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Abstract Existing stochastic rainfall generators (SRGs) are typically limited to relatively small domains due to spatial stationarity assumptions, hindering their usefulness for flood studies in large basins. This study proposes StormLab, an SRG that simulates precipitation events at 6‐hr and 0.03° resolution in the Mississippi River Basin (MRB). The model focuses on winter and spring storms caused by water vapor transport from the Gulf of Mexico—the key flood‐generating storm type in the basin. The model generates anisotropic spatiotemporal noise fields that replicate local precipitation structures from observed data. The noise is transformed into precipitation through parametric distributions conditioned on large‐scale atmospheric fields from a climate model, reflecting spatial and temporal nonstationarity. StormLab can produce multiple realizations that reflect the uncertainty in fine‐scale precipitation arising from a specific large‐scale atmospheric environment. Model parameters were fitted monthly from December–May, based on storms identified from 1979 to 2021 ERA5 reanalysis data and Analysis of Record for Calibration (AORC) precipitation. StormLab then generated 1,000 synthetic years of precipitation events based on 10 CESM2 ensemble simulations. Empirical return levels of simulated annual maxima agree well with AORC data and show an overall increase in 1‐ to 500‐year events in the future period (2022–2050). To our knowledge, this is the first SRG simulating nonstationary, anisotropic high‐resolution precipitation over continental‐scale river basins, demonstrating the value of conditioning such stochastic models on large‐scale atmospheric variables. StormLab provides a wide range of extreme precipitation scenarios for design floods in the MRB and can be further extended to other large river basins.
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This content will become publicly available on June 1, 2026
Impact of 21st century climate change on Mississippi River Basin discharge in CESM2 large ensemble projections
The Mississippi River Basin (MRB), the fourth-largest river basin in the world, is an important corridor for hy- droelectric power generation, agricultural and industrial production, riverine transportation, and ecosystem goods and services. Historically, flooding of the Mississippi River has resulted in significant economic losses. In a future with an intensified global hydrological cycle, the altered discharge of the river may jeopardize commu- nities and infrastructure situated in the floodplain. This study utilizes output from the Community Earth System Model version 2 (CESM2) large ensemble simulations spanning 1930 to 2100 to quantify changes in future MRB discharge under a high greenhouse gas emissions scenario (SSP3–7.0). The simulations show that increasing precipitation trends exceed and dominate increased evapotranspiration (ET), driving an overall increase in total discharge in the Ohio and Lower Mississippi River basins. On a seasonal scale, reduced spring snowmelt is projected in the Ohio and Missouri River basins, leading to reduced spring runoff in those regions. However, decreased snowmelt and spring runoff is overshadowed by a larger increase in projected precipitation minus ET over the entire basin and leads to an increase in mean river discharge. This increase in discharge is linked to a relatively small increase in the magnitude of extreme floods (2 % and 3 % for 100-year and 1000-year floods, respectively) by the late 21st century relative to the late 20th century. Our analyses imply that under SSP3–7.0 forcing, the Mississippi River and Tributaries (MR&T) project design flood would not be exceeded at the 100-year return period. Our results harbor implications for water resources management including increased vulnerability of the Mississippi River given projected changes in climate.
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- Award ID(s):
- 2147781
- PAR ID:
- 10637606
- Editor(s):
- Kaplan, J
- Publisher / Repository:
- Elsevier Global and Planetary Change
- Date Published:
- Journal Name:
- Global and Planetary Change
- Volume:
- 249
- Issue:
- C
- ISSN:
- 0921-8181
- Page Range / eLocation ID:
- 104742
- Subject(s) / Keyword(s):
- Mississippi River CESM2 large ensembles Emissions scenario Hydroclimate variability
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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