The results of joint use of these methods can be found in many publications for the last 30 years. For example, the vertical electrical sounding (VES) and time domain electromagnetic (TDEM) methods pairing for water surveying has already become classic, but we will not discuss it in this article. The simplest and most natural application of joint inversion is a combination of electrical and electromagnetic methods. This can be either specific boundaries or objects, or a part of the model or a range of depths. The main goal of joint inversion is to take the best from each dataset used and use this in constructing a joint resulting model that satisfies all the methods involved in the inversion. After all, the result of formal inversion is not a final solution and due to equivalence, especially in the areas of poor sensitivity of the section elements, the problem may have many, although often close, solutions. Application of joint criteria allows suppression of equivalence significantly, but only if, from the geological point of view, the criteria is chosen correctly. The use of joint inversions is a special way of incorporating a priori information, imposing some restrictions on parameters’ changes for the methods involved in the joint inversion. It should be noted that if the sections of different petrophysical properties have nothing in common, the algorithms of joint inversion should not be applied, since they will rather worsen the result. It is also possible to consider the images of petrophysical sections (their structures) as a common parameter. Joint inversion is an algorithm for solving an inverse problem for two or more methods that have something in common, such as boundaries, properties, or gradients of these properties. First, let’s define what a joint inversion is. In this short review article, we will discuss modern methods of joint inversion applied to hydrogeophysical problems. Speaking about joint inverse problems, one cannot but mention the pioneering work of Vozoff in this area, in the 1980s. Now in the era of rapid development of numerical modeling methods, geophysical methods are combined at the level of solving forward and inverse problems, i.e.

A successful combination of methods is the key to solving various geophysical problems.

Combining geophysical methods has been around for quite a long time and is an independent branch of geophysics.

Res2dinv model refinement