Real-time forecasting of flows

Abstract

The impacts brought on by flash flooding are widespread, posing a threat to property and human life. Flood warning systems are implemented in many countries to alert affected populations of potential hazards. However, many of these systems do not generate a forecast with a sufficient amount of lead-time to alert the affected populations. Therefore, stream discharge forecasts in real-time are necessary. Real-time stream discharge forecasts rely on the use of weather forecasts, predicting precipitation in a given area. Products used for weather forecasts include weather radar, satellite, and weather models. Integrating these products with a rainfall-runoff modelling technique, such as an adapted version of the unit hydrograph at a given point in a stream, allows for a stream discharge forecast before the occurrence of a precipitation event. A base unit hydrograph for the duration in excess of 10 minutes can be computed with the use of historic precipitation and stream flow data. It can then be applied to areas that do not have available data in real-time. The proposed model for the unit hydrograph for the duration in excess was computed using data from Southern Mexico, specifically from the states of Chiapas and Tabasco. It allows for the forecasting of stream flows after a first impulse of precipitation has fallen over the watershed, using a typical daily precipitation distribution. The area has witnessed major flood events; therefore the application of such a model would be of great use to prepare for potential flooding as well as the evacuation of communities located in the flood plain. The methodology developed in this model can be applied to other watersheds, where real-time data availability is limited. © 2014 WIT Press.