Fractal dimensions of the more than 200 large river networks of the former USSR were calculated. We use the term «fractal» as «a structure consisted of parts which are in some sense alike to the whole». River networks don’t possess the complete self-likeness – fractal dimension changes with the change of measurer unit and the chosen length of the rivers. Therefore the calculations were fulfilled with the measurer length lying within the

limits of 1–10 km. Fractal dimension of the river networks of the former USSR changes from 1.1 to 1.7, which corresponds to the aggregate length of the short rivers (1–10 km) consisting 20–80% of total river network length. Then all studied networks have fractal dimension more than Euclidian dimension of line (1) and less than Euclidian dimension of plane (2) as it should be accordingly to the fractal approach. There is a tendency for fractal dimension to grow with the height of the river basin and humidity of the territory. It is also strongly correlated with the network density. Fractal dimension as an index of the river length distribution has some advantages in comparison with the other morphometric indexes used. It augments significantly the possibility of the quantitative analysis of the drainage networks.

Annual denudation rates were calculated using data on the suspended sediments runoff module of the rivers. These rates vary widely: from less than 0.005 to more than 1.75 mm/year in the Caucasus, Pamir-Alai and Alps; from 0.002 to 0.4 mm/year in the Tien Shan. The most significant factors of denudation cutting of the mountains are topography, climate and composition of rocks. The maximum rates of denudation (more than 1 mm/year) occur in the highest and most humid parts of the mountains (Western Alps, Western Caucasus, etc.). The minimum values of annual denudation rate (less than 0.1 mm/year) are observed on the lower mountain slopes with little rainfall and with resistant to denudation sediments (eastern slopes of the Lesser Caucasus, the interior of the Tien Shan, etc.). Vegetation and human activities can both enhance and suppress exogenous processes and thus the denudation rate. In all these mountains tectonic uplift prevails over the denudation.

Isotope aging of volcanic plugs and lava flows, armouring contemporary landforms and fixating slopes of the valleys, proved that these forms haven’t changed significantly since Triassic time. These facts move the boundary between so called geomorphologic and pregeomorphologic stages of relief formation in the Eastern Transbaikalia from the Cretaceous-Paleogene planation epoch to earlier times. However in this region there are many pediments which evidence a deep cut of the earth’s surface leaving no possibility of the maintenance even of the Upper Jurassic landforms. The author considers this discrepancy as a geomorphological paradox of the East Transbaikalia relief formation.

The peculiarities of a coastal morphology of large man-made lakes under the wave-dominated, fluvial dominated and transitional environments were discussed. It was shown that the fluvial-dominated environment is similar to the one in a river delta. In the transitional environments, the gradual replacement of delta sub-environments by shallow areas is observed. In the wave-dominated environments the relief is similar to the characteristic relief of the sea coastal zone.

A complex approach for estimating sediment delivery from drainage basin slopes into river valley is proposed. The method includes morphometric analysis of drainage basin, mathematical modelling and radioactive isotope tracers application. The approach effectiveness is demonstrated by analysis of the River Lokna drainage basin slopes (Central Part of the European Russia). Total area of the drainage basin is 174.8 km².

Morphometric characteristics of 1293 elementary slopes (facets) were collected from the 1:100 000 scale topographic map and analysed. Average soil erosion rate from facet under conditions of bare fallow is 46.2±31.9 t/ha/year. For a range of locally typical crop rotations this value varies from 17.2±13.0 to 33.3±19.1 t/ha/year.

Mapping of drainage basin slopes allowed distinguishing areas with highest potential erosion rates. About 33% of elementary slopes of the studied drainage basin are characterized by the LS-factor value exceeding 1.5. In hypothetical case of cultivation of all basin slopes under bare fallow, 77% of elementary slopes will be characterized by very high and catastrophic potential erosion rates (>20 t/ha/year). For a range of locally typical crop rotations this percentage is reduced to 44%.

