Christopher Papadopoulos

Βottom-up management in catchment scale is deemed as the determinant way to avoid the conflict of the water users through the participation of stakeholders, strategy co-shaping and solutions co-creation. Water management cannot be one-dimensional but demands cross sectoral coop-eration. Usually, the difficulty lies in proper stakeholder training and their opinion inclusion, using a quantifiable manner in water management. The Laspias River watershed occupies an area of 221.8 km2, belonging to the River Basin District of Thrace and it is characterized by intense agricultural and industrial activity. Complying with the augmented water needs and pollution loads by respecting stakeholders’ opinion, this research aims to utilize a hybrid intuitionistic fuzzy multi-criteria-based methodology. It is a common difficulty to deal with supplier selection in resources management since it is a typically decision-making problem encompassing multiple (several conflicting) criteria, on which stakeholder’s opinions are usually imprecise and in a rather qualitative form. Therefore, the proposed method provides the mathematical tool to move into more comprehensive decisions with the public involvement. The weights are produced based on the stakeholder’s opinion. The alternatives’ ranking is achieved based on the fuzzified intuition-istic version of Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) and problems’ mitigation solutions’ hierarchy is achieved.

Bottom-up management in a catchment scale is deemed the optimal way to avoid conflicts among water users through the participation of stakeholders, strategy co-shaping, and solutions co-creation. Water management cannot be one-dimensional; it demands cross sectoral cooperation. Usually, the difficulty lies in proper stakeholder training and inclusion of their opinions, which should be used in a quantifiable manner in water management. The Laspias River watershed occupies an area of 221.8 km2 that includes the River Basin District of Thrace; it is characterized by intense agricultural and industrial activity. To comply with the augmented water needs and pollution loads this research aims to utilize a hybrid intuitionistic fuzzy multi-criteria-based methodology to address respectfully stakeholders’ opinion, this research aims to utilize a hybrid intuitionistic fuzzy multi-criteria-based methodology. It is often difficult to manage planning water management measures as the problems inc...

Drought is a complicated natural extreme event associated with the decline of water availability below the normal conditions of a hydrological system, both from a temporal and from a spatial point of view. This work aims to assess the drought impacts on groundwater fluctuation in a shallow coastal unconfined aquifer via fuzzy approach. Meteorological drought intensity is estimated by the Standardized Reconnaissance Drought Index (RDIst) based on precipitation (P) and potential evapotranspiration (PET). In addition, groundwater modeling is carried out using MODFLOW and then, the simulated values of water table (WT) of a coastal unconfined aquifer are utilized. In order to relate the RDIst with WT, a fuzzy linear regression (FLR) is applied. FLR based on Tanaka model produces a fuzzy band, where all the data must be included within, incorporating the system uncertainty. The suitability of the achieved fuzzy regression model is tested by using appropriate measures. The propounded metho...

This study proposes a hybrid fuzzy multi-criteria methodology for the selection of the most preferable site for applying managed aquifer recharge (MAR) systems by utilizing floodwaters. The use of MAR can increase water resources for later water utilization in case of drought. In this multi-criteria problem, seven recharge sites are under consideration, based on nine criteria, aiming to make a final list of their relative ranking. A fuzzy analytic hierarchy process (FAHP) based on the logarithmic fuzzy preference programming (LFFP) method is used to determine the weights of criteria. LFFP is an optimization-based method that produces a priority vector from a fuzzy pairwise comparison matrix. Furthermore, fuzzy inference systems (FIS) based on the Mamdani approach are used to estimate the rating of each alternative with respect to the criterion examined, and then the final evaluation of the alternatives is obtained. A FIS is a fuzzy if–then rule-based system where the experts’ qualit...

The aim of the research is the re-assessment of the flood risk when the sensitivity criteria used to evaluate the vulnerability are enhanced with adaptive-recovery capacity criteria and the exposure. Hence, in the proposed methodology, the vulnerability to flooding is addressed as a synthesis between the adaptive-recovery capacity, the exposure, and the sensitivity. To do so, a multicriteria ranking is proposed. The multicriteria ranking is based on the fuzziness in order to interpret the multicriteria synthesis of the widely-used multicriteria technique for order preference by similarity to ideal solution (TOPSIS) method. The case study areas are the Greek parts of the Nestos and Strymonas transboundary river basins.

