This video provides a short refresher on some aspects of matrix and vector algebra that we all learned at school but have since forgotten. It then does the same for a few basic statistical concepts. It is useful to watch this video before watching some of the other videos in this series. Presented by Dr …
This short video discusses what it means to calibrate a groundwater (or other) model. Calibration implies uniqueness. The quest for uniqueness is not a quest for truth. The uniqueness of a solution of an ill-posed inverse problem requires regularization. If properly applied, regularization yields a solution to that problem which is of minimized error variance. …
The importance of Tikhonov regularization in the solution of an ill-posed inverse problem in general, and in the calibration of a groundwater model in particular, is explained. Also explained is its ability to achieve a solution to an inverse problem that is of minimized error variance through the role that it bestows on expert knowledge …
Singular value decomposition (SVD) is explained. Also explained is the important role that SVD can play in solving an ill-posed inverse problem, and the insights that it can provide into what calibration of a groundwater model can and cannot achieve. Important concepts such as the null space are also discussed. An explanation is provided of …
Pilot points are often employed as a parameterization device for groundwater models. This is because they can provide a sound basis for highly-parameterized inversion while restricting parameters to a number which is low enough to allow filling of a Jacobian matrix using finite difference derivatives. The video discusses options for their emplacement, and how Tikhonov …
This video extends the discussion of the preceding video, while laying the foundation for ensuing videos. It explains how calibration based on manual regularization, whether performed automatically by software such as PEST or done manually by a modeller, may fail to find a parameter field that is of minimized error variance. It also shows that …
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In this continuation of the first video of this series, links between geostatistics and history matching of groundwater models are explored. The use of geostatistical concepts and tools in model calibration, and in calibration-constrained uncertainty analysis are also discussed. Some shortcomings of traditional geostatistics, and how these have been addressed by newer geostatistical concepts such …
This is the first of a two-part series. It discusses correlated random variables. It shows how knowledge of one such variable conditions estimation of the other, and reduces its uncertainty. These principles are then applied to regionalized random variables to demonstrate the concepts behind random parameter field generation and kriging. The semivariogram, and its relationship …
Canberra – 22nd July 2019 A 1-day Groundwater Modelling Uncertainty Workshop, hosted by the National Centre for Groundwater Research and Training (NCGRT) and sponsored by BHP and Rio Tinto was held in Canberra on Monday 22nd July 2019. This highly successful event was attended by over 100 participants from government, academia and private industry. It …
GMDSI is managed by the National Centre for Groundwater Research and Training (NCGRT) and administered by Flinders University.
