Apart from strong tidal currents, weirs have to be one of the most dangerous places on a river, however they play a significant role in the control of flow and water levels. For this reason it is important that they are correctly represented in a computer model when predicting flood situations. Our surveyors have just carried out a batch of weir surveys on the River Wey and have provided the model data to the client in a format that has allowed the user to quickly incorporate the weirs into an existing model and start producing model outputs straight away.