Conservation strategies and nutrient and sediment reduction in agricultural watersheds in light of Extreme Climate Events

Abstract:

Since the late 1960's, point sources of water quality impairment have been reduced due to their ease of identification and the passage of the Clean Water Act in 1972. However, water quality problems remain, and as further point-source control becomes less cost-effective, attention is being directed towards the role of agricultural nonpoint sources in water quality degradation. Some 15 years on, continuing water quality impairment has led to agricultural initiatives to reduce losses from the Chesapeake Bay Watershed and Mississippi River Basin. As in the U.S., the European Union Water Framework Directive requires widespread control of N and P inputs to rivers specifically to improve riverine ecology. These efforts are generally directed at providing financial support to farmers to implement conservation practices that limit nutrient runoff. While there are various practices available, their effectiveness is generally designed to be optimal for design criteria for storm events that normally have a 10- to 25-year return period. Given the recent increase in occurrence and intensity of storm events, there is a need to assess the effectiveness, targeting, and policies relating to implementation of conservation practice effectiveness, in light of extreme climatic events. Lessons from agriculture’s ubiquitous role in ongoing impairment of Lake Erie, Chesapeake Bay, Mississippi River Basin water resources, will be discussed along with the opportunities and challenges for agricultural systems to management and adapt to mitigate nutrient losses under extreme climatic events.