Current Trends and Approaches in Urban Hydrogeology

 

Ioan Bica (1), Constantin Radu Gogu (1),(2), Marin Palcu (1),(3)

(1) Technical University of Civil Engineering, Bucharest (Romania); (2) Romanian Academy, Center for Artificial Intelligence Bucharest,(Romania);(3)GeoAquaConsult, Bucharest(Romania)


In Europe numerous urban areas are located in flood plains of the rivers.  Sedimentary media (alluvial sediments, deltas, etc.) form particular frequently occurring environments within these valley fills. However, sedimentary media are normally significant aquifers due to their high permeability, storage and management ability, interaction with surface water, etc.
Traditionally the exploitation of this kind of aquifers has been significant because, among other reasons they are frequently highly accessible (in general there is no need for complex water catchments works, but wells and/or superficial boring usually between 10 to 100 m depth is sufficient in these cases). This same reason, among others, also contributes to the fact that they are highly vulnerable. In order to secure and guarantee the time and the use of these resources, a good hydrologic management is mandatory.
A reliable water management can be obtained by groundwater modeling. The models allow conceptualizing and quantifying the hydrogeological processes and simulate various scenarios as droughts, water resource exploitation, water quality evolution and contamination aspects, interaction with civil works in terms of hydraulical and geomechanical ground behavior.
These models can provide accurate results if they correctly reproduce the hydrogeological processes. Nevertheless, it is well-known that sedimentary media are normally extraordinarily heterogeneous, which is a paradox as it leads to simplified models based on the homogeneity of large zones characterizing the medium.
It has been demonstrated that it is possible to use homogeneous representative models giving information on the behavior of the aquifer regarding the water resources. Nevertheless, these models are completely inadequate to characterize pollution problems and their remediation, where the most important point is connectivity.
Hydrogeological modelling could represent correctly the considered processes only (1) if the genetic structure and evolution of the sedimentary medium is accurately known, (2) if the petrophysic and hydraulic properties can be correctly extrapolated, and (3) if the tools to implement these properties in the hydrogeological models are available. In order to be able to answer to these mentioned issues, available accurate and detailed geological description of the media is necessary. The information expressing this kind of description can be manipulated by spatial databases within a GIS environment.
The paper presents a software platform containing methodologies and tools that facilitate the integration of the 3D geological models in sedimentary media into the hydrogeological modeling of flow and contaminant transport. This is composed by a geospatial database and a set of tools allowing accurate stratigraphical analysis. The geospatial database is used for the management of a large amount of different data types coming from different sources (geophysical, geological, hydraulic, and others). Its structure allows storing accurate and very detailed geological core description that can be straightforwardly generalized and further upscaled.
The obtained methods and tools are used for spatial data manipulation, which support understanding the detailed geology of the sedimentary media and the integration of the geological processes that controlled their formation. From the existing data and the developed methods, the petrophysical characteristics could be extrapolated to the entire sedimentary volume considered at a local level, by using various techniques such as the deterministic or stochastic methods.

Buletinul Stiintific al Universitatii "Politehnica" din Timisoara
Seria HIDROTEHNICA
TRANSACTIONS on HYDROTECHNICS
Tom 52(66), Fascicola 1,2, 2007

 
 
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