RES Environmental Ltd were commissioned by Arup complete stage 2 verification of the Drainage Area Plan for Tralee in County Kerry, Ireland. The model was verified in accordance with Irish Water’s Wastewater Network Hydraulic Model Build and Verification Standard.

The model was verified using 81 flow monitors, 12 depth monitors and 13 river monitors. A Thiessen polygon rainfall profile variation was applied across 10 rain gauges. The flow survey was installed for 6 weeks.

There were varying flow conditions throughout the catchment which limited the level of verification which  could be achieved; transient, skewed and below resolution flows were recorded. In addition, there were significant operational issues at the pumping stations throughout the catchment which restricted verification. Some of the stations were in bad condition with evidence of the pumps not operating for large periods of the survey period and considerable tidal ingress.

Significant additional flows were identified throughout the catchment, the flow survey data showed a profile similar to a watercourse. The source of these flows was unknown. Dummy New UK subcatchments were modelled in a separate scenario and calibrated to be used for design storm simulations.

The predicted flooding mechanisms were compared against historic data and resident reports to establish the accuracy of the model in replicating the flooding. Known flooding was well represented.

Verification of the catchment was caried out to a high standard with strategic monitors throughout the catchment giving confidence in the flows draining to the more problem areas. The verified model is now ready to be taken forward to Stage 3, risk assessment and needs identification, and Stage 4, strategy, optioneering and future solutions design.