Chemical composition of waters and the phytoplankton of the lakes within the delta of the Selenga river

Field observations showed that the characteristics of chemical composition of waters and the development of plankton algae in the lakes within the delta of the Selenga river are determined by their flowage. The most open Lake Nekipelovskoe communicates with the Selenga outlets throughout a year, and Lake Zavernyaikha only at the period of an open channel. Lake Semenovskoe and Lake Khlystov Zaton are located in the islands and are isolated from the outlets. According to composition of main ions, the lakes under investigation refer to the hydrocarbonate class, the calcium group. The sum of ions in the water of Lake Nekipelovskoe approaches the one in the Selenga (86?221 mg/dm³), and the highest sums of ions were recorded in the wintertime in the lakes isolated from the outlets (446?743 mg/dm³). The lakes of the delta are characterized by a high trophicity. The maximum concentrations of total phosphorus in Lake Nekipelovskoe and Lake Zavernyaikha were 68 and 122 μg mg/dm³, and in Lake Semenovskoe and Lake Khlystov Zaton ?0.8 and ?0.63 μg mg/dm³, respectively. The most intense development of algae is observed in Lake Zavernyaikha, which is due to the high population of Baikal endemics. Lake Zavernyaikha showed a close negative correlation between the concentration of NO ₃ ^? , mineral phosphorus and phytoplankton biomass; the correlation coefficient was ?0.8 and ?0.63, respectively. The lakes exhibited increased contents readily hydrolysable organic matter, and a decrease in dissolved oxygen concentration in winter; hydrogen sulfide was repeatedly recorded in Lake Khlystov Zaton. The water quality in the lakes during the springtime varies from “quite clean” to “weakly polluted”; at low-water periods, especially in winters, it can drop to the category of “exceedingly dirty”. The water quality of the Selenga can be influenced by the lakes during spring floods when material accumulated during the wintertime is transported to the river outlets and further to Lake Baikal.     

Two treatments of the origin of ridge topography in the Kuraiskaya depression of Gornyi Altai

On the basis of the regularities of channel flow dynamics and the propagation of the emptying wave, it is shown that the value of the mean flow velocity above the field of giant ripples necessary for the ridge movement cannot be attained under given hydraulic and geomorphological conditions. Presented are the erosional dissection mechanisms for the surface of fluvioglacial deposits which contribute to the subparallel occurrence of ephemeral streams.     

The ecologo-geographical framework for the protection and recovery of taiga reindeer populations within the Konda river basin (Western Siberia)

The key aspects of reindeer ecology within the Konda river basin are considered. The study revealed the factors governing the characteristics of calving reindeer pastures determined by the structure of forest-bog landscapes of a different generalization level. A deficit of such pastures is regarded as the factor of differentiation of reindeer groups with respect to migrants and residents. It is shown that the individual geocomplexes have a multifunctional role. Of particular significance among them are the aufeis glades with outcrops of salt-saturated groundwater, and the dark-coniferous forests along river valleys rich in epiphytic lichens (beard lichens).     

Characteristics of extreme precipitation events within the Amur river basin in summer 2013

We investigated the precipitation characteristics for the summer period of 2013 on the basis of analyzing the daily precipitation amounts according to observational data from the Russian and Chinese meteostations on the territory of the Amur river basin. An analysis is made of the synchronism in the fluctuations of long-term series of precipitation amounts for two summer months (July and August) by using a modified algorithm for a classification of the fields of hydrometeorological characteristics, such as cluster analysis. The study revealed a poor correlation of precipitation amounts in different parts of the basin. We analyzed the interannual fluctuations in absolute maxima of the consecutive precipitation amounts for different periods of time (from 1 to 30 days). It is shown that precipitation over the summer period of 2013 that caused a disastrous flood in the lower reaches of the Amur were extreme primarily as regards the territory encompassed and the flood duration, which was due to a combination of synoptic processes of a different genesis. It was found that the precipitation amounts for periods shorter than 19 days in 2013 were not extreme in terms of intensity. A comparison was made with the year 1984 when there also occurred a flood on the Amur but not as violent. Parameters of the probability curves for 2013 and 1984 are presented for long-term series of maximum precipitation amounts for the summation period of 7 and 30 days. It is concluded that for calculating the maximum possible precipitation amounts which are necessary for assessing the maximum possible floods, it is appropriate to consider synoptic situations with long-lasting precipitation rather than separate short-lasting storm rains.     

