Transcript Phreatology - Vrije Universiteit Brussel

Base Flow
20/5/2009 | pag. 1
Contents
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Base flow definition
Base Flow Separation techniques
Base Flow Programmes
WHAT
Application & Results
Correlation
Conclusion
Definition
Base flow—That part of the
Stream discharge that is not
attributable to direct runoff
from precipitation or melting
snow ;it is usually sustained
by groundwater (AMS
glossary).
Images of low-flow and base-flow in Virginia streams ,
Kappahunnouh County stream.
Base flow
– Base flow is the ground water contribution to
streamflow.
– Necessary to understand the hydrologic budgets of
surface and ground water basins.
– Provide a ground water discharge flow measurement for
calibration of numerical models, (Yu and Schwartz
1999).
Baseflow separation
Baseflow separation techniques
– Graphical Separation techniques
– Filtering Separation techniques
Graphical Separation
Methods
Estimating the point where the
baseflow intersects the falling
limb
D = 0.827 A0.2 (Linsley et al, 1958).
D
A
Number of days between
the storm crest and the
end of quickflow
Area of the catchment in
square kilometres
(1a) constant discharge method
(1b) constant slope method
(1c) concave method
Filtering Separation
Methods
— Filtering methods tend not to have any hydrological basis (Nathan and
McMahon, 1990) .
— Aim to generate an objective, repeatable and easily automated index that
can be related to the baseflow response of a catchment.
— The baseflow index (BFI) or reliability index, is commonly generated from
this analysis.
— It includes :
Smoothed minima technique
Fixed interval method
Sliding-interval method
Recursive digital filters
Recursive digital filters
Filter Name
One-parameter
algorithm
Boughton twoparameter
algorithm
Filter Equation
qb ( i ) 
Source
k
1 k
qb ( i 1) 
q( i )
2k
2k
Comments
qb(i) £ q(i)
Chapman and
Applied as a single pass through the
Maxwell (1996)
data.
Boughton (1993) q
£ q(i)
Applied as a single pass through the
Chapman and data
Maxwell (1996) Allows calibration against other
baseflow information such as tracers, by
b(i)
qb ( i ) 
k
C
qb ( i 1) 
q( i )
1 C
1 C
IHACRES threeJakeman and
k
C
q

q

(
q


q
)
b (i )
b ( i 1)
(i )
q ( i 1)
parameter
Hornberger
1 C
1 C
algorithm
(1993)
Lyne and Hollick
algorithm
q f (i )  q f (i 1) (q(i )  q(i 1) )
1 
2
Extension of Boughton two-parameter
algorithm
qf(i) ³0
Lyne and Hollick
a value of 0.925 recommended for daily
(1979)
stream data
filter recommended to be applied in
Nathan and
three passes
McMahon,
Baseflow is qb = q - qf
(1990)
(Grayson et al, 1996; Chapman, 1999; Furey and Gupta, 2001
Filtering Separation
Methods
Filter Name
Chapman
algorithm
Filter Equation
q f (i ) 
3  1
2
q f (i 1) 
(q(i )  q(i 1) )
3
3
c3
Furey and Gupta q  (1   )q


(q(id 1)  qb(id 1) )
b (i )
b ( i 1)
filter
c1
Eckhardt
qb ( i ) 
Recursive digital
filter
Source
Chapman
(1991)
Mau and
Winter (1997)
Baseflow is qb = q - qf
Furey and
Gupta (2001)
Physically-based filter using mass
balance equation for baseflow through
a hillside
Remove the high-frequency quickflow
signal to derive the low-frequency
baseflow signal (Nathan and
McMahon, 1990)
(1  BFImax )aqb(i 1)  (1  a) BFImax qi
1  aBFImax
Comments
Eckhardt
(2005)
BFImax 0.80 for perennial streams
with porous aquifers,
BFImax 0.50 for ephemeral streams
with porous aquifers
BFImax 0.25 for perennial streams
with hard rock aquifers
Base FlowIndex (BFI)
– BFI is a dimensionless ratio, developed by Lvovich
(1979) and the Institute of Hydrology (1980).
– BFI = the volume of base flow divided by the volume of
total runoff for each year or for total period of record
– This index can present some information about the
proportion of the stream flow that originates from stored
sources
– The index can be calculated from stream flow data or
estimated from basin geology
Base Flow Programs
–
HYSEP: Hydrograph Separation Program (Sloto, R.A., and Crouse, M.Y., 1996 )
http://water.usgs.gov/software/HYSEP/
–
PART: A computerized method of base-flow-record estimation
(Rutledge A T 2007)
http://water.usgs.gov/ogw/part/
–
BFI: A Computer Program for Determining an Index to Base Flow (Wahl, K.L., and
Wahl, K. L., 1995 )
–
http://www.usbr.gov/pmts/hydraulics_lab/twahl/bfi/
–
BASEFLOWHEC1 (Excel spreadsheet) (Center for Research in Water Resources)
http://www.crwr.utexas.edu/gis/gishydro03/LibHydro/libhydro/baseflow.htm.
–
WETSPRO (Excel spreadsheet) (Willems, 2009)
ftp://bb50.bwk.kuleuven.be/hydr/patrick/programs
–
WHAT ( Lim et al 2005)
http://cobweb.ecn.purdue.edu/~what/,
–
RAP ( River Analysis Pacakge) ( Marsh et al 2003)
http://toolkit.ewater.com.au/Tools/RAP\
WHAT ( Web based
Hydrograph Analysis Tool)
WHAT
(Web based Hydrograph Analysis Tool)
Application
67 river gauging stations, each
with 10 years or more daily
discharge data.
0
29.12.1984
18.12.1984
07.12.1984
26.11.1984
15.11.1984
04.11.1984
24.10.1984
13.10.1984
Qb(OPM)
02.10.1984
21.09.1984
10.09.1984
30.08.1984
19.08.1984
08.08.1984
Qb(LMM)
28.07.1984
3
17.07.1984
4
06.07.1984
5
25.06.1984
14.06.1984
03.06.1984
Qt
23.05.1984
12.05.1984
01.05.1984
6
20.04.1984
09.04.1984
29.03.1984
18.03.1984
07.03.1984
25.02.1984
14.02.1984
03.02.1984
23.01.1984
12.01.1984
01.01.1984
Q (m3/s)
Base Flow Separation
Rummen/Melsterbeek L09_156
Qb(RDF)
Total flow Qt= 1.09 m3/s
Base flow Qb = 0.88 m3/s
Base Flow Index (LMM)= 0.84
BFI (OPM)= 0.83
BFI (RDF)= 0.77
2
1
Correlation
RDF
OPM
LMM
0.79
0.79
0.84
LMM
0.84
0.95
0.95
OPM
RDF
Conclusion
• Hydrograph separation procedures are still, to a large extent,
arbitrary (Nathan and McMahon, 1990; Chapman and Maxwell,
1996; Chapman, 1999; Eckhardt, 2005).
• It provide a repeatable methodology to derive objective measures or
indexes related to a particular streamflow source.
• The filtering results will probably be influenced by the size of the
considered catchment as well. The longer the travel time to the
catchment outlet, the more runoff peaks are dispersed. (K. Eckhardt,
2005).
Conclusion
• Six software was tested on Korea , ( WHAT, PART, RORA,
PULSE, BFI, and RAP), the WHAT methods was the simplest
and easiest to apply prediction stability. Overall, the
WHAT-RDF method gave the most stable results over
other methods (E A Combalicer et al., 2008).
• It always recommended to separate the Base flow with
more than one method.