Date of Award

2015

Document Type

Thesis - ECU Access Only

Publisher

Edith Cowan University

Degree Name

Doctor of Philosophy

School

School of Engineering

Faculty

Faculty of Health, Engineering and Science

First Supervisor

Dr Mehdi Khiadani

Second Supervisor

Professor Ray Froend

Abstract

Water resources management in the Pilbara region of Western Australia is vital to industry, economy and the environment. This dissertation has aimed to develop a comprehensive hydrological and hydrogeological assessment of water resources in the Yandi mine area located in the Weeli Wolli Creek catchment in the Pilbara. Water resources in this area have become increasingly vulnerable due to growing demand. Climate conditions, geology and hydrogeology, streamflow and the groundwater system of the study area were assessed. Lumped, data-driven and numerical models were employed to develop an understanding of the available surface water and groundwater resources.

Three equations were derived showing the rainfall-runoff relationship within Weeli Wolli Creek catchment and subsequent modelling was undertaken for more hydrology system evaluation. Artificial Neural Networks (ANNs) and IHACRES models were used to simulate the Marillana Creek streamflow discharge, upstream of Yandi. The results suggested that ANN models perform better for a complex catchment hydrological system, compared to IHACRES model.

A VISUAL MODFLOW model was used to investigate the groundwater system and its trend in the Yandi area. The model helped to understand the groundwater responses to future development with various pumping strategies and climate conditions. The scenario analysis assisted identification of zones vulnerable to a significant decline in groundwater level in response to dewatering. The analysis indicated that the maximum water level drawdown of 25m occurred in the aquifer from maximum annual pumping of 23GL. With respect to groundwater yield in particular, abstraction has a more direct impact on the groundwater system compared to climate change.

The recharge into the groundwater was estimated from the fluctuations of groundwater level, groundwater modelling and water balance method. The estimated recharge from these methods was comparable and consistent within 3 to 5% of rainfall. This suggests that direct rainfall infiltration is less, compared to localised infiltration. Two new equations, applicable to Australian conditions, were developed to estimate potential evapotranspiration (ET0). These equations form a part of the water balance equation for groundwater recharge estimation. An artificial intelligent model, based on the Honey-Bee Mating Optimization algorithm (HBMO), was introduced to calibrate the new ET0 equations. The newly developed equations had better performances than available popular equations.

The results of this study showed that the water resources in Yandi are considerably affected by progressing activities and their associated water requirements. A combination of multiple water assessments and modellings suggested that it is feasible to predict future access to surface water as a function of its influencing factors such as climate condition and mining activities. Scenario analysis in groundwater assessment suggested possible alternative future dewatering strategies in the Yandi mine area. The possible groundwater level recovery time is estimated to be one hundred years, which indicates this resource may not be a reliable option in future. Hydrological water balance analysis also indicated that the available surface water volume would decrease to half upon cease of discharge due to closure of mines in the study area, which is controversial condition for future water management.

This research can lead to the implementation of a sustainable water resources plan, and development of appropriate strategies.

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