Quoted from: https://www.smhi.se/en/research/research-departments/hydrology/hype-our-hydrological-model-1.7994 

The Hydrological Predictions for the Environment (HYPE) model is a semi-distributed catchment model, which simulates water flow and substances on their way from precipitation through different storage compartments and fluxes to the sea (Lindström et al., 2010). The model code is open source and describes hydrological processes in different subbasins, although the algorithms are not purely based on physical laws but of more conceptual nature. It is meant to be applied in a multi-basin manner to achieve high spatial distribution of flow paths in the landscape. It can be evaluated against point measurements in the river network and against spatially distributed observations, such as Earth Observations or interpolated products from in-situ monitoring. The model was initiated in 2003, applied for entire Sweden in 2008 and then for different continents (Pechlivanidis et and Arheimer, 2015; Donnelly et al., 2016; Hundecha et al., 2016; Andersson et al., 2017) and finally for the entire globe (Arheimer et al., 2019).

Among the model applications, the HYPE application for Sweden, S-HYPE (Strömqvist et al. 2012), is the one most frequently used operationally. For instance, it is used for operational forecasting of floods and droughts (e.g. Pechlivanidis et al., 2014), and assessments of water quality (e.g. Arheimer et al., 2015), as well as impacts from hydro-morphological alterations (e.g. Arheimer and Lindström, 2014) and climate change (e.g. Arheimer et al., 2017; Arheimer and Lindström, 2015) in Sweden. The model system is based on the HYPE model (Lindström et al., 2010) which is a catchment-based, process-oriented model, describing river flow generation from rainfall distribution and temperature. The model calculates evapotranspiration, snow storage and melt, soil moisture, groundwater fluctuations, routing in lakes and streams along the river network from source to sea.

The S-HYPE model is continuously developed and improved. The model has a large number of parameters, and is largely calibrated manually, making maximum use of hydrological judgement and experience. The S-HYPE model uses a daily time step. It is calibrated regionally, i.e. not tuned for individual stations but calibrated stepwise for specific hydrological processes using representative gauges from the full dataset to be robust enough for predictions also in ungauged basins (Arheimer and Lindström, 2013). In addition to this, there are deviations in a handful of key parameters (such as precipitation and temperature corrections) for parameter regions (Lindström, 2016).

To learn more about the HYPE model and its applications, please go to: hypeweb.smhi.se/.