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1.
V. M. Starodubtsev 《Water Resources》2017,44(1):12-15
The formation processes of a new delta-like object with a hydromorphic landscape in the upper part of the Kapchagai Reservoir on the Ili R.—an internal delta—are considered. The quantitative characteristics of the development of this delta are evaluated using data of Landsat-2, 5, and 7 space images over period 1975–2012. These processes were found to accelerate considerably in the wet year of 2012, and intense under-flooding and salinization of nearby lands were revealed in the Chilikskii alluvial fan on the southern wing of the Kapchagai delta. A consequence of this accumulative process was found to be the development of planar channel deformations of the Ili R. 30 km upstream the Kapchagai delta. 相似文献
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Similar to the loess in the Chinese Loess Plateau (CLP), the loess deposits in the Ili basin of Central Asia arid area play an important role in understanding the climate and environmental changes. However, in contrast to the intensively investigated loess deposits in the CLP, the Ili loess is still insufficiently known and poorly understood. The geochronology study of the Ili loess remains controversial. In order to examine the potential of optically stimulated luminescence (OSL) dating for the Ili loess, we carry out a combined luminescence and radiocarbon dating study on a 6.9 m loess section in the south margin of the Ili basin. Polymineral fine grains were investigated by post infrared (IR) OSL using a Multiple-Aliquot Regenerative-dose (MAR) protocol. Radiocarbon dating of organic carbon were carried in a 3 Megavolt (MV) multi-element Accelerator Mass Spectrometry (AMS). The results indicate that the OSL ages are in agreement with the observed stratigraphy in the field, which is well correlated with that of the CLP, but the AMS 14C ages are much younger than the OSL and assumed stratigraphical ages. Thus, the OSL dating technique may provide an absolute chronology in this loess section. Further methodological approaches and more samples analysis will lead to the improvement of this chronology for high-resolution paleoclimatic interpretation. 相似文献
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Desertification of delta landscapes, mainly soil cover, is considered on the example of the Ili River, which basin is located
in Kazakhstan and China. Long-term researches on the Ili River were begun in 1968 before creation of the large Kapchagay reservoir
and proceed with the use of the space imagery NASA/MODIS/Terra. Degradation of delta landscapes is differentiated in space
and in time depending on the features of the natural water regime and its transformation because of flow regulation. The main
accent in research has been made on the newest processes of desertification, caused by intensification of irrigation. Characteristics
of drying, desertification and salinization of soils in delta are estimated on the state of spring 2008. 相似文献
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Water level variations in the Kiliya Branch of the Danube Delta over the period of 40 years (1958–1997) were analyzed. These level variations were subdivided into three components related to long-term variations of the share of the branch runoff and its redistribution within a year resulting from the Danube flow regulation; subsidence of deltaic deposits; and backup caused by the rising Black Sea level. It was revealed that, during the low-flow period, this backup had propagated to the river mouth at a distance of 160 km. 相似文献
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Similar to the loess deposits on the Chinese Loess Plateau (CLP), a reliable chronology plays also an important role in revisiting past climate and environment changes recorded by the loess in Central Asia. Previously, a few luminescence and 14C ages, mainly covering the last glacial, were obtained for several loess sections in Central Asia, which are often controversial. Until now, there is still a lack of reliable high-resolution chronologies covering the late Pleistocene, especially the Holocene. Here, the fine-grained (4–11 μm) quartz single-aliquot regenerative-dose (SAR) optically stimulated luminescence (OSL) dating protocol is used to establish a detailed chronology of the uppermost part (∼5 m) of Talede loess in the Ili Basin Central Asia. Conventional tests of the SAR protocol and the general luminescence characteristics indicate that this protocol is suitable for dating the Talede loess. Finally, 15 closely-spaced quartz OSL ages, ranging from 0.72 ± 0.05 to 28.9 ± 2.12 ka and with no reversals, were obtained. Consistent with previous studies in the Ili Basin, two of the three 14C ages show discrepancy when compared with quartz OSL ages for the Talede loess section. The constructed OSL chronology of the Talede loess reveals that the dust accumulation is rapid during marine isotope stage (MIS) 2, especially during the Last Glacial Maximum (LGM), and is also continuous during the Holocene, with the dust accumulation rate exhibiting a relatively low level and an increasing trend. Comparison of the dust accumulation at Talede with that at other sites in the Ili Basin indicates that the rapid dust accumulation during the LGM is not universal, and the slow dust accumulation during the Holocene is probably true for the entire Ili Basin. Comparison of different grain sized quartz OSL ages from Central Asian loess show characteristics of both consistency and inconsistency, which needs to be further investigated. 相似文献
6.
