ADJUSTMENTS
To create a historical record of unregulated (or natural) flow, hydrologists take
records of observed (regulated) flows and adjust them by adding or subracting all
known upstream diversions that have records. The result is, at best, a close
approximation of what the flow would have been if all of the upstream adjustments
had not taken place. This record of historical flows is then used to calibrate
the forecast models.
Forecast points and their adjustments are listed in the following format:
NAME OF STREAM LOCATION (forecast point) HUC code NWS id PE Code Fcst Per
avg oct nov dec jan feb mar apr may jun jul aug sep per
+ NAME OF ADJUSTMENT NWS id PE Code
avg oct nov dec jan feb mar apr may jun jul aug sep per
- NAME OF ADJUSTMENT NWS id PE Code
avg oct nov dec jan feb mar apr may jun jul aug sep per
A + sign indicates water is diverted out of the river basin upstream. Therefore this
must be added back into the historical record to obtain unregulated flow. Conversely
a - sign indicates water is diverted into the river basin upstream and must be removed
from the historical record to obtain unregulated flow.
For upstream reservoirs, the monthly change in storage is added to obtain unregulated
flow. If the reservoir was filling (storing water) then the adjustment is positive. If
the reservoir level was decreasing (releasing more than the inflow) then the adjustment
ends up being negative.
PE Code - Physical Element Description Code.
QCMRZZZ - Historical data is observed data from the stream gage (usually USGS).
QCMPAZZ - Historical data is calculated at the CBRFC using the adjustments listed
QCMPBZZ - Historical data is from the operating agency (e.g. Reclamation)
LSMRZZZ - Historical end of month reservoir storage (volume)
EXAMPLE ENTRIES
GUNNISON - GUNNISON, NR 14020002 GUSC2 QCMPAZZ APR-JUL
AVG 21 17.0 14.8 13.5 11.6 15.1 37 118 148 68 35 20 370
+ GUNNISON - GUNNISON, NR GUSC2 QCMRZZZ
AVG 25 17.7 15.7 14.6 12.8 18.3 38 104 127 72 43 29 340
+ TAYLOR - TAYLOR PARK RES TPIC2 LSMRZZZ
AVG 70 69 68 67 66 62 61 75 95 91 83 74 29
GUNNISON - GUNNISON, NR forecast point name (river - site)
14020002 HUC basin code
GUSC2 National Weather Service 5 character station identifier
QCMPAZZ Historical data is calculated using the adjustments below.
APR-JUL Target period of Water Supply Forecasts
AVG 21 17.0 ..... 12 monthly volume averages plus April-July total.
Period of calculation for this example is 1981-2010
volume units are thousands of acre-feet (kaf)
21 October average
17.0 November average
...
370 Period average (Apr-Jul in this case)
ADJUSTMENTS:
+ GUNNISON - GUNNISON, NR GUSC2 QCMRZZZ (add observed streamflow at GUSC2)
+ TAYLOR - TAYLOR PARK RES TPIC2 LSMRZZZ (add change in reservoir storage TPIC2)
The observed flow of the Gunnison River at Gunnison, Colorado is regulated or affected by
the change in storage at Taylor Park Reservoir. When reservoirs are filling
(storing water), the adjustment made on the downstream point is positive (i.e., the flow
at Gunnison would have been higher if not for the reservoir).
Conversely, when reservoirs are being tapped or drained for use, the adjustment on the
downstream point is negative (i.e., the flow at Gunnison would have been lower at this time
of the year if not for the reservoir).
Diversions may also be negative adjustments, as in cases where water is diverted into the basin
from an adjacent watershed. In the adjustment below the Frying Pan River, inflow to Ruedi Reservoir,
is adjusted for diversions out of the Basin (Bousted Tunnel and Ivanhoe Tunnel) and also adjusted
for diversions into the basin (Hunter Creek, No Name Diversion, Midway Diversion).
FRYING PAN - RUEDI RES, BASALT, NR 14010004 RURC2 QCMPAZZ APR-JUL
AVG 5.1 3.8 3.2 2.7 2.3 3.2 8.5 41 63 26 9.7 5.8 139
+ FRYING PAN - RUEDI RES, BASALT, NR RURC2 QCMRZZZ
AVG 4.8 3.7 3.1 2.6 2.1 3.1 8.2 30 36 16.0 7.6 5.4 90
+ CHARLES H. BOUSTED TUN CBTC2 QCMRZZZ
AVG 0.17 0.1 0.09 0.09 0.09 0.11 0.29 13.3 30 10.0 1.99 0.27 53
+ BUSK-IVANHOE TUN BITC2 QCMRZZZ
AVG 0.09 0.03 0.02 0.02 0.02 0.02 0.04 0.91 2.5 0.99 0.27 0.13 4.4
- HUNTER CK DIV HCDC2 QCMRZZZ
AVG NA NA NA NA NA NA 0.01 0.99 2.4 0.68 0.07 0.01 4.1
- NO NAME DIV NNDC2 QCMRZZZ
AVG NA NA NA NA NA NA 0.0 0.68 1.17 0.2 0.01 0.0 2.1
- MIDWAY DIV MDDC2 QCMRZZZ
AVG NA NA NA NA NA NA 0.01 0.88 2.1 0.57 0.04 0.0 3.5