Transcript Review of SWRCB Water Availability Analysis

Review of
SWRCB
Water Availability Analysis
Emphasis
on
Dry Creek
Water
Availability Analysis
Purpose

Review Dry Creek Water Availability Analysis
for:



Defensibility
Accuracy
Focus of Review



Application of Rational Method
Specific review of calculations in Dry Creek Analysis
Alternative methods
Rational Method


Most Commonly used to estimate peak
flow
CALTRANS Highway Design Manual
CALTRANS Highway Design Manual
Chapter 819.2 Empirical Methods
“Rational Methods. Undoubtedly, the most popular and
most often misused empirical hydrology method is the
Rational Formula:
Q = 0.28 CiA
Q = Design discharge in cubic meters per second.
C = Coefficient of runoff.
I = Average rainfall intensity in millimeters per hour
for the selected frequency and for a duration
equal to the time of concentration”.
Typical Flood Hydrograph

Rational Method is used to estimate peak flow, but
is not used to estimate area under curve
Conclusion


Rational method is designed to estimate
peak flow rates
The Rational method may not be
defensible when used to estimate
annual runoff volume
Questions


Is there a way to test the applicability
of the Rational Method for determining
annual runoff volume for WAA?
Is there another simplified method that
can be applied?
Rainfall versus Runoff
Runoff = Coefficient * Rainfall Volume
Runoff = Coefficient * Rainfall * Area
Q = CiA
C=Q / iA
C = Relationship between rainfall and runoff
Testing The Rational Method
Compare relationships between rainfall and
runoff (C) in gaged watersheds to
relationships developed by SWRCB for
WAA
Calculating C for Gaged
Watersheds

