River Managed System for Flood Defense
The assessment and prediction of urban surface water runoff has become a core issue for urban stormwater management across the world and has generated an ever-increasing interest in modelling tools for risk assessment and BMP mitigation measures. Whilst hydraulic modelling approaches for stormwater flows and sewered conveyance are now well developed and tested, the modeling basis for non-point urban water quality is still somewhat rudimentary. This chapter focuses on statistical and numerical approaches that have been developed to quantify pollutant concentrations and loadings associated with stormwater runoff and to evaluate the performance effectiveness of BMP controls for sustainable water management in highly urbanised areas. 
There has been a widespread application of simple, first-order screening techniques primarily based on regression and probabilistic analysis. These are now being supplemented by generic GIS and process-based modeling techniques frequently employing coupled 1D-2D dual-drainage methodologies. In general it is alleged that the simpler meta-modeling approaches if appropriately calibrated and verified, can match the predictive outcomes from the more deterministic process-based methods. A brief review is also provided of some commercially available software packages intended to support decision-making for sustainable stormwater management.