Flooding is a recurring natural phenomenon that can have both life-giving and destructive aspects. In natural environments, floods are often an important element of the seasonal hydrologic cycle that provides water and nutrients to soil, supporting unique, rich and diverse ecosystems. However, flood events can also represent a destructive force that can endanger lives and cause significant damage in urban areas. Karst areas, in particular, are unique because of their special hydraulic characteristics in terms of flood occurrence, the dependence of ecosystems on such events, and attempts to actively store and manage floods. In this article, the hydraulic response of karst aquifers to heavy precipitation events, flood generation, and engineering interventions for flood control are discussed using several examples from karst areas in the Mediterranean region. Flooding mechanisms and regulatory structures in karst poljes are considered using several typical examples from the Dinaric mountain range. In addition, different variants of groundwater abstraction for increasing storage capacity and flood control are presented using examples from France and Montenegro. Managed aquifer recharge in karst areas and adjacent aquifers is demonstrated with examples from Jordan and Algeria. Finally, failed attempts at flood storage in karst reservoirs are presented with examples from Spain and Montenegro. These examples of flood retention in karst areas show the wide range of planning and technical measures and remind us of possible risks and failures in implementation as well as some positive and negative impacts on the environment and especially on ecosystems.

The main purpose of this study is to provide new estimations of optical properties for different aerosol species (Elemental (EC) and Organic Carbon (OC), sulfate (S), ammonium (AM) and nitrate (N)) over the Western Mediterranean Sea. This study is based on chemical measurements obtained over the French Mediterranean coastal region which were used to calculate the main optical properties (i.e., Mass Extinction Efficiency (MEE), Single Scattering Albedo (SSA) and asymmetry parameter (g)), which are relevant for Regional Climate Models (RCMs). Our results indicate that EC particles display averaged MEE (with associated uncertainty range) of 5.7 (4.6-6.9) m(2) g(-1) (at 550 nm), that is significantly lower than the value generally used (similar to 10 m(2) g(-1)) in RCM simulations conducted over this region. Such differences are mainly due to the inclusion of additional coarse modes in our optical calculations, which are not taken into account in RCMs that generally treat only fine EC particles. Concerning organics aerosols, we obtained a mean dry MEE (with associated uncertainty) of 2.7 (1.8-3.6) m(2) g(-1) (at 550 nm) lower than usually (similar to 5-7 m(2) g(-1)) referenced in RCMs. We also investigated the possible impact of absorbing brown carbon C-brown in our calculations showing large changes on dry MEE (from 2.7 to 4.5 m(2) g(-1), at 550 nm) and SSA (from 0.99 to 0.45, at 550 nm) for pure scattering and absorbing C-brown organics, respectively. Nitrate and ammonium particles, which are not well documented over this region, are characterized respectively by dry mean (and associated errors) MEE of 1 (0.8-1.2) m(2) g(-1) and 4 (2.4-5.6) m(2) g(-1) (at 550 nm), together with SSA of 0.89 (0.88-0.90) and 0.97 (0.96-0.98) at 550 nm. Such proposed values could be used to optimize RCMs over the Mediterranean basin for studying aerosol-climate interaction through feedbacks of particles on sea-surface fluxes, and hydrological cycle. (C) 2011 Elsevier B.V. All rights reserved.