The problem of the aral sea introduction


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THE PROBLEM OF THE ARAL SEA

Introduction

The Aral Sea is situated in Central Asia, between the Southern part of Kazakhstan and Northern Uzbekistan. Up until the third quarter of the 20th century it was the world ? fourth largest saline lake, and contained 10grams of salt per liter. The two rivers that feed it are the Amu Darya and SyrDarya rivers, respectively reaching the Sea through the South and the North. The Soviet government decided in the 1960s to divert those rivers so that they could irrigate the desert region surrounding the Sea in order to favor agriculture rather than supply the Aral Sea basin. The reason why we decided to explore the implications up to today of this human alteration of the environment is precisely that certain characteristics of the region, from its geography to its population growth, account for dramatic consequences since the canals have been dug. Those consequences range from unexpected climate feedbacks to public health issues, affecting the lives of millions of people in and out of the region.

By establishing a program to promote agriculture and especially that of cotton, Soviet government led by Khrouchtchev in the 1950s deliberately deprived the Aral Sea of its two main sources of water income, which almost immediately led to less water arriving to the sea. Not only was all this water being diverted into canals at the expense of the Aral Sea supply, but the majority of it was being soaked up by the desert and blatantly wasted (between 25% and 75% of it, depending on the time period). The water level in the Aral Sea started drastically decreasing from the 1960s onward. In normal conditions, the Aral Sea gets approximately one fifth of its water supply through rainfall, while the rest is delivered to it by the Amu Darya and Syr Darya rivers. Evaporation causes the water level to decrease by the same amount that flows into the Sea, making it sustainable as long as inflow is equal to evaporation on average. Therefore the diversion of rivers is at the origin of the imbalance that caused the sea to slowly desiccate over the last 4 decades.

Level of salinity rose from approximately 10g/l to often more than 100g/l in the remaining Southern Aral. Salinity of the rivers varies with place and time, as well as through the seasons. When going through the desert, rivers often collect some salt compounds residues in the ground that result in higher salinity, but may well be lowered again after going through irrigated lands. Dams also affect salinity, notably by reducing its variability with the seasons. Smaller lakes within the Aral Sea that have stopped being fed by river flows tend to have higher salinity due to evaporation, causing some or all fishes that either survived or had been reintroduced in the 1990s to die. Even re-watering those lakes does not compensate for the increased salinity over the years. In 1998, water level was down by 20m, with a total volume of 210km3 compared to 1,060km3 in 1960.

Most of the changes in climate and landscape in the Aral Sea basin that we are about to explore are at the least indirect products of Human induced changes. While we must remember at all times that society is responsible for the crisis that has unfolded in and around the Aral, the point we want to make is that most of the actual changes that have afflicted the Sea since the 1960s are the result of our environment’s reaction to the stresses society has imposed on it. Thus, the difficulty lies as much in understanding the way climate and other natural systems function as in being capable of weighing the potential consequences of our actions before we undertake them. Risk assessment combined with scientific understanding should undercut our actions more efficiently; adding an ethical dimension to the equation remains more than welcome in addition to those more accessible and quantifiable factors, but is too fragile to be the centerpiece on which our decisions rely before we commit to large scale actions which can often, as we are about to see, engender even larger responses from our environment.

Most of the changes in climate and landscape in the Aral Sea basin that we are about to explore are at the least indirect products of Human induced changes. While we must remember at all times that society is responsible for the crisis that has unfolded in and around the Aral, the point we want to make is that most of the actual changes that have afflicted the Sea since the 1960s are the result of our environment’s reaction to the stresses society has imposed on it. Thus, the difficulty lies as much in understanding the way climate and other natural systems function as in being capable of weighing the potential consequences of our actions before we undertake them. Risk assessment combined with scientific understanding should undercut our actions more efficiently; adding an ethical dimension to the equation remains more than welcome in addition to those more accessible and quantifiable factors, but is too fragile to be the centerpiece on which our decisions rely before we commit to large scale actions which can often, as we are about to see, engender even larger responses from our environment.

