Shurniak, RE & O'Kane, M 2009, 'Methods for simulating measured field responses for long-term performance of mine waste cover systems', in AB Fourie & M Tibbett (eds), Mine Closure 2009: Proceedings of the Fourth International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 473-484, https://doi.org/10.36487/ACG_repo/908_36
(https://papers.acg.uwa.edu.au/p/908_36_Shurniak/)
Abstract: Mine waste cover systems are typically a key component of mine closure plans. For this reason, and because 
cover systems generally encompass a large component of mine closure costs, it is critical that an acceptable 
level of risk in determining long-term cover system performance is achieved. Numerical simulations using 
computers are the most common tool used to evaluate the long-term water balance of mine waste cover 
systems. However, the accuracy of such simulations is dependent on the quality of data available to 
determine model inputs. The preferred method for ensuring the most representative model inputs are used is 
to simulate past performance of the cover using data generated from field performance monitoring, referred 
to as a field response model. The inputs from a model that provides a representative simulation of measured 
field responses can then be used as a basis for evaluating long-term mine waste cover system performance. 
Field response models attempt to recreate complexities of the real world in mathematical terms. Hence, all 
facets of a cover system’s water balance must be addressed in the model. This includes, but is not limited to, 
soil-plant-atmosphere interactions, evolution (weathering) of the cover layers, and heterogeneity (as well as 
layering) of materials. This paper presents the current methodology used by the authors to simulate these 
processes. In order to illustrate the methodology, results are presented for field response models developed 
at three sites situated in starkly contrasting climatic regimes: an arid to semi-arid site, a humid subtropical 
site, and a subarctic site. The examples show that following such a methodology can result in a highly 
accurate set of model inputs in almost any climatic region. 
Field response modelling is the most appropriate method of determining and validating a set of model inputs 
for a mine waste cover system. However, field response modelling requires the accurate prediction of 
complex soil-plant-atmosphere interaction with time. Hence, the modelling process requires many iterations 
before accurate estimates of field responses can be realised. The changes to the model made between 
iterations must be deliberate and documented to limit the number of iterations required to obtain calibration. 
This paper presents a methodology for cover system field response modelling that can be used to develop a 
calibrated field response model. The methodology is discussed, and examples of the application of the 
methodology are provided to illustrate the process. Application of this, or a similar methodology, is 
fundamental in developing a model that can be used as a basis for evaluating long-term cover system 
performance under a variety of conditions.