Evaluation of Dynamic Rating Curve Approaches to Estimate Discharge using Ultrasonic Sensors : A Case Study at Om Chhu in Bhutan

Abstract

Unsteady flow measurement in the natural river systems have remained one of the most challenging hydraulic problems. Despite several attempts, there is not even a method that has proven satisfactory to quantify the flow during unsteady conditions. Hydromet station adopts the rating curve to convert the flow depth to discharge in most cases. With the recent advancement in the field of Internet of Things (IoT), sensors are widely available to record the flow depth at a small temporal resolution. In the present study, IoTs and hydrometry were integrated to automatize the discharge estimation through non-contact technique coupling with dynamic rating curve formulae (DRcF) in the Himalayan river. The presented idea is suitable to quantify flow, especially in the Himalayan river with rapid flow characterized by high turbulence and velocity, because only a non-contact method is feasible. A pilot gauging station was established in Om chhu using an ultrasonic sensor to obtain the stage data that serves as the input to the DRcF. A comparative evaluation of DRcF revealed that all the DRcF selected estimated discharge without any inconsistencies or stability issues, although a few models were implicit.