Intense precipitation is a mixed blessing for agricultural producers. Depending on its timing, severity, and the antecedent environmental conditions, it can bring much needed relief from droughts and strengthen crop and livestock productivity, or it can exacerbate flooding on already saturated ground and decimate harvests. Current and future climate change will affect the nature of intense precipitation events (defined as the highest 10% events in daily precipitation distributions), further challenging the management of agricultural production systems. Understanding the potential negative impacts of future intense precipitation events is particularly important, given their ability to physically damage crops, delay planting and harvesting cycles, restrict root growth, and trigger oxygen deficiencies and nutrient loss. (See Nation’s Wettest 12-Month Period on Record Slows Down 2019 Planting Season)
To assess the impact of potential future increases in intense precipitation, we must first fully understand past patterns of intense precipitation, its variability, and impacts over time both at the regional and national levels. Once we establish how past heavy precipitation events affected production systems, various future scenarios can be incorporated into erosion, runoff, and crop-loss models to assess potential future impacts on agricultural systems. The information resulting from assessing these scenarios can be shared with farmers and land managers so that they can take precautionary steps and build adequate plans to mitigate potential negative impacts of heavy precipitation.
Scientists at the USDA Southern Plains Climate Hub and ARS Grazinglands Research Laboratory (GRL) in El Reno, Oklahoma are working to better understand both the past and the future of heavy precipitation events. A recent study that reviewed categorizations of intense precipitation events in the scientific literature found three well-reported categories for intense events: heavy, very heavy and extreme events. All precipitation events in these categories, the study also found, have been increasing since the early 1900s by 0.9% to 30%, at both regional and national levels.
In a second study by the scientists at GRL, the increasing trends in intense precipitation were used as the basis for modeling different precipitation intensification scenarios, focusing on heavy, very heavy, and extreme events in central Oklahoma. Using a weather generator model and a baseline observed precipitation record from central Oklahoma; the team showed that future occurrences of the most extreme precipitation events could increase by up to 40% at this location.
The implications of future climate change on extreme precipitation can be examined at national and even global scales. Ultimately, however, analyses of intense precipitation occurrences and changes are most useful at local and regional scales, where they can be used to examine impacts on key agricultural production variables such soil erosion, runoff, sediment transport, soil available water, and plant productivity. Therefore, the next step for scientists at GRL, is to incorporate these agricultural variables in various incremental scenarios of future intense precipitation events at central Oklahoma. Understanding these linkages will be essential for making informed and proactive decisions that minimize future production risk.