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The Uzboy is an enigmatic dry river channel in Western Central Asia. This 750km long channel regained life on several occasions after the end of the Würm glaciation (about 11,000 years BC), due to climatic episodes more humid than today and/or human deviations of the main course of the Amu Darya towards the west. Much of the Amu annual flow was div...
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Context 1
... irrigation drainage water originating from the Amu Darya flows to the Sary Kamysh depression through canals, which follow more or less ancient natural channels (Darya Lyk and Daudan Darya) (see Fig. 13), although the latter does reach the present lake. Sary Kamysh lake sits in an oval depression of tectonic origin, which was later affected by aeolian erosion during successive glaciations from 2 millions years ago to 10,000 BC. It was filled during the Holocene, partly by aeolian sand and dust, but mainly by alluvium of the Amu Darya ...
Context 2
... first section of the Uzboy from the sill has a very indistinct morphology, with wide channels oriented more or less NW-SE, between buttes-temoins of Sarmatian rocks (limestones, gypsum marls and marine sands), remnants of the Ust Urt plateau, and elongated dune massifs separating solonchaks (Fig. 3). Some are located along the banks of the channel, poorly defined and invaded by recent dunes, down to the Kugunek locality where the bed begins to be clearly defined with steep banks. Today these solonchaks are fed by small karstic springs and especially by precipitation filtering through the sand and reappearing at the boundary ...
Context 3
... Sary Kamysh lake, due to the channel cross-section at Daryalyk and Daudan Darya, at a time when irrigation specialists estimate the total water output of Amu Darya to Aral was about 60-70 km 3 /year, and eventually more. A large part of Amu water should have run through interdune channels east of the Uzboy, and dissipated in the Zaunguz desert (Fig. 13). It seems an unavoidable conclusion that a small part of the Amu flow (a few km 3 /year) flowed to the southeastern basin of the Aral, feeding more or less regularly a large lagoon. The problem of the western Aral basin and of the ''Small sea'' shrinkage is also linked to the disappearance of Syr Darya at the same time, as is attested ...
Citations
... The watershed is located between the following relief units: Ustyurt Plateau in the north and north-west, Turanian Plain in north-east and east and Karakum Desert in the south (Figure 1.A). Khorezm region that have disappeared today (Letolle, et al., 2007). Also, the Uzboy River used to connect the Caspian Sea, Saryamysh Lake, and the Amu Darya River, currently only the relict valleys remained (Tsvetsinskaya, et al., 2002). ...
... Since the 1960s, the construction of water supply canals for the irrigation of lands began in the region of the Amu Darya Delta (Gâștescu, 1990). The most important collectors are Daryalyk and Ozyernyi (Figure 1.B), which were built on the riverbeds of Daryalyk and Daudan rivers (Tsvetsinskaya, et al., 2002) and which carry an estimated flow of 800 m 3 /s from Amu Darya to Sarygamysh Lake (Letolle, et al., 2007). Therefore, Figure 2 shows the variation of discharges on the Amu Darya river at the Chatly hydrometric station located downstream of the channel branch. ...
The spatial dynamics of Sarygamysh Lake using remote sensing and G.I.S. techniques. Since ancient times, climate change has impacted the Earth's water bodies. However, in recent centuries, these changes have been determined, to a considerable extent, by human interventions, as is the case of the drying up of the Aral Sea. On the other hand, there are cases when the amount of water is increasing, a typical example being Lake Sarygamysh, which is located in Central Asia on the border between Uzbekistan and Turkmenistan. This is an anthropogenic lake, which was created after 1960 by diverting water from the Amu Darya river to it by irrigation canals. Therefore, the area of the lake has steadily increased from 1086 km2 in 1973 to 3970 km2 today. The purpose of this study is to perform an analysis of the spatial dynamics of Lake Sarygamysh using specific remote sensing techniques. The mapping of this dynamic in the last 50 years (1973-2022) is also considered, as well as the creation of a possible scenario of the expansion of the lake. Spatial dynamics of the lake was analysed using Landsat-type satellite images with a resolution of 60 m and 30 m, respectively. Supervised classification was used to extract the lake surface at different time points combined with S.I.G. techniques. for the spatialization of evolution. Also, S.I.G. techniques. were also used to propose a scenario regarding the expansion of the lake surface in the next 90 years, using the ArcGisPro software. The resulting data showed a rapid expansion of the lake surface in the last 50 years, with the trend remaining the same in the coming years. In conclusion, the resulting data showed a rapid expansion of the lake's surface in the last 50 years, with the trend remaining the same in the following years. Keywords: spatial dynamics, remote sensing, supervised classification, Sarygamysh Lake.
