Process-oriented concepts for adaptive water resource management. implications for urban hydrogeology

Abstract

The present thesis illustrates process-oriented methods for water resource monitoring, management and protection. The methods have been applied and tested for specific questions arising in the context of urban hydrogeology within selected areas in the region of Basel, Switzerland. The results contribute to an integrated perception of surface and subsurface water resources in urban areas. Although the topics of the investigations may differ in terms of objectives and scales, the concept and methods are characteristic for many hydrogeologic problems in urban environments. The basic principles of adaptive groundwater management include the identification of the current profiles of groundwater systems. The methods applied facilitate the evaluation of the sum of impacts and their interaction in time and space with changing hydrological, operational, technical and even geological boundary conditions. The thesis consists of five parts (Parts I-V), including this executive summary, an introduction, a general summary together with the discussion of results and conclusions. Each part represents an already published or submitted scientific article. The investigations address a variety of site-specific questions arising from different scales in the context of urban hydrogeology. All parts deal with impacts of engineering projects and infrastructure development on surface and groundwater systems. Part I illustrates that, with the aid of groundwater modeling, the dynamics of the groundwa­ter ?ow regime under changing spatial and temporal constraints could be simulated and evaluated successfully during the various project phases of a tunnel highway construction. The results allowed to optimize groundwater monitoring, management and protection and to progressively evaluate different engineering proposals. The methods presented in Part II exemplify quantitative data fusion for urban hydrogeology as a practical tool for subsurface characterization. The applied techniques allow integrating different type and quality data into groundwater models and to quantify the effect of groundwater flow budgets and velocities in individual sedimentary structures. Obviously, groundwater flow in heterogeneous media occurs largely through interconnected highly permeable sedimentary structures. In Part III process-oriented approaches for adaptive groundwater management in urban areas is illustrated by selected examples in the region of the city of Basel. The concept focuses on the influence of various water engineering projects on the future development of water resources and associated flow regimes. Further emphasis is on the transient character of river-groundwater interaction and the revision of existing protection concepts. Part IV and V illustrate the results of a project dealing with urban infrastructure maintenance and development at a smaller scale. Subsidence of a river dam and an adjacent highway, both constructed on gypsum-containing rock, required remedial construction measures. This case study presents comprehensive research within a gypsum karst site. Next to universal measurements and monitoring technologies, investigative methods with predictive character are developed that allow long-term predictions on the future evolution of the system and on further subsidence. This part further illustrates that the proposed concept and methods can be used for the setup of monitoring networks and the development of adaptive water management tools on the one hand, but also can be applied for basic research on the development of gypsum karst systems on the other hand. The various investigative methods for karst aquifer characterization complement each other and allow the interpretation of short-term impacts and long-term developments. The scientific achievements of this thesis include: (1) the implementation of a concept for adaptive and integrated water resource management; (2) the demonstration of integrating different methods and tools for process-oriented investigations in urban areas (monitoring, modeling, hydrogeophysics, etc.); (3) the fusion of qualitative and quantitative geological and hydrological information of different quality to describe aquifer heterogeneity; (4) the revision of existing protection concepts and approaches for risk assessment; (5) the application of karst evolution modeling based on genuine field data; (6) novel iterative approaches for the setup and combination of groundwater and karst evolution modeling techniques; (7) methods applied to characterize short-term impacts and long-term development of flow regimes in karst areas and (8) suggestions for monitoring strategies, including the development of tools that can be used for prediction in urban hydrogeology.