Khazheeva Z. I. Urbazaeva S. D. Bodoev N. V. Radnaeva L. D. Kalinin Yu. O. 《Water Resources》2004,31(1):64-67
The overall concentration of Cu, Pb, Zn, Cr, Mn, and Fe are determined in the water and bottom sediments of the Selenga River delta. The concentration of Cu, Pb, and Zn is found to decrease in the lower course of the river, at the delta outlet. The concentration of Mn and Fe is found to decrease in the downstream direction from the river's upper course along the investigated delta arms, whereas the concentration of Zn and Cr in certain arms exceeds their concentration in the upper section of the delta. 相似文献
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Water Resources - The current values of the components of the water balance of the Parana delta, one of the largest deltas of South America, as well as the results of calculations of the actual... 相似文献
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Three areas with different trends in water level variations over the period of many years have been distinguished within the Kuban Delta. It was found that the eustatic level rise of the Sea of Azov and soil subsidence on the sea edge of the delta and in the lower reaches of the Protoka Branch were responsible for the noticeable rise in water levels. A considerable water level drop caused by the river runoff regulation and erosion of the lower pool of the Krasnodarskii Waterworks was recorded in the upper part of the delta; in the rest part of the delta, water levels dropped insignificantly, which was partially due to the impact of the tectonic uplift. 相似文献
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Dust depositions are critical archives for understanding interior aridification and westerly climatic changes in Central Asia. Accurate and reliable dating of loess is very important for interpreting and correlating environmental records. There remains a disparity between luminescence ages and radiocarbon dating of late Quaternary loess from the Ili Basin in Central Asia. In this study, we establish a closely spaced quartz optically stimulated luminescence (OSL) chronology for the 20.5-m-thick Nilka loess section in the Ili Basin. Based on OSL ages, two intervals of higher mass accumulation rate occurred at 49–43 ka and 24–14 ka. We further compare these OSL ages with 23 accelerator mass spectrometry (AMS) 14C ages of bulk organic matter. The results indicate that the OSL and radiocarbon ages agree well for ages younger than ca. 25 14C cal ka BP. However, beyond 30 cal ka BP, there is no consistent increase in AMS 14C age with depth, while the OSL ages continue to increase. These differences confirm the observation that the AMS 14C ages obtained using conventional acid–base–acid (ABA) pretreatment are severely underestimated in other terrestrial deposits in Central Asia, which could be due to 2–4% modern carbon contamination. However, OSL dating is applicable for constructing an accurate chronology beyond 30 cal ka BP. We suggest caution when interpreting paleoenvironmental changes based on radiocarbon ages older than 25 cal ka BP. 相似文献
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伊犁盆地新构造运动与地震 总被引：2，自引：5，他引：2
从新生代地层展布及形变入手,说明伊犁盆地早第三纪以区域性抬升为主,晚第三纪开始断陷。当时盆地范围较大,沉积中心在我国境内;第四纪初构造变动强烈,南、北天山全面隆起,盆地渐趋缩小,其后仍以整体抬升为主,但东部抬升速率大于西部而带掀斜性质,沉积中心西移至巴尔喀什湖。中更新世冰川发育,晚更新世多风成黄土。用阶地(14)~C测年数据推算喀什河上游的抬升速率为2.86mm/a,中、下游为1.86mm/a。山体隆升与局部断陷使老断裂多次活动,新断裂相伴产生,喀什河断层垂直运行速率为2.5mm/a。断裂活动的压性特征及水文网络反映新构造应力场为南北方向的强烈挤压。本文还简述了伊犁盆地4条主要活动断裂带及其与地震活动的关系,特别指出契利克深大断裂震级频次高居北天山榜首,应加强地震地质基础性研究工作。 相似文献
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In the Pearl River Delta (PRD), river water quality deteriorates continually due to the population increase and ongoing industrialization and urbanization. In this study, a water quality management paradigm based on the seasonal variation is proposed. For better exploring the seasonal change of water quality, wavelet analysis was used to analyze the division of dry and wet seasons in the PRD during 1952–2009. Then water quality seasonal variation in 2008 and relevant impact factors were analyzed by multivariate statistic methods as a case to make some management measures. The results show that there are some differences of dry and wet seasons division among different years. Wet season mainly appear from April to September, which occupy the largest proportion among the 58 years (about 70%) and then followed by the wet season from May to October (about 13.8% of the total years). As to the water quality of 2008, significant differences exist between dry and wet seasons for 17 water quality parameters except TP, , Fe2+, and Zn2+. Levels of parameters pH, EC, CODMn, BOD5, , , and Cl? in dry season are much higher than those in wet season. In dry season the variations of river water quality are mainly influenced by domestic sewage, industrial effluents, and salt water intrusion. While in wet season, except the aforementioned pollution sources, drainages from cultivated land and livestock farm are also the main factors influencing water pollution. Thus, water quality management measures are proposed in dry and wet seasons, respectively. The results obtained from this study would further facilitate water quality protection and water resources management in the PRD. 相似文献
14.
