Introduction to the special issue on aquifer-sedimentology: problems, perspectives and modern approaches

Progress towards a better understanding of groundwater circulation and tran sport processes in aquifers demands a multidisciplinary approach to a host of unresolved problems. Although much progress has been made within recent years in interpreting the dynamic character of groundwater systems, many ke y issues remain to be addressed. In particular, several areas demand attent ion: the role of sedimentological information (heterogeneity) in groundwate r and transport models, the scaling-up of observations from outcrop scale t o larger scales and the integration of geological and geophysical informati on of different quality into the description of an aquifer structure. Still nowadays many of the heterogeneities cannot be recognized directly because of the limitation of measurement techniques. This is probably one of the r easons for the limited application of aquifer-sedimentology and geophysics in practical cases. In order to consolidate, expand, and make a larger numb er of people aware of the contribution of modem aquifer-sedimentology, incl uding modelling and ultra-high resolution geophysical methods, several line s of intervention were identified: (I) a better collaboration of the differ ent disciplines on site-specific applied problems; (2) development of new m odelling techniques combining data of different quality; (3) development of optimizing tools (position and number of wells, additional geophysical met hods, baysian techniques); (4) development of a 'common language' among sed imentologists and hydrogeologists to overcome communication problems. (C) 1 999 Elsevier Science B.V. All rights reserved.