydrologic Models
• Metcalf and Eddy, 1971 – Storm Water Management
Model (SWMM)
• Beven and Kirkby, 1979 - Topmodel
• Leavesley et al., 1983 – Precipitation Runoff Modeling
System (PRMS)
• Abbott et al., 1986 – Systeme Hydrologique Europeen
(SHE)
For much more complete lists, see
• Singh and Woolhiser, 2002. Mathematical Modeling of Watershed Hydrology. Journal of Hydrologic
Engineering, 7(4): 270-291, doi 10.1061/ASCE 1084-0699.
• Kampf and Burgess, 2007. A framework for classifying and comparing distributed hillslope and
catchment hydrologic models. Water Resources Research, 43, W05423, doi 10.1029/2006WR005370.
The structure of rainfall-runoff models
Mprecip
MET
Mveg
ΔMstor =
Mstr
Msoil
Mseep
see lectures 15 and 16
The structure of rainfall-runoff models
Mprecip
MET
Mveg
ΔMstor =
Msoil
Mseep
Mstr
The structure of rainfall-runoff models
[ P, T, Qr, RH, U … ]
Mprecip
MET
Model variables –
change with time
[ Ks, n, zo, LAI … ]
Model parameters –
describe system
characteristics
Mveg
ΔMstor =
Msoil
Mseep
Mstr
A topology of models
• Empirical – model structure is based on
observations
• Conceptual – model structure is based on
physics of system
see Clark, 1973. A review of some mathematical models
used in hydrology, with observations on their calibration
and use. Journal of Hydrology, 19: 1-20.
A topology of models
• Stochastic – model variables display
random variation
• Deterministic – model variables regarded
as free from random variation
see Clark, 1973. Journal of Hydrology, 19: 1-20.
A topology of models
• Lumped – no accounting for spatial
variation in input parameters or variables
• Distributed – incorporate spatial variability
in input parameters or variables
see Clark, 1973. Journal of Hydrology, 19: 1-20.
Representing the model domain*
* in distributed hydrologic models
from Kampf and Burgess, 2007
Representing physical conditions*
Initial conditions –
describe values of
variables in differential
equations at time zero
in the simulation
Mprecip
MET
Boundary conditions –
describe values of
variables in differential
equations along the
boundary of the model
domain
Mstr
Mseep
* in conceptual (physically-based) hydrologic models
Integrating geospatial technologies
source: The Modular Modeling System (MMS)
G. Leavesley, U.S.G.S.
Additional Resources
• V. P. Singh, 1995. Computer Models of
Watershed Hydrology. Water Resources
Publications, Highlands Ranch, CO.
• K. Beven, 2001. Rainfall-Runoff Modelling,
The Primer. John Wiley & Sons, New York.