Hydrologic Processes

8/20/2019 Hydrologic Processes

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LECTURE #5

HYDROLOGIC PROCESSES,

PARAMETERS, AND

CALIBRATION


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THE HYDROLOGIC CYCLE


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HYDROLOGY - HYDROLOGIC

COMPONENTS

Hydrologic Components:

Rainfall or SnowInterception

Depression storage

Evapotranspiration

InfiltrationSurface storage

Runoff

Interflow

Groundwater flow

adapted from EPA BASINS workshop

Evapotranspiration

Interception

Depression

storage

Ground surface

Capillary

rise

Precipitation

Infiltration

Soil moisture

Percolation

Groundwater

storage

Underground flow intoor out of the area

Groundwater

flow

Streamflow

Interflow

Surface

runoff

Channel pptn.


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HYDROLOGY - WATER BALANCE

Water balance equation

R = P - ET - IG - ΔS

where: P = Precipitation R = Runoff ET = Evapotranspiration IG

= Deep/inactive groundwater ΔS = Change in soil storage

Inter-relationships between components

Variation of components with time• consideration of soil condition, cover, antecedent

conditions, land practices



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STANFORD WATERSHED MODEL

To Stream

Actual ET

Potential ET

Precipitation

Temperature

Radiation

Wind,Dewpoint

Snowmelt

Interception

Storage

Lower Zone

Storage

Groundwater

Storage

InterflowUpper Zone

Storage

Overland Flow

Deep or Inactive

Groundwater

CEPSC*

BASETP*

AGWETP*

DEEPFR*

LZSN*

INFILT*

INTFW*UZSN*

AGWRC*

IRC*

Delayed Infiltration

Direct

Infiltration

NSUR*

SLSUR*

LSUR*

PERC

1

ET

2 ET

3 ET

4 ET

5 ET

LZETP*

* Parameters

Output

Process

Input

Storage

ET - Evapotranspiration

n Order taken to

meet ET demand

Decision


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PWATER STRUCTURE CHART

PWATER

Simulate water budget

for pervious land

segment

EVAPT

Simulate

interception

ICEPT

Simulate

interflow

INTFLW

Simulate

upper zone

behavior

UZONE

Simulate the

lower zone

behavior

LZONE

Simulate

groundwater

behavior

GWATER

Subsidiary

upper zone

subroutine

UZONES

Simulate

evapotrans-

piration (ET)

Subsidiary

upper zone

subroutine

ETUZS

ET from

lower zone

ETLZON

ET from

baseflow

ETBASE

Evaporate

from

interception

EVICEP

ET from

upper zone

ETUZON

ET from

active

ground

water

ETAGW

Dispose of

moisture

supply

Distribute

the water

available for

infiltration

and runoff

Determine

surface

runoff

Compute

inflow to

upper zone

DIVISN

DISPOS

SURFAC

PROUTEUZINF1/2

Divide

moisture

supply


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INTERCEPTION FUNCTION

Precipitation

CEPSC

Throughfall

Evaporation


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INFILTRATION DIAGRAM

line I - (Infiltration capacity)

line II - (Interflow +

Infiltration capacity)


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INFILTRATION FUNCTION IN HSPF

% AREA

I = INFILTINFILT ** INFFACINFFAC

(LZS /(LZS / LZSNLZSN))INFEXPINFEXP

IMAX = I * INFILD

IMAXIMAX

Potential

Runoff

Supply Rate

Infiltration

I

0 100500

II

LZS /LZS / LZSNLZSN I n f i l t r a t i o n R a t e ( i n / h r )

II

Inter-

flow

II = I *I * INTFWINTFW (2.0** (LZS /(2.0** (LZS / LZSNLZSN))))


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To Stream

Actual ET

Potential ET

Precipitation

Temperature

Radiation

Wind,Dewpoint

Snowmelt

Interception

Storage

Lower Zone

Storage

Groundwater

Storage

InterflowUpper Zone

Storage

Overland Flow

Deep or Inactive

Groundwater

CEPSC*

BASETP*

AGWETP*

DEEPFR*

LZSN*

INFILT*

INTFW*UZSN*

AGWRC*

NSUR*

SLSUR*

LSUR*

IRC*


Direct

Infiltration

PERC

1 ET

2 ET

3 ET

4 ET

5 ET

LZETP*

* Parameters

Output

Process

Input

Storage


n Order taken to

meet ET demand

Decision


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UPPER ZONE STORAGE FUNCTION


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SOIL PROFILE DRAINAGE PROCESSES

