Saman Javadi

Vulnerability evaluation of a coastal aquifer via GALDIT model and comparison with DRASTIC index using quality parameters

ABSTRACT In recent years, environmental assessments of groundwater resources have resulted in the development of models that help identify the vulnerable zones. An aquifer is investigated using both GALDIT and DRASTIC indices. The GALDIT model is developed to determine the vulnerability of coastal aquifers in terms of saltwater intrusion whereas the DRASTIC model is generally applicable to all aquifers. Having compared the results of both the GALDIT and DRASTIC models with quality parameters, the salinity model proved to be more appropriate in identifying the vulnerability of coastal aquifers. The results show a Pearson correlation coefficient between TDS and the GALDIT vulnerability map of 0.58 while the corresponding value for the DRASTIC index is 0.48. EDITOR D. Koutsoyiannis ASSOCIATE EDITOR A. Fiori

Groundwater risk mapping prediction using mathematical modeling and the Monte Carlo technique

Abstract Groundwater vulnerability to pollution and risk assessment are some of the main tools that groundwater resources management decision makers use to protect aquifers from being polluted by human activities at the surface. In this research study a new risk assessment method was investigated to better predict the vulnerable areas and incorporate risk probability into the forecast. The proposed method is a combination of the overlay-index algorithm and the processing simulation modeling method. For probability realization, the Monte Carlo method was used. In addition, an auxiliary program was developed to automate the calculation and post-processing of the results. To evaluate the proposed methodology, an aquifer in southwestern Iran was selected. Five thousand realizations were produced for use in the Monte Carlo method. The results showed that a risk map is different from a vulnerability map and the risk map is more realistic as a planning tool. It is necessary to use mathematical models and probability in long-term planning for groundwater management. This case study showed that the proposed method and the developed auxiliary program are easy to use and produce reliable results.

Lab-evaluation of applicability selected hydrogeological tracers in physical/chemical conditions

In this research, the effects of a number of physical/chemical factors such as pH, sunlight, temperature, and salinity, as well as adsorption in porous media on the applicability of selected groundwater tracers are evaluated. Tracers from different categories as fluorescent dye tracers (uranine, eosin, and rhodamine B), chemical salts (NaCl and KCl), and non-fluorescent dye tracer (KMnO4) have been tested. This research was conducted in the laboratory. The results show that uranine losses its florescence in acid environments, while in alkaline conditions its florescence increases. The results also show that due to photochemical decay, eosin is the most unstable tracer if subjected to sunlight. KMnO4 turns to brown under sunlight and high temperature conditions, and may lose its usefulness as a tracer. Results also confirm that the fluorescence intensity of rhodamine B decreases with increasing temperature and/or salinity. Uranine and eosin have high resistance against high temperature and salinity conditions. An important factor in ground water tracing is adsorption of tracer in porous media environment. Our research show that rhodamine B would easily adsorb to fine grain porous media, while uranine and eosin are of high resistance against adsorption; KMnO4 is adsorbed easily too.

A hybrid multiple criteria decision-making model for the sustainable management of aquifers

In this study, a hybrid multiple criteria decision-making (HMCDM) model was proposed for prioritizing scenarios for managing groundwater use from an aquifer. Three scenarios, including the construction of subsurface dams, the use of artificial recharge and reducing groundwater use by 5% and 10% were considered to assess the most sustainable development approach. The examined MCDM models were: simple additive weighting (SAW); and MTAHP which is a hybridization of the modified TOPSIS and the analytic hierarchy process models. The criteria proposed for determining the order preference of the scenarios included the sustainable development index (IU) and a modified water exploitation index as well as economic, social and environmental indices. To assess the technical and economic impacts of the management scenarios, modeling of the aquifer was simulated for a 3-year period using these scenarios. The results of the assessment indicated that the scenario of water withdrawal reduction by 10% was the best scenario determined in MTAHP followed by a reduction in groundwater withdrawal by 5%, the use of artificial recharge and the construction of a subsurface dam, respectively. The difference between the results of MTAHP and SAW models was in their first and third ranks, in such a way artificial recharge scored the first rank in SAW model and the third rank in MTAHP model, also withdrawal reduction by 10% scored third rank in SAW model and first rank in MTAHP model. The results of these two models have demonstrated that the construction of a subsurface dam in Shahrekord aquifer is not an appropriate management option. According to the results of this study, MTAHP models can be applied for ranking feasible management scenarios in aquifers using the redefined sustainable development and modified groundwater exploitation indices introduced in this study.