ENSO-induced drought hazards and wet spells and related agricultural losses across Anhui province, China

Using daily precipitation data from 25 meteorological stations for a period of 1961-2014, spatiotemporal features of wet spells and droughts and related impacts on agricultural production across Anhui province, China, were investigated with a linear regressive technique, the Standardized Precipitation Evapotranspiration Index (SPEI) and the modified Mann-Kendall trend test method. Results indicated that: (1) ENSO-induced wet spells and droughts accounted for 83 and 68% of the total wet spells and droughts and droughts were closely related to La Nina events of the same and subsequent years. Wet spells, however, were closely related to El Nino events; (2) a larger variability was found in the SPEI, showing larger flood and drought risks during spring and autumn than those during summer and winter seasons. Generally, wet spells in winter were relatively high and the drying tendency was identified in winter during recent years; (3) relations between SPEI and SSTA were shifting during warm and cold phases of ENSO. The warm phase of ENSO tended to have larger impacts on SPEI in southern Anhui province, and the cold phase of ENSO had a greater impact on the SPEI variation in northern Anhui province. Comparatively, SSTA had an increasing impact on wet spells and droughts with increasing lag time; and (4) the reduction of rice and maize production in southern Anhui province was found mainly during 1 year earlier to the ENSO events. The amount of reduction of maize was larger in northern Anhui province and Jianghuai region, years with maize reduction were more often in southern Anhui province. Irrigation in central Anhui province can mitigate the negative effects of wet spells and droughts.