Stream network morphology and storm response in humid catchments

Addressing scaling issues in hydrological modelling involves, among other things, the study of problems related to hydrological similarity between catchments of different scales. Recent research about catchment similarity relationships is based on distributed conceptual models of surface runoff production. In this type of hydrological modelling both infiltration excess and saturation excess runoff production mechanisms are considered. In many humid lowland areas overland flow is a rare phenomenon because of the specific conditions that prevail: moderate rainfall, high infiltration capacity and low relief. The complete drainage system in these regions consists of surface and subsurface components which have organized themselves in a given geological, geomorphological and climatic situation. A surface drainage network has developed through sapping erosion at the zone of groundwater exfiltration. The resulting hierarchical stream network is in equilibrium with large time-scale conditions and adjusts itself dynamically to the inter-year and seasonal meteorological fluctuations. Greater understanding of the interrelationships that underlie the storm response of catchments in humid lowland regions can be expected by focusing on stream network morphology as a function of topography, geology and climate. This paper applies the physically based mathematical model of stream network morphology, developed by De Vries (1977), to the Zwalmbeek catchment, Belgium. Based on this model and for different climatic conditions (expressed in terms of rainfall characteristics) the first-order stream spacing versus average water-table depth relationship is calculated. From field observations, digital elevation model derived channel network drainage densities and flood event analysis it is concluded that the 1% exceedance probability rainfall can be suggested as representative for the shaping climatic conditions in the catchment under study. The corresponding curves relating channel network characteristics, such as stream spacing, drainage density and channel geometry, to average water-table depth are basin descriptors and could be used for comparative studies (e.g. regional flood frequency analysis). The model further allows for the prediction of the expansion and shrinkage of the first-order channel network as a function of catchment wetness expressed in terms of the effective water-table depth.

[1]  F. Bretherton,et al.  Stability and the conservation of mass in drainage basin evolution , 1972 .

[2]  Keith Beven,et al.  On hydrologic similarity: 2. A scaled model of storm runoff production , 1987 .

[3]  J. J. Vries.  The groundwater outcrop-erosion model; evolution of the stream network in The Netherlands , 1976 .

[4]  R. L. Shreve.  Infinite Topologically Random Channel Networks , 1967, The Journal of Geology.

[5]  Keith Beven,et al.  On hydrologic similarity: 3. A dimensionless flood frequency model using a generalized geomorphologic unit hydrograph and partial area runoff generation , 1990 .

[6]  Keith Beven,et al.  Runoff Production and Flood Frequency in Catchments of Order n: An Alternative Approach , 1986 .

[7]  I. Rodríguez‐Iturbe,et al.  Scaling and Elevation in River Networks , 1989 .

[8]  Ignacio Rodriguez-Iturbe,et al.  Geomorphoclimatic estimation of extreme flow probabilities , 1983 .

[9]  Juan B. Valdés,et al.  A Physically Based Flood Frequency Distribution , 1984 .

[10]  Desmond E. Walling,et al.  THE VARIATION OF DRAINAGE DENSITY WITHIN A CATCHMENT , 1968 .

[11]  John L. Nieber,et al.  Regionalized drought flow hydrographs from a mature glaciated plateau , 1977 .

[12]  Peter A. Troch,et al.  Effective water table depth to describe initial conditions prior to storm rainfall in humid regions , 1993 .

[13]  Peter A. Troch,et al.  Hydrologic controls of large floods in a small basin: central Appalachian case study , 1994 .

[14]  P. Troch,et al.  A dynamic hillslope response model in a geomorphology based rainfall-runoff model , 1996 .

[15]  R. Horton.  EROSIONAL DEVELOPMENT OF STREAMS AND THEIR DRAINAGE BASINS; HYDROPHYSICAL APPROACH TO QUANTITATIVE MORPHOLOGY , 1945 .

[16]  Murugesu Sivapalan,et al.  On hydrologic similarity, 3. A dimensionless flood frequency model using a generalized GUH and partial area runoff generation , 1990 .

[17]  K. Beven,et al.  Similarity and scale in catchment storm response , 1990 .

[18]  R. L. Shreve.  Statistical Law of Stream Numbers , 1966, The Journal of Geology.

[19]  Conceptual basin-scale runoff process models for humid catchments : analysis, synthesis and applications , 1993 .