This paper studies, through the principles of fuzzy set theory, groundwater response to meteorological drought in the case of an aquifer system located in the plains at the southeast of Xanthi, NE Greece. Meteorological drought is expressed through standardized Reconnaissance Drought Index (RDISt) and Standardized Precipitation Index (SPI), which are calculated for various reference periods. These drought indices are considered as independent variables in multiple fuzzy linear regression based on Tanaka's model, while the observed water table regarding two areas is used as a dependent variable. The fuzzy linear regression of Tanaka is characterized by the inclusion constraints where all the observed data must be included in the produced fuzzy band. Hence, each fuzzy output can get an interval of values where a membership degree corresponds to each of them. A modification of the Tanaka model by adding constraints is proposed in order to avoid irrational behavior. The results show...

The consideration of a theoretical probability distribution regarding the annual cumulative discharge will provide a significant opportunity to characterize the intensity of the hydrological drought. However, the matching between the observed probabilities and the adopted theoretical probability distribution can not be identical. Hence, in this work this matching is achieved by using a fuzzy regression based methodology and the attributes of the log-normal distribution. Finally, an ascending procedure to classify the intensity of hydrological drought is proposed and it is applied in case of the Evros River.

This study aims to assess the short-term response of groundwater to the main hydro-meteorological variables of drought in a coastal unconfined aquifer. For this purpose, a multiple fuzzy linear regression-based methodology is implemented in order to relate rainfall, streamflow and the potential evapotranspiration to groundwater. Fuzzy regression analysis is recommended when there is a lack of data. The uncertainty of the system is incorporated into the regression coefficients which, in this study, are considered to be fuzzy symmetrical triangular numbers. Two objective functions are used producing a fuzzy band in which all the observed data must be included. The first objective function, based on Tanaka’s model, minimizes the total width of the produced fuzzy band. The second one includes the first while additionally minimizing the distance between the central value of the fuzzy output of the model and the observed value. Validity of the model is checked through suitability measures...

Drought is a complicated natural extreme event associated with the decline of water availability below the normal conditions of a hydrological system, both from a temporal and from a spatial point of view. This work aims to assess the drought impacts on groundwater fluctuation in a shallow coastal unconfined aquifer via fuzzy approach. Meteorological drought intensity is estimated by the Standardized Reconnaissance Drought Index (RDI st) based on precipitation (P) and potential evapotranspiration (PET). In addition, groundwater modeling is carried out using MODFLOW and then, the simulated values of water table (WT) of a coastal unconfined aquifer are utilized. In order to relate the RDI st with WT, a fuzzy linear regression (FLR) is applied. FLR based on Tanaka model produces a fuzzy band, where all the data must be included within, incorporating the system uncertainty. The suitability of the achieved fuzzy regression model is tested by using appropriate measures. The propounded methodology is applied in the eastern area of Nestos River Delta, Prefecture of Xanthi, Greece.

This chapter deals with the impact of meteorological drought on groundwater in a heterogeneous aquifer system located in the plain southeast of Xanthi, northeastern Greece, using fuzzy set theory. The research aims to investigate the linear relationship between meteorological drought and groundwater levels of shallow wells, as well as the key role of geology in drought propagation, in terms of time, to groundwater. The study area is bounded to the east by the Lake Vistonida, to the north by the River Kosynthos, to the west by the settlements of Vafeika and Genisea, and to the south by the hill of Avdira and the settlement of Nea Kessani. It is irrigated by a substantial number of wells (800 or more), predominantly shallow. The area exhibits strong heterogeneity in soil composition, consisting of coarse-grained fluvial deposits in the northwest and finegrained lake sediments in the southeast. To achieve the study's objective, fuzzy regression analysis based on Tanaka's approach is implemented. Tanaka's fuzzy linear regression model is reduced to a linear programming problem with inclusion constraints, ensuring that all observed data is included within the produced fuzzy band. The Standardized Reconnaissance Drought Index (RDI St) and Standardized Precipitation Index (SPI) serve as inputs (independent variables) of the multiple fuzzy linear regression model. These drought indices are used to estimate drought intensity and are calculated for several reference periods. Water table serves the dependent variable, recorded by two water table loggers installed in different geological formation areas. The multiple fuzzy linear regression model produces a water table