An observation‐based stochastic model for sediment and vegetation dynamics in the floodplain of an Alpine braided river

Riparian vegetation dynamics in Alpine rivers are to a large extent driven by the timing and magnitude of floods which inundate the floodplain, transport sediment, erode the river bed, and create and destroy suitable germination sites. Here we present a stochastic approach for studying sediment-vegetation dynamics lumped at the floodplain scale and driven by stochastic flood disturbances. The premise of the model is that floods erode riparian vegetation in the inundated part of the floodplain and expose bare sediment surfaces. In the absence of subsequent flooding these surfaces are gradually recolonized. The stochastic nature of the disturbance process and the deterministic rate of vegetation colonization are described by a Poisson arrival of floods and a process equation which treats the floodplain erosion and vegetation colonization processes, respectively. An analytical solution is developed to obtain the probability density function of the exposed sediment area. The model is applied to the Maggia River in Switzerland, where it reproduces the changes in riparian vegetation cover observed from aerial photographs with an absolute error less than 5%. The model has potential as a tool to study the impacts of changes in the disturbance regime on sediment and vegetation dynamics Copyright 2009 by the American Geophysical Union.

[1]  Peter Molnar,et al.  Floodplain forest dynamics in a hydrologically altered mountain river , 2006 .

[2]  P. Burlando,et al.  Modeling the interaction between groundwater and river flow in an active alpine floodplain ecosystem , 2008 .

[3]  R. Sparks,et al.  THE NATURAL FLOW REGIME. A PARADIGM FOR RIVER CONSERVATION AND RESTORATION , 1997 .

[4]  René Lefever,et al.  Noise-Induced Transitions: Theory and Applications in Physics, Chemistry, and Biology , 2007 .

[5]  I. Iorgulescu,et al.  Flooding tolerance of Central European tree and shrub species , 2006 .

[6]  J. Friedman,et al.  Mortality of riparian box elder from sediment mobilization and extended inundation , 1999 .

[7]  Monica G. Turner,et al.  Simulated recruitment of riparian trees and shrubs under natural and regulated flow regimes on the Wisconsin River, USA , 2006 .

[8]  V. Isham,et al.  Probabilistic modelling of water balance at a point: the role of climate, soil and vegetation , 1999, Proceedings of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences.

[9]  D. Merritt,et al.  Riparian vegetation and channel change in response to river regulation : a comparative study of regulated and unregulated streams in the Green River Basin, USA , 2000 .

[10]  S. Levin,et al.  A neutral metapopulation model of biodiversity in river networks. , 2007, Journal of theoretical biology.

[11]  David M. Merritt,et al.  HYDROLOGIC REGIMES AND RIPARIAN FORESTS: A STRUCTURED POPULATION MODEL FOR COTTONWOOD , 2004 .

[12]  Steven W. Running,et al.  Three-dimensional mapping of geomorphic controls on flood-plain hydrology and connectivity from aerial photos , 2002 .

[13]  Arthur V. Brown,et al.  The Role of Disturbance in Stream Ecology , 1988, Journal of the North American Benthological Society.

[14]  W. C. Johnson,et al.  Woodland Expansions in the Platte River, Nebraska: Patterns and Causes , 1994 .

[15]  F. Schweingruber,et al.  Ein Baumgrenzstandort : Das Wildwasserbett der Maggia im Tessin, Schweiz. Eine dendroökologische Studie , 1991 .

[16]  David L. Strayer,et al.  Effects of Land Cover on Stream Ecosystems: Roles of Empirical Models and Scaling Issues , 2003 .

[17]  Gregor T. Auble,et al.  Relating Riparian Vegetation to Present and Future Streamflows , 1994 .

[18]  J. Pizzuto.  Channel adjustments to changing discharges, Powder River, Montana , 1994 .

[19]  Maureen M. Toner,et al.  RIVER HYDROLOGY AND RIPARIAN WETLANDS: A PREDICTIVE MODEL FOR ECOLOGICAL ASSEMBLY , 1997 .

[20]  J. R. Wallis,et al.  Some ecological consequences of a computer model of forest growth , 1972 .

[21]  C. Paola,et al.  Riparian vegetation controls on braided stream dynamics , 2001 .

[22]  Patrick B. Shafroth,et al.  RIPARIAN VEGETATION RESPONSE TO ALTERED DISTURBANCE AND STRESS REGIMES , 2002 .

[23]  S. Rood,et al.  Effective disturbance: Seedling safe sites and patch recruitment of riparian cottonwoods after a major flood of a mountain river , 2006, Wetlands.

[24]  R. Muneepeerakul,et al.  Effects of river flow scaling properties on riparian width and vegetation biomass , 2007 .

[25]  Christian Glenz.  Process-based, spatially-explicit modelling of riparian forest dynamics in Central Europe , 2005 .

[26]  C. Nilsson,et al.  Basic Principles and Ecological Consequences of Changing Water Regimes: Riparian Plant Communities , 2002, Environmental management.

[27]  Irene A. Stegun,et al.  Handbook of Mathematical Functions. , 1966 .

[28]  Cliff R. Hupp,et al.  Hydrological and geomorphological impacts on riparian plant communities , 2000 .

[29]  H. D. Miller,et al.  The Theory Of Stochastic Processes , 1977, The Mathematical Gazette.

[30]  C. Paola,et al.  Dynamic single-thread channels maintained by the interaction of flow and vegetation , 2007 .

[31]  S. Rood,et al.  Streamflow requirements for cottonwood seedling recruitment—An integrative model , 1998, Wetlands.

[32]  Yasuyuki Shimizu,et al.  Vegetation effects on the morphological behavior of alluvial channels , 2007 .

[33]  Luca Ridolfi,et al.  Riparian vegetation distribution induced by river flow variability: A stochastic approach , 2006 .

[34]  Alexander S. Flecker,et al.  Biodiversity conservation in running waters , 1993 .

[35]  Werner Horsthemke,et al.  Noise-induced transitions , 1984 .

[36]  W. Lewis,et al.  Restoration of riparian forest using irrigation, artificial disturbance, and natural seedfall , 1995 .

[37]  J. Friedman,et al.  EXTREME FLOODS, CHANNEL CHANGE, AND RIPARIAN FORESTS ALONG EPHEMERAL STREAMS , 2002 .

[38]  Andrea Rinaldo,et al.  On biodiversity in river networks: A trade‐off metapopulation model and comparative analysis , 2007 .

[39]  K. Tockner,et al.  Riverine flood plains: present state and future trends , 2002, Environmental Conservation.

[40]  A. Porporato,et al.  A stochastic process for the interannual snow storage and melting dynamics , 2007 .

[41]  Robert H. Webb,et al.  Experimental Flooding in Grand Canyon , 1997 .