Evaluation of groundwater usage in relationship to groundwater vulnerability to sea water intrusion in Cilacap CoastalSalsabiila Bayu Nugrahaeni, Ignasius Loyola Setyawan Purnama and Vincentia Anindha PrimacintyaE3S Web Conf., 325 (2021) 08004DOI: https://doi.org/10.1051/e3sconf/202132508004