Similarity and scale in catchment storm response

TLDR

Very little progress had been made in linking small‑scale variability of topography, soil, and rainfall to catchment‑scale storm response. This work presents the first systematic theoretical framework for understanding surface runoff generation across scales. The authors introduce the concept of a representative elementary area (REA) as a fundamental scale where continuum assumptions hold, and explore hydrologic similarity to separate environmental control effects from catchment size. Initial results suggest the framework can guide future investigations of hydrologic scale and similarity, encouraging further research.

Abstract

Until recently, very little progress had been made in understanding the relationship between small‐scale variability of topography, soil, and rainfalls and the storm response seen at the catchment scale. The work reviewed here represents the first attempt at a systematic theoretical framework for such understanding in the context of surface runoff generation by different processes. The parameterization of hydrological processes over a range of scales is examined, and the concept of the “representative elementary area” (REA) is introduced. The REA is a fundamental scale for catchment modeling at which continuum assumptions can be applied for the spatially variable controls and parameters, and spatial patterns no longer have to be considered explicitly. The investigation of scale leads into the concept of hydrologic similarity in which the effects of the environmental controls on runoff generation and flood frequency response be investigated independently of catchment scale. The paper reviews the authors' initial results and hopefully will motivate others to also investigate the issues of hydrologic scale and similarity.