Application of radioactive isotopic tracer allowed us to obtain an independent evaluation of the model validity. Comparison of soil loss rates obtained independently by the model and the ¹³⁷Cs radioactive tracer for the morphologically simple short runoff-dissipating slope has shown high degree of coincidence. However for the more complex long convex slope the model produced higher values of soil loss rates (sometimes more than twice) than the ¹³⁷Cs-based estimates. It can be explained by the fact that the model takes no account of within-slope sediment redeposition which cannot be estimated by its current version.

The authors suggest the method for digital elevation models (DEMs) compiling aimed to plotting the boundaries of the drainage catchments for the lowland relief (West Siberia as an example). The proposed method allows taking into account the local contemporary depressions – traps of the suspended sediment yield and surface runoff. In the result the higher precision of the basins boundaries pattern is obtained. In this method additional information from the topographic maps is used. The DEM compiled with the use of the suggested method helps to significantly increase the accuracy of the West Siberian catchments’ automatic plotting.

Present paper results detailed investigation of sediment redistribution rates on different land-use units at the small catchment Bodomo, located in the loess belt of Tajikistan to the east from Dushanbe. Radiocesium dating is used for determination soil loss/gain along 7 slopes with different aspect, located at the typical for given area land-used parcels (tillage, pasture, orchards). Initial inventory of ¹³⁷Cs fallout at the reference site is varied taking in account decay in range   3945-4210 kBk/m². It is confirmed that initial inventory of ¹³⁷Cs fallout is relatively uniform and it is possible to apply ¹³⁷Cs technique for evaluation of sediment redistribution rates. It was established, that maximum annual soil losses for period 1989-2006 is observed for the arable lands, and they change depending from slope angles in range  50-90 t/ha per year. Mean annual erosion rates on pasture for period 1963-2006 are varied in range 4-11 t/ha per year depending from cover of soil and vegetation. However, sediment produced by sheet and rill erosion   contributes not more than 10-15% from total volume of sediment originated from the catchment area. Gully erosion and scree processes, developed on the sides of erosion forms of the different order, are the main contributors into catchment denudation.

The lake Krasnoye lies on the 3d terrace of the Moscow River in the periglacial region of the Moscow and Valdai glaciations. It has rounded conical shape 300 m in diameter and 9 m in depth, and is surrounded by a gentle rim 2-6 m in height and 100-150 m in width. Deposits of the rim (sand and sandy-loam) have lumpy, practically non layered structure which is similar to gravitational deposits of the slope foot. Authors suggest that these deposits might be formed at the foot of the large ancient pingo existed here in the periglacial conditions, from the slopes of which unconsolidated sediments crept and were washed down. The impact origin of this rimmed depression should by reject because of the complete absence of the deep rocks ejecta.

According to the comparative analysis of digital elevation models (DEM) based on large scale topographic surveying at the Bykovo site, a 746 m² maximal extension of landslide movement area was revealed in 2006, which was caused by maximum rainfall and the reservoir water level highest in the observation period. The areas prone to erosional form development on the landslide slope increased on 100 m².

It was established that the Rassvet site on 2000 m extent in alluvial and deluvial loams and sandy loams with interlayers of medium sands is exposed to abrasive wash-out. The width of the shore slope edge retreat ranged from 0 to 8 m during the last three years. According to GPS survey data, the maximum volume of washed-out soil material reached 13860.0 м³ over the 2006–2007 period. The total volume of the gullies in the edge of abrasive bench amounted to 1360.1 м³ (2007).

The volume of soil, lost at the Zakoryukovo site in the loess-like sediments as a result of a small shore edge retreat and erosional processes constituted 2590 м³ in the same period.

The highest volume increase (on 4486.34 m³ from 2004 to 2008) was revealed at karst-erosional mechanism on the Khadahan site.

Based on interpretation of images (1971—1980), the mid-term dynamics of linear growth of shore gullies on the abrasive Uley site ranged from 0 to 44 m, average growth rate accounted for 1-2 m, with maximum of 4 m per year.

At the present stage the shore zone of the Bratsk reservoir is marked by lack of stabilization of abrasion processes. The response reaction of local geosystems (dynamics of the processes, their interaction, and environment change) is characterized by a certain cyclicity corresponding to water level fluctuations.

