Land cover change in the Middle River Vistula catchment -- Influence of land-use and water management practices on flows in the middle River Vistula -- Analysis of impact of climate variability on extreme flows in the Middle Vistula Basin -- The bed topography and discharge measurements at the Swiderskie Islands Nature Reserve, the Vistula River, Poland -- Rainfall-runoff modelling of the middle River Vistula tributaries -- Distributed modelling of flow in the Middle River Vistula -- Sensitivity analysis of the distributed flow routing model for middle River Vistula - multi-method approach -- Influence of channel processes and vegetation in the Vistula river valley in Warsaw on flood safety -- Semi-distributed flood forecasting system for the River Vistula reach -- Stochastic transfer function based emulator for the on-line flow forecasting. This book presents the novel formulation and development of a Stochastic Flood Forecasting System, using the Middle River Vistula basin in Poland as a case study. The system has a modular structure, including models describing the rainfall-runoff and snow-melt processes for tributary catchments and the transformation of a flood wave within the reach. The sensitivity and uncertainty analysis of the elements of the study system are performed at both the calibration and verification stages. The spatial and temporal variability of catchment land use and river flow regime based on analytical studies and measurements is presented. A lumped parameter approximation to the distributed modelling of river flow is developed for the purpose of flow forecasting. Control System based emulators (Hammerstein-Wiener models) are applied to on-line data assimilation. Medium-range probabilistic weather forecasts (ECMWF) and on-line observations of temperature, precipitation and water levels are used to prolong the forecast lead time. The potential end-users will also benefit from a description of social vulnerability to natural hazards in the study area.