Comparative Assessment of Water Balance Calculations: MONERIS and WetSpass Models in the Koppány Catchment

Accurate water balance is important for both water resource management and nutrient emission modeling. This study compares the water balance results from the MONERIS (Modeling Nutrient Emissions in River Systems) model with those from WetSpass (Water and Energy Transfer between Soil, Plants, and Atmosphere under quasi-Steady State) and field-measured data in Hungary's Koppány basin, a 660 km² hilly catchment. MONERIS uses empirical equations of water balance components: precipitation, evapotranspiration, runoff, and groundwater recharge. WetSpass adds spatially explicit hydrological and land-use information. The most characteristic features of the Koppány catchment are a high proportion of agricultural land, large-field arable farming of approximately 63% of the total area of the catchment and total agricultural lands of 72% of the total area of the catchment, and relatively low population density of approximately 29 inhabitants per square kilometer (inh./km²).  The Koppany catchment has a mean annual flow of approximately 1.26 m³/s. Water quality is seriously affected by eroding soil conditions within the catchment and severe point-source contamination by wastewater effluents: treated wastewater makes up approximately 8% of the total flow.

The present study furthers nutrient emission modeling through showing the relative strengths and weaknesses of lumped empirical and spatially distributed process-based techniques.

 

Keywords: Water Balance, MONERIS, WetSpass, Koppány Catchment , Nutrient Emission modeling