Finding behavioral parameterization for a 1-D water balance model by multi-criteria evaluation

Abstract

Evapotranspiration is often estimated by numerical simulation. However, to produce accurate simulations, these models usually require on-site measurements for parameterization or calibration. We have to make sure that the model realistically reproduces both, the temporal patterns of soil moisture and evapotranspiration. In this study, we combine three sources of information: (i) measurements of sap velocities; (ii) soil moisture; and (iii) expert knowledge on local runoff generation and water balance to define constraints for a "behavioral" forest stand water balance model. Aiming for a behavioral model, we adjusted soil moisture at saturation, bulk resistance parameters and the parameters of the water retention curve (WRC). We found that the shape of the WRC influences substantially the behavior of the simulation model. Here, only one model realization could be referred to as "behavioral". All other realizations failed for a least one of our evaluation criteria: Not only transpiration and soil moisture are simulated consistently with our observations, but also total water balance and runoff generation processes. The introduction of a multi-criteria evaluation scheme for the detection of unrealistic outputs made it possible to identify a well performing parameter set. Our findings indicate that measurement of different fluxes and state variables instead of just one and expert knowledge concerning runoff generation facilitate the parameterization of a hydrological model.

A Comparative Investigation of Various Pedotransfer Functions and Their Impact on Hydrological Simulations

“…The differences in model behavior due to soil parameterizations through different PTFs were already analyzed in a study by [58] using a 1D hydrological model. They showed that even when the very same soil was considered in the entire parameterization scheme, and simulated transpiration and soil moisture were consistent with observations, yet the runoff processes or total water balance could be estimated incorrectly.…”

Hydrology of the Carpathian Basin: interactions of climatic drivers and hydrological processes on local and regional scales – HydroCarpath Research

“…Evapotranspiration plays an important role in the estimation of the water balance on many hydrologically relevant spatial and temporal scales (Casper et al, 2019). Without measuring evaporation and transpiration on the field scale, which is complicated due to the extreme heterogeneity of the whole relevant factors in the environment, the upscaling of point measurements to hillslope, catchment and regional scales cannot be completed (Burt et al, 2005).…”