Parsimonious hydrological modelling for resource development

Parsimonious hydrological modelling for resource development

The format and content of this dissertation has been structured to meet the written and implicit requirements of the University of Southern Queensland's Engineering Doctorate and to demonstrate the levels of innovation and intellectual excellence expected of any doctorate.

The research reported in this dissertation was initiated by hydrological design and analysis challenges encountered professionally, predominantly in developing data scarce regions of the world. The research spans four themes; catchment yield, catchment (spatial) rainfall synthesis, flood and contaminant routing, and the variance damping characteristics of linear storage.

The overarching notion across all these themes is that with limited calibration data simple parsimonious models provide the highest predictive reliability.

Many aspects of this and related research has been reported in engineering journals, conference papers and oral presentations to peers. My theme contributions documented in
this dissertation include:

Catchment Yield

· A single calibration parameter catchment yield model with an extensive worldwide database.

· An auto calibrating disaggregation model that takes the mean annual runoff from the yield model and disaggregates this runoff to daily timestep (and finer) rainfall excess.

· A deterministic baseflow filter that objectively defines the baseflow fraction and storage constant. This filter is based on a simple quickflow and slowflow storages in
parallel conceptual model of hillside runoff and maybe combined with the disaggregation model to produce a daily runoff series, or with a flood model for design flood synthesis.

· A rugged terrain calibration procedure that allows the yield model to be calibrated using measured runoff and estimated potential evapotranspiration when catchment
rainfall is unknown or poorly defined.

Catchment Rainfall

· A methodology for defining the attenuating effects of catchments on rainfall input variance and the equivalent number of independent gauges required to synthesise
catchment rainfall with the correct variance.

A procedure for synthesising catchment (spatial) daily rainfall over a triangular network that preserves nearest neighbour correlations and total and conditional wet
and dry day probabilities.

Flood and Contaminant Routing

· A pragmatic methodology for scaling rainfall runoff models that reduces the impacts of catchment schematisation on flood calibration and prediction and facilitates the
inclusion of contaminant dispersion in routing models.

· The development of a formal definition for ramp and triangular input unit hydrographs applicable to any instantaneous unit hydrograph shape that facilitates the
'routing' of flood and contaminant hydrographs by convolution generally and in particular through the 'fractional' storages required to maintain scalability in routing models of large catchments with low slope downstream reaches.

· A parameter efficient nonlinear lag/storage equation based on dimensional analysis and similitude principles that reduces the lag/storage equation predictor from three to two fitting parameters and for which the constant in this formulation may be universal.

Linear Storage Damping

· A fundamental analysis of the damping effects of linear storage on random and temporally correlated inputs that has been made with, for example, application to flood and baseflow synthesis and reservoir storage reliability analysis.

· A seasonal scale approach to estimating minimum streamflows that provides an alternate estimate to daily simulation.

· A procedure for reservoir storage analysis on catchments with large heavily damped baseflows.

History shows Civil Engineering and Engineering Hydrology in particular has advanced, by an interesting, variable mix of pragmatic 'learn by doing' innovation and rigorous scientific experimentation and analysis. The University of Southern Queensland Engineering Doctorate aims to draw together these parallel synergistic contributions to professional engineering. Hopefully this dissertation contributes by example to this objective.