... The remaining portions of the Aral Sea and the newly formed Aralkum are located in Central Asia. In the literature, the Aral Sea surface in 1960 is usually placed between approximately 67,000 and 68,000 km 2 , depending on the data source and methodology used to estimate its area (Létolle et al. 2007;Micklin 2010). ...
The Aral Sea, once the fourth largest freshwater lake on Earth, has lost circa 90% of its original water surface in 1960. Maps of different land cover categories provide a suitable baseline to plan and implement effective measures to combat ongoing desertification, such as reforestation of dried out Aral Sea soils. In this study, we used satellite-based remote sensing data and applied a machine learning method (Random Forest) to map land cover in the Aralkum in 2020. We tested different satellite data from optical (Landsat-8, Sentinel-2) and Radar instruments (Sentinel-1) and trained a random forest model for classifying different combinations of these data sets into ten distinct land cover classes. We further calculated per-pixel uncertainty based on posterior classification probability scores. An accuracy assessment, based on in-situ data, revealed that the average overall accuracy of land cover maps was 86.8%. Fusing optical and radar instruments achieved the highest overall accuracy (88.8%, with lower/higher 95% confidence interval values of 87.6%/89.9%, and a Kappa value of 0.865. Classification uncertainty was lower in more homogeneous landscapes (i.e. large expanses of a single land cover class like water or shrubland). Only around 9% of the study area was still water in 2020, while 32% was covered by saline soils with high erosion risk. Several potential applications of this land cover map in the Aralkum exist – spanning many areas of environmental impact assessment, policy, and planning and management or afforestation. This methodological framework can similarly provide a useful template for more broadly assessing large-scale, land dynamics at high-resolution in the entire Aralkum and surrounding areas.
... It accounted for ∼15% of all DPS registered in the Karakum-Kyzylkum. The lake dried in the 18th Century following the natural migration of the Amu Darya course toward the Aral Sea (Létolle et al., 2007) but was restored in the 1960s to collect irrigation wastewater. The influx of water varies interannually and seasonally, causing strong fluctuations in the lake's level exposing both old and modern alluvial sediments (Kostianoy et al., 2013;Orlovsky et al., 2012). ...
The first inventory of dust emission sources in Central Asia and northwestern China (35–50°N, 50–100°E) derived from the twice daily MODIS imagery from 2003 to 2012 is presented. A high‐resolution (1 km) dust enhancement product was generated to produce maps of dust point sources (DPS), indicating geographical locations of the observed dust emissions, and gridded data sets of dust emission frequencies. About 13,500 DPS were detected over an area of ∼5 × 10⁶ km², however, their distribution was uneven. The highest frequency of DPS occurred in the northern and eastern Taklimakan, in the Aralkum, and in the regions, which were not widely reported in literature before, the Balkh delta in northern Afghanistan and the pre‐Aral, from the northern Caspian coast to the Betpak‐Dala desert in Kazakhstan. South of the Aral, DPS were mainly associated with fluvial features: drying lakes, dry river beds, alluvial deposits and agricultural activity which is closely linked to water availability in this arid region. In the pre‐Aral and Balkhash‐Junggar regions, land damaged by wildfire was the main source of dust. In China and eastern Kazakhstan dust emissions peaked in spring; in Central Asia and western Kazakhstan—in summer. The Aralkum was active throughout the year with a positive trend in emission frequency over the study period. Locations of DPS did not always correlate with high atmospheric optical depth (AOD) particularly west of the Aral and in the southern Taklimakan where few DPS were detected despite the high AOD values. This was attributed to dust transport from the upwind sources.
... Additionally, endorheic desert basins are prone to evaporite precipitation and accumulation (Schütt, 1998), which can provide a surface and channel banks that are highly stabilized, as illustrated by the examples from the Bolivian Altiplano and the Amargosa River in Death Valley (Ielpi, 2019). Here we also note that one of the most spectacular examples of an endorheic basin meandering systems is the currently inactive Uzboy Channel (Karakum Desert, Turkmenistan), which preserves channels formed under an arid palaeoclimate from the Upper Pliocene to Preglacial Quaternary (Fet and Atamuradov, 1994;Létolle et al., 2007). However, the Uzboy channel is excluded from analysis herein since it is not possible to estimate the vegetation content for when this system was active. ...
