| Basis for inference of wetland function | |||
| Code | Baseline for inference | Methodology | Limitiations |
| With/out | Comparison of the same basin, with or without a wetland | This approach is restricted to catchment model simulations, in which the model is calibrated in either the "with" or "without" wetland case, as occurs in modelled catchment. Model runs with the wetland case reversed generate simulated hydrological outputs. Differences between observed and simulated outputs are attributed to the presence of the wetland. | One case is simulated
only Stability of model parameters Response of wetland replacement zone |
| Drained | Comparison of the same wetland basin before and after drainage; or neighbouring drained and undrained wetlands | Hydrological outputs from a wetland are observed prior to drainage. The wetland is drained, and outputs are observed after drainage. Differences in the pre- and post- drainage outputs are attributed to the wetland. alternately, outputs from two adjacent catchments, each with wetlands, are observed. One of the catchments is drained, and differences between the outputs between the two catchments are attributed to the presence of the wetland. | Response
of replacement land-use in drained wetland Initial short-term responses
to drainage may differ from long-term responses |
| Pair | Comparison of paired basins, one with wetland the other without | Hydrological outputs are observed from two catchments, similar in all respects except that one catchment contains a wetland while the second does not. Differences between the outputs are attributed to the presence of the wetland. | If two catchments are otherwise identical, why does only one have a wetland? |
| Mult.. | Comparison of several basins with varying proportions of wetland | Hydrological outputs are observed from several catchments, each containing different proportions of wetland. Differences between the outputs are attributed to greater or lesser presence of wetland. | Variability in non-wetland characteristics amongst several catchments |
| In-out | Comparison of inflows and outflows of a wetland system | Hydrological inputs and outputs associated with a single wetland are measured. Differences between inputs and outputs are attributed to the presence of the wetland. | Measurement of
all inputs and all outputs Accounting for changes of storage within the wetland |
| Same | Comparison of wetland hydrological response with response elsewhere in the same basin | Hydrological outputs from a single wetland are measured as well as outputs from other non-wetland portions of the same catchment. Differences between the outputs are attributed to the wetland. | |
| Comp | Conclusions relating to individual components of the wetland through the development of an understanding of a component process | Individual component processes are observed and understood within a single wetland. The understanding of the processes is the basis for inferring the influence of that process on the hydrological output. (T = topography, V = vegetation, S = Soil, WC = water content, GW = groundwater, ET = evapotranspiration) | Extrapolation
of a single process in isolation Internal variability within wetland |