The Aral Sea: From Desiccation to Restoration
Tyler Cripps, Brenna Pavan, & Kaylynne Sparks
Keywords: Aral Sea, Restoration, Afforestation, Desertification
Summary
The Aral Sea was once the fourth biggest inland sea in the world, encompassing over 66,000 square kilometres and reaching 20 metres deep in some spots (Glantz, 2007). It is fed by the Syr Dar’ya and the Amu Dar’ya, two of the largest rivers in Central Asia (Glantz, 2007). The Sea is situated between Kazakhstan and Uzbekistan, and was once an oasis embedded in the great deserts of the region (Micklin, 2007). The massive water body cooled the region, and supported vital fisheries, agriculture, animal husbandry, and biodiversity. It was also a hub for transportation. (Micklin, 2007).
Today, the Aral Sea has been reduced to four tiny, salinized seas. There are many negative social, economic, and environmental implications caused by this desiccation. Options for a complete restoration of the Aral Sea are believed to be financially or politically infeasible (Micklin, 2007). However, damming projects to reduce salinity in the remaining lakes as well as planting of trees to stabilize soil are underway and show great promise in restoring the ecosystems health and biodiversity. The future of the Aral Sea is still unclear as greater funding is needed in order to increase the speed at which restoration can occur. |
Ecological Genealogy
The Aral Sea had been at a relatively consistent water level for over ten millennia (Micklin, 2010). In the 1960s the Soviet Union began to implement irrigation projects for agriculture in the region (Cretaux, Letolle, & Berge-Nguyen, 2013). Within a few years the area of farmland increased from 4 billion hectares to 8 billion hectares (Cretaux et al., 2013). Increasing volumes of water were diverted from the Syr Dar’ya and Amu Dar’ya to irrigate this farmland and build reservoirs (Cretaux et al., 2013). Eventually, so much water was diverted that there was not enough inflow for the Aral Sea to maintain water levels and the Sea began to shrink.
Climate change has also affected the water levels of the Aral Sea by increasing the rate of evaporation. On a local scale, the reduced size of the Aral Sea has limited its cooling function in the region. The climate has shifted from a maritime climate to an arid, continental or desertic climate; this has increased the temperature which, in turn, increases the rate of evaporation (Micklin, 2007). The rate of evaporation has also been exacerbated by rising global temperatures, and mass irrigation of crops has contributed to increased evapotranspiration (Cretaux et al., 2007). The combination of water diversion and rising temperatures became too much in the 1970s and water levels began to steadily decline (Micklin, 2007). The progression of the desiccation of the Aral Sea is seen in Figure 2. In the 1980s, |
the Aral Sea split into the South Aral (fed by Syr Dar’ya) and the North Aral (fed by the Amu Dar’ya). Then, in 2005 the South Aral split into three water bodies: a deep western basin, a shallow eastern basin, and the Gulf of Tshche-Bas (Micklin,
2007). These water bodies can connect through channels in wet years, but still remain largely separated (Figure 3). All of the Seas have experienced large increases in salinity because the evaporation of water concentrates the existing and inflowing salts from agricultural runoff. Salinity in the Aral Sea increased by 14% in just the first 10 years of its receding, making it too saline for most freshwater species to survive (Glantz, 1999). The South Aral has continued to lose volume and is becoming increasingly salinized, but the North Aral has reached a balance. Its smaller surface area has reduced evaporation, and the water levels are maintained by the Amu Dar’ya, groundwater inflow, and precipitation (Cretaux et al., 2013).
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Present Tense
The Aral Sea historically was both greatly influenced and supported by economic activities, and the present is no different. In both Uzbekistan and Kazakhstan the irrigated agriculture sector, especially cotton production, is economically important (White, 2014). In Uzbekistan, many people’s livelihoods now depend on agriculture rather than the declining fishing jobs that used to be central to the economy (Karimov et al., 2005), making it difficult to slow any loss of water through irrigation. The agriculture sector is also important in Kazakhstan, though not as significantly as in Uzbekistan, and the fishing industry is still a source of many jobs (White, 2014). The catch numbers and available jobs in the fishing industry have been declining as the Aral Sea has drained, forcing many people to find jobs elsewhere, often having to travel to neighbouring towns for work (Chen, 2018). Many former fishing villages exist along what used to be the shoreline of the Aral Sea (Chen
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& Weidman, 2018), and abandoned boats can be found seemingly in the middle of the desert (Figure 4). Recently in the North Aral, there has been a slow resurgence of the fishing industry, with the fishing limit for 2018 being set at 8 200 tons (Chen, 2018), a significant increase from recent years.
The ecosystems supported by the North Aral and the South Aral Seas are significantly altered by the increasing salinity. The North Aral is a single body of water in Kazakhstan, with an average salinity of approximately 8g/L (Chen 2018), and a maximum depth of 42m (EORC, 2007). In recent years when salinity was high, flounders were the only fish in the North Aral with steady or increasing population numbers. As salinity has decreased with damming projects over time, freshwater species are increasing in number and diversity (Chen, 2018). The biodiversity of the North Aral is increasing, but the current levels are still well below those of the Aral Sea historically. The South Aral Seas
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are shallower than the North Aral, with a maximum depth of 26m. The salinity in the Western Basin is 120g/L and in the Eastern Basin the salinity of 280g/L is so high that there is almost no biodiversity in the area, with brine shrimp being the main inhabitants (Reimov & Fayzieva, 2014). There are much larger areas of dried up sea bed surrounding the current South Aral Seas, most of which contain too much salt or other accumulated contaminants to support anything but halophyte species that were not historically common in the region (Reimov & Fayzieva, 2014).