ABSTRACT
The influence of biotic processes in controlling the development of meandering channels in fluvial systems is controversial. The majority of the depositional history of the Earth’s continents was devoid of significant biogeomorphic interactions, particularly those between vegetation and sedimentation processes. The prevailing perspective has been that prevegetation meandering channels rarely developed and that rivers with braided planforms dominated. However, recently acquired data demonstrate that meandering channel planforms are more widely preserved in prevegetation fluvial successions than previously thought. Understanding the role of prevailing fluvial dynamics in non- and poorly vegetated environments must rely on actualistic models derived from presently active rivers developed in sedimentary basins subject to desert-climate settings, the sparsest vegetated regions experiencing active sedimentation on Earth. These systems have fluvial depositional settings that most closely resemble those present in prevegetation (and extra-terrestrial) environments. Here, we present an analysis based on satellite imagery which reveals that rivers with meandering channel planforms are common in modern sedimentary basins in desert settings. Morphometric analysis of meandering fluvial channel behaviour, where vegetation is absent or highly restricted, shows that modern sparsely and non-vegetated meandering rivers occur across a range of slope gradients and basin settings, and possess a broad range of channel and meander-belt dimensions. The importance of meandering rivers in modern desert settings suggests that their abundance is likely underestimated in the prevegetation rock record, and models for recognition of their deposits need to be improved.
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... Its course across the Karakum Desert has changed repeatedly in the past. Until late Pleistocene to early Holocene times, Amu Darya waters used to flow even largely into the Caspian Sea south of the Karabogaz Bay via the Uzboy River ( Fig. 1; Zavialov 2005;Létolle et al. 2007). The Unguz depression may represent another relict course of the Amu Darya towards the Caspian Sea ( Fig. 1; Boomer et al. 2000). ...
Major deserts do not necessarily consist of eolian dunes as quartz-rich as those of the Great Nafud, Rub' al Khali, Sahara, and Mega-Kalahari sand seas accumulated in anorogenic settings of Arabia and Africa. The Karakum dune field of Turkmenistan is one of the several examples of central Asian deserts bound by recent or recently reactivated orogenic belts where eolian sand includes abundant sedimentary and subordinately metamorphic and volcanic lithic fragments. Feldspatho-litho-quartzose detrital modes and epidote-amphibole-garnet heavy-mineral suites of southern Karakum dune sand compare well with those in mountain branches of the Amu Darya, indicating provenance from the western Pamir mountains of Tajikistan in the east. Dunes closer to the Caspian Sea in the west contain additional carbonate or felsic volcanic grains which, together with decreasing heavy-mineral concentration and increasing ZTR indices, reveals local recycling of cover strata exposed in the Kopeh-Dagh and Balkhan zone. Our data suggest that the huge Amu Darya River, which in Plio-Pleistocene to historical times has repeatedly changed its course across Turkmenistan from westward toward the Caspian Sea to northward toward the Aral Sea, represents the major sediment source for the Karakum Desert. Together with the Taklamakan sand sea of the Tarim basin, the Ordos and adjacent deserts of northern China, and the Thal and Thar deserts of the western Himalayan foreland basin, the Karakum would thus represent another example of large dune field principally fed by one major fluvial feeder system.
... Reconstructions based on archaeological studies and historical accounts tend to explain the most extreme Aral Sea regressions by a diversion at the head of the Amu Darya delta to the west through the Daudan Darya and Darialyk (Kunya Darya) channels into the Sarykamysh basin. The channel cross-section at Daudan Darya and Daryalyk could not carry more than 20-30 km 3 per year, so that the diversion of the Amu Darya flow can never be total and a residual inflow would always reach the southern part of the Aral Sea (Letolle et al. 2007). ...
... The annual discharge of the Uzboi channel cannot be higher than 10 km 3 so that the eventual water excess would be diverted and dissipated in the dunes of the Zaunguz desert (northern part of the Karakum desert). Besides the Amu Darya diversion, geomorphological features indicate that the Uzboi would be activated also in case the Aral Sea would enter into extreme transgressive conditions with water levels at +54-56 m a.s.l. and merge with the Sarykamysh (Tolstov and Kes 1960;Kes and Klyukanova 1999;Letolle et al. 2007). ...
