ОСОБЕННОСТИ ПРОГНОЗА ДИНАМИКИ РОДНИКОВОГО СТОКА В БЕРЕГОВОЙ ЗОНЕ ИВАНЬКОВСКОГО ВОДОХРАНИЛИЩА

Abstract

Ivankovo reservoir is the main source of drinking water supply in Moscow. Its coastal zone, where different types of springs are unloaded, is a barrier (or source) for the entry of pollutants into the reservoir. The aim of this research is to forecast increments in descending springs water flow and to evaluate trends of hydrochemical indicators (calcium, magnesium ions, hydrocarbonates and chlorine) of springs water quality over 13 years. The basis of the work are materials of regime observations on reference spring located on the Volga II floodplain terrace, for the period 2006-2018. When processing hydrochemical data in order to compare the results, two approaches were used. One is separation of data array into two groups in chronological order (2006-2012 and 2013- 2018), the other – is arrangement according to water content of the year, where the first group is the years of low and medium water content, the second is high. It is proposed to describe the relationship between amount of precipitation and increment of flow rate by an ordinary differential equation, which will allow to predict the flow rate of the downstream springs of the region using amount of precipitation in increments by the next six months. The obtained result was verified on groundwater level regime data for the well 3020, drilled on the II floodplain terrace, for the period 2001-2003. The maximum correlation coefficient between the increment of the groundwater level and the amount of precipitation is observed at a similar step. When analyzing the equation, the value of the amount of precipitation was obtained, which separates the mode of increasing or decreasing the flow rate of the spring (groundwater level). For the spring, this figure is 296, for the well – 316 mm. A statistical analysis of long-term dynamics of the spring runoff hydrochemical components showed that a median value is a more sensitive characteristic to changes in external conditions than an arithmetic average for hydrocarbonates and calcium. An upward direction shift of the median value of bicarbonates and calcium ions concentration in spring waters was revealed when using a nonparametric criterion. The long-term average gradient was 1 mg dm-3 year-1 for bicarbonates, and 0.17 mg dm-3 year-1 for calcium. The approaches used to divide the data into groups for calcium and magnesium give different estimates of trends, for hydrocarbons they were the same, for chlorides they are contradictory. Statistical analysis of the data, separated in chronological order, showed that for calcium and magnesium there was a significant upward trend, while with the approach for water availability of year no trends were found.