Evaluation of DRAINMOD 6.1 for Hydrological Simulations of Peat Extraction Areas in Northern Finland

DRAINMOD 6.1 was evaluated for hydrological simulation of two drained (1.0 m drain depth, 20 m spacing) peat extraction areas in Northern Finland. Water table depth (WTD) and drainage outflow were recorded continuously during two years, and the data were used for model calibration and validation. Despite some under- and overestimation of certain events, WTD fluctuations simulated quite accurately, whereas the model did not simulate drainage outflow well compared to observed data, especially for daily runoff. Mean absolute error (MAE) was 11.29 and 9.09 cm and Nash–Sutcliffe modeling efficiency (EF) was 0.64 and 0.62 for both study sites during the validation period, indicating good agreement between predicted and observed WTD. These results demonstrate that DRAINMOD 6.1 can satisfactorily simulate the WTD fluctuations in peat extraction areas in the cold climate of northern Finland, but further studies are needed to improve the model to better include frozen condition and peat extraction activities.