CONSIDERATION OF THE VALIDITY OF THE STATISTICAL CHARACTERISTICS OF pH IN SURFACE WATERS

pH is one of the most important parameters characterizing the state of water systems. The arithmetic mean values of samples are often used when averaging serial pH measurements in water bodies, as is usually done for other characteristics of the state of the natural environment (temperature, salinity, oxygen concentrations, suspended solids, etc.). However, in this case such an operation is illegal, since the addition of logarithms, which by definition are pH, is non-additive. The authors conducted a study to determine the extent to which pH variability in natural objects such an operation would not distort the results. For this, several samples of the pH index were generated in various ranges of its theoretically possible and natural variability. It was established that with pH variability of less than a unit characteristic of marine pH values, the statistical characteristics of the indicator and [H+ ] concentrations differ slightly, and the medians of the samples coincide. It is concluded that with such ranges characteristic of the waters of the oceans, there is no need to recalculate previously obtained results. However, for the estuaries of rivers flowing into tidal seas, as shown by field measurements, the pH variability in the mixing zone of sea and river waters is several times higher. Similar situations may occur when heavy precipitation falls on the water surface, as well as during floods. In these cases, a simple averaging of the pH values will no longer be correct. In such cases, the use of other averaging algorithms and the choice of stable statistical characteristics are required.

ASSESSMENT OF MAXIMUM INSTANT DISCHARGE OF VARIOUS FREQUENCY AT UNGAUGED MOUNTAINOUS RIVER KHEMCHIK (TUVA REPUBLIC) BASED ON MATHEMATICAL MODELLING

the article presents the results of application of distributed deterministic hydrological model Hydrograph for estimation of maximum discharge values of different frequency at the ungauged catchment of the Khemchik River (Khemchik village, Tuva Republic). The catchment area is 1750 km2 , the average and maximum elevation — 2200 and 3600 m, respectively. Due to the lack of detailed information, a schematization of the catchment and the parameterization of the model are proposed, based on general ideas about the water balance and the processes of runoff formation of the main landscapes — rocky talus, coniferous forest and steppe. Parameters and algorithms are verified based on the results of streamflow modeling at two studied catchments: the Tapsy River — Kara-Khol (302 km2 ) and the Khemchik River — Iyme (25500 km2 ). Modelling of runoff formation processes with daily time step for the Khemchik River — Khemchik village was conducted for the period 1966–2012 using observational data at Teeli meteorological station. For the transition from daily to instant discharges, the dependence of the observed values of instant and daily streamflow at the studied gauges has been applied. On the basis of simulated discharge series, the frequency curve was built and the obtained curve was compared with the calculation data according to the standard methodology SP 33-101-2003 “Determination of the main calculated hydrological characteristics” using the analogue river. Simulated maximum instant discharges for entire frequency interval of up to 1% are 1.3–5 times higher than the values obtained by standard methodology SP 33-101-2003. The results of model calculations is indirectly confirmed by the evidences of regular flooding of the Khemchik village provided by the Ministry of Emergency Situations of the Tuva Republic, which is not predicted by the values obtained by the standard methods.

EXPERIENCE OF USING GLS-1500 SCANNER IN ENGINEERING-GEODETIC SURVEYING OF ROADS

modern geodetic technologies allow us to quickly obtain relevant, precise and reliable geospatial data. An example of such a technology is ground-based laser scanning. Currently, this technology is actively used in the performance of engineering and geodetic surveys of roads. The devices and software of different companies are used, differing in their accuracy characteristics and functionality. The article focuses on the experience of the use of GLS-1500 ground-based laser scanner produced by TOPCON and ScanMaster ground-based laser scanning data processing software for engineering and geodetic surveys in order to repair nine sections of the Federal highway R-256 "Chuysky tract" with a total length of over than 100 km. The article also describes the options used for registration of scanning data, the features of their use depending on the availability of geodetic control on the object. The order of processing the results of ground-based laser scanning using ScanMaster software is considered. According to the results of field work on ground-based laser scanning of nine sections of the R-256 highway, the time and accuracy of scanning data were estimated. The method of estimation of time spent on scanning works is also described. The issue of evaluating the accuracy of obtaining the scan data in the ScanMaster software is considered. It is noted that the accuracy of the geodetic reference, thus, the accuracy of the absolute orientation of the scans can be estimated by the differences between the coordinates of the marks that were scanned from the location of the device and calculated by ScanMaster software, and their specified values obtained from the equalization of the geodetic control. In conclusion, it is stated that the optimal time and accuracy of scanning with GLS-1500 device are achieved by using the geodetic reference of the scans by the inverse length-angle intersection at two points of the geodetic control.

2D INVERSION OF DIPOLE-DIPOLE AXIAL ARRAY WITH LINEAR CAPACITIVE ELECTRODES FOR ENGINEERING TASKS

at present, the range of tasks solved by geophysical methods is expanding. This is facilitated by the progress in the development of geophysical equipment, methods for performing field work and data processing. At the same time, the conditions of research are complicated. Often it is the site of industrial facilities or urban areas. The main factors complicating the implementation of the geophysical researches at urban areas are the high level of industrial noise and solid coverage. The article discusses the possibility of using resistance technology with 2D data inversion when solving engineering problems in urban areas. The conditions of the use of the measurement technique with capacitive electrodes for approximation by grounded electrode array at a direct current are shown. The results of the comparison of the dipole-dipole method with capacitive electrode array and its equivalent with galvanic grounded electrodes are presented. To assess the effectiveness of using of the capacitive electrodes array for solving engineering tasks in the city, the authors carried out researches on a site of regularly emerging subsidence of pavement in the center of St. Petersburg. According to the research results, a 2D resistivity section of the pavement deformation was constructed. The results were interpreted using geological information. The studies revealed a spatial correlation of the identified anomalies of specific electrical resistances with the local site of the embankment pavement destruction. The possible causes of the identified anomalies are described. The results of electrical prospecting with linear capacitive electrodes can be used for detailing engineering geological structure of urbanized areas.