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Alice Springs recreational dam hydrology report project 6



Alice Springs recreational dam hydrology report project 6


Jackson, D.; Paige, D.


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







Publisher name

Northern Territory Government

Place of publication



Report no. 12/1979

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Attribution International 4.0 (CC BY 4.0)

Copyright owner

Northern Territory Government



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Technical Report WRD79012 Viewed at 00:02:46 on 18/02/2010 Page 142 of 153. I I I I I I I I I I I I I I I I I I I 40 3.3 DMASS Computer Programme The DMASS (daily, monthly annual sediment summary) computer programme integrates instantaneous values of suspended sediment transport rate over time. The programme is based on a standard DMAS {daily, monthly annual summary) fot flow volumes (Lee 1979) that has been modified to include a power relationship between instantaneous sediment transport rate and inst~ntaneous flow. This relationship is of the form C = AQ where C is the instantaneous sediment transport rate in g/8 Q is flow rate in m3 /s and A and b are constants. The DMASS and DMAS programmes were run using historical flows (1953 - 1978) at G.S. 006009 to develop relationships between suspended sediment load and flow volume on a monthly basis. Two runs were made: one assuming 1965 conditions applied throughout the historical record and the other assuming 1979 conditions applied. Figure 5 shows the derived points and the fitted relationship for 1979 conditions and the fitted relationship for 1965 conditions. Because there is generally only one flow per month in the historical record, the monthly relationships between sediment load and stream flow reflect the relationships for individual hydrographs obtained from field data. The points in the monthly relationships approximate a power relationship and 1965 condition values are again ten times 1979 condition values An estimate of annual load for each of 105 years was made by substituting the monthly flow volumes derived synthetically (section3 Part A) into the monthly power relationship to obtain monthly sediment loads and then summing the monthly loads over twelve months. Because 1965 and 1979 are representative of extreme climatic conditions, an average relationship (figure 5) was used in a particular year if the rainfall for that year was within one standard deviation of the mean for the 105 year rainfall record. Otherwise the 1965 (drought condition) or 1979 (wet condition) relationship was used as appropriate. The results from this method of classifying catchment condition are shown in Table 3, along with t~e results from the assumptions that the catchment is in one of the two extremes (either drought or wet conditions) for the entire 105 years.