Use approximately 38 Stream gages and
approximately 16 Precipitation gages in
North Coast Region
Stream Gage Data Used for Evaluation
Map
Number1
34
39
41
42
43
45
46
47
48
50
53
54
55
56
58
59
60
61
63
65
69
73
74
78
79
82
89
91
94
95
97
99
101
102
105
109
112
Drainage
Average
Area
Drainage
Basin
USGS Gage
(Square
Area
Precip.
ID Number
Gage Name
Miles)
(Acres)
(in/yr)
11453700
CAPELL C TRIB NR WOODEN VALLEY CA
0.9
557
24.3
11456000
NAPA R NR ST HELENA CA
81.4
52,096
48.0
11456500
CONN C NR OAKVILLE CA
55.4
35,456
36.8
11457000
DRY C NR NAPA CA
17.4
11,136
34.0
11458200
REDWOOD C NR NAPA CA
9.8
6,266
27.6
11458500
SONOMA C A AGUA CALIENTE CA
58.4
37,376
35.4
11459000
PETALUMA R A PETALUMA CA
30.9
19,776
27.4
11460000
CORTE MADERA C A ROSS CA
18.1
11,584
42.0
11460100
ARROYO C. MADERA D PRES A MILL V. CA
4.7
3,002
39.5
11460170
PINE C A BOLINAS CA
7.8
5,011
32.0
11460920
SALMON C A BODEGA CA
15.7
10,048
45.3
11460940
RUSSIAN R NR REDWOOD VALLEY CA
14.1
9,024
40.5
11461000
RUSSIAN R NR UKIAH CA
100.0
64,000
47.8
11461400
EF RUSSIAN R TRIB NR POTTER VAL CA
0.3
160
31.2
11462500
RUSSIAN R NR HOPLAND CA
362.0
231,680
41.3
11463200
BIG SULPHUR C NR CLOVERDALE CA
85.5
54,720
53.5
11463940
FRANZ C NR KELLOGG CA
15.7
10,048
34.3
11464000
RUSSIAN R NR HEALDSBURG CA
793.0
507,520
47.7
11464500
DRY C NR CLOVERDALE CA
87.8
56,192
43.3
11465800
SANTA ROSA C NR SANTA ROSA CA
12.5
8,000
35.8
11467500
SF GUALALA R NR ANNAPOLIS CA
161.0
103,040
61.0
11468000
NAVARRO R NR NAVARRO CA
303.0
193,920
50.0
11468010
ALBION R NR COMPTCHE CA
14.4
9,216
45.5
11468500
NOYO R NR FORT BRAGG CA
106.0
67,840
55.0
11468540
PUDDING C NR FORT BRAGG CA
12.5
8,000
51.5
11469000
MATTOLE R NR PETROLIA CA
245.3
156,986
48.9
11472200
OUTLET C NR LONGVALE CA
161.0
103,040
62.0
11473000 MF EEL R BL BLACK BUTTE R NR COVELO CA
367.0
234,880
59.0
11473600
SHORT C NR COVELO
15.2
9,728
41.8
11473700
MILL C NR COVELO CA
95.6
61,184
42.7
11474000
EEL R BL DOS RIOS CA
1484.0
949,760
58.7
11474500
NF EEL R NR MINA CA
248.0
158,720
59.2
11475000
EEL R A FORT SEWARD CA
2107.0 1,348,480
64.4
11475500
SF EEL R NR BRANSCOMB CA
43.9
28,096
74.5
11475700
TENMILE C NR LAYTONVILLE CA
50.3
32,192
73.0
11477700
LITTLE VAN DUZEN R NR BRIDGEVILLE CA
36.2
23,168
63.7
11478500
VAN DUZEN R NR BRIDGEVILLE CA
222.0
142,080
69.2
Number
Average
Coincidental Used for
Basin
Runoff
Runoff Stream and
Analysis
Precip.
Volume
Rainfall Precip. Record of Smaller
(AF/yr)
(AF/yr)
Ratio (%)
(years)
Basins
1,127
669
*
59
4
208,384
71,237
34
23
108,755
22,424
21
13
31,544
14,225
*
45
15
14,423
6,947
*
48
8
110,384
52,272
47
19
45,174
13,528
30
13
40,544
19,471
*
48
20
9,888
5,300
*
54
9
13,348
9,940
*
74
3
37,906
17,899
*
47
13
30,457
17,599
*
58
5
254,686
130,832
51
42
416
94
*
23
2
797,173
525,118
66
45
244,093
139,001
57
14
28,699
17,001
*
59
5
2,018,748 1,037,864
51
50
202,781
121,437
60
23
23,881
13,346
*
56
10
524,210
294,702
56
14
808,000
345,060
43
34
34,945
14,428
*
41
4
310,933
142,536
46
34
34,364
15,040
*
44
8
639,127
946,996
148
47
532,373
330,852
62
15
1,154,820
752,062
65
12
33,887
18,680
*
55
10
217,856
118,922
55
11
4,649,542 2,370,522
51
11
782,906
467,556
60
15
7,241,771 3,559,010
49
19
174,430
126,061
72
9
195,796
133,785
68
13
122,984
120,222
98
9
819,242
630,217
77
34
Precipitation Stations
Station
Number
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
Station Name
Oakville 1 WNW
Calistoga
Duttons Landing
Graton
SantaRosa
Ukiah
Healdsburg
Cloverdale
Napa_st_hosp
philo
Ukiah 4 WSW
Branscomb 3 NNW
Fort Bragg 5 N
Bridgeville 4 NNW
Richardson Gr St Pk
Garberville
Shelter Cove Av
Scotia
Hyampom
Willits 1 NE
Covelo
Number of
Years in
Record
23
49
20
51
63
86
67
34
78
34
40
15
46
36
36
21
12
67
4
32
37
Average
Precipitation
(in/yr)
32.7
38.7
20.3
41.9
30.3
37.2
42.0
44.5
24.3
40.5
51.3
83.8
40.6
69.5
70.8
59.4
63.3
48.8
42.8
53.4
43.2
SWRCB WAA - Rational Formula Values
River
Napa
Napa
Napa
Napa
Napa
Napa
Napa
Napa
Napa
Napa
Napa
Napa
Napa
Napa
Napa
Napa
Napa
Napa
Napa
Napa
Napa
Napa
Napa
Napa
Navarro
Navarro
Navarro
Navarro
Navarro
Navarro
Russian
Russian
Russian
Russian
Russian
Russian
Russian
Russian
Russian
Russian
Russian
Russian
Russian
Russian
Russian
Russian
Russian
Russian
Russian
Russian
Russian
Russian