This chapter reveals how ecological zones and their division into steppe and sown, nomadic and sedentary people, helped Russian ethnographers to understand the heritage and urban neighbourhood principles of Bukhara. It charts the launch and significance of ethnographic enquiry into this former oasis city within the context of Eurasianism, and illuminates the notion of soil in Russian thought, together with the central role it played in the study of the interrelationship between environmental factors and socio-cultural changes. The evidence will be used to present ethnographic accounts as a way of transferring knowledge between Asia and Europe, and argue in favour of a flexible approach negotiating between nature and culture, and as a process of hybridization, whereby cultures come together and, by learning from each other, create a pathway towards Eurasian integration and global intellectual interaction.
... Reconstructions based on archaeological studies and historical accounts tend to explain the most extreme Aral Sea regressions by a diversion at the head of the Amu Darya delta to the west through the Daudan Darya and Darialyk (Kunya Darya) channels into the Sarykamysh basin. The channel cross-section at Daudan Darya and Daryalyk could not carry more than 20-30 km 3 per year, so that the diversion of the Amu Darya flow can never be total and a residual inflow would always reach the southern part of the Aral Sea (Letolle et al. 2007). ...
... The annual discharge of the Uzboi channel cannot be higher than 10 km 3 so that the eventual water excess would be diverted and dissipated in the dunes of the Zaunguz desert (northern part of the Karakum desert). Besides the Amu Darya diversion, geomorphological features indicate that the Uzboi would be activated also in case the Aral Sea would enter into extreme transgressive conditions with water levels at +54-56 m a.s.l. and merge with the Sarykamysh (Tolstov and Kes 1960;Kes and Klyukanova 1999;Letolle et al. 2007). ...
This chapter presents the first results and interpretations of a selected dataset of rock carvings from the Karakorum mountains. The research is focused on early Buddhist carvings and their spread and role within networks of the early Silk Roads in Central Asia from the 2nd–1st century BCE. The rock carvings and their archaeological context are studied to gain insight into routes from Gandhara through the Karakorum range. The first part presents the general aims and relevance. The second and third parts describe the analysis and interpretation of the Karakorum dataset, followed by the main points of discussion and conclusions to incite future investigations.
... Reconstructions based on archaeological studies and historical accounts tend to explain the most extreme Aral Sea regressions by a diversion at the head of the Amu Darya delta to the west through the Daudan Darya and Darialyk (Kunya Darya) channels into the Sarykamysh basin. The channel cross-section at Daudan Darya and Daryalyk could not carry more than 20-30 km 3 per year, so that the diversion of the Amu Darya flow can never be total and a residual inflow would always reach the southern part of the Aral Sea (Letolle et al. 2007). ...
... The annual discharge of the Uzboi channel cannot be higher than 10 km 3 so that the eventual water excess would be diverted and dissipated in the dunes of the Zaunguz desert (northern part of the Karakum desert). Besides the Amu Darya diversion, geomorphological features indicate that the Uzboi would be activated also in case the Aral Sea would enter into extreme transgressive conditions with water levels at +54-56 m a.s.l. and merge with the Sarykamysh (Tolstov and Kes 1960;Kes and Klyukanova 1999;Letolle et al. 2007). ...
The Chinese empire experienced a large expansion to the arid regions in the west during the Han Dynasty (206 BCE–220 CE). The Hexi Corridor, the Yanqi Basin, the southeastern part of the Junggar Basin and the Tarim Basin became part of the empire. The expansion of the Han Dynasty was accompanied by the significant intensification of irrigation farming along rivers draining the Qilian, Tianshan and Kunlun Mountains. Sedimentological and geochemical analyses and dating of lake sediments and shorelines revealed that four large lakes in the region experienced falling levels, or were almost or completely desiccating. The level of Zhuyeze Lake was falling rapidly ca. 2100 years before present (a BP), and the accumulation of lake sediments was replaced by an alluvial fan setting in large parts of the basin. Lake Eastern Juyan desiccated ca. 1700 a BP. Lake Bosten experienced low levels and increasing salinities at ca. 2200 a BP. Lake sediments in the Lop Nur region were mostly replaced by aeolian sands during a period of near-desiccation at 1800 a BP. In contrast, records from fifteen lakes farther in the west, north or south of the Han Dynasty realm indicate relatively wet climate conditions ca. 2000 years ago. Thus, dramatic landscape changes including the near and complete desiccation of large lakes in the arid western part of today’s China probably resulted from the withdrawal of water from tributaries during the Han Dynasty. These changes likely represent the earliest man-made environmental disasters comparable to the recent Aral-Sea crisis.
