Inter-annual variability of the dates of formation of the highest snowmelt intensity and maximum flood discharge in the Inva River basin (Perm Krai)

The inter-annual variability of the dates of formation of the highest intensity of snowmelt and the maximum spring flood discharge is considered on the example of the Inva River basin for the period 2010–2020. Meteorological and catchment factors have a key influence on the duration of snowmelt, the amount of snow melted per day, water discharge and, accordingly, the levels of water outlets on the floodplain. The applied geo-information model of snowmelt takes into account spatially distributed meteorological information and the characteristics of the floodplain meteorological information and catchment underlying surface features. Model allowed obtaining daily values of the melted snow layer, snowpack and the proportion of remaining snow cover. The basin time which characterizes the period between the peak of the runoff layer and the corresponding peak of water discharge, the peak of the runoff layer and the corresponding peak of water discharge. The results of comparison of snow reserves and frequency of water level exceedance of the adverse event (AE) mark at the gauging station of Inva-Kudymkar for the multi-year period 1970–2020 showed that for the period 2010–2020 the snow reserves were on average 10% higher, and the frequency of exceedance of the AE mark is on average once in 2 years. The application of GIS-technologies allowed visualization of the process of snowmelt and flooding of urban areas. The snowmelt factors of 2017 resulted in flooding of 2.0 km² of the territory of Kudymkar town, including 52 households.