The difficulties of regional groundwater resources assessments in arid areas

الملخص EN

The paper discusses the hydrogeological characteristics of regional groundwater systems in arid areas.

The difficulties of defining geological detail at large scales are raised and the importance of understanding lithological multi-layering and local structural aberrations.

Emphasis is placed upon the variable character of hydraulic diffusivity within aquifer units and the importance of vertical hydraulic conductivity in intervening non- aquifer units.

Recharge and discharges from the system are discussed together with the problem of representing groundwater flows in unstressed systems.

The importance of using abstraction data for model calibration and the degree of calibration that can be expected are noted.

It is concluded that the models produced allow bulk flow interrogation of the regional systems and afford general principles of groundwater management and supply protection to be pursued, but not local impact details.

It is stressed that the groundwater resources represented should not be interpreted beyond the depths of abstraction accessibility.