ASSESSMENT OF POSSIBLE CONSEQUENCES OF OUTBURST FLOODS BY THE EXAMPLE OF THE BODOMDARA RIVER VALLEY (TAJIKISTAN)
V.A. Iudina (Kurovskaia)1, S.S. Chernomorets1, I.N. Krylenko1,2, T.A. Vinogradova3, I.V. Krylenko1, E.A. Savernyuk1, A.G. Gulomaydarov4, I.I. Zikillobekov4, U.R. Pirmamadov4, Yu.Kh. Raimbekov4
1Lomonosov Moscow State University, Leninskie Gory 1, Moscow, 119991, Russia
2Water Problems Institute, RAS, Gubkina str. 3, Moscow, 119333, Russia
3Research and Production Association Gidrotekhproekt LLC, Oktyabrskaia dtr. 55A, Valdai, Novgorod region, 175400, Russia
4Aga Khan Agency for Habitat in the Republic of Tajikistan, Rudaki ave. 34, Dushanbe, 737450, Tajikistan
Keywords: outburst floods, debris flows, transport-shift model, FLO-2D model, model of lake outburst, Tajikistan
Abstract
The prerequisites and modeling of possible outburst floods in the valley of the Bodomdara River (Tajikistan) are considered using detailed field data. According to the route survey results, Lake Bodomdara Upper is a supraglacial lake, which assumes possibility of its outburst leading to a cascade outburst flood. The depression of Lake Bodomdara Lower is relatively stable, and its outburst is possible without cascade flooding at anomalously high temperatures, upon snowmelt combined with extreme rainfall. Two probable scenarios are considered: (I) the outburst of Lake Bodomdara Lower (its volume comprised 328 000 m3 according to the bathymetric survey of 2020) and (II) the cascade outburst flood of Lake Bodomdara Upper (700 000 m3). Digital elevation model (DEM) ALOS PALSAR (12.5 m) and DEM based on images from an unmanned aerial vehicle for the Bodmodara River alluvial fan were used for predicting flood consequences. The outburst flood hydrographs for scenarios I and II were obtained using the lake outburst model developed by Yu.B. Vinogradov and an empirical formula, respectively. The material increment was estimated in the transport-shift model of mudflow formation. The resulting hydrograph was applied for zoning the Bodomdara and Shahdara river valleys with a total length of 75 km based on the FLO-2D model. According to the modeling, the maximum water discharge at the top of the alluvial cone of the Bodomdara River will reach 143 m3/s under scenario I and 348 m3/s under scenario II.
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