Basin-analogy for calculating spring flood volumes at insufficiency of meteorological data (Tuba river as a case study)

Abstract

Relevance. The necessity in provision of insufficient data on streamflow formation factors when predicting floods in the poorly explored and unstudied basins. For this purpose, in hydrological calculations and forecasts the method of hydrological analogy is applicable. Aim. To study probable application of the hydrological analogy method in calculations of spring flood volumes of a mountain river. The analysis was carried out by the example of the basins of the Tuba river and its tributaries (rivers Amyl, Kazyr and Kizir), as well as neighboring catchments (rivers Abakan and Syda). Methods. Integrated geographical-hydrometeorological analysis, correlation and regression analysis, and the hydrological analogy method. Results. We calculated total winter precipitation in the Amyl basin by means of (traditionally used in hydrology) elevation dependences, estimated average annual precipitation in the Tuba basin using modern glaciation data, and built a stochastic predictive model of flood runoff volume on the Amyl river (settl. Kachulka) based on the relationship between precipitation for the previous winter and flood periods. The influence of liquid (flood) precipitation on the forecast quality was analyzed. A comparative analysis of other Tuba tributaries (Kazyr, Kizir), including neighboring basins (rivers Abakan and Syda) in terms of their application as basins-analogies was performed. For instance, a feasible use of the Amyl basin as an analogy for forecasting flood runoff depth of the Tuba river (vill. Bugurtak) was analyzed. Conclusions. The correlation analysis of flood volumes of the Tuba, its main tributaries and neighboring rivers suggests that as an analogy the application of basins with similar conditions for precipitation formation (slope orientation relative to the direction of the prevailing moisture-bearing air masses) and average catchment elevation is currently favored. The Amyl basin use as the Tuba analogy is expedient for a medium-term forecast of melt runoff volumes (excluding liquid (flood) precipitation).