Hydrological Signatures Based on Event Runoff Coefficients in Rural Catchments of the Iberian Peninsula

摘要

Hydrological signatures are indices that help to describe the behavior of catchments. These indices can also be used to transfer information fromgauged to ungauged catchments. In this study, different approaches were evaluated to determine volumetric runoff coefficients in 18 small/medium experimental gauged catchments of the Iberian Peninsula and to fit runoff calculations based on precipitation data for gauged andungauged catchments. Using data derived from 1962 events, rainfall-runoff relationships were characterized and compared in order to evaluatethe various hydrological response patterns. Volumetric runoff coefficients and cumulative runoff and precipitation ratios of the events that generatedrunoff (Rcum) minimized the root mean square error. A linear fit for the estimation of Rcum in ungauged catchments was based on mean annual precipitation,rates of infiltration, the fraction of forest-land use, and the catchment channel length. Despite high catchment heterogeneity, Rcum resultedin a suitable parameter to evaluate hydrological variability in rural gauged and ungauged catchments. In 50% of the catchments, the precipitationaccounted for less than 50% of the runoff variation. Annual precipitation, antecedent rainfall, and base flow did not have a high significance inrainfall-runoff relationships, which illustrates the heterogeneity of hydrological responses. Our results highlight the need for signature characterizationsof small/medium rural catchments because they are the sources of runoff and sediment discharge into rivers, and it is more economicaland efficient to take action to mitigate runoff in rural locations.