Ninth International Conference on Permafrost ... - IARC Research

Ni n t h In t e r n at i o n a l Co n f e r e n c e o n Pe r m a f r o s ta river dam constructed upstream from a floodplain talik; sothere is no way to tell how much these changes can influencethe natural complex under discussion. Very probably, theywill cause reduction of the talik followed by degradationof the woods. To prevent such a trend of developments, itis necessary to perform continuous monitoring of the talikcondition downstream from the dam and, in the case of areal threat, to propose efficient ways to reduce the damageto a minimum. Unfortunately, the methods traditionally usedin permafrost science are hardly suitable for accomplishingeven the first of these aims, because a reasonable degree ofaccuracy requires numerous measurements that are verylabor consuming. Less laborious biological methods are onlycapable of ascertaining the ecological disturbance when itbecomes irreparable.The most practical approach is based on our recentresearch of convective heat exchange between riversand contiguous aquifers by means of estimates of rivers’heat balance (Mikhailov 2002, 2008). Accounting for allcommonly considered components, the residual is total heatflux into ground ( qgr ) of which the conductive constituentis virtually a negligible part (Mikhailov 2002). All other heatfluxes can be calculated accurately enough, thus the same istrue for the sought quantity. Long-term estimates of qgr weremade for large sections of 6 rivers (Mikhailov 2008). As aresult, the general patterns of seasonal variation of this valuehave been established. One of these sections is located onthe Kolyma River between Seimchan and Baligichan (seeFig. 2). It belongs to the upper part of the floodplain talikunder discussion, subjected to the strongest influence of thereservoir regulations.Developing further this approach, the pattern of variationsof qgr in this section can be determined as dependent onhydrometeorological conditions during the whole periodof observations. Comparison of these data sequences withthose obtained after the dam construction will bring to lightthe influence of reservoir regulations. The results of suchanalyses will become more and more reliable with time.As a first approximation, a steadfast tendency of decreaseof qgr (all other factors being equal) will be indicative of theforthcoming reduction of the talik.Apparently, the only way to increase heat transfer tothe floodplain talik is either by specifying additionalflushes from the reservoir or manipulating the parametersof the regular ones (e.g., needed for the shipping). But itis a comprehensive analysis of the dynamics of the rivertemperature and discharge, together with the qgr values, thatcan enable a rational choice of optimal periods and minimaldurations and volumes of the flushes.The most essential advantages of the approach discussedare the following:1. Decrease of qgr precedes any significant changes ofboth the talik size and—all the more—the conditions offloodplain phytocenoses. It gives time to elaborate and discusswith the authorities proposals for necessary adjustments inthe reservoir regulations.2. Analysis of the fundamentally new information obtainedin the course of monitoring will undoubtedly improve ourknowledge of regularities of convective heat exchange inriver valleys. Besides the basic significance, in the practicalaspect it will make the aforesaid proposals more realistic.3. The most necessary part of data for estimating qgr isstandard hydrometeorological information. Additionalresearch will be needed only to improve the accuracy of theresults obtained and (probably) to verify the fact of the talikreduction.It is also important that the Ust’-Srednekan hydroelectricpower station will function together with the existing one(Kolymskaya station). Such a complex is far more flexiblethan a single station and in principle allows for moreconsiderable adjustments. This offers grounds for optimismas regards the acceptability of the would-be proposals forgovernmental and economic bodies. In that case, we may havea good example of sensible compromise between conflictinginterests and demands based on improved knowledge of thefunctioning of natural complexes.ReferencesMikhailov, V.M. 2002. Quantitative methods of indicationof floodplain taliks (theoretical premises). KriosferaZemli (Cryosphere of Earth) 6: 20-28 (in Russian).Mikhailov, V.M. 2008. Convective heat exchange betweenrivers and floodplain taliks. Proceedings of the <strong>Ninth</strong><strong>International</strong> <strong>Conference</strong> on Permafrost, Fairbanks,Alaska, June 29–July 3, 2008 (this proceedings).Vaskovsky, A.P. 1958. New data on the distribution limits ofcenoses-forming trees and shrubs in the Far North-East of the USSR. In: Materials on Geology andMinerals in the North-East of the USSR 10: Magadan,187-204 (in Russian).90