1 23 Natural Hazards Journal of the International Society for the Prevention and Mitigation of Natural Hazards ISSN 0921-030X Nat Hazards DOI 10.1007/s11069-014-1499-3 Identification of long-term annual pattern of meteorological drought based on spatiotemporal methods: evaluation of different geostatistical approaches Bardia Bayat, Mohsen Nasseri & Banafsheh Zahraie