Russian
Russian
Russian
Watershed
Carneros
Carneros
Browns Valley crk
Dry Crk
Redwood Crk
Browns Valley Crk
Browns Valley Crk
Browns Valley Crk
North Slough
Lower Napa River
Fagan Crk
Bale Slough
Bale Slough
Milliken Crk
Unst
Sarco Crk
Tulucay Crk
Blossom Crk
Bear Canyon
Conn Crk
Dry Crk
Napa R
Carneros
Biter Crk
Anderson Creek
Unnamed Stream
Unnamed Stream
Witherell Creek
Unnamed Stream
Unnamed Stream
1. Franz Creek
Stream
Unst
Unst
Unst
Wing Canyon
Unst
Unst
Unst
Unst
Unst
Unst
Unst
Unst
Unst
Unst
Napa R
Unst
Unst
Unst
Unst
Unst
Unst
Unst
Unst
Unst
Navarro River
Beebe thence Rancheria
Floodgate Creek
Anderson Creek
Navarro River
Con Creek thence Anderson
2. Maacama Creek 1. Franz Creek
1. Unnamed
2. Maacama Creek 1. Franz Creek
1. Unnamed
2. Maacama Creek 1. Franz Creek
1. Unnamed
2. Maacama Creek 1. Franz Creek
Unnamed
Unnamed
Unnamed
Unnamed
Unnamed
Unnamed
Unnamed
Unnamed
Unnamed
Unnamed
Unnamed
Unnamed
Unnamed
Unnamed
Unnamed
Unnamed
Unnamed
Unnamed
Unnamed
Unnamed
Unnamed
2. Maacama Creek
2. Maacama Creek
2. Maacama Creek
2. Maacama Creek
Bidwell Creek
Bidwell Creek
Bidwell Creek
Bidwell Creek
Mark West Creek
Bidwell Creek
Bidwell Creek
Santa Rosa Creek
Santa Rosa Creek
Russian River
Russian River
Barelli Creek
Russian
Barelli Creek
Barelli Creek
Barelli Creek
Barelli Creek
Barelli Creek
Barelli Creek
Barelli Creek
Barelli Creek
Application
Number
30824
30824
30856
30737
30929
30803
30914
30914
30584
30610
30587
30597
30597
31020
30490
30753
30858
30965
30287
30655
30738
30827
30913
30935
30348
30492
30717
30718
30721
30735
29715
29715
29715
29715
29784
29784
29784
29784
29802
29983
29998
30051
30336
30364
30365
30534
30534
29760
29760
30656
30259
30259
30259
30259
29772
Flow, Q
Runoff
Precipitation, I
(AF/yr) Coefficient, C
(in/yr)
94
0.52
25.0
28
0.39
25.0
16
0.39
26.0
1,637
0.51
39.9
126
0.49
30.0
80
0.47
25.0
38
0.54
25.0
2,814
0.48
25.0
570
0.46
25.0
80
0.28
23.0
772
0.44
21.8
26
0.44
34.2
1,322
0.40
34.2
421
0.49
26.0
1,160
0.41
39.0
47
0.42
26.0
5,140
0.50
25.0
1,430
0.49
45.0
2,585
0.52
38.0
1,090
0.44
32.7
41
0.51
39.9
455
0.41
25.0
112
0.33
25.0
2,464
0.63
37.1
156
0.45
40.4
252
0.41
47.3
24
0.46
40.4
884
0.57
40.0
336
0.54
41.5
1,896
0.60
42.0
60
0.40
40.1
76
0.40
40.1
44
0.40
40.1
13
0.40
40.1
162
0.40
48.5
73
0.40
48.5
60
0.40
48.5
37
0.40
48.5
51
0.43
41.3
201
0.40
40.1
33
0.44
48.5
42
0.42
30.1
1,138
0.46
30.1
38
0.40
30.8
23
0.40
41.0
51
0.40
43.7
80
0.40
43.7
24
0.40
41.3
40
0.40
41.3
16
0.40
41.3
378
0.60
40.8
584
0.55
40.8
2,242
0.60
40.8
21,721
0.55
40.8
113
0.52
40.8
Area, A
(acres)
87
34
19
966
103
82
34
2,814
595
150
967
21
1,159
397
871
52
4,934
778
1,570
908
24
531
163
1,267
103
156
15
465
180
903
45
57
33
10
100
45
37
23
34
150
19
40
988
28
28
35
55
17
29
11
185
312
1,098
11,607
64
Average Annual Runoff Volume Versus Precipitation Volume
4,500,000
Q
4,000,000
SWRCB
Slope = 0.544
R2 = 0.998
Runoff Volume (AF/yr)
3,500,000
3,000,000
Gage Data
Slope = 0.509
R2 = 0.971
2,500,000
2,000,000
1,500,000
Gage Data
1,000,000
SWRCB - Method
500,000
iA
0
0
1,000,000
2,000,000
3,000,000
4,000,000
5,000,000
Precipitation Volume (AF/yr)
6,000,000
7,000,000
8,000,000
Average Annual Runoff Volume Versus Precipitation Volume
4,500,000
Q
4,000,000
SWRCB
Slope = 0.544
R2 = 0.998
Runoff Volume (AF/yr)
3,500,000
3,000,000
Gage Data
Slope = 0.509
R2 = 0.971
2,500,000
2,000,000
1,500,000
Gage Data
1,000,000
SWRCB - Method
500,000
iA
0
0
1,000,000
2,000,000
3,000,000
4,000,000
5,000,000
Precipitation Volume (AF/yr)
6,000,000
7,000,000
8,000,000
Average Annual Runoff Volume Versus Precipitation Volume
(Smaller Basins Only)
25,000
Q
SWRCB
Slope = 0.544
R2 = 0.998
Runoff Volume (AF/yr)
20,000
Gage Data
Slope = 0.498
R2 = 0.917
15,000
10,000
SWRCB - Method
Gage Data
5,000
iA
0
0
5,000
10,000
15,000
20,000
25,000
30,000
Precipitation Volume (AF/yr)
35,000
40,000
45,000
Average Annual Runoff Volume Versus Precipitation Volume
(Smaller Basins Only - Largest SWRCB Basin Removed)
25,000
Q
SWRCB
Slope = 0.506
R2 = 0.985
Runoff Volume (AF/yr)
20,000
Gage Data
Slope = 0.498
R2 = 0.917
15,000
10,000
Gage Data
5,000
SWRCB - Method
iA
0
0
5,000
10,000
15,000
20,000
25,000
30,000
Precipitation Volume (AF/yr)
35,000
40,000
45,000
Adjustments for Current Use


