Stochastic modeling of hydrologic variability of geographically isolated wetlands: Effects of hydro-climatic forcing and wetland bathymetry

Abstract

We examined temporal variability in hydrology of geographically isolated wetlands (GIWs), and derived analytical expressions for probability density functions (pdfs) for water storage volume and water stage. We conceptualize a GIW as a non-linear reservoir, subject to stochastic “shot-noise” (Poisson rainfall inputs) modulated by recession through both evapotranspiration and drainage during inter-event periods. The analytical pdfs are defined by four key dimensionless parameters which characterize temporal variability of wetland hydrologic conditions: scaled aridity index (ϕ∗), mean daily stage jump (r), relative rate constants for the two recession processes (ε), and wetland shape coefficient (β). These parameters define the similarity or diversity of hydrologic regimes in GIWs at a location or at different sites by capturing the essential features of the landscape: stochastic hydro-climatic forcing, bathymetry, and groundwater or upland connectivity. We illustrate the utility of the analytical pdfs using observed data from an isolated wetland in Florida.