Desiccation of the Aral Sea: A Water Management Disaster in the Soviet Union

Micklin, Philip

doi:10.1126/science.241.4870.1170

Cited by 450 publications

(236 citation statements)

References 1 publication

(1 reference statement)

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“…Changes in the water level caused severe changes in the water chemistry and the redox milieu of the lake. The water has been getting constantly saltier since then, starting from 10 g kg À1 in the early 1960s (Micklin, 1988). Estimates of the decrease in volume from satellite images and increase in salinity are in good agreement.…”

Section: Discussionsupporting

confidence: 61%

Hydrochemical properties of the Aral Sea water in summer 2002

Friedrich

Oberhänsli

2004

Journal of Marine Systems

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In August 2002, new hydrochemical and hydrophysical data were collected in the Aral Sea. The survey includes crosssections in three locations: within the Small Aral close to Tastubek Bay, in the Large Aral at the northern tip that is Tschebas Bay and within the western basin at Chernishov Bay. All three locations represent different stages in the hydrochemical evolution of the Aral Sea.Depth profiles of pressure, temperature, conductivity, pH and dissolved oxygen were measured with a YSI 6600 profiler. Water samples were taken with a Niskin bottle and analyzed for dissolved oxygen and nutrients by standard photometric methods. Major anions and cations were analyzed by ion chromatography and ICP-OES, respectively. Benthic flux experiments were carried out with sediment cores in a batch mode assay on-site.In the Small Aral, the changes in the hydrochemical properties are not as dramatic as in the Large Aral. The Small Aral represents a brackish inland water body with salinities of 17 -18 g kg À1 . The wind-mixed layer reached 8 m during the survey. The salinity is vertically and horizontally almost uniform. Below 8 m, a temporally hypoxic layer forms during summer. Salt redissolution was found to be an important source of salt in the water. About 33.5 g SO 4 2À m À2 day À1 and about 30.7 g Cl À m À2 day À1 are released from the sediment in summer.In the Large Aral, the salinity distribution is uniform in shallow waters (less than 5 m) but varies strongly in deeper water. Tschebas Bay at the northern tip of the large Aral represents a shallow lagoon with a maximum depth of about 6 m. The water column was well mixed down to the bottom (f6 m) having salt concentrations of 82 g kg À1 on average. Almost no gradients in dissolved substances were observed. It is suspected that salinity is balanced by fresher water inflow originating from the Syr Darya flowing south and by groundwater exfiltration. Chernishov Bay in the north of the western basin is meromictic. Below a windmixed layer, a very strong pycnocline of 20 g kg À1 per m at 5 m depth isolates the water below from exchanges with the water above and led to the formation of huge anoxic water body down to the bottom at about 25 m depth. Below 10 m, the water contains hydrogen sulphide. The salt concentration increases from 82 g kg À1 in the surface water to 110 g kg À1 at depth. The salt release from the sediment is as high as 1143 g SO 4 2À m À2 day À1 and 1626 g Cl À m À2 day À1 . Benthic release of salt is considered as an important source for salt in the bottom water of the western basin and in sustaining the stable density stratification. D

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Section: Discussionsupporting

confidence: 61%

Hydrochemical properties of the Aral Sea water in summer 2002

Friedrich

Oberhänsli

2004

Journal of Marine Systems

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“…Apart from those observations, Micklin (1988), Brown (1991), and Sneider (1992 reported on temperature, surface features, and environmental changes generated due to the diversion of water from the Amudarya and the Sirdarya, the two rivers that feed of the Aral Sea, without any quantitative discussion.…”

