8. Hydrological Analysis of Severe Rainstorms in North West India

On the basis of available daily rainfall data of hundred years (1901–2000) of various rain gauge stations in North West India severe rainstorms which caused heavy floods in various river basins have been studied. The most severe rainstorms which measured 50 cm or more in a day have been selected for detailed study and analysis. During monsoon period, whenever a western disturbance approaches the prevailing meteorological conditions like low pressure or trough, the accentuation causes very heavy rainfall resulting in unprecedented floods causing immense loss to life and property. These most severe rainstorms caused by the tropical disturbances have been analysed for depth area duration (DAD) statistics. The application of the derived results while designing any hydraulic structure in catchments of this region will ensure the safety of structures against extreme flows. The computed DAD values are the estimation of probable maximum precipitation (PMP) and can be used to compute maximum probable design discharge in this region.The derived curves are readily useable for preparing design of new hydraulic structures and checking the safety of existing works for likely extreme precipitation in this region and thus the recurring heavy damages due to unprecedented floods can be mitigated to a reasonable extent.