Chemical characteristics of the surface water and algae in lakes in the Seduiyakha River basin are presented. Specific features of components of limnetic ecosystems under the influence of anthropogenic factors in the territory of an oil–gas condensate field are shown. Ambiguous response of algal communities to changes in the aquatic environment is revealed. 相似文献
15.
The glacier is an important and stable water supply in Central Asia. Monitoring the change of glacier and understanding the impacts of glacier change on river discharge are critical to predict the downstream water availability change in future. Glacier changes were discussed and their impacts on river discharge were evaluated by hydrological modeling with a distributed hydrological model SWAT under two land use and land cover scenarios (1970 and 2007) in Tekes watershed, the most important source of water discharge to the Ili River. Compared to the glacier area of 1511 km2 in 1970s it decreased by 332 km2 in 2007, which resulted in the contribution the discharge from precipitation in the glacier area to the average annual discharge of the watershed changing from 9.8% in the period 1966–1975 to 7.8% in the period 2000–2008. In the month scale, with the decrease of glacier area, the distribution of the contribution of monthly discharge from precipitation in the glacier area to the total of the watershed changed from bimodal pattern to unimodal pattern. By linking a hydrological model to remote sensing image analysis and Chinese glacier inventories to determine glacier area change our approach in quantifying the impacts of glacier changes on hydrology at different scales, will provide quantitative information for stakeholders in making decisions for water resource management. 相似文献
16.
The interaction among tidal currents, sediment transport, and long-term changes of the sea bottom in the Colorado River Delta
have been investigated applying a two dimensional nonlinear hydrodynamic-numerical finite differences model. The system was
forced by the dominant M
2 tidal component at the open boundary. We carried out calculations to study the morphodynamics of the actual bathymetry caused
by the bedload sediment transport. To investigate the origin of actual morphological features, we performed experiments using
a smoothed bathymetry, in which the islands Montague, Gore, and Pelícano were eliminated. Under the imposed tidal hydrodynamics,
the results indicate that the bedload transport contributes significantly in the genesis of sandbanks and in the formation
and maintaining of the Montague and Gore Islands. 相似文献
17.
Doan Van Binh Sameh A. Kantoush Tetsuya Sumi Nguyen Phuong Mai Trieu Anh Ngoc La Vinh Trung Tran Dang An 《水文研究》2021,35(2):e14030
The hydrogeomorphology of the Vietnamese Mekong Delta (VMD) has been significantly altered by natural and anthropogenic drivers. In this study, the spatiotemporal changes of the flow regime were examined by analysing the long-term daily, monthly, annual and extreme discharges and water levels from 1980 to 2018, supported by further investigation of the long-term annual sediment load (from the 1960s to 2015), river bathymetric data (in 1998, 2014 and 2017) and daily salinity concentration (from the 1990s to 2015) using various statistical methods and a coupled numerical model. Then, the effects of riverbed incision on the hydrology were investigated. The results show that the dry season discharge (i.e., in March–June) of the Tien River increased by up to 23% from the predam period (1980–1992) to the postdam period (1993–2018) but that the dry season water level at My Thuan decreased by up to −46%. The annual mean and monthly water levels in June at Tan Chau and in January and June–October at My Thuan in the Tien River decreased statistically, even though the respective discharges increased significantly. These decreased water levels instead of the increased discharges were attributed to the accelerated riverbed incision upstream from My Thuan, which increased by more than three times, from a mean rate of −0.16 m/year (−16.7 Mm3/year) in 1998–2014 to −0.5 m/year (−52.5 Mm3/year) in 2014–2017. This accelerated riverbed incision was likely caused by the reduction in the sediment load of the VMD (from 166.7 Mt/year in the predam period to 57.6 Mt/year in the postdam period) and increase in sand mining (from 3.9 Mm3 in 2012 to 13.43 Mm3 in 2018). Collectively, the decreased dry season water level in the Tien River is likely one of the main causes of the enhanced salinity intrusion. 相似文献
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