Testing the INCA model in a small agricultural catchment in southern Finland

Abstract

Nutrient leaching from agricultural production is still recognised as a major environmental problem in Finland. To estimate agricultural nitrogen loading under changing land-use and climate conditions, the Integrated Nitrogen Model for Catchments (INCA) was applied in Savijoki, a small (15.4 km 2 ) agricultural catchment, which represents the intensively cultivated areas in south-western Finland. Hydrological calibration and testing of the INCA model was first carried out in Savijoki during 19812000. In spite of heterogeneous soil and land-use conditions, INCA was able to reproduce the overall hydrological regime in the stream. The model was calibrated further in respect of nitrogen processes during 19952000. The model was able, reasonably well, to simulate the overall annual dynamics of the inorganic N concentrations in the stream water and the annual N export from the catchment. The average simulated NO 3 -N export was 550 kg N km 2 yr 1 and the observed one (constituting more than half of the annual total N export) was 592 kg N km 2 yr 1 . For NH 4 -N, the simulated export was somewhat higher than that measured but NH 4 -N was only 4% of the total N export. In spite of some underestimation of flow and N concentration during extreme hydrological conditions, the INCA model proved to be a useful tool for analysing flow pattern and inorganic nitrogen leaching in a small agricultural catchment, characterised by a rapid response to rainfall.

Uncertainty assessment of a process-based integrated catchment model of phosphorus

“…To date, there has been no published uncertainty analysis performed on INCA-P, although the in-stream part of the model structure has been subject to both sensitivity and uncertainty analysis (Wade et al 2001(Wade et al , 2002b. There have also been numerous assessments of the ability of the integrated catchment model of nitrogen (INCA-N) to predict nitrogen dynamics at the catchment scale (Granlund et al 2004;Limbrick et al 2000;McIntyre et al 2005;Raat et al 2004;Rankinen et al 2006). The model developers envisage that INCA-P could be used as part of a model hierarchy in which steady-state models, e.g.…”

Screening variability and change of soil moisture under wide-ranging climate conditions: Snow dynamics effects

“…The modeling approach of Rankinen et al ( 2004a ) was developed within the frame of the Integrated Nitrogen Model for Catchments (INCA) model and tested for conditions in Finland (Limbrick et al 2000 ; Granlund et al 2004 ; Rankinen et al 2004b ). Following this approach, the manifestation of measured precipitation P as snow ( P snow ) or liquid water rainfall ( P water = P − P snow ) is at any point in time first determined on the basis of mean air temperature T A [Θ] as with T U [Θ] and T L [Θ] being temperature thresholds, above and below which precipitation is considered to fall entirely as water (Eq.…”

Adaptation of the Integrated Nitrogen Model for Catchments (INCA) to seasonally snow-covered catchments

“…4), where a 10 year time-series was available. Calibration of the INCA model to the Savijoki catchment is described in detail by Granlund et al (2004). The degree-day model with fixed parameterisation was able to simulate the duration of the snow covered period, the date when snow cover started to accumulate and the date when snow cover was melted.…”