WAA is assessed using unimpaired flow
not historically gaged flow
Adjustment for current use may result
in C determined from gaged basins to
more closely resemble SWRCB method
Gage Flow Adjustment for Historical Use
600,000
Q
SWRCB
Slope = 0.544
R2 = 0.998
Runoff Volume (AF/yr)
500,000
Gage Data
Slope = 0.509
R2 = 0.971
400,000
350,860
345,060
Navarro River gage
300,000
200,000
Gage + Use
Gage
100,000
14,429
14,225
0
0
iA
Dry Creek gage
200,000
400,000
600,000
800,000
Precipitation Volume (AF/yr)
1,000,000
1,200,000
Conclusion


Rational method may be useful for
screening level analysis
Must be very cautious

Results can vary significantly


Variation in precipitation can have significant
effect on results
Variation in basin characteristics can also cause
wide variation in results
Can a Better Simplified Method
be Developed?
Criteria for Method Development


Defensibility
Purpose

Screening tool





5%-10% criteria
Level of Detail
Time step
Accuracy
Level of effort for applying method
Possible Alternative Method
Using Simplified Approach

Develop equation using method
employed in USGS analysis “Magnitude
and Frequency of Floods in California”
-June 1977
USGS Method

Performed analysis using 705 basins in
California in 6 regions


141 stream flow gages used in North Coast Region
Use gage data and corresponding basin
characteristics to develop simplified equation
by determining how various factors influence
runoff
USGS Approach


Use approach developed by USGS for
developing equations for peak runoff,
but use this approach to develop
equations for annual runoff volume.
Focus on basin characteristics that
affect runoff volume rather than peak
flow
USGS Method

Consideration of Basin Characteristics









Drainage area
Mean annual precipitation
Precipitation intensity
Mean annual potential ET
Main channel slope
Main length
Altitude index
Surface-storage index
Forest cover
Average Annual Runoff Volume Versus Drainage Area
25,000
Runoff Volume (AF/yr)
20,000
Slope = 1.674
R2 = 0.908
15,000
10,000
5,000
0
0
2,000
4,000
6,000
8,000
Drainage Area (acres)
10,000
12,000
14,000
Issues

Actual form of equation will be determined based
on regression results

Must include adjustment to unimpair flow

Significant work involved in developing equations

Simplified approach may not provide required
level of accuracy and detail

Allow for more detail analysis if applicants believe
results are incorrect
Limitations of Simplified
Methods




Estimation of seasonal runoff
Estimation of February median
Error in estimation may be too large
even for screening analysis
Ignores stream-groundwater interaction
Conclusion

SWRCB WAA appears to be adequate for
preliminary screening analysis; however
when water availability is close to
screening criteria additional analysis may
be needed
Conclusion and Suggestions





Develop more robust method
Apply a method that uses seasonal or monthly
time step
Develop better estimate of February median
Enhance method for estimating historical use
Use more precipitation gages in estimates