Hydrologic similarity among catchments under variable flow conditions

Abstract

Abstract. An assessment of regional similarity in catchment stream response is often needed for accurate predictions in ungauged catchments. However, it is not clear whether similarity among catchments is preserved at all flow conditions. We address this question through the analysis of flow duration curves for 25 gauged catchments located across four river basins in the northeast United States. The coefficient of variation of streamflow percentiles is used as a measure of variability among catchments across flow conditions. Results show that similarity in catchment stream response is dynamic and highly dependent on flow conditions. Specifically, within each of the four basins, the coefficient of variation is high at low flow percentiles and gradually reduces for higher flow percentiles. Analysis of the inter-annual variation in streamflow percentiles shows a similar reduction in variability from low flow to high flow percentiles. Greater similarity in streamflows is observed during the winter and spring (wet) seasons compared to the summer and fall (dry) seasons. Results suggest that the spatial variability in streamflow at low flows is primarily controlled by the dominance of high evaporative demand during the warm period. On the other hand, spatial variability at high flows during the cold period is controlled by the increased dominance of precipitation input over evapotranspiration. By evaluating variability over the entire range of streamflow percentiles, this work explores the nature of hydrologic similarity from a seasonal perspective.

Controls on hydrologic similarity: role of nearby gauged catchments for prediction at an ungauged catchment

“…6) illustrates the preference of high predictability catchments towards humid regions. Our previous work (Patil and Stieglitz, 2011) characterized streamflow similarity among nearby catchments across multiple flow conditions. Patil and Stieglitz (2011) suggested that the competing influences of precipitation input and evaporative demand determine the conditions at which regional streamflow similarity is manifested.…”

“…Our previous work (Patil and Stieglitz, 2011) characterized streamflow similarity among nearby catchments across multiple flow conditions. Patil and Stieglitz (2011) suggested that the competing influences of precipitation input and evaporative demand determine the conditions at which regional streamflow similarity is manifested. Consistent with their suggestion, the results presented here show that streamflow similarity among nearby catchments is more likely to occur in regions where annual precipitation exceeds evaporative demand (i.e., low energy environments).…”

“…However, in many parts of the world, developed as well as developing, rivers are not gauged for continuous monitoring. Developing strategies for prediction at ungauged basins (PUB; Sivapalan et al, 2003) is required not only for the above practical applications, but also for advancing our process understanding of the controls on regional variability in landscape hydrologic response (Patil and Stieglitz, 2011;Wagener et al, 2004).…”

Catchment classification based on characterisation of streamflow and precipitation time series

“…Values of α Q tending to 0 indicate strongly correlated data, values close or higher than 1 show absence of correlation. Actually, the analysis of the correlation structures would require stationary time series, whereas streamflow observations (as well as rainfall ones) exhibit a strong dependency on the season (see also the recent analysis by Patil and Stieglitz, 2011); to solve this problem, the above cited papers assume stationarity on a seasonal basis, estimating separate coefficients for the different seasons or months. In addition, if trends were present, Eq.…”

“…Nathan and McMahon, 1990;Laaha and Bloeschl, 2006;Vezza et al, 2010) or the entire flow duration curve (e.g. Singh et al, 2001;Ley et al, 2011;Patil and Stieglitz, 2011;Sauquet and Catalogne, 2011). On the other hand, such representations do not allow to take into account the sequential order and the stochastic nature of the streamflow process; these properties would, for example, be crucial if the regionalisation aimed, as often needed in the hydrological practice, at the parameterisation of a rainfall-runoff model at fine temporal scale and the catchment similarity should therefore be guaranteed in terms of continuous streamflow generation.…”