Chemical Characteristics of Groundwater and its Suitability for Irrigation Purpose in Jombang Regency, East Java, Indonesia

Abstract— The utilization of groundwater in the agricultural sector in Jombang regency is to meet the needs of irrigation water in sub-optimal land and to supply water for irrigation in the dry season on land that has been irrigated by surface water. The existence and potential of groundwater as a source of irrigation water should be available, not only in the quantity but also with the quality is good. The objectives of this study were to identify chemical characteristics of groundwater and to assess of groundwater quality for irrigation purpose. Twenty five groundwater samples were collected in the study area from bore wells ranging in depth between 61 – 127 m BGL on the confined aquifer. Chemical chracteristics of groundwater samples were analyzed using Piper trilinear diagram based on major ionic concentrations. Base on this analysis, discovered 6 water types of groundwater samples i.e. Ca2+–HCO3– type, mixed Ca2+–Mg2+–SO42– type, mixed Na+–Ca2+–HCO3– type, Ca2+–SO42– type, Na+–SO42– type, and Na+–HCO3– type. To define the quality of groundwater for irrigation, groundwater samples were analyzed by using EC25?C, SAR, and RSC values. The classification of irrigation water base on EC25?C and SAR show that most of groundwater samples into C2-S1 class indicating low sodium and medium salinity hazard. On the basis of RSC all groundwater samples are safe for irrigation purpose. All water type of groundwater samples in the study area are suitable for irrigation purpose. Keywords— Chemical characteristics, groundwater, irrigation, Jombang regency.