THE EFFECTS OF LONG-TERM DRAINAGE AND RESTORATION ON WATER TABLE LEVEL AND WATER CHEMISTRY IN THE VASYUGAN MIRE (WESTERN SIBERIA)

References: 17th International Multidisciplinary Scientific GeoConference SGEM 2017, www.sgem.org, SGEM2017 Conference Proceedings, ISBN 978-619-7408-04-1 / ISSN 1314-2704, 29 June - 5 July, 2017, Vol. 17, Issue 31, 663-668 pp, DOI: 10.5593/sgem2017/31/S12.083

ABSTRACT

An investigation of the effects of long-term drainage and restoration on the water table level and water chemistry was carried out within the area drained in 1975–1980 of Vasyugan Mire (Ob-Irtysh interstream area) with a pine–shrub–sphagnum community. The method of statistical analysis included estimation of time series and spectral analysis. In conditions of unsatisfactory operation of the drainage network, a comparative analysis of the data showed that average seasonal levels were close to natural conditions. An established trend of the maximum water levels within the drained area was revealed. Comparison of the chemical composition of the waters showed higher concentrations of Ca2+, NH4+, SO42-, HCO3- , CL-, and TOC on the drained territory, and the increase in mineralization was 24%. Comparative analysis showed a higher content of humic acids (14%) and fulvic acids (18%) in the waters of the investigated drained bog in comparison with a similar pristine bog. Analysis of the long-term dynamics of the content of organic substances in the waters of the drained bog revealed a statistically significant trend associated with a decrease of the content of humic acids. The average concentrations of humic acids and fulvic acids over the observation period vary cyclically, and on the whole within the study area, cycles of 2–4 years can be identified. Analyzing the behavior of the time series with the spectral analysis, it was revealed that the first four harmonics of the humic acid water content series include the periods 12, 6, 4, and 2 months, and for fulvic acids - 21, 9, 5, and 2 months, while the dispersion of the series is 65–81 %.

Keywords: water table level, water chemistry, restoration, spectral analysis, Vasyugan Mire.