Snowmelt-Related Flood Risk in Appalachia: First Estimates from a Historical Snow Climatology

Abstract

A first attempt has been made toward quantifying the risk of snowmelt-related flooding in the central and southern Appalachian Mountains of the United States (from 35° to 42°N). In the last decade, two major events occurred within the region, prompting this study. Snowfall and snow depth data were collected from the cooperative observer network, quality controlled, and summarized at seasonal resolution (December–March). For establishing regional patterns, the period of 1971–2000 was selected. For testing fits of candidate probability distributions, and for focusing on the sparsely sampled higher elevations, this criterion was relaxed to include as many data from the mid- to late century as were reasonably admissible. Results indicate that the two-parameter Gumbel distribution fit best both the seasonal total snowfall and seasonal maximum snow depth. That distribution was then used to map return periods associated with critical seasonal snowfall and maximum snow depth masses. Seasonal snowfall amounts linked to a role for snowmelt in flooding were found to occur at return periods of from 2–5 yr in Pennsylvania and West Virginia to 10–200 yr in North Carolina. More generally, at elevations of at least 600 m throughout the region, return periods of 10–25 yr were estimated for critical levels of two flood-related criteria: seasonal total snowfall and maximum snow depth. In addition to providing valuable climatological information to aid forecasters and analysts, the results also support the need for further work toward understanding the role of snow in Appalachian floods.

Seasonality of monthly runoff over the continental United States: Causality and relations to mean annual and mean monthly distributions of moisture and energy

“…1b) is that basins west of the Appalachians exhibit increased SI(Q) compared to basins on the east. This is primarily due to increased snow from the winter precipitation resulting in relatively concentrated snow-melt season over the western Appalachian basins (Dingman, 2002;Graybeal and Leathers, 2006). Most of the basins in MEAS-3 and MEAS-4 have an aridity index ranging between 0.5 and 1.5 ( Fig.…”

Forest operations, extreme flooding events, and considerations for hydrologic modeling in the Appalachians—A review

“…Additionally, the storms producing these floods have some of the largest 6 h rainfall amounts in the world (Crippen and Bue, 1977;Hicks et al, 2005). Notable floods are usually the result of large tropical systems, unusual thunderstorms, or rains coupled with spring snowmelt in the north (Neary et al, 1986;Neary and Swift, 1987;Sturdevant-Rees et al, 2001;Graybeal and Leathers, 2006), and therefore there is not necessarily a dominant flood season in some parts of the Appalachians (Lecce, 2000). Floods become a concern for rainfalls >50 mm day À1 , but risk is not necessarily directly related to rainfall amount (Miller, 1990).…”

A review of global satellite-derived snow products

“…the snow-albedo feedback). Snow also modulates the hydrologic cycle (Dyer, 2008;Graybeal and Leathers, 2006;Leathers et al, 1998;Todhunter, 2001); influences ecosystem functioning (Jones et al, 2001); and is a significant resource for many mid latitude populations and for populations whose water is derived from mountainous and northerly cold regions (Barnett et al, 2005;Barry et al, 2007). Snow observations are critical for the validation of climate models Frei et al, 2003MacKay et al, 2006;Roesch et al, 1999).…”