Changes in glacial lakes and glaciers of post-1986 in the Poiqu River basin, Nyalam, Xizang (Tibet)

Glacial lakes and glaciers are sensitive indicators of recent climate change. In the Poiqu River basin of southern Tibet, 60–100 km NW of Mt. Everest, Landsat imagery defines post-1986 changes in the size and distribution of both glacial lakes and glaciers. Total area of glaciers in the 229-km² drainage area has decreased by 20%. The number of glacial lakes with areas in excess of 0.020 km² has increased by 11%, and the total area of glacial lakes has increased by 47%. The areas of typical large glacial lakes of the area (Galongco, Gangxico, and Cirenmaco) have increased by 104, 118, and 156%, respectively, and these increases are confirmed by field investigations.Comparing the 1986 data, the area of glaciers in the basin headwaters has decreased by 46.18 km² to a present total area of 183.12 km², an annual rate of change of 3.30 km²/year. Trends indicate that the total area of glaciers will continue to decrease and that both the numbers and areas of glacial lakes will continue to increase. Accompanying these trends will be an increased risk of debris flows, formed by entrainment of sediment in glacial-outburst floods and in surges from both failure and avalanche- and landslide-induced overtopping of moraine dams. Based on both the local and world-wide history of catastrophes from flows of these origins, disaster mitigation must be planned and appropriate engineering countermeasures put in place as soon as possible.     

Forest resources of the Selenga river basin

This paper discusses some issues relating to the present state of forest resources and forest utilization within the Selenga river basin on the trans-boundary territory of the Republic of Buryatia and Mongolia, their transformation due to economic exploitation, ecologoeconomic problems, and the avenues for their solution.     

Exogenous processes and soil formation within a small river basin of Western Transbaikalia in the second half of the Holocene

We determined the sequence of formation of deposits on the first terrace above the Tarbagataika river floodplain, and a change of the sedimentation and soil-formation stages for the last 7 kyr. We reconstructed the accumulation dynamics of the sediment layer and calculated the mean sediment accumulation rates for different time intervals. The phases of intensification of erosion-accumulation and aeolian processes were recorded. The study revealed the main stratigraphic boundaries reflecting the fundamental changes of the settings of sedimentation: 7 cal. kyr BP, a change of riverbed sedimentation for floodplain sedimentation; 5.4 cal. kyr BP, intensification of erosion-accumulation processes due to climate aridization on the Atlantic-Subboreal boundary, and active input of erosion products to the floodplain; 4 cal. kyr BP, active filling of the river valley with horizontally layered polygenetic fine-grained sands and sandy loams containing intercalations of humic warps in conditions of the overlapped (built-up) floodplain with an increase in humidification in the middle of the Subboreal period and, as a consequence, an increase in the height of floods; 3.4 cal. kyr, the layer under investigation leaves the floodplain regime of sedimentation and accumulation of aeolian-deluvial deposits, and 1 cal. kyr, intensification of erosion-accumulation processes due to climatic and anthropogenic changes. We reconstructed the chronology and specific features of the pedogenesis stages which record the phases of temporal cessation of floodplain and slope sedimentation on the study territory. The results obtained are in good agreement with data on the hydraulicity of rivers, the stages of soil formation and on the manifestation of exogenous processes on the territories of Russia and Mongolia.     

Changes in the summertime atmospheric circulation over East Asia and formation of long-lasting low-water periods within the Selenga river basin

We examine the formation patterns of the low-water periods 1976?C1982 and 1996?C2011 for the Selenga river. One of the immediate reasons for the low-water periods under consideration is the attenuation of the circulation in the zone of convergence of monsoon flows and mid-latitude flows over Mongolia and North China. Unlike the low-water periods of the preceding decades, a decrease in precipitation amounts during the current low-water period is taking place concurrently with large-scale climatic changes.     

The water balance of the Selenga river basin

The averaged amounts of atmospheric precipitation, river runoff and evaporation are estimated for the Selenga river basin, including the territory of Mongolia. The results of calculations are represented by point estimates of mathematical of the balance components, and by confidence intervals of their values.     