AND FUNCTIONS

LZS /LZS / LZSNLZSN

PERC = 0.1 *PERC = 0.1 * INFILTINFILT * INFFAC ** INFFAC * UZSNUZSN ** UZSUZS -- LZSLZS 33

UZSN LZSNUZSN LZSN

From UZSFrom UZS

To lower zone or groundwaterTo lower zone or groundwater

1.01.0

0.00.0

0.50.5

F r a c t i o n t o L Z S

F r a c t i

o n t o L Z S

0.00.0 1.01.0 2.02.0

To GroundwaterTo Groundwater

To Lower ZoneTo Lower Zone


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To Stream

Actual ET

Potential ETPrecipitation

Temperature

Radiation

Wind,Dewpoint

Snowmelt

Interception

Storage

Lower Zone

Storage

Groundwater

Storage

InterflowUpper Zone

Storage

Overland Flow

Deep or Inactive

Groundwater

CEPSC*

BASETP*

AGWETP*

DEEPFR*

LZSN*

INFILT*

INTFW*UZSN*

AGWRC*

NSUR*

SLSUR*

LSUR*

IRC*


Direct

Infiltration

PERC

1 ET

2 ET

3 ET

4 ET

5 ET LZETP*

* Parameters

Output

Process

Input

Storage


n Order taken to

meet ET demand

Decision

OVERLAND FLOW FUNCTION


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OVERLAND FLOW FUNCTION

SUB SURFACE FLOW FUNCTIONS


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SUB-SURFACE FLOW FUNCTIONSInterflow

IFWO = K2 * IFWS + K1 * INFLOIFWS = interflow storage at start of time step

INFLO = addition to interflow storage during time-

step

K2 = 1.0 - e-K

K1 = 1.0 - K2/K

K = - ln(IRC)dt/24

IRC = Interflow recession parameter

Baseflow

AGWO = KGW * AGWS * (1.0 + KVARY * GWVS)

AGWS = active groundwater storage

GWVS = antecedent index increased by drainage

to AGWS, decreased 3% each day

KVARY = input parameter KGW = 1.0 - (AGWRC)dt/24

AGWRC = Groundwater recession parameter


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To Stream

Actual ET


Temperature

Radiation

Wind,Dewpoint

Snowmelt

Interception

Storage

Lower Zone

Storage

Groundwater

Storage

InterflowUpper Zone

Storage

Overland Flow

Deep or Inactive

Groundwater

CEPSC*

BASETP*

AGWETP*

DEEPFR*

LZSN*

INFILT*

INTFW*UZSN*

AGWRC*

NSUR*

SLSUR*

LSUR*

IRC*


Direct

Infiltration

PERC

1 ET

2 ET

3 ET

4 ET

5 ET LZETP*

* Parameters

Output

Process

Input

Storage


n Order taken tomeet ET demand

Decision

EVAPOTRANSPIRATION FUNCTIONS


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EVAPOTRANSPIRATION FUNCTIONS

AND HIERARCHY

1st from baseflow (BASETP)

2nd from interception

3rd from UZS @ potential if UZS /

UZSN > 2.0; else prorated foreffective area

4th from active groundwater

(AGWETP)

5th from LZS

% AREA Less Than% AREA Less Than

i n

c h / D T

i n

c h / D T

100%100%

ET Potential

Actual ETActual ET

0%0% 50%50%

ET Opportunity MAX

0.250.25 LZSLZS DT_DT_

11 -- LZETPLZETP LZSNLZSN 2424* *MAX =


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To Stream

Actual ET


Temperature

Radiation

Wind,Dewpoint

Snowmelt

Interception

Storage

Lower Zone

Storage

Groundwater

Storage

InterflowUpper Zone

Storage

Overland Flow

Deep or Inactive

Groundwater

CEPSC*

BASETP*

AGWETP*

DEEPFR*

LZSN*

INFILT*

INTFW*UZSN*

AGWRC*

NSUR*

SLSUR*

LSUR*

IRC*


Direct

Infiltration

PERC

1 ET

2 ET

3 ET

4 ET

5 ET LZETP*

* Parameters

Output

Process

Input

Storage


n Order taken tomeet ET demand

Decision

A A A S


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PWATER PARAMETERS:

