Investigating hydrologic connectivity and its association with threshold change in runoff response in a temperate forested watershed

Hydrological studies across varied climatic and physiographic regions have observed small changes in the ‘states of wetness’; based on average soil moisture, can lead to dramatic changes in the amount of water delivered to the stream channel. This non-linear behaviour of the storm response has been attributed to a critical switching in spatial organization of shallow soil moisture and hydrologic connectivity. However, much of the analysis of the role of soil moisture organization and connectivity has been performed in small rangeland catchments. Therefore, we examined the relationship between hydrologic connectivity and runoff response within a temperate forested watershed of moderate relief. We have undertaken spatial surveys of shallow soil moisture over a sequence of storms with varying antecedent moisture conditions. We analyse each survey for evidence of hydrologic connectivity and we monitor the storm response from the catchment outlet. Our results show evidence of a non-linear response in runoff generation over small changes in measures of antecedent moisture conditions; yet, unlike the previous studies of rangeland catchments, in this forested landscape we do not observe a significant change in geostatistical hydrologic connectivity with variations in antecedent moisture conditions. These results suggest that a priori spatial patterns in shallow soil moisture in forested terrains may not always be a good predictor of critical hydrologic connectivity that leads to threshold change in runoff generation, as has been the case in rangeland catchments. Copyright © 2007 John Wiley & Sons, Ltd.

[1]  Jon Finch,et al.  Can soil moisture be mapped onto the terrain , 2004 .

[2]  S. K. Jenson,et al.  Extracting topographic structure from digital elevation data for geographic information-system analysis , 1988 .

[3]  Jeffrey J. McDonnell,et al.  Scale effects on headwater catchment runoff timing, flow sources, and groundwater‐streamflow relations , 2004 .

[4]  C. D. Kimpe,et al.  Saturated hydraulic conductivity in pedogenetic characterization of podzols with fragipans in quebec , 1976 .

[5]  Günter Blöschl,et al.  How well do indicator variograms capture the spatial connectivity of soil moisture , 1998 .

[6]  G. Lovett,et al.  Sugar maple and nitrogen cycling in the forests of Eastern North America. , 2004 .

[7]  G. Webber,et al.  COMPARISON OF CHEMICAL COMPOSITION OF SOILS AND BEDROCK OF MONT ST. HILAIRE, QUEBEC , 1965 .

[8]  Murugesu Sivapalan,et al.  Linking hydrologic parameterizations across a range of scales: hillslope to catchment to region , 1993 .

[9]  M. Sklash,et al.  The Role Of Groundwater In Storm Runoff , 1979 .

[10]  Edzer Pebesma,et al.  GSTAT: a program for geostatistical modelling, prediction and simulation , 1998 .

[11]  Andrew W. Western,et al.  The Tarrawarra Data Set: Soil moisture patterns, soil characteristics, and hydrological flux measurements , 1998 .

[12]  Günter Blöschl,et al.  Reply to comment by Tromp van Meerveld and McDonnell on Spatial correlation of soil moisture in small catchments and its relationship to dominant spatial hydrological processes , 2005 .

[13]  Günter Blöschl,et al.  Advances in the use of observed spatial patterns of catchment hydrological response , 2002 .

[14]  R. Grayson,et al.  Geostatistical characterisation of soil moisture patterns in the Tarrawarra catchment , 1998 .

[15]  Timothy C. Coburn,et al.  Geostatistics for Natural Resources Evaluation , 2000, Technometrics.

[16]  W. Rouse,et al.  Time and Space Variations in the Radiant Energy Fluxes Over Sloping Forested Terrain and Their Influence on Seasonal Heat and Water Balances at a Middle Latitude Site , 1969 .

[17]  Pascale M. Biron,et al.  The effects of antecedent moisture conditions on the relationship of hydrology to hydrochemistry in a small forested watershed , 1999 .

[18]  Erwin Zehe,et al.  Predictability of hydrologic response at the plot and catchment scales: Role of initial conditions , 2004 .

[19]  J. Bear.  Dynamics of Fluids in Porous Media , 1975 .

[20]  K. Beven,et al.  Macropores and water flow in soils , 1982 .

[21]  L. Nyberg.  Spatial variability of soil water content in the covered catchment at Gårdsjön, Sweden , 1996 .

[22]  A. James,et al.  Investigating the applicability of end‐member mixing analysis (EMMA) across scale: A study of eight small, nested catchments in a temperate forested watershed , 2006 .

[23]  R. Grayson,et al.  Toward capturing hydrologically significant connectivity in spatial patterns , 2001 .

[24]  Jeffrey J. McDonnell,et al.  Comment to “Spatial correlation of soil moisture in small catchments and its relationship to dominant spatial hydrological processes, Journal of Hydrology 286: 113 134” , 2005 .

[25]  James P. McNamara,et al.  An approach to understanding hydrologic connectivity on the hillslope and the implications for nutrient transport , 2003 .

[26]  K. Beven,et al.  A physically based, variable contributing area model of basin hydrology , 1979 .

[27]  Günter Blöschl,et al.  Preferred states in spatial soil moisture patterns: Local and nonlocal controls , 1997 .

[28]  Günter Blöschl,et al.  Spatial correlation of soil moisture in small catchments and its relationship to dominant spatial hydrological processes , 2004 .

[29]  Luis S. Pereira,et al.  Coping with Water Scarcity , 2009 .

[30]  A. Wild,et al.  USE OF FLUORESCENT DYES TO MARK THE PATHWAYS OF SOLUTE MOVEMENT THROUGH SOILS UNDER LEACHING CONDITIONS: 2. FIELD EXPERIMENTS , 1979 .

[31]  T. Dawson.  Hydraulic lift and water use by plants: implications for water balance, performance and plant-plant interactions , 1993, Oecologia.

[32]  J. Roberts.  The influence of physical and physiological characteristics of vegetation on their hydrological response , 2000 .

[33]  Nigel T. Roulet,et al.  The baseflow and storm flow hydrology of a precambrian shield headwater peatland , 1998 .

[34]  Shoji Noguchi,et al.  Seasonal hydrologic response at various spatial scales in a small forested catchment, Hitachi Ohta, Japan , 1995 .

[35]  Günter Blöschl,et al.  Observed spatial organization of soil moisture and its relation to terrain indices , 1999 .

[36]  John F. Dowd,et al.  Runoff generation in relation to soil moisture patterns in a small Dartmoor catchment, Southwest England , 2003 .

[37]  Philip Marsh,et al.  A conceptual framework for runoff generation in a permafrost environment , 1999 .

[38]  Jeffrey J. McDonnell,et al.  The role of event water, a rapid shallow flow component, and catchment size in summer stormflow , 1999 .