Since the new ecosystems of the areas are so different, the restoration efforts also differ greatly between the Seas. In the North Aral, a large 12km dam project was completed in 2005 (Chen, 2018). The goal of this project, which also included the repairing of dikes in the surrounding area, was to stop the outflow of water from the North Aral to raise the water level and decrease salinity. This project has been successful so far, with a 3.3m water level increase after only seven months (Chen, 2018). The increase in water retention has decreased the salinity enough that freshwater fish species are able to survive (Chen, 2018).
Since the new ecosystems of the areas are so different, the restoration efforts also differ greatly between the Seas. In the North Aral, a large 12km dam project was completed in 2005 (Chen, 2018). The goal of this project, which also included the repairing of dikes in the surrounding area, was to stop the outflow of water from the North Aral to raise the water level and decrease salinity. This project has been successful so far, with a 3.3m water level increase after only seven months (Chen, 2018). The increase in water retention has decreased the salinity enough that freshwater fish species are able to survive (Chen, 2018).
The South Aral Sea area does not have as much of an aquatic focus for restoration. The government of Uzbekistan has begun a project planting saxaul trees (Haloxylon ammodendron), a halophyte species, to stabilize saline soils and combat desertification in the dried seabed (Qobil & Harris, 2018). Currently the project has forested approximately half a million hectares (Qobil & Harris, 2018), with a goal to stabilize soils and prevent the dust storms that have become common in the region. These dust storms carry salt and contaminated soils long distances, causing respiratory issues and other human health concerns (Chen & Weidman, 2018). |
Future Trajectories
The future of the Aral Sea will probably lean towards a novel ecosystem, with a slow and steady change to a new equilibrium point. This shift has already been observed. Phragmites, an invasive tall reed, has had great success in spreading throughout the dried seabed (Morimoto et al., 2005). Along with the reeds, annual hyperhalophytes have spread rapidly and are thriving in the high salt environment that prevents the growth of many other organisms. As water levels fluctuate psammophytes take over. Growth of these plants have led to more complex soil properties and advancing successional stages, and will likely continue to change the ecosystems in the future.
At its current pace, the South Aral seabed is predicted to be covered in shrub forest in 150 years (Qobil & Harris, 2018). |
Further investment and international aid into planting the South Aral will allow for faster planting, as there are still over 3 million hectares not yet planted (Qobil & Harris, 2018). Increased investment could convert the Aral Sea into an area with stable soils and a thriving saxaul forest, with new terrestrial biodiversity.
While the ecosystem health of the Aral Sea has decreased since the 1960s it is unlikely we will see the drying of the entire sea in the future (Micklin, 2010). This is due to the constant inflow of drainage water, ground water, and precipitation. Micklin (2010) found that even if the flow from the Amu and Syr Dar’ya was reduced to zero, there would still be spots that would retain significant amounts of water. However, the remaining lakes would have high salinity, and would not be suitable for fish or most other aquatic life. The only fishery would be brine shrimp production, which could support some local industry, but not as much as a current or past levels.
While the ecosystem health of the Aral Sea has decreased since the 1960s it is unlikely we will see the drying of the entire sea in the future (Micklin, 2010). This is due to the constant inflow of drainage water, ground water, and precipitation. Micklin (2010) found that even if the flow from the Amu and Syr Dar’ya was reduced to zero, there would still be spots that would retain significant amounts of water. However, the remaining lakes would have high salinity, and would not be suitable for fish or most other aquatic life. The only fishery would be brine shrimp production, which could support some local industry, but not as much as a current or past levels.
Although The Aral Sea may never fully dry up, projects such as the damming of the North Aral Sea show that there is promise for the restoration of the ecosystem. Moreover, there is even the opportunity to rebuild the fishing industry in the area, as some increases in production are already being observed. While the extinction of native fish species is final, introduced species could improve the biodiversity. This rebirth of the fishing industry has prompted Kazakhstan to consider furthering the damming efforts in the North (Pala, 2001). Their plan would raise the dam by 6m and would result in the surface area of the lake to increase by 50%. This would allow for further growth of fisheries in the region, and could lead to more damming. Building on the damming programs would allow for greater retention of water to further decrease salinity, increase total area of the North Aral Sea, and promote biodiversity.
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If restoration efforts continue as they are, the increasing of both the total area and the quality of marine habitat will encourage populations of remaining freshwater species to recover. Even if restoration efforts were intensified over time, the changed size and ecology of the area means it is unlikely that the North Aral will reach the same level of biodiversity seen in the South Aral Seas.
There are also suggestions being put forward on how to increase the flow of water to the Aral Sea. By using groundwater for agricultural irrigation rather than water from the Amu and Syr Dar’ya, outflow would increase and could lead to the improvement of the ecosystem (Micklin, 2016). Furthermore, there is the possibility of switching from high water demand crops such as rice and cotton, to grains, vegetables, and soybeans in order to reduce water consumption. Both of these changes would allow for better connectivity between the lakes and assist in the reduction of salt levels. However, optimistic plans at this level are unlikely to happen without removal or reduction of economic and political barriers (Micklin, 2016).
There are also suggestions being put forward on how to increase the flow of water to the Aral Sea. By using groundwater for agricultural irrigation rather than water from the Amu and Syr Dar’ya, outflow would increase and could lead to the improvement of the ecosystem (Micklin, 2016). Furthermore, there is the possibility of switching from high water demand crops such as rice and cotton, to grains, vegetables, and soybeans in order to reduce water consumption. Both of these changes would allow for better connectivity between the lakes and assist in the reduction of salt levels. However, optimistic plans at this level are unlikely to happen without removal or reduction of economic and political barriers (Micklin, 2016).
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