Water levels

The primary effect of the Aral Sea desiccation has been the significant loss of water in the sea. The water level has dropped approximately 23 meters since the onset of its primary sources of water being diverted (Zavialov 2005). Although the water level has fluctuated up to a few meters in the past due to natural variability in the water flow from the rivers, by 1970, the water loss exceeded the limit of natural water level variation that has occurred in the past.

The water budget is determined by several components: Inflow from the river, evaporation, precipitation rates, and groundwater inflow. Net evaporation is defined as the difference between evaporation and precipitation at the surface (Micklin 2007). The river inflow has been rapidly decreasing since 1960. Net evaporation has also decreased, but at a slower rate while the groundwater inflow has remained approximately the same. As a result, there was a net deficit of water to the sea. The figure below shows the components of water balance that resulted in the net deficit of incoming water flow (Micklin 2007).

In the first desiccation period, water level dropped by about 21 cm/year. In the next decade, water level decreased by 57 cm/year, and afterwards the drop in water level started accelerating faster. The acceleration of the rate of water loss from the Aral Sea can be explained by the positive feedback between evaporation and Sea Surface Temperature. As the lake loses water, it becomes shallower. The incoming solar radiation for a given square area now has to heat up a smaller volume of water, thus the water temperature at the surface increases faster. This in turn lowers the specific humidity at the surface, which further increases the rate of evaporation, thus eating a positive feedback loop.

Another factor that accelerated the evaporation is that the salinization of the lake has lead to vertical stratification. Stratification is characterized by a rapid change in water temperature and salinity level at a given horizontal or vertical region. Under this condition, the surface of the lake has a much lower salt concentration than the bottom of the lake, and thus heats up faster than if the salt concentration was distributed evenly.

Another factor that accelerated the evaporation is that the salinization of the lake has lead to vertical stratification. Stratification is characterized by a rapid change in water temperature and salinity level at a given horizontal or vertical region. Under this condition, the surface of the lake has a much lower salt concentration than the bottom of the lake, and thus heats up faster than if the salt concentration was distributed evenly.

After 1990 the rate of water loss has been slowly decreasing. There are negative feedback systems that could have slowed down the loss of water in the region. First, is that as the sea surface area decreases, so does evaporation, which slows down the desiccation process. Another negative feedback is due to increased salinity - as salinity increases, the evaporation also decreases, which partially offsets the positive feedback of water loss. Overall, the presence of both positive and negative feedback systems influences the rate of water loss in the area.

Correlation of Salinity with Water Level

The desiccation of the Aral Sea was also characterized by a sharp increase in the salinity of sea water. The salinity of water is determined by the mass of salts dissolved in the water and the volume of water. As the sea level dropped because of water loss, the inflow of salts to the sea exceeded the salt discharge, and as a result, salinity levels of the sea rose. In the first decade, the salinity increased by 14%, which exceeded the threshold for many commercial fish (Glantz 1999). As a result commercial fishing catches fell from 43,430 tons in 1960 to zero in 1980 (Bosch, 44). From 1960 to 2004, surface salinity increased from 10ppt in 1960 to 92ppt in 2004 (Zavialov 2005). The steep rise in salinity is one of the curses that hit the Aral Sea region when the Sea started shrinking, and is, with the visible water loss, the element which alters landscape the most. As the sea separated into different parts, the difference in salinity between the eastern basin and the western basin also started growing, with higher salinization in the eastern (smaller) basin (Zavialov 2005). Scientists were able to observe two types of correlations between water and salt which increase the salinity of water as a result.

Negative Correlation: This obvious correlation explains how the diminishing level of water creates more salinity, as a given amount of salt gets diluted into a smaller volume. The diminishing level of the Aral Sea has therefore caused the steep rise in salinity (V.M.Lelevkin). Considering this fact, and based on changes over the last 40 years, we can predict that melting glaciers, growth population, and an increasing trend of water usage will lead to less water flowing into the Aral and thus to an increase in salinity.

