water courses 17 history 8 water courses regulation 6 water quality 5 flood control 5 inland water traffic 5 hydrology 4 more ... sewerage 4 floods 4 documentary photographs 3 channels 3 embankments 3 inland navigation 3 inland waterways 3 hydrological balance 2 deciduous trees 2 waste water 2 repairs 2 navigation ways 2 plavební kanály 2 lock chambers 2 mildews 2 river basin 2 water flow rate 2 dams 2 rebuildings 2 waterways 2 water transport 2 water management 2 water levels 2 less ...