This report is the manual for the nutrient transport model HBV-NP. It contains detailed description of the model, its different versions, of data required by the model and the format of input and output files. It also contains instructions for running the model and using the post-processing program for source apportionment.
The HBV-NP model simulates nitrogen (N) and phosphorus (P) transformation and transport in a catchment. The basic computation units are subbasins, which are parts of a larger catchment. The model simulates the nutrients in fractions; inorganic nitrogen, organic nitrogen, soluble reactive phosphorus and particulate phosphorus.
In addition, the sum of these fractions can be obtained as total nitrogen and total phosphorus. The model handles nutrient loads from different land use, rural households, industrial and urban point sources, storm water, bank erosion, release from lake bottoms and atmospheric deposition. The model considers mixing of water in soil, shallow groundwater, rivers and lakes, and nutrient transformation processes in shallow groundwater (only nitrogen), rivers and lakes