A top-down model to generate ensembles of runoff from a large number of hillslopes

Abstract

We hypothesize that total hillslope water loss for a rainfall-runoff event is inversely related to a function of a lognormal random variable, based on basin-and point-scale observations taken from the 21 km2 Goodwin Creek Experimental Watershed (GCEW) in Mississippi, USA. A top-down approach is used to develop a new runoff generation model both to test our physical-statistical hypothesis and to provide a method of generating ensembles of runoff from a large number of hillslopes in a basin. The model is based on the assumption that the probability distributions of a runoff/loss ratio have a space-time rescaling property. We test this assumption using streamflow and rainfall data from GCEW. For over 100 rainfall-runoff events, we find that the spatial probability distributions of a runoff/loss ratio can be rescaled to a new distribution that is common to all. © 2013 auther(s).