Postglacial environmental change in the valley of Malye Chily River (the basin of Lake Teletskoye), northeastern Russian Altai

The evolution and current state of landscapes around Lake Teletskoye have not previously been studied in detail. In the valley of the Malye Chily River, which flows into Lake Teletskoye, the timing of dam failure and draining of two moraine-dammed lakes has been identified. Botanical analysis, ash content determination, and radiocarbon dating of two peat profiles provide insight into postglacial evolution of wetlands related to this landscape. We found clear evidence of the disappearance from the peat of higher vascular species that, today, grows mostly in the plains of Siberia. Correlation of the data obtained with the accepted chronology of the Holocene events in the Russian Altai suggests the following stages of postglacial environmental change in the Malye Chily River valley: (1) the continuation of the Late Würm glaciation degradation (before 7000?cal. yr BP); (2) Holocene Climate Optimum (7000–5000?cal. yr BP); (3) Akkem cooling (5000–4200?cal. yr BP); (4) warm period (4200–3700?cal. yr BP); and (5) Historical cooling (3700–1600?cal. yr BP).     

Hydrologo-morphological approach to regionalization of the Selenga river basin

We examine the evolutionary stages of scientific views on the formation history of the delta plain of the Selenga river and adjacent territories, based on cartographic material and national investigations spanning the period 1701?C2009. We suggest the regionalization of the Selenga river from hydromorphometric attributes of erosion-accumulation, abrasion-accumulation and neotectonic processes. The study is based on comparing topographic maps, guides for navigation and space images (1898?C2009) as well as on experimental data obtained by the authors.     

国际河流流域国的合作——以红河流域为例

本文首先对国际河流流域国的合作进行简单介绍，分析了国际河流作为一个系统整体行动所具有的动力特征是多目标协调，最后，进一步分析了促成各流域国之间合作的动力因素和阻力因素，并概括了通常情况下国际河流争端解决的途径。     

Early postglacial history of the southeastern Assiniboine Delta,glacial Lake Agassiz basin

New stratigraphic evidence from the Rossendale area, Manitoba, Canada, provides insight into the early postglacial evolution of the southeastern Assiniboine Delta. In this region, much of the upper 13+ m of sediment accumulation is characterized by multiple cycles of sandy rhythmites interbedded with massive to laminated silt. These sediments were deposited rapidly by traction or turbidity currents and record the construction of the Assiniboine fan-delta during the deep-water Lockhart Phase of glacial Lake Agassiz (>10.8 ¹⁴C ka BP). Shortly before ∼10 ¹⁴C ka BP, fluvial incision into deltaic deposits occurred locally at the Rossendale Gully site in response to the regression of glacial Lake Agassiz during the Moorhead Phase. Plant macrofossils deposited in the gully by 10 ¹⁴C ka BP provide the first information on early postglacial plant colonization of the distal Assiniboine delta. These data suggest initial establishment of Scorpidium scorpioides, Potamogeton spp., Scirpus spp., and other wetland plants, followed by colonization of uplands by a Picea-Populus assemblage. Importantly, because the gully is located in a protected depression behind the Campbell beach, evidence of water table rise from aquatic macrophytes suggests that glacial Lake Agassiz transgressed to the Campbell level during the early Emerson Phase (∼10 ¹⁴C ka BP). Furthermore, no evidence exists for a post-Lockhart rise in Lake Agassiz above the Upper Campbell beach. If Agassiz stood at the Campbell level during the early Emerson Phase, then drainage through the southern outlet may have been possible at this time. This scenario, if true, may suggest that the northwestern outlet was temporarily closed by a glacial advance shortly before 10 ¹⁴C ka BP. This is the first in a series of ten papers published in this special issue of Journal of Paleolimnology. These papers were presented at the 47th Annual Meeting of the International Association for Great Lakes Research (2004), held at the University of Waterloo, Waterloo, Ontario, Canada. P.F. Karrow and C.F.M. Lewis were guest editors of this special issue     

Water use in the transboundary basin of the Amur river

This paper summarizes the problems and consequences associated with water use in the Russian and Chinese parts of the Amur river basin. Taking into consideration the set of indicators involving the water withdrawal, the utilization of source water, the volumes of recirculated and repeated-consecutive water supply, the volumes of waste waters, the capacity of pollution control facilities, etc., an outline is given of the present status of water use in the national parts of the basin. The future amounts of water consumption are forecasted, and it is shown how it will increase in the Russian as well as the Chinese parts. An analysis of the spatiotemporal dynamics of water-use indicators revealed the differently directed tendencies in the water-use pattern in the Russian and Chinese parts of the Amur river basin, and the existence of quantitative disproportions caused by a different degree of development and a different intensity of economic growth. In the Russian part of the basin, the amounts of water used have stabilized in recent years after a decrease, whereas they are increasing steadily in the Chinese and Russian parts where the highest proportion of water is used to meet agricultural and production needs, respectively. It is shown that water use, the density of the water-economy structure and the discharges of pollutants in the Chinese part of the basin are larger by factors of several tens than those in the Russian part. The manufacture of water-intensive industrial products and the load of agriculture on water resources also differ by factors of several tens. The indicator of population size is used to characterize the degree of development of the basin’s territory. For the Russian part of the basin the study revealed a dependence of water consumption on the population size and on the volumes of water-intensive products in the production facilities with a low coefficient of recirculated water use. This dependence can also be extended to the Chinese part where circulated water supplies are being used only moderately.     

