Flood simulation in the Kama river basin 2005
Climate warming is causing an increase in the total moisture content on the planet and in the number of heavy rainfall cases. Modern flood warning systems are still not effective enough, especially in places with a sparse network of meteorological observations. Mathematical models of the atmosphere based on complete equations of hydrodynamics allow us to calculate the intensity of precipitation with high detail with sufficient advance. This paper examines the issue of combining a regional atmospheric model WRF-ARW with a hydrological model for RiverFlow 2D GPU size in order to assess the accuracy of reproduction of rain floods on two rivers of the Ural Kama region: Usva and Obva on June 23-24, 2005. The rise of water levels in the rivers was caused by convective and frontal precipitation on the frontal systems of a deep southern cyclone. In some observation points, up to 50 mm of precipitation fell during the period of 12 hours. At the first stage of the study, model precipitation fields were obtained in nodes of a regular grid with a step of 3 km. The simulation was performed under the condition of non-hydrostatic approximation and direct (without parameterization) simulation of convection on the calculated grid. Then the procedure of preliminary assimilation of precipitation by the hydrological model was carried out. For a mountainous, an underestimation of flood water consumption was found in comparison with the actual data. For the Obva River catchment, an overestimation of the maximum costs compared to the actual costs was revealed. To increase the accuracy of the forecast of maximum levels, it is necessary to take into account the processes of evaporation and infiltration for the period preceding the development of the flood. The results obtained can be taken into account when preparing forecasts of heavy rains occurrence and when developing flood forecast techniques.