An analysis of the surface water resources of the upper Taieri River, Otago
Simmers, I. (1975). An analysis of the surface water resources of the upper Taieri River, Otago (Thesis, Doctor of Philosophy (PhD)). The University of Waikato, Hamilton, New Zealand. Retrieved from https://hdl.handle.net/10289/12764
Permanent Research Commons link: https://hdl.handle.net/10289/12764
To plan a water resource survey data collection programme, it is vital to first establish the purpose for which the gathered data are to be used, and the degree of precision of the information at a particular confidence level that will be adequate. Purpose will determine the required data precision. Precision requirements will in turn dictate minimum record lengths of each variable necessary to estimate population parameters at a point, and the network density needed for parameter estimation over an area. This study is concerned with the data requirements and analyses for the planning of an irrigation scheme in the Maniototo Plains and Styx Basin, Central Otago. The 95 percent confidence level is adopted for required data precision. Allowable standard errors of population parameter estimates are stated to be 10 percent for streamflow and precipitation and five percent for temperature. Measured monthly, seasonal, and annual parameter values of these variables are summarised and discussed. Although the data collection networks are shown to be theoretically acceptable for most purposes, the measured data do not allow estimation of all the needed total - and sub-catchment population parameters at the required precision level. Record synthesis is necessary in order to increase the amount of information contained at this stage in the precipitation and streamflow data series. Techniques chosen for time series extension and spatial extrapolation are linear7 curvilinear and multiple regression analyses, water balance, conceptual and stochastic models. Each model is described, and limitations or advantages outlined. Also discussed are the theoretical aspects which concern precision of population parameter estimates from blended data, standard errors of prediction for synthetic records, and the relative simulation and prediction abilities of the models chosen. Split-record techniques are used to evaluate within and between model efficiencies. Addition of synthesised records to the precipitation and streamflow data series still does not permit estimates of all required population parameters at the levels of precision stated as needed. In some instances, record extension results in a decrease in statistical information. For design of any irrigation scheme to proceed now, therefore, the chosen error criteria must be judged too stringent for the Upper Taieri data. If the calculated standard errors cannot be accepted, all precipitation and streamflow records from the study area will require extension by additional observations. The study is also used as an opportunity to check the validity of commonly. accepted concepts of 'regional hydrology', at least within the East Otago Region. It is concluded that for low flows, hydrological homogeneity cannot be assumed to equate with uniformity of basin characteristics. Regions are better defined in terms of allowable areal variation for stated hydrological parameters. The study area is not hydrologically homogeneous by the defined criteria. Further, the boundaries of hydrologically similar regions vary dependent on which streamflow parameter is considered. Results are presented in British units throughout this study, since these are the units in which the basic data were measured and analysed.
The University of Waikato
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