地理学发展视角下的历史流域研究

流域是地理学研究的重要区域单元,是区域响应的敏感区和研究热点,许多地区的自然灾害与人为损害都与流域的历史演变紧密相关。近年来出现的历史流域研究,就是对这种现象进行科学规律探寻的反映。由于这一研究涉及到自然、历史、社会、文化、管理、生态等多学科领域,枝叶浩繁。因此,仅从地理学发展的视角,揭示流域研究的地理特征、流域演变多种因素的相互作用,以及人类发展与历史流域的耦合关系。历史流域研究也具备地理学研究和发展的特点,具有综合性、历史演变性、空间相对稳定性、应用性等研究特征。在地理学发展视角下开展历史流域研究,对拓展地理研究思维,具有一定的实践意义,为流域的综合管理和可持续发展提供科学依据。     

雅鲁藏布江流域降水时空变化特征

雅鲁藏布江流域是全球气候变化的敏感区,该流域降水变化对青藏高原的水系统、生态系统和山地灾害系统的演变具有重要影响。本文通过流域水文分析,将雅鲁藏布江流域的三大水资源区细分为9个分区。基于雅鲁藏布江流域1979—2018年降水数据,综合分析了雅鲁藏布江流域及9个分区的年、干湿季、月降水量以及日、小时尺度极端降水的时空变化特征,探讨了降水和典型大尺度大气环流因子的相关性。结果表明：① 1979—2018年间,在流域尺度上,各时间尺度降水整体上均呈上升趋势。其中,年降水量上升趋势最大,为2.5 mm·a^-1;年、干湿季降水量以及典型小时尺度极端降水（Rx3hour、Rx12hour）均在95%信度水平下显著上升。在水资源分区尺度上,各分区不同时间尺度降水的变化趋势呈现更明显的非一致性,所有分区除小时尺度极端降水均呈上升趋势外,其余时间尺度降水的趋势变化方向各异。② 雅鲁藏布江流域降水存在明显的空间分异性,且降水空间分异性会随着降水指标时间尺度的缩短而增强。各时间尺度降水整体上均呈现出自东部向西部逐渐减少的趋势,流域东南部（分区Ⅲ-2）始终是高值中心,流域中西部（分区Ⅰ-2、Ⅱ-1）存在区域性高值中心。③ 北半球副热带高压和北半球极涡对雅鲁藏布江流域降水变化具有显著影响。研究结果有助于掌握当地降水的多尺度变化特征,可为雅鲁藏布江流域和青藏高原地区的水循环研究、水资源开发利用和山洪灾害防治等提供科学基础。     

汾河流域降水变化趋势的气候分析

利用汾河流域39个测站近45 a(1956-2000年)的月降水量资料,采用线性趋势估计、T显著性检验和多项式回归方法分析了降水时空变化。结果表明,汾河流域降水空间分布南多北少、由下游向上游逐渐减少。年、汛期(6～9月)降水量呈逐年减少趋势,且在全流域具有普遍性,平均降水倾向系数-26．1 mm/10 a、-22．2 mm/10 a,流域趋于干旱化。20世纪50、60年代流域降水偏多,70、80年代接近常年水平,90年代偏少最甚。气候跃变参数结果显示,汾河流域汛期降水没有跃变。     

Cartographic study of the soil-geographical regularities within the Amur basin

We have generated the “Dominant Soils” geoinformation layer (digital coverage), the base for the general-purpose soil map for the Amur river basin encompassing the trans-boundary territories of Russia, China and Mongolia. It relies on the principle of maximum possible retention of information from the source soil maps, and on unification of soil-cartographic material. We demonstrate the geographical regularities of soil occurrence within the entire basin, and the specific character of its separate regions.