Indicadores de clasificación contable

The previous demonstration focused on the different approaches that are applied in karst in order to address pragmatic issues related to hydrology, mapping, or 3D organization of the aquifer. It appears that although a multitude of approaches do exist; rare are those which provide a concrete and organized workflow leading to an explicit conceptual model of the system. Such a conceptual model is however a prerequisite for the description of the groundwater flow-system.

Regarding the hydrological, 3D modeling and mapping approaches, it seems obvious that most of them cannot be compared to each other as they do not explicitly present the same conceptual model of the system. Often the conceptual model assumed for a given approach is even not explicitly described. This is a real limitation for applying such approaches – especially regarding practical issues. It is therefore very difficult for the user to select a modelling approach according to a given hydrogeological question. Ideally, the user/modeler should provide an explicit and clear formulation of the hydrogeological question as well as a clear knowledge of the karst context. Based on that, he must explicitly describe the conceptual model of the system required to address the question. Finally the user/modeler should be convinced that the selected modelling approach addresses his hydrogeological question. One difficulty the karst hydrogeologist is to construct his conceptual model of the studied system as no approach does exist for this purpose.

For many practical questions, a good conceptual model is a 3D representation of the flow system. These are the motivations for elaborating KARSYS, which was developed for this purpose. The approach should further be compatible with mapping concepts, with conduits generation approaches and with hydrogeological simulation models. These are the specifications for developing KARSYS (§. 5) and its specific extensions (§. 6).

The KARSYS approach

5.

5.1. Introduction

As described in the previous chapters, karst aquifers are of great significance in terms of groundwater resources, energy, natural hazards, etc. These chapters also point out that many methods do exist for assessing characteristics of karst aquifers.

These methods reveal accurate for depicting one or several characteristics of flow-systems for given conditions.

However most of them do not explicitly present a conceptual model of the aquifer and of the flow-systems.

They usually fail to provide concrete image which synthetizes existing data / observations and simple principles of karst hydrology. Different methods focusing on space or time are often combined but results are barely compared or even synthetized. This often leads to divers and sometimes contradictory interpretations for a same site.

The motivation for KARSYS was to develop a pragmatic approach for synthetizing data and few principles of

karst hydrology in a 3D conceptual model. It is expected that this explicit 3D model intends to document the

main characteristics of karst aquifers and of flow-systems and will serve as a basis for further investigation or for designing numerical models.

The basic idea goes back to the work initiated by L. Kiraly in the beginning of the 1970’s when the author established the 1/50’000 hydrogeological map of the canton Neuchâtel (Kiraly [1973a]). Unlike existing maps which are mostly based on geomorphological description, this document provides a systematic concept for documenting karst aquifers and their characteristics over a whole region. Thanks to geological and hydraulic principles, groundwater bodies were delineated and confined / unconfined parts were distinguished. Flows were not explicitly shown but users may infer the main flow-paths by themselves. Basically, the KARSYS approach combines and summarizes similar concepts and principles as those promoted by L. Kiraly. It also includes concepts and principles which have been developed by other authors such as Palmer [1986] or Jeannin 1996 regarding the development of the conduits and the organization of the flow-systems.

The development of KARSYS has been initiated before the thesis starts. Statement of the approach is presented in Jeannin et al. [2013]. The authors provide the main steps of the approach as well as a series of applications at global and regional scales. This paper gives the state of art. However, conditions for application, modus and limitations were not fully developed and clearly formalized. These are the main focus of this chapter.

As noticed in the description of the Swisskarst project at the beginning of the document; KARYS Original 3D has been applied in various geological and geomorphological contexts and for different issues. Indeed, between 2010 and 2014, the KARSYS Original 3D approach has been applied on the following tests sites (cf. Table 5—1). The application of KARSYS to these sites was highly instructive and made it possible in all cases to improve the hydrogeological knowledge of the considered aquifers (and flow-systems). These various applications were opportunities to test the developed approach and to improve it from a technical point of view: (i) to define

conditions for applying the approach, (ii) to define validation procedures for resulting models and (iii) to asses advantages and limitations of the approach. Various processes of the approach have been made semi- automatic in order to optimize long and recurrent tasks. Scripts and other dedicated routines have been developed to make the routine faster; these have not been detailed here.

Test sites Issues Sites characteristics References

Jura sites of the southern Jura

(VD, CH) hydropower potential Assessment of

Tectonic folded / thrusted setting, relevant geological and hydrological

data Jeannin et al. [2010a] Jura part of the Bernese

canton (BE, CH)

Assessment of karst groundwater aquifers

and reserves

Tectonic folded / thrusted setting, relevant geological and hydrological

data Malard et al. [2012] Beuchire-Creugenat and

Voyeboeuf-Bonnefontaine karst flow-systems (JU, CH)

Assessment of karst flood-hazards

Tabular / horsts and grabens environment, relevant geological and

hydrological data Vouillamoz et al. [2013]

Picos de Europa (Spain)

Assessment of karst aquifers structuration and organization of the

main flow-paths

Tectonic slices setting, poor geological

and hydrological data Ballesteros et al. [2013]

Trovsko-Banjška plateau (Slovenia)

Assessment of karst groundwater aquifers

and reserves

High elevated thrusted plateau, poor and contradicting geological data,

relevant hydrological data Turk et al. [2013] Kanin massif

(Julian Alps, Slovenia)

Assessment of karst groundwater aquifers

and reserves

Tectonic slices setting, poor and contradicting geological and

hydrological data Turk et al. [2014]

Hoch-Ybrig, Helvetic Alps (Schwyz, CH)

Assessment of the karst flow-systems organization and evaluation of tracing

scenarios

Tectonic folded / thrusted setting, plastic deformation, relevant geological

data, poor hydrological data ISSKA [2013a]

Helvetic Alps, canton Sankt- Gallen (S Gallen, CH) Assessment of karst aquifers organization in the perspective of geothermal probes regulation

Tectonic folded / thrusted setting, plastic deformation, relevant geological

data, poor hydrological data ISSKA [2013b]

Prealps, canton Fribourg (Fribourg, CH) Assessment of karst aquifers organization in the perspective of geothermal probes regulation

Composite, tectonic folded / thrusted and slices setting, plastic and ductile deformation, relevant geological data,

poor hydrological data

ISSKA and GeoAzimut [2014]

Table 5—1. Test sites where the KARSYS approach has been applied in the frame of the Swisskarst

project

In addition to KARSYS Original 3D, different extensions have been realized in the frame of this thesis. These are presented in the next chapter (§. 6).