Positive Correlation: It happens when both underground water and salinity rise at the same time. When agriculture uses furrow irrigation, soil receives an excessive amount of water from rivers and canals. Water then gets filtered by depositing the salt in the soil. Excess water accumulated in groundwater that remains after filtration raises the water table (top layer of underground water). Risen groundwater dilutes and moves upward the salt resting in the soil. Water moves upward and salt concentration increases in the surface layers of the soil. The water then evaporates during day time, leaving the salt behind as it becomes like a layer of snow on the surface of the ground. Similar effects have been observed in Australia as well (Australian Academy of Science).

Positive Correlation: It happens when both underground water and salinity rise at the same time. When agriculture uses furrow irrigation, soil receives an excessive amount of water from rivers and canals. Water then gets filtered by depositing the salt in the soil. Excess water accumulated in groundwater that remains after filtration raises the water table (top layer of underground water). Risen groundwater dilutes and moves upward the salt resting in the soil. Water moves upward and salt concentration increases in the surface layers of the soil. The water then evaporates during day time, leaving the salt behind as it becomes like a layer of snow on the surface of the ground. Similar effects have been observed in Australia as well (Australian Academy of Science).

Melting Glaciers

It would seem unlikely that an inland sea in Uzbekistan could affect something so vast as earth’s climate. Yet the truth is that the shrinking sea and salty dust storms have already changed the climate in the region to the point of an unlikely return to the stability once present in the area. With the shrinking sea there is not enough surface area to disrupt frigid north winds. Nor does the sea contribute the moisture it once did to the snowfall in mountains of neighboring and more distant regions. In addition to the temperature steadily increasing the dust and salt storms are coating the mountain glaciers nearby and causing a decrease in the overall volume of ice. The degree of melting is over twelve times the rate of the pre-cotton growing era and as there is less moisture in the air to replace the dissipating snow the glaciers continues to diminish. As the glaciers continue to melt the weather will become less likely to experience the sort of seasonal stability it once did.

We have just looked at the intricate behaviors of climate systems in the Aral region, including their interactions and the chain reactions that we call positive feedbacks. Not only did they reshape the landscape and natural balance of the region, they also affected dramatically the populations that live or used to live in this area. Public health, access to drinkable water, migrations due to changing landscape and consequences of vanishing wildlife are all matters that turn out to rely on stable climatic and hydrologic conditions. Appalling observations that followed the climatic changes of the past decades have increased the toll of the irresponsible decisions that were taken by the Soviet Union in the 1960s and of the inactions that followed. Endemic levels of anemia, respiratory diseases and other kidney troubles were reached around the 1980s among the neighbor populations of the Aral region, without anything preventing such diseases from spreading since changes in local climate were at their origin. We will now explore the range of consequences on the human plan that these changes truly had.

Important Demographic Changes Over the Last Decades

Changes in population are important to understand the Aral Sea crisis for various reasons that we will explore. Between 1950 and 1988, the population of the Aral Sea basin grew dramatically - from 13.8 to 33.2 million people, comprising increases from 8.1 to 19.9 million in Uzbekistan, 1.0 to 2.2 million in Kirghizstan, 2.0 to 5.1 million in Tadzhikistan, 1.5 to 3.5 million in Turkmenistan, and 1.2 to 2.4 million in Kazakhstan (all within the sea-basin limits). In 1990, the population of the Aral Sea basin numbered 34 million. Mean annual rates of population increase in the late 1980s amounted to 2.85% in Uzbekistan, 2.60% in Kirghizstan, 3.2% in Tadzhikistan, 2.65% in Turkmenistan, and 1.06% in southern Kazakhstan (as compared with 0.95% in the USSR as a whole) (Kasperson 1995). Today, after two decades of intense demographic growth, the situation has clearly changed (see Figure #1), for we see that the mean of the population growth rate in the Aral Basin has diminished.

