Platte River Ecosystem Resources and Management, with Emphasis on the Big Bend Reach in Nebraska
Tables
Table 14. Pulse flow recommendation for the central Platte River valley ecosystem during May and June.
| Period |
Flow (CFS) |
Duration (Days) | Frequency (Yrs) Exceedence (%) | |
| Very Wet | May 1 - June 30* | >16000 | 5** | 1 in 5 (20%) |
| Wet | May 1 - June* | > 12000 | 5** | 1 in 2.5 (40%) |
| Normal | May 20 - June 20 | > 3000 | 7-30*** | 3 in 4 (75%) |
| Dry | May 11 - June 30 | none**** | all remaining (100%) |
* At least 50% of these pulse flows should occur during May 20 to June 20,
with May 1 to June 30 as the timeframe for broadest benefit for channel maintenance,
and instream and wet meadow habitats. Occurrence between February 1 and June
30 would accomplish the necessary effects for channel maintenance. The 10-year
running average for the mean annual pulse flow targets should range from approximately
8,300 cfs to 10,800 cfs.
** The duration of these pulse flows should emulate the historic, natural
pattern: (a) ascended over approximately 10 days, (b) cresting for approximately
5 days, and (c) descending over approximately 12 days.
*** The target is for a 10-year running average for the 30-day exceedence
flow (i.e., 10-year running average of the annual level exceeded for 30 consecutive
days) of at least 3,400 cfs. A flow of 3,000 cfs should be exceeded for 7-30
days in at least 75% of years. Pulse flows should be followed by descending
flows approximating a rate of 800 cfs/day.
**** No pulse flows during May and June in driest years; target flows identified
in (Bowman 1994), apply under dry year conditions.
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