PWAT-PARM2

FOREST - Fraction of the PLS covered by forest

LZSN - Lower zone nominal soil moisture storage

INFILT - Index to the infiltration capacity of the soil

LSUR - Length of the assumed overland flow plane

SLSUR - Slope of the assumed overland flow plane

KVARY - Variable groundwater recession parameter

AGWRC - Basic groundwater recession rate

(when KVARY is zero)

PWATER PARAMETERS


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PWATER PARAMETERS:

PWAT-PARM3

PETMAX - Air temperature below which ET will be reduced below the

input value (used when CSNOFG = 1)

PETMIN - Air temperature below which ET will be zero regardless of

the input value (used when CSNOFG = 1)

INFEXP - Exponent in the infiltration equation

INFILD - Ratio between the max and mean infiltration capacities over

the PLSDEEPFR - Fraction of groundwater inflow which will enter deep

(inactive) groundwater

BASETP - Fraction of remaining potential ET which can be satisfied

from baseflow

AGWETP - Fraction of remaining potential ET which can be satisfied

from active groundwater storage

PWATER PARAMETERS


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PWATER PARAMETERS:

PWAT-PARM4

CEPSC - Interception storage capacity

UZSN - Upper zone nominal soil moisture storage

NSUR - Manning’s N for the assumed overland flow plane

INTFW - Interflow inflow parameter

IRC - Interflow recession parameter, i.e., the ratio of interflow

outflow rate today / rate yesterday

LZETP - Lower zone ET parameter; an index to the density of

deep-rooted vegetation


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• Models are approximations of reality; they can not

precisely represent natural systems

• There is no single, accepted statistic or test thatdetermines whether or not a model is valid

• Both graphical comparisons and statistical tests arerequired in model calibration and validation

• Models cannot be expected to be more accurate thanthe errors (confidence intervals) in the input and

observed data• A ‘weight-of-evidence’ approach is becoming the

preferred practice for model calibration and validation

CALIBRATION ISSUES

‘Basic Truths’ in modeling natural systems

CALIBRATION/VALIDATION


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• Mean runoff volume for simulation period (inches)

• Annual and monthly runoff volume (inches)

• Daily flow timeseries (cfs) – observed and simulated daily flow

– scatter plots

• Flow frequency (flow duration) curves (cfs)

• Storm hydrographs, hourly or less, (cfs)


COMPARISONS

“Weight-of-Evidence” Approach



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• Precipitation

• Total Runoff (sum of following components)

– Overland flow

– Interflow

– Baseflow

• Total Actual Evapotranspiration (ET) (sum of followingcomponents)

– Interception ET

– Upper Zone ET – Lower Zone ET

– Baseflow ET

– Active Groundwater ET• Deep Groundwater Recharge/Losses


COMPARISONS

Water Balance Components



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Graphical Comparisons:

• Timeseries plots of observed and simulated values for fluxes (e.g.,

flow) or state variables (e.g., stage, sediment concentration, biomass concentration)

• Observed and simulated scatter plots, with 45o linear regressionline displayed, for fluxes or state variables

• Cumulative frequency distributions of observed and simulatedfluxes or state variable (e.g., flow duration curves)

Statistical Tests:

• Error statistics, e.g., mean error, absolute mean error, relative error,relative bias, standard error of estimate, etc.

• Correlation tests, e.g., correlation coefficient, coefficient of model-fit efficiency, etc.

• Cumulative Distribution tests, e.g., Kolmogorov-Smirnov (KS) test


COMPARISONS

Graphical/Statistical Procedures & Tests

R & R2 VALUE RANGES FOR MODEL


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R & R VALUE RANGES FOR MODEL

PERFORMANCE

Criteria

0.6 0.7 0.8 0.9

Poor Fair Good Very Good

Poor Fair Good Very Good

0.75 0.80 0.85 0.90 0.95

R2

Daily Flows

Monthly Flows

R

HYDROLOGIC (PWATER) CALIBRATION


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HYDROLOGIC (PWATER) CALIBRATION

• Annual Water Balance -Runoff = Prec. - Actual ET - Deep Perc. -Δ Storage

Key Parameters: Repre. Precipitation (MFACT)

LZSN

LZETPINFILT

DEEPFR

• Groundwater (Baseflow) Volume and Recession -

Runoff = Surface Runoff + Interflow + Baseflow

Key Parameters: INFILT

AGWRC/KVARY

DEEPFR

BASETP/AGWETP

• Surface Runoff + Interflow (Hydrograph Shape) -

Key Parameters: UZSN

INTFWIRC

LSUR, NSUR, SLSUR

COMPONENTS OF HYDROGRAPH


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COMPONENTS OF HYDROGRAPH

Surface runoff -

overland flow

Interflow - flow

through surficiallayers of soil

B a s e f l o w

R u n o f f

I n t e r f l o

w

Baseflow -

groundwaterseepage from

springs and

aquifers directly to

the stream channel


HYDROGRAPH SENSITIVITY TO INFILT


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HYDROGRAPH SENSITIVITY TO INFILT

