Territory Stories

Alice Springs recreational dam hydrology report project 6

Details:

Title

Alice Springs recreational dam hydrology report project 6

Creator

Jackson, D.; Paige, D.

Collection

E-Publications; E-Books; PublicationNT; Report no. 12/1979

Date

1979-10-01

Notes

Date:1979-10

Language

English

Publisher name

Northern Territory Government

Place of publication

Darwin

Series

Report no. 12/1979

File type

application/pdf

Use

Attribution International 4.0 (CC BY 4.0)

Copyright owner

Northern Territory Government

License

https://creativecommons.org/licenses/by/4.0/

Parent handle

https://hdl.handle.net/10070/228346

Citation address

https://hdl.handle.net/10070/674275

Page content

Technical Report WRD79012 Viewed at 00:02:46 on 18/02/2010 Page 145 of 153. I I I I I I I I I I I I I I I I I I I I 42 Estimates of the time required to fill the reservoir with silt are 120 years, 40 years and 400 years for average, dry and wet conditions respectively. Those estimates of useable reservoir volume and time to fill with silt are lower limits. Brune's analysis uses mean annual sediment loads. r-or the Todd Catchment median values are up to 50% lower than mean values and are a better estimate of the most frequently occuring annual load in the arid environment. Furthermore a detention time of 0.42 years (150 days) is uniealistie in relation to typical lengths of hydrographs (one to three days) and the short length of the dam at top water level (1600m). For a typical 1 in 10 year hydrograph in which mean daily flow is of the order of 100 m'/s; detention time = 5.1 Mm' 100 x 3600 x 24 x 10- 6 Mm 3 /day = 0.59 days 0.002 year. Trap efficiency from Brunets curve approaches 5% for a 0.002 year detention time instead o the 95% obtained for a 0.42 year detention time. Table 5 shows reworked estimates of useable reservoir capacity for a 0.002 year detention time and the median annual sediment load. Table 5 PERCENTAGE OF ORIGINAL CAPACITY REMAINING AFTER DIFFERENT PERIODS OF OPERATION ASSUMING 5% TRAP EFFICIENCY. Time 25 Years 50 Years 100 Years Suspended Average Conditions 99 98 97 Sediment Relationship Dry ( 1965) Wet (1979) Conditions Conditions 98 97 [Neglig~blel 94 Reduct~on