Measurement of water level and discharge in urban stormwater and sewers during intense rainfall events presents many challenges for the hydrographer. Faced with fast peak response times, complex flow conditions, interactions with groundwater and surface water bodies as well as safety issues, there has been demands on technique and technology to enable the collection of accurate data.

The functional design criteria of stormwater drains and sewer networks now incorporate allowances for climate change in many countries. With aging infrastructure, sea level change and more intense rainfall events, there is a growing demand for accurate measurement methods as well as active monitoring systems that can notify relevant emergency services in real-time.

This paper looks firstly at the impact of climate change on the hydraulic operation of storm and sewer systems, drawing on case studies to highlight the increasing demand for accurate data. The difficulties faced by the hydrographer when measuring data during peak events is also addressed as well as the typical technologies employed. Finally, hydrometric data collection in cities is faced with operational demands which drive real-time decision making and responses to extreme events. Case studies are provided along with emerging technologies that are enabling data collection and transmission.