Major features of bank erosion within the middle course of the Lena River are related to the hydrological conditions of flowing water contact with different floodplain levels, and variations in floodplain lithology. Formative discharges of the spring freshet correspond to the frozen sandy strata of the high floodplain banks, thus promoting thermal erosion of the latter. Effectiveness of the thermal erosion increases with the increase in bank height and is highest for high floodplain and terrace levels. Morphology of the banks depends not on the rate of their washing out, but on the influx of the sediments at their base. Volume of eroded bank material exceeds the annual bedload runoff due to the large extent of the eroded bank within the studied Lena River reach.

River channels characterized by the multi-thread patterns are most complex form points of view of morphology, structure and deformation regime. The paper presents an analysis of the largest river channel deformations at the adjoint braids with an example of the Lena River reach near its confluence with the Aldan River including the three consecutive braids – Haityallah, Omulagan and Arbyn. During the 20^th century and the first decade of the 21^st century the studied Lena River reach has experienced periodic shifts of the main arm, associated changes of discharge ratios between arms within braids and the resulting relocation of the navigable fairway track. Temporal patterns of discharge fluctuations in the Lena and Aldan Rivers do not coincide, causing alternations of the dominant influence of the main river flow onto its tributary or the opposite during the peak discharge periods. It is shown that the intermittent phase of temporal transformation of the adjoint braids channel pattern into the parallel arms channel pattern occurs between the longer stages of dominant development of left or right arms. Duration of that phase depends mainly upon the average water discharge relatively to its long-term fluctuations (increases during higher runoff periods and decreases during lower runoff periods), flow backing conditions caused by the inflowing tributary (the Aldan River) affecting the entire length of the studied Lena River reach and local channel deformation conditions. In general, such a transitional phase of the channel development (between the alternating stages of dominance of left or right arms within the adjoint braids chain) can last for significant period of 10-15 years or even more. Duration of the transitional phase is comparable to that of the alternating stages of dominance of left or right arms on large- or medium-sized rivers where parallel arms pattern of the multi-thread channel does not develop. In turn, channel deformations at the adjoint braids exert significant influence on development of main arms of the internal delta situated at the confluence of the Lena and Aldan Rivers, where the main control is associated with alternation of flow backing or no backing conditions related to different discharge ratios between the main river and its main tributary.

Anthropogenic evolution of semiarid and arid plains of the Eastern Atlas margin in the Holocene and today is described. In the history of Medjerda river valley three stages of man induced aridization were considered: 6.6–6.0, 4.7, and 3.0–2.7 ky b.p.; in the arid shotts region situated further south aridization took place at 13–9, 8.5–7, 6.5–5, and 4 ky b.p.–present time. It means that aridization in the northern regions had begun approximately 6 ky earlier than in the south. Arid transformation of the landscapes due to human impact appeared to be enormous. Medjerda River protracted a large delta into the Mediterranean Sea due to human activity in its valley, the Bon Peninsular and the Dgerba Island gained anthropogenic flat plain relief, landscape of valleys and lakes in the Sahel Tunisia transformed into one of the agricultural plains, sores depressions, and rare lakes. 

It is turned 90 years from the date of O.K. Chediya birth recently – honored worker of science of the Kyrgyzstan, Doctor of geological-and-mineralogical sciences. During 50 years he worked in the Central Asian mountain regions: the Pamir and the Tien Shan. From 1950-th the main line of his research lied in Neotectonics with rest on Geomorphology, Stratigraphy and Quaternary Geology. Actually at that moment newest tectonics was in development, there were no prepared methods and guided. Researchers faced with difficult tasks, all the more in mountain regions. It could be said quite literary that Chediya was instrumental in the Pamir and the Tien Shan neotectonics development, as well as S.S. Schuitz. Main Chediya’s scientific achievements are: development of special methods in newest tectonic movements’ quantity characteristics research, detachment of seismogenic zones and its seismic hazard evaluation, and also important seismotectonic and seismic zoning mapping. Chadiya attended to academic staff training: 17 masters and 19 doctoral papers were defended under his control. Also Chediya’s intelligence, high level of culture and moral are should be noted.

Chronic of XXXIII Plenary meeting of the Geomorphological Committee RAS “Geomorphology and Cartography” in Saratov.