Relief and geomorphologic hazards in the urban areas of Abkhazia

Based on the results of geomorphologic surveys carried out in 2021–2022 with the involvement of published materials, an original large-scale (from 1:25 000 to 1:100 000) description of relief of urban areas of the Republic of Abkhazia (Gagra, Pitsunda, Gudauta, Noviy Afon and Sukhum) was compiled, and unprecedented general geomorphologic maps were prepared, with morphogenesis-based legends. According to their morphostructure position and geomorphologic structure, the cities are grouped as follows: 1) completely lying in the area of the coastal-marine relief (Pitsunda and Gudauta); 2) located mainly within the sea terraces and erosion-denudation hills (Sukhum and Gagra); 3) completely located in the low mountains with a predominance of strongly dissected structural-denudation, fluvial and slope relief (Noviy Afon). A field survey revealed about 300 areas with unfavorable and dangerous geomorphologic processes within the urban areas, 44% of them are in Sukhum, 26% in Gudauta, 11% in Gagra, 10% in Pitsunda, 9% in Noviy Afon. The leading geomorphologic hazards in all spectra are suffusion, erosion and biogenic processes. A list of other processes in a spectrum is predetermined by the geomorphologic position of cities. The widest range, which in addition to the above-mentioned processes, includes also karst, mudflows and landslide processes (i.e. the most dangerous ones), is typical for urban areas with a complex relief structure, abundant in steep slopes and located within a narrow strip separating the spurs of the Main Caucasian Range from the sea (Gagra, Noviy Afon). The risk of destruction of street infrastructure (roadbed, communications, etc.) by dangerous geomorphologic processes was qualitatively estimated and its high dependence on the geomorphologic position of a particular section of the city has been established. In particular, the distribution patterns of recorded unfavorable and dangerous geomorphologic processes made it possible to state that the most favorable conditions for the construction and operation of urban infrastructure and buildings in general are within the leveled surfaces of the Late Pleistocene marine terraces, as well as the upper levels of floodplain terraces in the valleys of large rivers. Other levels of relief have certain disadvantages that impede the development of territories. Thus, the construction on the surface of the Holocene marine terrace is possible only if the foundations are waterproofed and soil is dumped in the lower areas. The development of high sea terraces, erosion-denudation and structural-denudation relief is difficult because of the high density of erosion dissection.

1. Baburin V.L., Badina S.V. Ocenka social’no-ekonomicheskogo potenciala territorii, podverzhennoj neblagoprijatnym i opasnym prirodnym javlenijam [Evaluation of the social-economic potential of natural hazard-subjected territories], Vestn. Mosk. un-ta, Ser. 5, Geogr., 2015, no. 5, p. 9–16. (In Russian)

2. Baburin V.L., Badina S.V. Prognozirovanie social’no-jekonomicheskih ushherbov ot opasnyh prirodnyh processov dlja turisticheskogo klastera “Kurorty Severnogo Kavkaza” [Forecasting of probable socio-economic losses from natural hazards (case study of the “Northern Caucasus resorts” tourist cluster)], Vestn. Mosk. un-ta, Ser. 5, Geogr., 2021, no. 2, p. 25–34. (In Russian)

3. Balabanov I.P. Paleogeograficheskie predposylki formirovanija sovremennyh prirodnyh uslovij i dolgosrochnyj prognoz razvitija golocenovyh terras Chernomorskogo poberezh’ja Kavkaza [Paleogeographic preconditions of modern natural conditions formation and long-term forecast of the evolution of Holocene terraces of Caucasus Black Sea coast], Moscow, Vladivostok, Dal’nauka Publ., 2009, 352 p. (In Russian)

4. Balabanov I.P., Nikiforov S.P. Gagrskij zaliv. Rekreacionnyj potencial prirodno-geologicheskih uslovij pribrezhno- morskoj zony [The Gagra Bay. Recreational potential of natural-geological conditions of the sea coastal zone], Moscow, Avtorskaja kniga Publ., 2016, 288 p. (In Russian)

5. Barkov I.M. Novyj Afon: Ocherk: S vidom Monastyrja [New Athos: Sketch: View of the Monastery], Saint Petersburg, Sinod. tip. Publ., 1904, 24 p. (In Russian)

6. Bredihin A.V. Organizacija rekreacionno-geomorfologicheskih sistem [Organization of recreational-geomorphological systems], Doctor of Science Thesis in Geography, Moscow, 2008, 396 p. (In Russian)

7. Chernjavskij V.I. Kratkij ocherk Abhazii [Brief sketch of Abkhazia], Saint Petersburg, tip. V. Bezobrazova i K° Publ., 1877, 24 p. (In Russian)

