We have gathered a range of videos to help you deepen your understanding of decision-support modelling and to enable you to implement appropriate modelling solutions.  Some of these are educational videos, others are recordings of GMDSI hosted webinars. Most of these videos are of general interest, describing the theoretical and conceptual outcomes of history-matching, while some are more specific and of a more technical nature.

1. General

Videos and webinars in this section are of general interest. They discuss a wide range of topics, addressing the core concepts that underpin decision-support modelling without going into too much technical detail. These videos are of interest for both modellers, those who procure models and regulators.

Groundwater Modelling and the Scientific Method: Part 1

This is the first of a two-part series recorded by John Doherty. The first video is philosophical. The second video provides two real-world examples of the philosophy at work. This first video begins by examining the scientific method. It then examines the way in which decision-support groundwater modelling is commonly

Groundwater Modelling and the Scientific Method: Part 2

This is the second of a two-part series recorded by John Doherty. The first video is philosophical. The second video provides real-world examples of the philosophy at work. Two examples are discussed. Both of these are the subject of GMDSI worked example reports. The first example illustrates how, through simultaneous

How Complex Should a Groundwater Model Be? by Catherine More and John Doherty Because environmental systems are complex, models must be complex too. Otherwise, how can they simulate the impact of human management on natural systems? This applies especially to groundwater systems. After all, water flows through heterogeneous media and interacts with surface water bodies in

Seeking Common Ground: Modellers and Geologists

On 28th October, 2020 GMDSI hosted a discussional webinar whose purpose was to address tensions which sometimes arise between modellers and hydrogeologists If you would like to watch the webinar, click here. After the webinar, some of our listeners had their say – you can read their comments or contribute your

Uncertainty in Groundwater Modelling 101 by Catherine Moore and John Doherty We have talked about uncertainty before – in last year’s webinar series. We have been asked to talk about it some more. Our target audience for this webinar are those who are not necessarily modellers but who must work with modellers, and who

Webinar series: Decision-Support Modelling Principles and Practice

In May and June 2020, GMDSI offered a four-part webinar series on decision-support modelling principles and practice. John Doherty and Catherine Moore presented the first three of these webinars, while the fourth was presented by John Doherty and Jeremy White (USGS and co-author of the PEST++ suite). The webinars were

Who cares? What will it cost?

Approaches to improve the value of models and to reduce total project costs. Presented by Ty Ferre, University of Arizona. Download on VIMEO

2. Advanced

Videos and webinars in this section are a bit more technical. These introduce how to undertake decision-support modelling in practice, as well as providing examples of real-world cases. They discuss the challenges of groundwater modelling calibration, history-matching and uncertainty quantification.  


Christmas cracker

We are calling this our “Christmas Cracker” webinar for two good reasons. Firstly, it was held just 10 days before Christmas. Secondly, it was entertaining, and easy to listen to.


1. Vectors and Statistics

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

2. What is Calibration?

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

3. Well Posed Inversion

This video shows how parameters can be estimated when model calibration constitutes a well-posed inverse problem. However, in groundwater modelling, well-posedness does not occur unless

4. Problems with Manual Regularisation

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

5. Tikhonov Regularization

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,

6. Singular Value Decomposition

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

7. Pilot Points

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


Basic Geostatistics – Part 1

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

Basic Geostatistics – Part 2

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

PEST Software

What is PEST?

This video provides an overview of PEST and the three families of utility software that accompany it. It also provides a brief discussion of the

Getting the Most out of PEST – Part 2

This second video of a two-part series covers calculation of finite-difference derivatives, defences against model output numerical granularity, some aspects of observation weighting, termination criteria,


On 22 September 2020, Jeremy White and Mike Fienen from the USGS presented a GMDSI sponsored webinar on PEST++ V5.  PEST++ V5 includes a wide