Automated hydrologic analysis of ungauged basins in Serbia using open source software

Drainage basins are for the most part ungauged or poorly gauged not only in Serbia but in most parts of the world, usually due to insufficient funds, but also the decommission of river gauges in upland catchments to focus on downstream areas which are more populated. Design discharges are needed for these rivers where no streamflow data are available, for various applications. Examples include river training works for flood protection measures or erosion control, design of culverts, water supply facilities, small hydropower plants, etc. This study deals with the application of freely available and open source software and datasets for automating rainfall–runoff analysis of ungauged basins, applying geographical information systems techniques and programming to methodologies currently in use in hydrological practice. The geomorphometric module was tested on more than 100 catchments throughout Serbia (using a digital terrain model) and compared to manually calculated values (using topographic maps). The discharge estimation module was tested on 21 catchments where data were available and compared to results obtained by frequency analysis of measured discharges. The geomorphometric module of the calculation system showed excellent results, saving a great deal of time that would otherwise have been spent on manual processing of geospatial data, while the discharge estimation module showed a need for improved hydrological models.