DEVELOPMENT OF A HYDRO-STATISTICAL MODEL OF ESTABLISHING THE LIMITS OF STREAMS AND ITS VERIFICATION (ON THE EXAMPLE OF THE VYATKA-RIVER BASIN)

Abstract

A new unique method for establishing the shoreline of watercourses has been offered. In accordance with the Russian Water code, the border of rivers and streams is the shoreline with a long-term average annual water level for the ice-free period. That level is unknown in advance: it cannot be directly measured afield; it is not given in hydrological directories, as it is not considered to be characteristic, and on cartographic materials the outlines of water bodies are given at the average water level for the summer-autumn low flow period. To determine the desired level, the authors proposed a new method using the example of the Vyatka River. The method is based on a hydrolytic statistical model: the predicted parameter is the value of ΔH (the excess of the long-term average water level for the ice-free period over the average level of the summer-autumn low flow period), and the predictors (factors) of the model are the conditions of flow formation and passage. These factors are connected with ΔH by a power dependence, which has coefficients established by the least squares method from observations at 17 hydrological stations. The average calculation error ΔH was 5.4 ± 2.2 cm (significance level 0.05). The equation allows for any point or segment of the watercourse to calculate the desired level, and then establish a shoreline using large-scale maps. In this case, hydrometric observations are not needed. Mapping of the shoreline of the Vyatka River within the Kirov city and comparison of its position with the shoreline on a detailed space image received on a date close to the calculated level show that the standard error of the planned coastal position does not exceed 1.3 m, which meets the requirements to the accuracy of land boundaries of the water fund.