Mixing Model Approaches to Estimate Storm Flow Sources in an Overland Flow‐Dominated Tropical Rain Forest Catchment

Mixing Model Approaches to Estimate Storm Flow Sources in an Overland Flow‐Dominated Tropical... Previous hydrometric studies demonstrated the prevalence of overland flow as a hydrological pathway in the tropical rain forest catchment of South Creek, northeast Queensland. The purpose of this study was to consider this information in a mixing analysis with the aim of identifying sources of, and of estimating their contribution to, storm flow during two events in February 1993. K and acid‐neutralizing capacity (ANC) were used as tracers because they provided the best separation of the potential sources, saturation overland flow, soil water from depths of 0.3, 0.6, and 1.2 m, and hillslope groundwater in a two‐dimensional mixing plot. It was necessary to distinguish between saturation overland flow, generated at the soil surface and following unchanneled pathways, and overland flow in incised pathways. This latter type of overland flow was a mixture of saturation overland flow (event water) with high concentrations of K and a low ANC, soil water (preevent water) with low concentrations of K and a low ANC, and groundwater (preevent water) with low concentrations of K and a high ANC. The same sources explained the streamwater chemistry during the two events with strongly differing rainfall and antecedent moisture conditions. The contribution of saturation overland flow dominated the storm flow during the first, high‐intensity, 178‐mm event, while the contribution of soil water reached 50% during peak flow of the second, low‐intensity, 44‐mm event 5 days later. This latter result is remarkably similar to soil water contributions to storm flow in mountainous forested catchments of the southeastern United States. In terms of event and preevent water the storm flow hydrograph of the high‐intensity event is dominated by event water and that of the low‐intensity event by preevent water. This study highlights the problems of applying mixing analyses to overland flow‐dominated catchments and soil environments with a poorly developed vertical chemical zonation and emphasizes the need for independent hydrometric information for a complete characterization of watershed hydrology and chemistry. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Water Resources Research Wiley

Mixing Model Approaches to Estimate Storm Flow Sources in an Overland Flow‐Dominated Tropical Rain Forest Catchment

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Publisher
Wiley
Copyright
Copyright © 1995 by the American Geophysical Union.
ISSN
0043-1397
eISSN
1944-7973
D.O.I.
10.1029/95WR01651
Publisher site
See Article on Publisher Site

Abstract

Previous hydrometric studies demonstrated the prevalence of overland flow as a hydrological pathway in the tropical rain forest catchment of South Creek, northeast Queensland. The purpose of this study was to consider this information in a mixing analysis with the aim of identifying sources of, and of estimating their contribution to, storm flow during two events in February 1993. K and acid‐neutralizing capacity (ANC) were used as tracers because they provided the best separation of the potential sources, saturation overland flow, soil water from depths of 0.3, 0.6, and 1.2 m, and hillslope groundwater in a two‐dimensional mixing plot. It was necessary to distinguish between saturation overland flow, generated at the soil surface and following unchanneled pathways, and overland flow in incised pathways. This latter type of overland flow was a mixture of saturation overland flow (event water) with high concentrations of K and a low ANC, soil water (preevent water) with low concentrations of K and a low ANC, and groundwater (preevent water) with low concentrations of K and a high ANC. The same sources explained the streamwater chemistry during the two events with strongly differing rainfall and antecedent moisture conditions. The contribution of saturation overland flow dominated the storm flow during the first, high‐intensity, 178‐mm event, while the contribution of soil water reached 50% during peak flow of the second, low‐intensity, 44‐mm event 5 days later. This latter result is remarkably similar to soil water contributions to storm flow in mountainous forested catchments of the southeastern United States. In terms of event and preevent water the storm flow hydrograph of the high‐intensity event is dominated by event water and that of the low‐intensity event by preevent water. This study highlights the problems of applying mixing analyses to overland flow‐dominated catchments and soil environments with a poorly developed vertical chemical zonation and emphasizes the need for independent hydrometric information for a complete characterization of watershed hydrology and chemistry.

Journal

Water Resources ResearchWiley

Published: Sep 1, 1995

References

  • Identifying flow paths in models of surface water acidification
    Beck, Beck; Kleissen, Kleissen; Wheater, Wheater
  • Examining the contributions of glacial till water to storm runoff using two‐ and three‐component hydrograph separations
    Hinton, Hinton; Schiff, Schiff; English, English
  • A comparison of chemical and isotopic hydrograph separation
    Hooper, Hooper; Shoemaker, Shoemaker

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