394560 - Adapting Global Climate Model Precipitation Projections to Hydrologic Design
Wednesday, June 6
10:30 AM - 12:00 PM
Location: Lake Superior B
Katharine Hayhoe, Lubbock, TX – Atmos Research and Consulting; George Herrmann, Lubbock, TX – Desert Sky Engineering; Jennifer Jacobs, Durham, NH – University of New Hampshire; Sabu Paul, Manassas, VA – Michael Baker International; Anne Stoner, Urbana-Champaign, IL – Atmos Research and Consulting; Wilbert Thomas, Cary, NC – Michael Baker International; David Thompson, Carson City, NV – Thompson Hydrologics
Increasingly, engineers must make estimates of discharge associated with a particular risk (or set of risks) to design a hydraulic structure or stormwater management facility considering potential climate change. As part of a National Cooperative Highway Research Program (NCHRP) study “Applying Climate Change Information to Hydrologic and Hydraulic Design of Transportation Infrastructure” the authors examine issues and propose strategies for adapting Global Climate Model (GCM) precipitation output as inputs to rainfall/runoff models used in hydrologic design.
The use of hydrologic rainfall/runoff models requires precipitation inputs on a daily time step in some situations and in other situations, the engineer requires the data at a more temporally disaggregated sub-daily level of detail. Engineers have relied on the assumption of nonstationarity to apply historical information to future periods during which the transportation infrastructure will serve its intended purpose. However, with projections of a changing climate, transportation agencies and policy makers are asking engineers to consider future scenarios without relying on nonstationarity. To accomplish this, engineers using rainfall/runoff models need estimates of future daily and sub-daily precipitation as inputs at watershed-level spatial scales. As discussed in this paper, suitable Global Climate Model (GCM) output is limited at a daily time-scale and is even more limited at a sub-daily time scale. GCM output is also generally available on a spatial scale larger than required to model smaller watersheds.
This paper addresses two primary challenges faced by the climate science and engineering communities in providing engineers with estimates of future sub-daily and daily precipitation data and offers recommendations for actionable guidance in these areas. The first challenge addressed is the identification, development, and application of sub-daily precipitation estimates from GCMs. The second challenge is adapting the spatial scales of GCM output to watershed scales that engineers require for both daily and sub-daily precipitation data.