DETERMINATION OF ESTIMATED HYDROLOGICAL CHARACTERISTICS IN THE ABSENCE OF HYDROMETRIC OBSERVATIONS: POTENTIAL FOR THE USE OF REGIONAL GRIDDED RIVER RUNOFF REANALYSIS

Engineers in the field of hydrology often face the task of determining the hydrological characteristics for river gauges not covered by a regular network of hydrometric observations. This task is usually solved using classical methods and approaches, as described in SP 33-101-2003 «Determination of Basic Hydrological Characteristics», and is highly time-consuming, both in terms of search and acquisition of hydrological data and the timeconsuming computational procedure. At the same time, modern progress in hydrological modeling allows us to look at the solution to this problem from a different angle. Thus, in this paper we propose to reduce the problem of determining the characteristics of river runoff in the absence of observation data to a simpler problem of determining the characteristics of river runoff in the presence of observation data. For this purpose, we propose to use regional gridded reanalysis of river runoff R5 as a source of model-based runoff approximation in the river gauges of interest. The results of the performed calculations show high potential of the proposed approach for determining the characteristics of river runoff. Thus, for the studied Upper Volga river basins the deviations of the calculated values from the reference data of the State Hydrological Institute are negligeable. R5 runoff reanalysis was developed using freely distributed software and open data sources – GR4J conceptual hydrological model and WFDEI meteorological reanalysis. The R5 database covers both a large geographical domain within the European territory of Russia and a long time period (1979–2016) and is freely available at: https://zenodo.org/record/2600695.