Scaling of Floods with Geomorphologic Characteristics and Precipitation Variability Across the Conterminous United States
We developed the laws of scaling of floods (duration, peak, volume) with geomorphologic characteristics of the basin (i.e., drainage area, slope, elevation) and precipitation patterns (rainfall accumulation, variability) using a multi-level Bayesian approach. The spatial organization of scaling exponents is also investigated. The baseline model quantifies the scaling of floods to geomorphologic characteristics. The dynamic model quantifies the scaling of floods to antecedent precipitation distribution which is further conditioned on geomorphologic characteristics. Results show that small and low-elevation basins have a stronger response to antecedent rainfall distribution in amplifying flood peaks, while high-elevation steeper basins have a lower response for flood duration and volume.
Previous flood scaling works have exclusively focused on the flood peaks and rainfall-runoff attributes without much attention to the scaling of flood duration and volume. However, flood duration and volumes can provide critical information for water resources facilities and critical infrastructure systems. The proposed scaling models on flood duration and volumes, in addition to the flood peak now fully document the scaling exponents of floods in relation to the regional climate and catchment geomorphologic conditions. This study advances flood predictions by better informing the flood attributes in the context of dynamical land-atmosphere perturbations.
Using long records of streamflow and precipitation observations, we identified different scaling relationships between the catchment factors, preceding precipitation, and the duration, peaks, and volume of floods. Larger basins located at higher elevations are found to have decreasing scaling rates with flood peaks when interacting with the preceding precipitation patterns. Overall, low-elevation flat basins across the Eastern, Southern, and Northwestern US have a larger positive response to precipitation in amplifying flood attributes.