Children and young people occupy a significant place in the age structure, owing to the high natural increase of population. Children and teenagers up to 15 years of age comprise 42.5 per cent of the population in the Aral region (as compared with 26.8 per cent in the former USSR). Therefore, there are fewer people of working age here than in other parts of the world. (Kasperson 1995) Large variations in river water levels and large scale pollution caused the principal environmental changes of the Aral region. Although water consumption through fisheries, industry, power generation and public use of water increased, consumption in these branches taken together never exceeded 3-4 km³ per year (Figure #2), or a relatively low portion of the available water. Clearly, the development of agriculture and, more specifically, the growth of irrigation have been the main engines of environmental change (Kasperson 1995).

Children and young people occupy a significant place in the age structure, owing to the high natural increase of population. Children and teenagers up to 15 years of age comprise 42.5 per cent of the population in the Aral region (as compared with 26.8 per cent in the former USSR). Therefore, there are fewer people of working age here than in other parts of the world. (Kasperson 1995) Large variations in river water levels and large scale pollution caused the principal environmental changes of the Aral region. Although water consumption through fisheries, industry, power generation and public use of water increased, consumption in these branches taken together never exceeded 3-4 km³ per year (Figure #2), or a relatively low portion of the available water. Clearly, the development of agriculture and, more specifically, the growth of irrigation have been the main engines of environmental change (Kasperson 1995).

Demographics and Water consumption

While population has grown, so has the need for fresh water. Uzbekistan has already elaborated trading schemes of water against natural gas with Kirghistan. According to data from the World Bank, the current distribution of available water per capita is as follows:

Uzbekistan - 2596 m3/ per person/annually

Turkmenistan - 4044 m3/ per person/annually

Tajikistan - 1843 m3/ per person/annually

Kyrgyzstan - 1371 m3/ per person/annually

  • Kazakhstan - 1943 m3/ per person/annually

Poverty:The Main Cause for Population Growth

The Central Asian republics enjoyed, during Soviet times, state safety nets and subsidies in order to transform the region mainly into an agricultural and oil and gas source for the Soviet Union. This transformation occurred because of the warm climate and of the labor specialization pushed forward in the region. But when those republics gained their independence in 1991, the transition from a centralized economy to a market one brought severe economic hardship for most of the population. It was followed by a liberation of prices and hyperinflation. This brought a sharp surge in poverty, as many state-provided privileges disappeared abruptly too. For instance, in Tajikistan, poverty reached up to 83% of the population at some point. As a result of that poverty, populations, birth and death rates increased dramatically. Life expectancy shrank due to worsening public health services (Amarakoon 2004-2005). Data dramatically changes when it comes to population who live near the Aral Sea. This region has the highest child mortality rate (75 children per 1000 newly born), and in the Karakalpakstan region, which is at the epicenter of the crisis, there is a high level of maternity deaths observed: about 120 women per 10,000 births. Due to increased dust storms, high concentrations of pesticides in the air, and poor quality of water, rates of diseases such as tuberculosis, infections and parasites, typhus, hepatitis and paratyphoid dramatically increased (Mahambetova 1999).

Population seen as Agrarian Labor Force

Governments in the region play a primary role in the large share of the agricultural sector in the economy, which employs an even larger share of the labor force. Aside from Kazakhstan, all Central Asian countries depend largely on the agricultural sector for their exports and thus monetary activities (CIA-WorldFactbook). Due to a lack of modernization of the agricultural sector, particularly looking at the absence of tractors, it employs a large portion of the population in order to produce in huge quantities agrarian products which include cotton (major one), rice and wheat. Governments pressure local farmers to produce a certain level of crops by buying them below the market price. This results in increasing further the reliance of farmers on a large labor force, and prevents them from mechanizing and investing in tractors. The vicious circle in place stimulates a larger family size as it rewards extra hands to work on the field. According to UNESCO-Institute of Water Education, cotton consumption is responsible for 2.6 per cent of the global water use. As a global average, 44 per cent of that water is used for cotton growth and processing not for serving the domestic market but for export. In Uzbekistan, a major cotton producer and water consumer, 41 percent of cultivated land was devoted to cotton, 32 percent to grains, 11 percent to fruits, 4 percent to vegetables, and 12 percent to other crops (Mongabay 2008).

