Mantilla, Ricardo听1听;听Gupta, Vijay K听2
1听Department of Civil, Environmental, and Architectural Engineering.
Cooperative Institute for AV名湿 in Environmental Sciences (CIRES).
University of Colorado at Boulder.
2听Department of Civil, Environmental, and Architectural Engineering.
Cooperative Institute for AV名湿 in Environmental Sciences (CIRES).
University of Colorado at Boulder.
For over 30 years, observations have shown that power laws relate annual peak-flow quantiles to drainage basin area (Figure 1). However, little progress has been made to understand the underlying physical processes that produce these features. Following theoretical work by Gupta and others, we have formulated an alternative framework to address the problem of peak flows scaling. This new framework predicts that statistical scaling of peak flows occurs during individual rainfall-runoff events. Preliminary data analysis of peak flows during individual rainfall-runoff events in Walnut Gulch Basin in Arizona agrees with this result (Figure 2).
In order to study this framework in real basins, we redefine the concept of basin response. Traditionally, basin response to a rainfall event refers to the hydrograph at the outlet of the basin. We extend this concept to include the spatial structure of peak flows for all complete order streams. We use numerical simulations in the Walnut Gulch Basin in Arizona (150 km^2) to test how different assumptions about runoff dynamics for hillslopes and channels impact basin response to a rainfall event (Figure 3). We find that statistical scaling of simulated peak flows does not hold under unrealistic assumptions of runoff dynamics. This result suggests that a more comprehensive view of the basin response to rainfall events can yield better understanding of the physical mechanisms that produce floods.