Hydrological Model

The hydrological model for the Sava River Basin - Sava HEC-HMS was developed using the industry-standard software HEC-HMS, HEC-GeoHMS, and HEC-DSSVue. The main goal of the Sava HEC-HMS model is to produce discharge hydrographs throughout the Sava River Basin so the hydrographs can be coupled with and imported into the hydraulic model. However, the applications of the hydrologic model are numerous including incorporation into the flood forecasting system, flood risk management planning, water supply and drought contingency planning, and climate change studies.

The Sava HEC-HMS modeling developed is actually a library of about 21 separate HEC-HMS models consisting of a basin-wide integrated model and individual models for each major Sava River tributary. The compilation of models provides the cooperating countries the flexibility in future use to model at different scales, basin-wide or individual tributary basin.

Using HEC-GeoHMS, a detailed subbasin delineation and river network were produced with additional manual manipulation of the DEM (SRTM30) to account for some of the natural and man-made features within the basin such as karst geology, levees, and canals especially in the flatter areas of the basin where these features are less defined by the resolution of the DEM.

The Sava HEC-HMS model consists of 235 sub-basins, which were carefully selected to take the local hydrology into account. A unique local characteristic is the presence of karst; this affected the sub-basins boundaries and the parameterization of the sub-basins. The hydrological model is forced with observed precipitation, observed temperature data and a long term monthly averaged evapotranspiration. The input data set is harmonized to time steps of 1 hour. The precipitation data of meteorological stations is transformed to the sub-basins via inverse distance method. Temperature is transformed via weighting factors and is corrected for altitude.

Model is incorporated into the Sava Flood Forecasting and Warning System.