Implications of the 2015–2016 El Niño on Coastal Mississippi-Alabama Streamflow and Agriculture

In this paper, we evaluate the impacts of historic strong El Nino events on the coastal Mississippi-Alabama (MS-AL) hydroclimate. The normal physical association is that the increase in soil moisture, as a result of greater precipitation, is also associated with increased streamflow. When compared to the historic (1960-2015) long-term average, January through August streamflow volumes for five unimpaired streamflow gages located in coastal MS-AL exhibit an average increase of similar to 20% following a strong El Nino event. This overall increase was due to above-average precipitation during the winter-spring (January through April) season, with the corresponding average increase in streamflow volume for the five gages similar to 32%. In evaluating the temporal (monthly) variability of streamflow, we observe that the summer (June through August) season was dry following strong El Nino events, with streamflow volumes for the five gages decreasing by an average of similar to 21%. The agricultural industry in coastal MS-AL produces a variety of crops including cotton and peanuts. The typical planting season for these crops ends in mid-June with harvesting occurring in early September. Thus, the primary growing season for these crops is June-August. Given the lack of impoundments and irrigated lands in coastal MS-AL, the agricultural sector would be severely impacted by an El Nino driven drier summer. When evaluating the influence of the 2015-2016 El Nino on January through August 2016 streamflow, a similar pattern was observed in which high winter-spring streamflow was followed by diminished summer streamflow.