New Methods for Optimal Management of Karstic Aquifers: Case of Big Spring Missouri

Monday, December 4, 2017: 4:30 p.m.
Alain Mangin, Ph.D. , Ramboll, Irvine, CA
Farid Achour, PhD , Site Solution and Water Resources, Ramboll, Irvine, CA

The results obtained during these last decades on karstic systems have clearly emphasized their specificities. These specificities are mainly due to the organization of voids in the karst, which, due to the mechanisms of their emplacement, are distributed in an extremely heterogeneous way. Moreover, all the voids do not have the same function with respect to the flows. In saturated medium (saturated karst), some voids (the drains) ensure the propagation of waters: it is the transmissive function, while others (systems connected to the drainage) give an account of their storage which corresponds to the storage function. These properties determine a highly non-linear hydrodynamical behaviour with all its consequences: sensitivity to initial conditions, high unpredictability, and impossibility of using simple deterministic modelling. Due to the permeability contrasts between drains and ancillary systems, depending on the duration of the events (floods), only parts of the aquifer are involved. Therefore, over time, the karstic aquifer possesses a variable geometry.

To better study, exploit and manage Karstic aquifers, a new approach using systemic analysis is currently used by Ramboll Environ. This approach uses a different state of mind than the conventional hydrogeological approach and requires an abundant collection of continuous data - using transducers - of the various parameters that monitor the functioning of the karstic aquifer (discharges, water levels, rainfall). This approach involved the development of a set of methods and high-performance software to extract information from the collected data, to recognize the physical signatures that are responsible for it and thus, whatever the difficulty encountered, including non-linearities, characterize the dynamics of systems and predict their behaviours. These methods are called correlative and spectral analyses, continuous or discontinuous wavelet analyses, Rescaled Range Analysis, fractal or multifractal analyses and attractor analyses.

The application of these methods to Big Spring, Missouri allowed the establishment of an “Identity Card” of the spring, encompassing all information necessary for an optimal management of the spring.

Alain Mangin, Ph.D., Ramboll, Irvine, CA

Farid Achour, PhD, Site Solution and Water Resources, Ramboll, Irvine, CA
Dr Farid Achour is a Senior Science Advisor and Senior Manager at Ramboll Environ in Irvine California. He has a MS in Hydrogeology and a PhD in Earth Sciences from the University of Besanson in France, he joined the Swiss institute of Hydrogeology for post doctoral researches on water availability in semi arid areas. Dr Achour has 20 years of experience in quantitative hydrogeology and data analysis applied to environmental projects with specialty in geological and hydrogeological characterization and remediation in porous and fractured medias, fate and transport modeling in porous and fractured media, surface water-ground water interaction analysis, and geochemical modeling. Expertise also includes geostatistics, statistics applied to environmental projects.

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