Performance indicators for urban storm water systems: a review

Over the past two decades, performance assessment based on performance indicators (PI) has been one of the areas showing the greatest advancement in the water sector. This practice may be defined as any approach that aims to measure effectiveness and/or efficiency of an activity or process using PI, supporting the decision-making process and encouraging the continuous improvement of a water utility. Despite the potential benefits, few projects and initiatives of performance assessment based on PI have been undertaken regarding storm water systems. The present article aims to review studies that have been carried out in the area to provide a state of the art on the subject, understand the applicability of the existing methodologies and their limitations, and to point out future directions. The review revealed that most of the research works were of limited scope, focusing on single storm water systems or some specific aspects of their performance, and also gave an inappropriate definition and selection of PI, compromising their further application. The identified gaps emphasise the need for a new methodology to provide a reference framework in the field. Such methodology should be objective, standardised and well-adapted to different contexts, driven by objectives and criteria and based on PI and targets.