Modeling Impact of Cross Drainage Works on Flood Propagation Dynamics

River bed and flood plain geometries are formed as a response to centuries of natural erosional and depositional processes. Any human intervention made in the course of a river has the potential to create a disturbance in its flow pattern. The present study considers the possible consequences of changes made in the flood plain of a river and is an attempt to show how investigation and modeling prior to execution of water resources projects can be largely beneficial in desisting from unintended disasters. The Ghaggar River is a non- perennial stream that has its origin in the Shivalik Hills of Himachal Pradesh, India. It passes through the two states of Punjab and Haryana into Rajasthan. A flood investigation and modeling study was done for the Ghaggar River where it was attempted to simulate the change in the pattern of the flow in the main channel, and the propagation of excess waters in the flood plains, as a result of impediment created by the embankments of the Hansi-Butana Link canal, constructed recently during 2007-09. The study used daily rainfall data for the 2009 and 2010 monsoon seasons which was obtained from the India Meteorological Department. The modeling was done with the help of the MIKE SHE hydrologic model coupled with the MIKE 11 hydrodynamic model in order to estimate the peak river stage, the time to peak, and the recession time that was needed for the flood plains to get back to their normal dry state. It was found that the maximum impact of the canal embankment was felt on the flood recession time. The importance of the study was felt, when in the 2010 monsoons, the canal embankment that was acting as an obstruction to the speeding flood wave, cracked at places and fragments of the canal body were washed away by the flood water. Large areas of cultivated and inhabited land became inundated and stayed under water for weeks, when the volume of water captured by the canal embankments gradually drained through the various outlets made in the canal body. Fractured Portion Of Hansi Butana Link Canal