Section: Surface-feature-induced Climatic Changesmentioning

confidence: 99%

Man‐made climatic changes in the Ganges basin

Adel

2002

Intl Journal of Climatology

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Climate data pertaining to the Ganges basin in Bangladesh were analysed to find any climatic changes in the wake of the upstream water diversion by the Farakka Barrage. Whereas the diversions have been continuing from at least 30 international rivers upstream of Bangladesh, the diversion from the Ganges is the best known and has a wider coverage than all other diversions. The diversion reduced the Ganges' discharge through the delta by about 60% from a prediversion average value of 1932 m 3 s −1 , decreased water availability in flood plains, ponds, canals, and ditches by about 50%, dropped the groundwater table, and caused changes in surface features. It took about 5 years of diversions beyond the test run year of 1975 for the environment to react to set 1981 as the baseline year. During the post-baseline era:(1) heating degree days and cooling degree days were respectively 1.33 and 1.44 times more than their counterparts during the pre-baseline era; (2) the summertime and wintertime average temperatures were respectively 1°C more and 0.5°C less than the corresponding values during the pre-baseline era; (3) the mode 32°C of summertime maximum temperatures was 1°C higher and occurred 414 times more, and the mode 25°C of wintertime temperature was 1°C less and occurred 17 times less than the corresponding quantities during the pre-baseline era; (4) the average value of maximum relative humidity has increased by more than 2% and that of minimum relative humidity has dropped by the same amount; (5) the mode 95% and 70% of maximum and minimum relative humidity values have occurred 1322 times and 84 times more respectively than their pre-baseline counterparts; and (6) the frequency for 100 mm or more rainfall and the monthly average rainfalls have dropped by about 50% and 30% respectively. The solution to the climatic changes lies in the restoration of the virgin Ganges flow, dredging of the Ganges and its distributaries to remove shoals and siltation, and re-excavation of canals for water discharge to depleted surface water bodies to re-establish the lost wetland ecosystems. The findings are useful for climate modellers to predict the climatic changes due to changes in surface features, for policy makers of governments of riparian countries constructing dams/barrages on international rivers for unilateral diversion of water, and for donor agencies who finance such projects.

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“…Such oscillations may create extreme conditions for many taxa and the resulting biodiversity is characterized by a low number of highly specialized species (cataudella et al, 2015). also, we have to mention that increasing the water salinity level affects the Potamogeton pectinatus production, there by disturbing the web food of waterbirds whose diet includes a range of fauna items and aquatic plants including ducks ( van Wijk, 1988;Micklin, 1988;Bunn, arthington, 2002;kingsford, Thomas, 2004). our data on waterbird diversity variables and its variability over four years of study highlights this decrease in biodiversity, since we have measured lower values of Simpson, Shannon and evenness markedly in the wintering season.…”

Section: Discussionmentioning

confidence: 99%

Multi-annual and seasonal patterns of waterbird assemblages in a Mediterranean coastal lagoon (El Mellah lagoon) of Northeastern Algeria

Telailia¹,

Boutabia²,

Khemis

et al. 2017

Ekológia (Bratislava)

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telailia S., Boutabia L., khemis El-Hak M.D., Elafri a., Djebbari n.: Multi-annual and seasonal patterns of waterbird assemblages in a Mediterranean coastal lagoon (El Mellah lagoon) of northeastern algeria. Ekológia (Bratislava), vol. 36, no. 2, p. 146-158 , 2017. recently, Mediterranean coastal lagoons have raised considerable environmental concerns. Long-term studies of seasonal changes in waterbird assemblages are therefore extremely important in terms of ecological relevance and conservation of these sensitive ecosystems. an ornithological survey of four years was carried out in a typical costal wetland (El Mellah lagoon) of northeastern algeria. intra-seasonal comparison of waterbird assemblages (diversity indices) demonstrates clear changes between the wintering and the breeding periods. it seems that the first one was rich in term of species number than the second season (43 against 24). in contrast, the breeding seasons were more equilibrate (high values of Simpson, Shannon and evenness index). additionally, curves in the diversity/dominance diagram revealed that both wintering and breeding assemblages share the same characteristics of community structure, few dominant species (with intermediate relative abundance) and many rare species with the relative abundance lower than 0.1. invertebrates (25 species) and piscivorous (11 species) are the most abundant guilds over the four years of study (no significant differences among years have been calculated). The marked decline in bird species diversity recorded in this study (in comparison with previous studies) is mainly due to salinity oscillations (due to aquaculture activities) and may be of concern to wetland managers and it might be useful to provide some guidelines about the characteristics that coastal lagoons have to follow in the construction process to enhance the biodiversity.

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Desiccation of the Aral Sea: A Water Management Disaster in the Soviet Union

Cited by 450 publications

References 1 publication

Hydrochemical properties of the Aral Sea water in summer 2002

Hydrochemical properties of the Aral Sea water in summer 2002

Man‐made climatic changes in the Ganges basin

Multi-annual and seasonal patterns of waterbird assemblages in a Mediterranean coastal lagoon (El Mellah lagoon) of Northeastern Algeria

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