Next‐Generation Intensity‐Duration‐Frequency Curves for Hydrologic Design in Snow‐Dominated Environments

Abstract

There is a renewed focus on the design of infrastructure resilient to extreme hydrometeorological events. While precipitation‐based intensity‐duration‐frequency (IDF) curves are commonly used as part of infrastructure design, a large percentage of peak runoff events in snow‐dominated regions are caused by snowmelt, particularly during rain‐on‐snow (ROS) events. In these regions, precipitation‐based IDF curves may lead to substantial overestimation/underestimation of design basis events and subsequent overdesign/underdesign of infrastructure. To overcome this deficiency, we proposed next‐generation IDF (NG‐IDF) curves, which characterize the actual water reaching the land surface. We compared NG‐IDF curves to standard precipitation‐based IDF curves for estimates of extreme events at 376 Snowpack Telemetry (SNOTEL) stations across the western United States that each had at least 30 years of high‐quality records. We found standard precipitation‐based IDF curves at 45% of the stations were subject to underdesign, many with significant underestimation of 100 year extreme events, for which the precipitation‐based IDF curves can underestimate water potentially available for runoff by as much as 125% due to snowmelt and ROS events. The regions with the greatest potential for underdesign were in the Pacific Northwest, the Sierra Nevada Mountains, and the Middle and Southern Rockies. We also found the potential for overdesign at 20% of the stations, primarily in the Middle Rockies and Arizona mountains. These results demonstrate the need to consider snow processes in the development of IDF curves, and they suggest use of the more robust NG‐IDF curves for hydrologic design in snow‐dominated environments.

Regional Snow Parameters Estimation for Large‐Domain Hydrological Applications in the Western United States

“…Berghuijs et al () explored the dominant flood‐generating mechanisms across the continental United States and found that snowmelt and ROS events were more robust predictors of the flooding response than rainfall over the western United States. This is further confirmed by Yan et al (), Yan, Sun, Wigmosta, Skaggs, Leung, et al () who found that the standard precipitation‐based intensity‐duration‐frequency curves often significantly underestimate extreme events in snow‐dominated environments, suggesting a critical role of snow in flooding in those environments. With a warming climate, ROS‐driven flood risk is projected to increase significantly in many western United States river basins with more frequent ROS events at high elevations where seasonal snowpack persists even in a warmer climate (Musselman et al, ).…”

“…We acquired SWE measurements and meteorological records consisting of daily minimum/maximum air temperature and daily total precipitation from 785 active National Resource Conservation Service SNOTEL stations across the western United States, all operated by the U.S. Department of Agriculture Natural Resources Conservation Service. All data from the 785 SNOTEL stations were first screened using the quality assurance and quality control procedures that were initially developed by Serreze et al () and later enhanced by Yan et al (). To develop regional parameters and evaluate the spatial variation of model skill, we selected 246 SNOTEL stations with the longest common period of reliable records from Water Years (WYs) 2007 through 2013.…”

“…Hydroclimatic extremes in the western United States are often linked to spring snowmelt, particularly during rain‐on‐snow (ROS) events (Berghuijs et al, ; Kampf & Lefsky, ; Kattelmann, ; Marks et al, ; McCabe et al, ; Waylen & Woo, ; Yan et al, ; Yan, Sun, Wigmosta, Skaggs, Hou, & Leung, ). Berghuijs et al () explored the dominant flood‐generating mechanisms across the continental United States and found that snowmelt and ROS events were more robust predictors of the flooding response than rainfall over the western United States.…”

Impact of Atmospheric Rivers on Surface Hydrological Processes in Western U.S. Watersheds

“…More evaluation of the simulated precipitation is also described in Chen et al (). The simulated snowpack is evaluated using snow water equivalent from the Snow Telemetry (SNOTEL) stations (Yan et al, ) during the water years of 2006–2013. The SNOTEL data set has been quality controlled, and water years 2006–2013 are chosen to provide a continuous data record.…”

Observed Spatiotemporal Changes in the Mechanisms of Extreme Water Available for Runoff in the Western United States

“…Although the aforementioned studies provide significant findings about how the mountain snowpack is changing under a warming climate, none of these studies has explicitly examined the changes in specific mechanisms that provide water at the land surface available to generate runoff ( W ). The W ‐generating mechanisms can be classified as rainfall on snow‐free ground, snowmelt only, and rain‐on‐snow (ROS; Yan et al, ). Understanding the changes in different W ‐generating mechanisms has direct implications for water resources management, because rainfall mechanism alone poorly explains the spatial and temporal variabilities of flood risk across the western United States (Berghuijs et al, ).…”