Application of Hybrid-Ihacres models for water availability in Siak River Manyuk Fauzi, Ermiyati, Suprasman, Siswanto, Alfian Malik, Doli Ananta Putra and Andica Putra MATEC Web Conf., 276 (2019) 04017 Published online: 15 March 2019 DOI: 10.1051/matecconf/201927604017