Effect of urbanization on the long-term persistence of streamflow records.

Abstract

We investigate here the effect of urbanization on the temporal behavior of streamflow records. To this end, we analyzed daily streamflow records from 22 urban basins using the scaling exponents for long-term correlated records and the multifractality strength. Additionally, we separated the streamflow into fast and slow components and performed the analysis separately on each of these time series. Overall, results indicate that in the most urbanized basins, with percent impervious cover greater than 25, the long-term correlation exponents for streamflow are generally lower than in the least urbanized basins (percent impervious cover less than 10), while the multifractality strength does not seem to be appreciably affected by the urbanization process. Based on the correlation exponents, we also found that in the most urbanized basins streamflow records tend to be more similar to quickflow and precipitation than in the least urbanized basins. Thus, the loss of long-term persistence in the most urbanized basins may be explained by their lesser ability, due to thecombined presence of impervious surfaces and conventional stormwater infrastructure, to filter the precipitation forcing. We conclude that the correlation exponents can be usefulfor assessing the temporal alteration of streamflow in urban basins.