RESEARCH ARTICLE Comprehensive studies of hydrogeochemical processes and quality status of groundwater with tools of cluster, grouping analysis, and fuzzy set method using GIS platform: a case study of Dalcheon in Ulsan City, Korea S. Venkatramanan & S. Y. Chung & R. Rajesh & S. Y. Lee & T. Ramkumar & M. V. Prasanna Received: 2 November 2014 /Accepted: 26 February 2015 # Springer-Verlag Berlin Heidelberg 2015 Abstract This research aimed at developing comprehensive assessments of physicochemical quality of groundwater for drinking and irrigation purposes at Dalcheon in Ulsan City, Korea. The mean concentration of major ions represented as follows: Ca (94.3 mg/L)>Mg (41.7 mg/L)>Na (19.2 mg/L)> K (3.2 mg/L) for cations and SO 4 (351 mg/L)>HCO 3 (169 mg/L)>Cl (19 mg/L) for anions. Thematic maps for physicochemical parameters of groundwater were prepared, classified, weighted, and integrated in GIS method with fuzzy logic. The maps exhibited that suitable zone of drinking and irrigation purpose occupied in SE, NE, and NW sectors. The undesirable zone of drinking purpose was observed in SW and central parts and that of irrigation was in the western part of the study area. This was influenced by improperly treated effluents from an abandoned iron ore mine, irrigation, and domestic fields. By grouping analysis, groundwater types were classified into Ca(HCO 3 ) 2 , (Ca,Mg)Cl 2 , and CaCl 2 , and CaHCO 3 was the most predominant type. Grouping anal- ysis also showed three types of irrigation water such as C1S1, C1S2, and C1S3. C1S3 type of high salinity to low sodium hazard was the most dominant in the study area. Equilibrium processes elucidated the groundwater samples were in the saturated to undersaturated condition with respect to arago- nite, calcite, dolomite, and gypsum due to precipitation and deposition processes. Cluster analysis suggested that high contents of SO 4 and HCO 3 with low Cl was related with water-rock interactions and along with mining impact. This study showed that the effluents discharged from mining waste was the main sources of groundwater quality deterioration. Keywords Fuzzy theory . GIS . Grouping analysis . Equilibrium processes . Cluster analysis Introduction Municipal, agricultural, and industrial growths have accelerated the contamination and deterioration of groundwater quality. The regulatory limits for drinking water proposed by WHO (2006) and US EPA (1994) have ranges according to the impact against human health during different seasons of year. Desirable limits from any regulatory Responsible editor: Michael Matthies S. Venkatramanan : S. Y. Chung (*) : R. Rajesh Department of Earth & Environmental Sciences, Institute of Environmental Geosciences, Pukyong National University, 599-1 Daeyeon-dong, Nam-gu, Busan 608-737, South Korea e-mail: chungsy@pknu.ac.kr S. Venkatramanan e-mail: venkatramanansenapathi@gmail.com S. Venkatramanan e-mail: venkat@pknu.ac.kr S. Y. Lee HLW Disposal Research Center, Korea Atomic Energy Research Institute, 989-111 Daedeok-daero, Yuseong-gu, Daejeon 305-353, South Korea T. Ramkumar Department of Earth Sciences, Annamalai University, Annamalai Nagar, Tamil Nadu 608002, India M. V. Prasanna Department of Applied Geology, Faculty of Engineering and Science, Curtin University, CDT 250, 98009 Miri, Sarawak, Malaysia Environ Sci Pollut Res DOI 10.1007/s11356-015-4290-4