Cotton production has three main negative effects:

  • Consumes large amounts of water in furrow irrigation structure
  • Requires more labor force due to the lack of financial capacity of farmers
  • Pollutes water and the environment because of mixing used field water full with chemicals and fertilizers with river or drinkable underground water.
  • A backdrop to this swiftly deteriorating ecosystem is the struggle to retain the once ample supply of vegetation being grown in the region. The thirstiest of the crops are predictably cotton and rice. The first of which, cotton, still puts Uzbekistan as second cotton exporter in the world. With government quotas for cotton growth unabated, the toll to the environment continues to grow and ravage the region. One third of the foreign currency earned by the country is dependent on the cotton grown in the arid land of the Aral Sea region.

With desertification of the area the poorly constructed system for irrigation has become a much more worrisome problem. The salty, sandy and dry soils that support the unlined canals now absorb much of the water intended for crops. Additionally, the water evaporates more rapidly in the drying climate and sandy earth. As little as one fifth of the water is reaching its destination while much of the water left behind en route causes widespread salty flood plains. Buildings and fields have been collapsing for decades and many miles of once resourceful farmland have become salt marsh (Percoda). “A United Nations report in 2001 estimated that 46 percent of Uzbekistan's irrigated lands have been damaged by salinity, up from 38 percent in 1982 and 42 percent in 1995” (Tavernise). Some of the remaining crop yields have diminished by as much as two thirds and on many accounts the yield has decreased by half.

With desertification of the area the poorly constructed system for irrigation has become a much more worrisome problem. The salty, sandy and dry soils that support the unlined canals now absorb much of the water intended for crops. Additionally, the water evaporates more rapidly in the drying climate and sandy earth. As little as one fifth of the water is reaching its destination while much of the water left behind en route causes widespread salty flood plains. Buildings and fields have been collapsing for decades and many miles of once resourceful farmland have become salt marsh (Percoda). “A United Nations report in 2001 estimated that 46 percent of Uzbekistan's irrigated lands have been damaged by salinity, up from 38 percent in 1982 and 42 percent in 1995” (Tavernise). Some of the remaining crop yields have diminished by as much as two thirds and on many accounts the yield has decreased by half.

Uzbekistan depends on the unused water of its neighbor, Kyrgyzstan, for fresh water. With little supply of its own the demand for water in Uzbekistan continues to grow. All of the regional soils are saturated with salt. Depending on the crop up to four times the fresh water is needed for any reasonable growth as would be needed under normal growing conditions. To decrease the salinity of the soil the croplands are flushed at least four times. This process also eliminates many of the minerals and salts that are needed for productivity of the land. To compensate for the loss of vital nutrients in the soil the people of the region utilize a severe amount of fertilizers and pesticides. Pesticide use in some areas is over twenty times the national average and the health standards of some crops exceed the allowable limits in nitrate and pesticides by two to four times (Percoda).

What should be done?

  • diversification of agrarian sector to reduce the amount of water consumed and wasted
  • use more underground water and less surface water
  • implement technology such as dripping irrigation system, which is a low-consuming water system for irrigation purposes. Such system can precisely distribute water together with fertilizers through tubes, and has thus become known as 'fertigation'. The irrigation water use efficiency can thus be increased by 35–103% compared with that of furrow (traditional) irrigation (Ibragimov).

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