Catchment descriptors to optimise hydrometric networks

Operational needs commonly dictate the evolution of hydrometric networks. Such an approach can fail to meet long-term water management information objectives. This paper investigates how spatial descriptors can be used to assess the strategic value of individual catchments in the UK gauging station network. A catchment utility index (CUI) is presented based on an automated implementation of the Flood Estimation Handbook pooling-group procedure for assessing catchment similarity. The CUI is derived from the frequency with which gauged catchments across the UK are called in the pooling-groups for around four million catchments. Several case studies illustrate how the index is interpreted and used—in combination with the hydrometric performance of gauging stations and the degree of disturbance to the natural flow regime—to identify the most strategically useful gauged catchments. Such information is an essential component in guiding network evolution and in improving the effectiveness of procedures to estimate river flows in ungauged catchments.