... Reconstructions based on archaeological studies and historical accounts tend to explain the most extreme Aral Sea regressions by a diversion at the head of the Amu Darya delta to the west through the Daudan Darya and Darialyk (Kunya Darya) channels into the Sarykamysh basin. The channel cross-section at Daudan Darya and Daryalyk could not carry more than 20-30 km 3 per year, so that the diversion of the Amu Darya flow can never be total and a residual inflow would always reach the southern part of the Aral Sea (Letolle et al. 2007). ...
... The annual discharge of the Uzboi channel cannot be higher than 10 km 3 so that the eventual water excess would be diverted and dissipated in the dunes of the Zaunguz desert (northern part of the Karakum desert). Besides the Amu Darya diversion, geomorphological features indicate that the Uzboi would be activated also in case the Aral Sea would enter into extreme transgressive conditions with water levels at +54-56 m a.s.l. and merge with the Sarykamysh (Tolstov and Kes 1960;Kes and Klyukanova 1999;Letolle et al. 2007). ...
Paleo-climatic, environmental, archaeological studies and historical accounts concerning the behavior of the Aral Sea during the last 2000 years point to a number of water level regressions similar or deeper than the modern one. This article is focused on the causes of such regressions, which are variously attributed to climatic change, diversion of river courses and anthropogenic water withdrawal. The first factor has been researched by several geo-specialists and its potential impact has been preliminarily evaluated. The second factor has been considered only in the case of the Amu Darya river. The third factor—water withdrawal for irrigation purposes—has been hypothesized, though never deserved specific analysis. The article provides a quantitative evaluation of the total hectares covered by the medieval urban systems of the Syr Darya and Amu Darya river basins, and of the coefficient of water use per hectare of walled towns during the X-XII centuries AD. Estimates of annual volumes of anthropogenic water withdrawal allow the investigation of the complex interaction of the three factors above in determining the hydrological conditions of the Aral Sea. On the basis of the calculation of possible scenarios of water mass balance, the occurrence of transmission losses by medieval diversions of the Syr Darya course has been suspected as the main cause of lake regressions, which is supported by geological considerations, archaeological data and historical accounts.
... Reconstructions based on archaeological studies and historical accounts tend to explain the most extreme Aral Sea regressions by a diversion at the head of the Amu Darya delta to the west through the Daudan Darya and Darialyk (Kunya Darya) channels into the Sarykamysh basin. The channel cross-section at Daudan Darya and Daryalyk could not carry more than 20-30 km 3 per year, so that the diversion of the Amu Darya flow can never be total and a residual inflow would always reach the southern part of the Aral Sea (Letolle et al. 2007). ...
... The annual discharge of the Uzboi channel cannot be higher than 10 km 3 so that the eventual water excess would be diverted and dissipated in the dunes of the Zaunguz desert (northern part of the Karakum desert). Besides the Amu Darya diversion, geomorphological features indicate that the Uzboi would be activated also in case the Aral Sea would enter into extreme transgressive conditions with water levels at +54-56 m a.s.l. and merge with the Sarykamysh (Tolstov and Kes 1960;Kes and Klyukanova 1999;Letolle et al. 2007). ...
The final centuries BCE (Before Common Era) saw the main focus of trade between the Far East and Europe switch from the so called Northern Route across the Asian steppes to the classical silk roads. The cities across central Asia flourished and grew in size and importance. While clearly there were political, economic and cultural drivers for these changes, there may also have been a role for changes in climate in this relatively arid region of Asia. Analysis of a new ensemble of snapshot global climate model simulations, run every 250 years over the last 6000 years, allows us to assess the long term climatological changes seen across the central Asian arid region through which the classical Silk Roads run. While the climate is comparatively stable through the Holocene, the fluctuations seen in these simulations match significant cultural developments in the region. From 1500 BCE the deterioration of climate from a transient precipitation peak, along with technological development and the immigration of Aryan nomads, drove a shift towards urbanization and probably irrigation, culminating in the founding of the major cities of Bukhara and Samarkand around 700–500 BCE. Between 1000 and 250 BCE the modelled precipitation in the central Asian arid region undergoes a transition towards wetter climates. The changes in the Western Disturbances, which is the key weather system for central Asian precipitation, provides 10% more precipitation and the increased hydrological resources may provide the climatological foundation for the golden era of Silk Road trade.
