Integration of photogrammetry from unmanned aerial vehicles, field measurements and discrete fracture network modeling to understand groundwater flow in remote settings: test and comparison with geochemical markers in an Alpine catchment

Abstract

Fast and cost-effective techniques for hydrogeological modeling are of broad interest for water resources exploitation, especially in remote settings, where hydrogeological measurements are difficult to perform. Unmanned aerial vehicles (UAV)-based techniques are potentially useful for these aims, but their application is still limited. In this study, a field-based approach and UAV-based approach are integrated for the computation of a discrete fracture network model of a fractured aquifer in the Central Alps. Then, calculated directions of the hydraulic conductivity components were compared with a geostatistical analysis of geochemical markers from sampled spring waters, to infer a conceptual model of groundwater flow. The comparison of field-based and UAV-based fracture measurements confirmed a good matching for fracture orientations and recognized a more reliable estimation of fracture dimensions for the UAV-based dataset. Nonetheless, an important variable for hydrogeological modeling—fracture aperture—is not measurable using UAV, as this requires field measurements. The calculated directions of the main conductivities fit well with the analyzed geochemical markers, indicating the presence of two partially separated fractured aquifers and describing their possible groundwater flow paths. The adopted integrated approach confirms UAV-based measurements as a potential tool for characterization of fracture sets as the input for hydrogeological modeling and for a fast and effective surveying tool, reducing time and cost for other following measurements.

Behavior Data Analysis of English Learners Based on Discrete Dynamic System Modeling Method

“…e modeling technology of discrete dynamic system under linear constant system has been mature. However, compared with the behavior data processing of learners in the education industry, the ordinary discrete dynamic modeling technology cannot meet the research needs [5]. e main reason is that the behavior data generated by learners are multifaceted and multiple types of composite data, which is fundamentally di erent from a single type of variable data.…”

Review of discrete fracture network characterization for geothermal energy extraction

“…UAVs are characterized by their megapixel photosensors, and are therefore capable of collecting numerous (~10 2 -10 3 ) photos of the outcrop with a certain percentage (e.g., 70%) of spatial overlap. After the photos have been taken, the next step is to extract information on the geometry of rock discontinuities by manual digitalization of joints, bedding planes, and faults (Binda et al, 2021). The UAV for applications in geosciences are characterized by different airframes polystyrene, plastic, aluminum, and carbon fiber for the most modern (Giordan et al, 2020).…”

Geochemical Markers as a Tool for the Characterization of a Multi-Layer Urban Aquifer: The Case Study of Como (Northern Italy)

“…Groundwater exploitation for human and industrial use requires the knowledge of the main natural and anthropogenic factors that can affect water quality. Host rock geochemistry and tectonic structural features are natural attributes known to play a major role in groundwater chemical composition and flow path, in addition to the hydrology and geomorphology of the region [4][5][6][7][8]. These attributes, moreover, can greatly affect geochemical background values and can cause high concentrations of potentially toxic elements (PTEs, e.g., As, Ni, Cr, Pb, U, Li), which in turn can negatively affect water quality for human use and consumption [3,[9][10][11].…”

“…Geochemical markers are valid tools used to reconstruct groundwater circulation in these contexts. Different chemical variables, such as major ions [12], trace elements [4], and water isotopes [13], can provide helpful insights for the estimation of groundwater circulation and the determination of recharge areas. Their combined use can therefore provide information to develop and test conceptual models of groundwater circulation in complex systems, identify source waters and evaluate potential subsurface interconnections and mixing between local and regional aquifers [5].…”