Volume 16 [2014]

The evaluation of the performance of the developed model, using appropriate statistical indices, clearly indicates that the risk of surface ozone values exceeding the European Union (EU) threshold for human health protection can be successfully predicted. This suggests that the proposed ANN model can be used to issue warnings for the general public and especially certain sensitive groups of the population. 

Due to the fact that water systems belong to critical infrastructure, diverse methods of its management assessment during crisis situations are applied. In these methods both technical aspects and human factors, that have an impact on safety of water supply to the recipient, are considered. Also assessment tools for water supply were applied for failure assessment in the water supply system (WSS) management. The safety functioning of WSS is associated with analysis of relations between threats, reducing the frequency of their appearing, and, if threats appear, with the identification of their causes and reducing their negative consequences. Undesirable events are the result of phenomena independent from the human will, as well as those related to human activity, that in a significant way influence the WSS functioning. Crisis situations that are affected by such undesirable events having nonrandom (rare events do not have the statistical stability), but also not-determined character, demand specific and interdisciplinary research methods. 

This paper studies the characteristics of the heat waves that were observed in Athens, Greece since 1951. A heat wave is detected when two temperature criteria are fulfilled at the city centre: the daily maximum temperature value is at least 37 ^oC and the daily average temperature value is at least 31 ^oC. Information about the intensity, duration, timing in season and annual frequency of occurrence of heat waves were extracted. The slope of the linear fit of the annual number of heat wave days indicated that 1.30 more heat wave days per year were observed after 1992. The intensity and the duration of heat waves have also increased since 90s, while heat wave days have been detected during the whole summer since then, even during the first days of September. Additionally, air quality at the centre and at a suburb of Athens during the heat wave days that were identified during the last decade is examined. The daily average value of PM₁₀ concentration exceeded 50 μg m^-3 in 65% and 59% of the heat wave days at the urban and the suburban site, respectively, while the information and the alert O₃ threshold were exceeded in 17% and 5% of the heat wave days, respectively, at the suburban site. The degradation of air quality during heat wave days is also verified by the means of the common air quality index. Moreover, it was found that O₃ levels decrease when heat waves last more than 6 days. 

Present investigation is an exertion to explore safe means of water for the community in the water scare region. In order to accomplish such goal origin of springs as well as chemical analyses of groundwater samples from different locations were carried out. Four zones are discovered on the basis of nature of water points, rock types and water chemistry. These zones are Hard Rocks Springs (HRS), Valley Springs (VS), Recharge Areas Aquifers (RAA) and Central Valley Aquifers (CVA). HRS are originated from thick successions of limestone (Kirthar Limestone) and thick packages of channelized sandstone and conglomerates of the Siwalik Group. It is recommended that Chiltan, Parh, Kirthar, Dhok Pathan and Soan formations may be focused for future needs of safe water supply in the Quetta valley. This study includes the analysis of different physico-chemical parameters such as Total dissolved solids (TDS), pH, turbidity, Electrical conductivity (EC), hydrochemical facies, Sodium Adsorption Ration (SAR), Sodium Percent (Na%), Kelleys Index (KI), Permeability Index (PI), major cation and anions to assess the quality of groundwater sources. The outcomes of groundwater analyses were equated with various drinking water standards e.g., NSDWQ-Pak, USEPA, and EU. The results are plotted for determination of lateral variations and to empathize the reasons of these variations. The affects of rock types, geological structures as well as anthropogenic causes on origin and results are discussed systematically. The hydrochemical facies identified show that the alkaline earth exceeds alkalies, strong acids exceeds weak acids, mixed type (no cation, anion exceeds 50%), no dominant cation and anion types but water of VS is calcium chloride and sulfate type. The water is classified as C2-S1 (HRS), C3-S1 (CVA & RAA) and C3-S2 (VS) based on SAR and EC values, which intend that most water samples can be used for irrigation safely except water samples collected from VS. Based on the Na% the water samples are categorized as excellent to good and good to permissible limits. The water is suitable for irrigation as all samples bear KI less than 1. The PI values in the water samples studied (less than 40) also contemplate that the water is desirable for irrigation use, although caution is needed of VS water.