HYDROGRAPH SENSITIVITY TO INTFW


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HYDROGRAPH SENSITIVITY TO INTFW

HSPF PWATER PARAMETERS AND


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TYPICAL/POSSIBLE VALUE RANGES (#1)

RANGE OF VALUES

NAME DEFINITION UNITS TYPICAL POSSIBLE FUNCTION OF...

COMMENT

MIN MAX MIN MAX

PWAT - PARM2

FOREST Fraction forest cover none 0.0 0.50 0.0 0.95 Forest cover Only impact when Snow is active

LZSN Lower Zone NominalSoil Moisture Storage

inches 3.0 8.0 2.0 15.0 Soils, climate Calibration

INFILT Index to InfiltrationCapacity

in/hr 0.01 0.25 0.001 0.50 Soils, land use Calibration , divides surface andsubsurface flow

LSUR Length of overland f low feet 200 500 100 700 Topography Estimate from maps or GIS

SLSUR Slope of overland flowplane

none 0.01 0.15 0.001 0.30 Topography Estimate from maps or GIS

KVARY Variable groundwater recession

none 1.0 3.0 1.0 5.0 Baseflowrecessionvariation

Used when recession rate varieswith GW levels

AGWRC Base groundwater recession

none 0.92 0.99 0.85 0.999 Baseflowrecession

Calibration



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RANGE OF VALUES


COMMENT

MIN MAX MIN MAX

PWAT - PARM3

PETMAX Temp below which ET isreduced

deg. F 35.0 45.0 32.0 48.0 Climate Reduces ET near freezing

PETMIN Temp below which ET isset to zero

deg. F 30.0 35.0 30.0 40.0 Climate Reduces ET near freezing

INFEXP Exponent in infiltrationequation

none 2.0 2.0 1.0 3.0 Soils variability Usually default to 2.0

INFILD Ratio of max/meaninfiltration capacities

none 2.0 2.0 1.0 3.0 Soils variability Usually default to 2.0

DEEPFR Fraction of GW inflow todeep recharge

none 0.0 0.20 0.0 0.50 Geology, GWrecharge

Accounts for subsurface losses

BASETP Fraction of remaining ETfrom baseflow

none 0.0 0.05 0.0 0.20 Riparianvegetation

Direct ET from riparianvegetation

AGWETP Fraction of remaining ETfrom active GW

none 0.0 0.05 0.0 0.20 Marsh/wetlandsextent

Direct ET from shallow GW



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S S N


RANGE OF VALUES


COMMENT

MIN MAX MIN MAX

PWAT - PARM4

CEPSC Interception storagecapacity

inches 0.03 0.20 0.01 0.40 Vegetationtype/density, landuse

Monthly values usually used

NSUR Mannings’ n (roughness)for overland flow

none 0.15 0.35 0.10 0.50 Surfaceconditions,residue, etc.

Monthly values often used for croplands

UZSN Upper zone nominal soilmoisture storage

inches 0.10 1.0 0.05 2.0 Surface soilconditions, landuse

Accounts for near surfaceretention

INTFW Interflow inflow parameter none 1.0 3.0 1.0 10.0 Soils,topography, landuse

Calibration, based onhydrograph separation

IRC Interflow recessionparameter none 0.5 0.7 0.3 0.85 Soils,topography, landuse

Often start with a value of 0.7,and then adjust

LZETP Lower zone ET parameter none 0.2 0.7 0.1 0.9 Vegetationtype/density, rootdepth

Calibration

IWATER STRUCTURE CHART


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IWATER STRUCTURE CHART

RETN EVRETNIROUTE

IWATER

Simulate

water budget

for

imperviousland segment

Simulate

moisture

retention

Determine how

much of the

moisture supplyruns off

Evaporate from

retention

storage

IWATER CALIBRATION


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IWATER CALIBRATION

Impervious

area process

IWATER

parameter

Interception RETSC

Overland flow LSUR, NSUR, SLSUR

Evaporation (no parameter, occurs at PET)

Documents

Hydrologic Processes