Entries by Mikael Mulugeta

North Atlantic Tropical Cyclones and U.S. Flooding

These results indicate that flooding from TCs is not solely a coastal phenomenon but affects much larger areas of the United States, as far inland as Illinois, Wisconsin, and Michigan. Moreover, the authors highlight the dependence of the frequency and magnitude of TC flood peaks on large-scale climate indices, and the role played by the […]

Roles of Climate and Agricultural Practices in Discharge Changes in an Agricultural Watershed in Iowa

An outstanding question is related to the contribution of changes in the climate system and in land use/land cover and agricultural practices in explaining changes in discharge. We address this question by developing statistical models to describe the changes in different parts of the discharge distribution. We use rainfall and harvested corn and soybean acreage […]

Spatial and temporal modeling of radar rainfall uncertainties

For the first time, the authors present a methodology based on conditional copulas to generate ensembles of random error fields with the prescribed marginal probability distribution and spatio-temporal dependencies. Villarini, G., B.-C. Seo, F. Serinaldi, and W.F. Krajewski. “Spatial and temporal modeling of radar rainfall uncertainties,” Atmospheric Research, 135-146, pp. 91-101, 2014.

Release Time Component of a Hydrograph

This research introduces another concept of partial release time, and a parametrical equation for its estimation is suggested. Furthermore, the fundamental relation between time base and excess rainfall duration for linear systems is clarified, giving rise to a formula for time base of Clark hydrograph. Finally, it will be theoretically shown that release time is […]

Four-dimensional reflectivity data comparison between two ground-based radars: Methodology and statistical analysis

To identify radar calibration differences, radar reflectivity is compared for well-matched radar sampling volumes viewing common meteorological targets. Seo, B.-C., W.F. Krajewski, and J.A. Smith. “Four-dimensional reflectivity data comparison between two ground-based radars: Methodology and statistical analysis,” Hydrological Sciences Journal, 59, pp. 1320-1334, 2014.

On the skill of numerical weather prediction models to forecast atmospheric rivers over the central United States

This study focuses on the verification of the skill of five numerical weather prediction models in forecasting AR activity over the central United States. We find that these models generally forecast AR occurrences well at short lead times, with location errors increasing from one to three decimal degrees as the lead time increases to about […]

Capabilities of Large-Scale Particle Image Velocimetry to Characterize Shallow Free-Surface Flows

Irrespective of their spatial extent, free-surface shallow flows are challenging measurement environments for most instruments due to the relatively small depths and velocities typically associated with these flows. A promising candidate for enabling measurements in such conditions is Large-scale Particle Image Velocimetry (LSPIV). Muste, M., A. Hauet, I. Fujita, C. Legout, and H.-C. Ho. “Capabilities […]

Horton laws for hydraulic–geometric variables and their scaling exponents in self-similar Tokunaga river networks

We used the observed exponents of depth and slope to predict the Manning friction exponent and to test it against field exponents from three studies.  Finally, we briefly sketch how the two anomalous scaling exponents could be estimated from the transport of suspended sediment load and the bed load. Gupta, V. K. and O.J. Mesa. “Horton […]

Exploring the Effects of Hillslope-Channel Link Dynamics and Excess Rainfall Properties on the Scaling Structure of Peak-Discharge

We use the rainfall-runoff model CUENCAS and apply it to three different river basins in Iowa to investigate how the interplay among rainfall intensity, duration, hillslope overland flow velocity, channel flow velocity, and the drainage network structure affects these parameters. Ayalew, T.B., W.F. Krajewski, R. Mantilla, and S.J. Small. “Exploring the Effects of Hillslope-Channel Link Dynamics and Excess Rainfall […]

Connecting the power-law scaling structure of peak-discharges to spatially variable rainfall and catchment physical properties

We have conducted extensive hydrologic simulation experiments in order to investigate how the flood scaling parameters in the power-law relationship Q(A)=αAθ, between peak-discharges resulting from a single rainfall–runoff event Q(A) and upstream area A, change as a function of rainfall, runoff coefficient (Cr) that we use as a proxy for catchment antecedent moisture state, hillslope overland flow velocity (vh), […]