Simulated Impacts of El Nino/Southern Oscillation on United States Water Resources

The El Ni?o/Southern Oscillation (ENSO) phenomena alter global weather patterns with consequences for fresh water supply. ENSO events impact regions and their natural resource sectors around the globe. For example, in 1997 and 1998, a strong El Ni?o brought warm ocean temperatures, flooding, and record snowfall to the west coast of the United States. Research on ENSO events has improved long range climate predictions, affording the potential to reduce the damage and economic cost of these weather patterns. Here, using the Hydrologic Unit Model for the United States (HUMUS), we simulate the impacts of four types of ENSO states (Neutral, El Ni?o, La Ni?a, and strong El Ni?o) on water resources in the conterminous United States. The simulations show that La Ni?a conditions increase water yield across much of the country. We find that water yield increases during El Ni?o years across the south while declining in much of the rest of the country. However, under strong El Ni?o conditions, regional water yields are much higher than Neutral, especially along the West Coast. Strong El Ni?o is not simply an amplification of El Ni?o; it leads to strikingly different patterns of water resource response.