8. Dbar R.S., Strochan T.P., Zhiba R.Ju. Opasnye prirodnye javlenija na territorii Abhazii. Ocenka riskov s ispol’zovaniem GIS – tehnologij [Natural hazards within the territory of Abkhazia. Risk evaluation using GIS technologies], Vestn. AN Abhazii, Ser. Estestvennye nauki, 2020, no. 10, p. 208–229. (In Russian)

9. De Monpere F.D. Puteshestvie vokrug Kavkaza [Voyage around the Caucasus], vol. I, Proc. of Institute of Abkhazian culture, Georgian branch of AS USSR, iss. VI, Svidetel’stva inostrancev ob Abhazii, Sukhumi, Abgiz Publ., 1937, 169 p. (In Russian)

10. D’jachkov-Tarasov A.N. Gagry i ih okrestnosti [Gagra and its vicinities], Tiflis, tip. K.P. Kozlovskogo Publ., 1903, 100 p. (In Russian)

11. Dubljanskij V.N., Klimenko V.I., Vahrushev B.A., Iljuhin V.V. Karst i podzemnye vody gornyh massivov Zapadnogo Kavkaza [Karst and groundwater of West Caucasus mountain massifs], Leningrad, Nauka Publ., 1985, 150 p. (In Russian)

12. Fedina A.E. Fiziko-geograficheskoe rajonirovanie, izd. 2 [Physical-geographical zoning, 2nd iss.], N.A. Gvozdeckij (ed.), Moscow, Lomonosov Moscow State un-ty Publ., 1981, 128 p. (In Russian)

13. Fedorov P.V. Stratigrafija chetvertichnyh otlozhenij Krymsko- Kavkazskogo poberezh’ja i nekotorye voprosy geologicheskoj istorii Chernogo morja [Quaternary deposits stratigraphy of Crimean and Caucasian coast and a few questions of geological history of the Black Sea], Publications of Geological Institute of AS USSR, iss. 88, Geol. ser., no. 17, Moscow, AS USSR Publ., 1963, 165 p. (In Russian)

14. Gagry: Klimaticheskaja stancija na Chernomor. poberezh’e [Gagra: Climatic station at the Black Sea coast], Saint Petersburg, tip. A.S. Suvorina Publ., 1905, 79 p.

15. Geomorfologija gorodskih territorij: konstruktivnye idei [Geomorphology of urban territories: constructive ideas], Je.A. Lihacheva, S.I. Bolysov (eds.), Moscow, Media-Press Publ., 2017, 176 p. (In Russian)

16. Gvozdeckij N.A. Kavkaz: ocherk prirody [The Caucasus: sketches of the nature], Moscow, Geografgiz Publ., 1963, 264 p. (In Russian)

17. Koronovskij N.V. Geologija Rossii i sopredel’nyh territorij [Geology of Russia and adjacent territories], Moscow, Akademija Publ., 2011, 240 p. (In Russian)

18. Kozlov A.L. Predvaritel’nyj otchet o geologicheskih issledovanijah v b. Suhumskom uezde v 1929 g. [Preliminary report about geological studies in Bol’shoj Suhumskij uezd, 1929], Izvestija Vsesojuznogo geologorazvedochnogo ob’edinenija, vol. 51, iss. 68, 1932, p. 999–1026. (In Russian)

19. Kuftyreva N.S., Lashhija Sh.V., Mgeladze K.G. Priroda Abhazii [The nature of Abkhazia], Sukhumi, Abgosizdat Publ., 1981, 441 p. (In Russian)

20. Leontiev O.K., Nikiforov L.G., Saf’ianov G.A. Geomorfologiya morskikh beregov [Geomorphology of sea coasts], Moscow, izd-vo MGU, 1975, 336 p. (in Russian)

21. Lihacheva Je.A., Timofeev D.A. Rel’ef sredy zhizni cheloveka (ekologicheskaja geomorfologija) [The topography of human life environment (ecological geomorphology)], Moscow, Media-Press Publ., 2002, 640 p. (In Russian)

22. Lihacheva Je.A., Timofeev D.A., Zhidkov M.P. Gorod – ekosistema [City as an ecosystem], Moscow, In-te of Geography of RAS Publ., 1996, 336 p. (In Russian)

23. Markov K.K. Osnovnye problemy geomorfologii [The main problems of geomorphology], Moscow, OGIZ Publ., 1948, 43 p. (In Russian)

