Contribution of the dynamic visualization of a 3D hydrogeological conceptual model to the participatory management of groundwater resources

Groundwater is an essential water resource for domestic use, agriculture and other socioeconomic activities, as well as ecological services around the world. Participative approach to water resources management is essential, and requires all stakeholders to have sufficient knowledge and understanding of processes taking place, from rainfall to recharge, drainage and discharge ([De Marsily and Besbes, 2017]). Understanding unseen processes require abstraction and imagination. In many cases, detailed 3D conceptual models may help non-specialists to understand underground environments and thereby address questions related to the management of groundwater resources ([Jeannin et al., 2013, Malard, 2018]). In order to increase the understanding of dynamic hydrogeological processes, a flow animation module (FAM) has been developed within Visual KARSYS (https://www.visualkarsys.com/); a web tool dedicated to 3D conceptual modelling of complex aquifers. Concepts and principles of 3D conceptual models and of the new FAM are presented and discussed in this paper with an application to a volcanic aquifer in Indonesia

A pluridisciplinary methodology for intregrated management of coastal aquifer - Geological, hydrogeological and economic studies of the Roussillon aquifer (Pyrénées-Orientales, France)

In order to study Mediterranean coastal water management, a pluridisciplinarity approach is developed. Reservoir geology and some of its tools, used in oil prospecting, are applied to build a detailed sedimentary model. The analysis of depositional environments and sedimentary process allows the correlation of pre-existing data (outcrop, borehole, and seismic profile) using Genetic stratigraphy (onshore domain) and seismic stratigraphy (offshore domain). The interpretation results in a better knowledge of the sedimentary geometries following correlations between onshore and offshore domains. It is thus possible to differentiate the coastal groundwater aquifers precisely and to establish their relative connections. At the same time, hydrogeological investigations such as hydrochemistry and geophysical prospecting allow us to elaborate the hydrogeological conceptual model of the case studies. Variable-density flow and solute transport simulations constitute the hydrogeological work. Experimental economy constitutes the third part of this integrated methodology. It assesses the effectiveness of institutional arrangements to cope with aquifer overexploitation. Feed-back from these three fields of research will also authenticate our methodology. This approach applied on Roussillon basin (South-west of French Mediterranean coastline) could be exported to many other coastal area

Contribution of the dynamic visualization of a 3D hydrogeological conceptual model to the participatory management of groundwater resources

Groundwater is an essential water resource for domestic use, agriculture and other socioeconomic activities, as well as ecological services around the world. Participative approach to water resources management is essential, and requires all stakeholders to have sufficient knowledge and understanding of processes taking place, from rainfall to recharge, drainage and discharge ([De Marsily and Besbes, 2017]). Understanding unseen processes require abstraction and imagination. In many cases, detailed 3D conceptual models may help non-specialists to understand underground environments and thereby address questions related to the management of groundwater resources ([Jeannin et al., 2013, Malard, 2018]). In order to increase the understanding of dynamic hydrogeological processes, a flow animation module (FAM) has been developed within Visual KARSYS (https://www.visualkarsys.com/); a web tool dedicated to 3D conceptual modelling of complex aquifers. Concepts and principles of 3D conceptual models and of the new FAM are presented and discussed in this paper with an application to a volcanic aquifer in Indonesia

Hydro-socio-economic implications for water management strategies: the case of Roussillon coastal aquifer

In many Mediterranean coastal areas, agriculture, drinking water supply, tourism and industry strongly depend on the available groundwater resources. As a result of the significant economic development during the last three decades along the coast, abstractions from coastal aquifers have increased tremendously, frequently leading to overexploitation and saltwater intrusion. Geological, hydrogeological and socio-economical studies as a multidisciplinary approach on a coastal Mediterranean aquifer- the Roussillon - have been carried out in order to design effective water management strategies on areas sensitive to seawater intrusion risk. Geology provides geometry and architecture of the different aquifers, hydrogeology assess the seawater intrusion risk while socio-economic study includes consulting the stakeholders with the aim of suggesting water management and policy option acceptable to the majority of population. This paper then highlights the economic interests at stake, diversity of viewpoints expressed by stakeholders and political dimension of the issue, which are likely to be encountered for all similar situations on both sides of the Mediterranean Sea

Mathematical modeling of karstogenesis: an approach based on fracturing and hydrogeological processes

The karstogenesis of a synthetic aquifer is analyzed as a function of the matrix permeability and the fracture density affecting the carbonate reservoir. The synthetic carbonate aquifer generation results from numerical simulations based on Discrete Fracture Network (DFN) and groundwater flow simulations. The aim is to simulate karstogenesis processes in an aquifer characterized by a fracture network, while matching field reality and respecting geometrical properties as closely as possible. DFN are simulated with the soft REZO3D that allows the generation of 3-D realistic fracture networks, especially regarding the relative position of fractures that control the overall network connectivity. These generated DFN are then meshed and considered to perform groundwater flow simulation with the model GroundWater (GW). At each time step and for each fracture element, flow velocity and the mean groundwater age are extracted and used in an analogical dissolution equation that computes the aperture evolution. This equation relies on empirical parameters calibrated with former speleogenesis studies. In this paper, karstogenesis simulations are performed using fixed-head hydraulic boundary conditions within a single stratum as a function of two fracture density settings. The results are interpreted in terms of head fields, mean groundwater age distributions; while total flow rate and average aperture are analyzed as a function of time. The effect of fracture density and rock matrix permeability are then assessed

Geological and Morphometric Characteristics of Quaternary Pyroclastic Aquifers in Salak and Pangrango Stratovolcano.

Indonesia is located in a subduction zone formed by the collision of continental and oceanic plates. Many volcanoes form as a result of these conditions along the arc. Springs on the volcano's slopes are widely used for domestic, irrigation, and industry water use. Investigating the characteristics of aquifers and springs is essential to ensure groundwater sustainability by providing a robust geological framework. Meanwhile, groundwater in a volcanic geological setting has good quality characteristics because of its occurrence process, which interacts with many minerals in pyroclastic rocks that act as aquifers. The study area is located in the Lido Catchment Area (LCA), which is situated between two distinct volcanic slopes. Geological and morphometric analysis at LCA is the basis of important information relating to its hydrogeological systems. The analysis of thin rock sections and parameters of the physical properties of water in groundwater springs supports our research. We applied a comprehensive geological and morphometric analysis to obtain detailed information about the aquifer. This study aimed to determine the characteristics of aquifers in pyroclastic rocks and their relationship to the formation of springs. From the research conducted, the characteristic of water can be distinguished based on the geological conditions of its constituents. There are 6 different lithological characteristics in the study area: polymictic breccia, monomictic breccia, lapilli, lapilli tuff, coarse tuff, and fine tuff. From the lithology variations obtained, breccia, lapilli, and coarse tuff can play a good role as aquifers. Geological correlations and groundwater systems in the study area show groups of superficial, mixed, and alteration springs. The system of water flows in aquifers through inter-grains or rock fractures. The types of springs in LCA are dominated by depression and fracture types. These results are fundamental information for understanding hydrogeological systems in future volcanic geological settings

27. De la carte géologique à la carte hydrogéologique

La cartographie du sous-sol fournit des informations essentielles concernant les eaux souterraines (la présence et la dimension des réservoirs leur exploitation, leur gestion…) par l’intermédiaire des cartes et des coupes géologiques, ainsi que des notices explicatives. Les informations reportées sur une carte géologique concernent les formations géologiques affleurantes, avec un code couleur selon l’âge des formations, leurs inclinaisons (pendage*) et la présence de failles (figure 1). Il ex..