Temporal variations in the water quality of beton spring, Gunungsewu karst area, Indonesia

Beton Spring is a water source used for fulfilling the basic needs of domestic activities, irrigation, and fisheries. Concerning water resources, it is particularly unique in that its upper course is an allogenic river with enormous groundwater potential. This research was intended to study the temporal water quality at Beton Spring. For this reason, the spring water was sampled periodically for one year. The water quality was assessed according to the drinking water quality standards, namely Regulation of the Minister of Health of the Republic of Indonesia No. 90 of 2002 and the standards set by experts. The analyses of trilinear and rectangular Piper diagrams were performed in Easy Quim v5.0 software. The analysis results showed that, temporally, the spring water had good quality because almost all samples collected in the dry and rainy seasons met the standards. The trilinear Piper diagram revealed that the Beton Spring mainly contained unpolluted and calcium-enriched groundwater. Meanwhile, the rectangular Piper diagram indicated the abundance of average bicarbonate waters, with only a few samples categorized into cation exchange-controlled groundwater.