Hydraulic response of the Hippargi barrage and Almatti reservoir on the Krishna river and its tributaries, India

In the last decade or so the frequent flooding of the Krishna river has caused severe damage resulting in huge loss of property, infrastructure and livelihood, especially in the south-western part of the state of Maharashtra, India. According to media and social activists, this is caused by the Almatti Dam and the Hippargi Barrage on the Krishna River in the state of Karnataka in India, located at 198.26 and 78.80 km, respectively, downstream from the Maharashtra-Karnataka state border. Unfortunately, a scientific study has not been carried out in this respect which is the need of the hour to either accept or reject this claim. The backwater and hydraulic response of both these structures is always a cause of dispute between these two states. In this study, an unsteady flow analysis using a georeferenced HEC RAS model on the Krishna River and its two tributaries Warna and Panchganga, with a total length of 518.32 km is carried out. The resulting hydrodynamic response of the Almatti reservoir is determined by the comparative study of the water surface profile, velocity distribution and water spread area with and without this dam. The response of the Hippargi barrage is found by using this same methodology. The results show that during extreme flood situations, the backwater effect of the Hippargi barrage is up to 35 km and that of the Almatti reservoir is up to 102 km, which is far from the border between the states of Maharashtra and Karnataka, India, proving that the claim made by the media and social activists is false. It is very clear that the response of these two structures is seen within the Karnataka state boundary and does not have any impact on the flood inundation in Maharashtra, especially in the south-western districts of Kolhapur and Sangli. The methodology suggested in this work can be useful for solving intra-state, interstate or international conflicts emerging due to the existence of hydraulic structures on the downstream side of a river.