Polyak et al. (Reports, 7 March 2008, p. 1377) reported speleothem data leading to their inference that the western Grand Canyon incised much earlier than previously thought. This contradicts several lines of published geological knowledge in the region, hinges upon unjustified hydrogeological assumptions, and is based on two anomalous data points for which we offer alternative explanations.

Groundwater resources from karst aquifers play a major role in the water supply in karst areas in the world, such as in Switzerland. Defining groundwater protection zones in karst environment is frequently not founded on a solid hydrogeological basis. Protection zones are often inadequate and as a result they may be ineffective. In order to improve this situation, the Federal Office for Environ...

Deep porous reservoirs are subject to charge and discharge of fluids (oil, gas or water), either naturally or induced by human exploitation. This leads to a variation in pressure inside the reservoir and consequently to a deformation of the overlying material. The knowledge of the ground surface displacements allows inferring the fluid migrations and the hydromechanical properties in the porous...

The aquifers of the Spanish Mediterranean coast are generally subjected to intense exploitation meet growing water supply demands. result is salinization due marine saltwater intrusion, causing a deterioration in quality pumped, limiting its use for community needs, and not always being well delimited. To prevent deterioration, groundwater control network usually allows precise knowledge areas ...

This work sets out a physical-stratigraphical reconstruction of the superficial aquifer in the Brindisi area; this site is recognized to be at significant environmental risk (Law no. 426/98) by the Italian government. Geological, hydrogeological and geophysical methodologies were applied. The geological characterisation consisted of surface 5 and subsoil surveys. The existing stratigraphical, g...

The hydrogeological conditions of a region strongly influence the low flow behaviour of river systems. The quantification of the hydrogeological conditions of a catchment and the application of hydrogeology for estimation purposes is very difficult. Up till now only a few solutions are found in the literature. This paper discusses a river network approach using hydrogeological conditions to est...

Exploring the relationship between agricultural nitrogen (N) loading on a dairy farm and groundwater reactive N concentration such as nitrate (NO3) is particularly challenging in areas underlain by thin soils and karstified limestone aquifers. The present study on such a site aims to relate changes in detailed paddock specific agronomic N-loading, hydrogeological and geological site characteris...