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Title: Effect of Spatial Heterogeneity of Runoff Generation Mechanisms on the Scaling Behavior of Event Runoff Responses in a Natural River Basin

Abstract

This paper investigates the effects of spatial heterogeneity of runoff generation processes on the scaling behavior of event runoff responses in a natural catchment, the Illinois River Basin near Tahlequah in Oklahoma. A previous study in this basin had revealed a systematic spatial trend in the relative dominance of different runoff generation mechanisms, with the fraction of total runoff generation due to the subsurface stormflow mechanism shown to increase in the downstream direction, while surface runoff generation by saturation excess showed a corresponding decrease. These trends were attributable to corresponding systematic trends in landscape properties, namely, saturated hydraulic conductivity of soils and topographic slope. Considering the differences in the timing of hillslope responses between the different runoff generation mechanisms, this paper then explores their impacts on the runoff routing responses, including how they change with increasing spatial scale. For this purpose we utilize a distributed, physically based hydrological model, with a fully hydraulic stream network routing component. The model is used to generate instantaneous response functions (IRF) for nested catchments of a range of sizes along the river network, as well as quantitative measures of their shape, e.g., peak and time-to-peak. In order to decipher and separate the effects ofmore » landscape heterogeneity from those due to basin geomorphology and hydrologic regime, the model simulations are carried out for three hypothetical cases that make assumptions about regarding landscape properties (uniform, a systematic trend, and heterogeneity plus the trend), repeating these simulations under wet and dry antecedent conditions. The simulations produced expected (consistent with previous theoretical studies) and also somewhat surprising results. For example, the power-law relationship between peak of the IRF and drainage area is shown to be flatter under wet conditions than under dry conditions, even though the (faster) saturation excess mechanism is more dominant under wet conditions. This result appears to be caused by partial area runoff generation: under wet conditions, the fraction of saturation area is about 30%, while under dry conditions it is less than 10% for the same input of rainfall. This means travel times associated with overland flow (that mostly contributes to the peak and time to peak) are in fact longer under wet conditions than during dry conditions. The power-law relationship between peak and drainage area also exhibits a scaling break at around 1000 km2, and this can be shown to be related to the peculiar shape of the catchment, which is reflected in a corresponding scaling break in the mainstream length versus drainage area relationship (i.e., Hack’s Law) at about 1,000 km2.« less

Authors:
;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1015514
Report Number(s):
PNNL-SA-77123
Journal ID: ISSN 0043-1397; WRERAQ; KP1703020; TRN: US201111%%635
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Water Resources Research, 47:Article No. W00H08
Additional Journal Information:
Journal Volume: 47; Journal ID: ISSN 0043-1397
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; DRAINAGE; GEOMORPHOLOGY; HYDRAULIC CONDUCTIVITY; HYDRAULICS; RESPONSE FUNCTIONS; RIVERS; ROUTING; RUNOFF; SATURATION; SHAPE; SOILS; runoff partitioning, spatial heterogeneity, instantaneous response function, scaling behavior

Citation Formats

Li, Hongyi, and Sivapalan, Murugesu. Effect of Spatial Heterogeneity of Runoff Generation Mechanisms on the Scaling Behavior of Event Runoff Responses in a Natural River Basin. United States: N. p., 2011. Web. doi:10.1029/2010WR009712.
Li, Hongyi, & Sivapalan, Murugesu. Effect of Spatial Heterogeneity of Runoff Generation Mechanisms on the Scaling Behavior of Event Runoff Responses in a Natural River Basin. United States. https://doi.org/10.1029/2010WR009712
Li, Hongyi, and Sivapalan, Murugesu. 2011. "Effect of Spatial Heterogeneity of Runoff Generation Mechanisms on the Scaling Behavior of Event Runoff Responses in a Natural River Basin". United States. https://doi.org/10.1029/2010WR009712.
@article{osti_1015514,
title = {Effect of Spatial Heterogeneity of Runoff Generation Mechanisms on the Scaling Behavior of Event Runoff Responses in a Natural River Basin},
author = {Li, Hongyi and Sivapalan, Murugesu},
abstractNote = {This paper investigates the effects of spatial heterogeneity of runoff generation processes on the scaling behavior of event runoff responses in a natural catchment, the Illinois River Basin near Tahlequah in Oklahoma. A previous study in this basin had revealed a systematic spatial trend in the relative dominance of different runoff generation mechanisms, with the fraction of total runoff generation due to the subsurface stormflow mechanism shown to increase in the downstream direction, while surface runoff generation by saturation excess showed a corresponding decrease. These trends were attributable to corresponding systematic trends in landscape properties, namely, saturated hydraulic conductivity of soils and topographic slope. Considering the differences in the timing of hillslope responses between the different runoff generation mechanisms, this paper then explores their impacts on the runoff routing responses, including how they change with increasing spatial scale. For this purpose we utilize a distributed, physically based hydrological model, with a fully hydraulic stream network routing component. The model is used to generate instantaneous response functions (IRF) for nested catchments of a range of sizes along the river network, as well as quantitative measures of their shape, e.g., peak and time-to-peak. In order to decipher and separate the effects of landscape heterogeneity from those due to basin geomorphology and hydrologic regime, the model simulations are carried out for three hypothetical cases that make assumptions about regarding landscape properties (uniform, a systematic trend, and heterogeneity plus the trend), repeating these simulations under wet and dry antecedent conditions. The simulations produced expected (consistent with previous theoretical studies) and also somewhat surprising results. For example, the power-law relationship between peak of the IRF and drainage area is shown to be flatter under wet conditions than under dry conditions, even though the (faster) saturation excess mechanism is more dominant under wet conditions. This result appears to be caused by partial area runoff generation: under wet conditions, the fraction of saturation area is about 30%, while under dry conditions it is less than 10% for the same input of rainfall. This means travel times associated with overland flow (that mostly contributes to the peak and time to peak) are in fact longer under wet conditions than during dry conditions. The power-law relationship between peak and drainage area also exhibits a scaling break at around 1000 km2, and this can be shown to be related to the peculiar shape of the catchment, which is reflected in a corresponding scaling break in the mainstream length versus drainage area relationship (i.e., Hack’s Law) at about 1,000 km2.},
doi = {10.1029/2010WR009712},
url = {https://www.osti.gov/biblio/1015514}, journal = {Water Resources Research, 47:Article No. W00H08},
issn = {0043-1397},
number = ,
volume = 47,
place = {United States},
year = {Thu May 26 00:00:00 EDT 2011},
month = {Thu May 26 00:00:00 EDT 2011}
}