24. Pasternackij F.I. Klimatolechebnye punkty na Chernomorskom pobere-zh’e Kavkaza [Climatis treatment sites at the Black Sea coast of the Caucasus], Saint Petersburg, tip. P.P. Sojkina Publ., 1899, 91 p. (In Russian)

25. Prendel’ R.A. Otchet o rezul’tatah ekskursii, proizvedennoj letom 1878 g. po pribrezhnoj polose Abhazii i Chernomorskogo okruga [Report on the results of excursion held in summer 1878 along the shoreline of Abkhazia and Chernomorskij okrug], Zapiski Novoros. ob-va estestvoispyt, 1879, vol. 5, iss. 2, p. 1–9. (In Russian)

26. Rummel’ V.Ju. Materialy dlja opisanija russkih kommercheskih portov i istorii ih sooruzhenija, vypusk XXX, Kerch’ – glubokij port, sudohodnyj kanal ot reki Kubani k Anape. Suhum. Rezul’taty izyskanij, provedennyh v 1896-97 gg. [Materials for description of Russian commercial sea ports and the history of their construction. Issue XXX. Kerch’ – a deep sea port, ship canal from Kuban’ river to Anapa. Sukhumi. The results of investigations held in 1896–1897], Saint Petersburg, Upr. vodjanyh i shossejn. soobshh. i torg. portov Publ., 1900, 42 p. (In Russian)

27. Saf’janov G.A. [Subaquatic canyons: their dynamics and interaction with the upper part of the continental shelf], Geografiya i geomorfologiya shelfa [Geography and geomorphology of continental shelf], Moscow, Nauka Publ., 1978, p. 29–37. (In Russian)

28. Saf’janov G.A. Geomorfologija morskih beregov [Seacoasts geomorphology], Moscow, Moscow St. Univ. Publ., 1996, 400 p. (In Russian)

29. Safronov I.N. Geomorfologija Severnogo Kavkaza [Geomorphology of the Northern Caucasus], Rostov-on-Don, Rostovskij univ. Publ., 1969, 221 p. (In Russian)

30. Seleznev M. Rukovodstvo k poznaniju Kavkaza [Instruction to studying the Caucasus], Saint Petersburg, tip. Morskogo kadetskogo korpusa Publ., 1850, 179 p. (In Russian)

31. Shevcov M.S. Paleocenovye i smezhnye s nimi sloi Suhuma, ih fauna i stroenie prilegajushhego k Suhumu rajona [Paleocene and contiguous layers of Sukhumi area, their fauna and structure of area adjacent to Sukhumi], publications of Geol. Scient-Res. Inst. of Phys.-Math. Faculty of the 1st Moscow State University, Moscow, 1929, 60 p. (In Russian)

32. Shhukin I.S. Obshhaja geomorfologija, t. 2 [General geomorphology, vol. 2], Moscow, Moscow St. univ. Publ., 1964, 564 p. (In Russian)

33. Simonov Ju.G. Regional’nyj geomorfologicheskij analiz [Regional geomorphologic analysis] Moscow, Moscow St. univ. Publ., 1972, 252 p. (In Russian)

34. Sizikov M. Puteshestvie na Kavkaz i prebyvanie neskol’ko dnej v Novo-Afonskom Simono-Kananitskom monastyre [Caucasus voyage and several day staying at New Athos Simon the Cananite monastery], Moscow, tip. I. Efimova Publ., 1884, 23 p. (In Russian)

35. Spiridonov A.I. Geomorfologija evropejskoj chasti SSSR [Geomorphology of the European part of USSR], Moscow, Vysshaja shkola Publ., 1978, 332 p. (In Russian)

36. Tanfil’ev G.I. Ocherk glavnejshih rajonov chernomorskogo poberezh’ja [The sketch of the most important areas of the Black Sea coast], Saint Petersburg, 1904, 54 p. (In Russian)

37. Van V.G., Eremenko E.A., Kazhukalo G.A. et al. [Abkhazia coasts morphogenetic types and modern trends of coastal zone evolution], Issledovanija molodyh geografov, sb. statej uchastnikov zimnih studencheskih jekspedicij [Young geographers researches: collect. of articles of winter student expedition members], M.S. Savoskul, N.L. Frolova (еds.), 2022, р. 33–45. (In Russian)

38. Voskresenskij S.S. Geomorfologija SSSR [Geomorphology of USSR], Moscow, Vysshaja shkola Publ., 1968, 368 p. (In Russian)

39. Zenkovich V.P. Berega Chernogo i Azovskogo morej [The coasts of Black Sea and Azov Sea], Moscow, Geografgiz Publ., 1958, 380 p. (In Russian)