Desiccation of the Aral Sea
One of the major issues Kazakhstan is facing today is the desiccation of the Aral Sea. Mismanagement of Soviet irrigation projects has caused the level of the Aral Sea to drop by approximately 23m, decreasing its size by 50%. This change in size has changed the climate in the area and has also revealed 3 million hectares of land that are now subject to erosion. The Soviet irrigation program that is at the origin of the Aral Sea desertification problem was a program to promote agriculture implemented by the Soviet government in the 1950's. In the program, the Aral Sea's two main sources of water income was diverted in order to irrigate the desert region surrounding the Sea in an attempt to boost agriculture. However, the majority of the water being diverted at the expense of the Aral Sea supply, but the majority of it was being soaked up by the desert and wasted (between 25% and 75% of the water, depending on the time period). 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 the inflow is equal to evaporation on average. This means that the diversion of the rivers is at the origin of the imbalance that has caused the sea to slowly dry up and become desert over the last 40 years or so. The remaining water in the Aral Sea and smaller lakes within the sea that have stopped being fed by river flows tend to have higher salinity levels than they did before, due to evaporation - causing some or all fish that have either survived or been reintroduced in the 1990's to die. Even rewatering these lakes does not compensate for the increased salinity over the years.
As the Sea's water began to drop over time, the rate of water loss accelerated. This is because the Sea was continuously becoming shallower as it lost more water, and as the Sea became shallower the water temperature at the surface increased faster because the sun only had to heat up a smaller volume of water rather than a large one. This temperature increase in turn lowered the specific humidity at the surface, which further increased the rate of evaporation, thus creating a loop.
However, after 1990 the rate of water loss has been slowly decreasing. One of the reasons why this might be happening is that as the Sea's surface area decreases, so does evaporation. Another reason is the increased salinity of the Sea - as salinity increases, the evaporation also decreases.
One of the many problems associated with the desiccation of the Aral Sea is the lack of commercial fish able to live in the Sea's waters, which now have a high salinity level due to loss of water. As a result of this rise in salinity, commercial fishing catches fell from 43,430 tons in 1960 to zero tons in 1980.
During the desiccation period, the Aral Sea region has experienced significant desertification. This desertification is characterised by degradation of the land and natural resources to the point where they can no longer be used. The decline in the groundwater level is one of several factors that influence the desertification. Vegetation in the region was reduced by at least 40% as a result of frequent low-water periods and the piling up of salt at the surface of the Amu Darya and Syr Darya deltas. A side effect of the decrease in the protective vegetation cover was intensified winds, which led to more dust storms in the area. Six million hectares of agricultural land were destroyed as a result of salinization and desertification.
The Aral Sea desiccation has contributed to climate change in the area. Before the desiccation period, the Aral Sea regulated the climate in the region by softening strong Siberian winds in the winter, and cooling off the area in the summer. It is hard to measure the exact amount of change in climate that the desiccation of the Aral Sea has directly caused as the entire Central Asian region has seen an increase in air temperature, but two studies on the area have arrived at the conclusion that the shrinking of the Sea directly accounts for 50-66% of the temperature increase around the Sea. The temperature hasn't only changed for the summer - temperatures have also decreased during the winter. The total result of the change in the weather in accordance with the desiccation of the Aral Sea is that there are shorter and hotter summers, longer and colder winters, and a decrease in precipitations.
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 the inflow is equal to evaporation on average. This means that the diversion of the rivers is at the origin of the imbalance that has caused the sea to slowly dry up and become desert over the last 40 years or so. The remaining water in the Aral Sea and smaller lakes within the sea that have stopped being fed by river flows tend to have higher salinity levels than they did before, due to evaporation - causing some or all fish that have either survived or been reintroduced in the 1990's to die. Even rewatering these lakes does not compensate for the increased salinity over the years.
As the Sea's water began to drop over time, the rate of water loss accelerated. This is because the Sea was continuously becoming shallower as it lost more water, and as the Sea became shallower the water temperature at the surface increased faster because the sun only had to heat up a smaller volume of water rather than a large one. This temperature increase in turn lowered the specific humidity at the surface, which further increased the rate of evaporation, thus creating a loop.
However, after 1990 the rate of water loss has been slowly decreasing. One of the reasons why this might be happening is that as the Sea's surface area decreases, so does evaporation. Another reason is the increased salinity of the Sea - as salinity increases, the evaporation also decreases.
One of the many problems associated with the desiccation of the Aral Sea is the lack of commercial fish able to live in the Sea's waters, which now have a high salinity level due to loss of water. As a result of this rise in salinity, commercial fishing catches fell from 43,430 tons in 1960 to zero tons in 1980.
During the desiccation period, the Aral Sea region has experienced significant desertification. This desertification is characterised by degradation of the land and natural resources to the point where they can no longer be used. The decline in the groundwater level is one of several factors that influence the desertification. Vegetation in the region was reduced by at least 40% as a result of frequent low-water periods and the piling up of salt at the surface of the Amu Darya and Syr Darya deltas. A side effect of the decrease in the protective vegetation cover was intensified winds, which led to more dust storms in the area. Six million hectares of agricultural land were destroyed as a result of salinization and desertification.
The Aral Sea desiccation has contributed to climate change in the area. Before the desiccation period, the Aral Sea regulated the climate in the region by softening strong Siberian winds in the winter, and cooling off the area in the summer. It is hard to measure the exact amount of change in climate that the desiccation of the Aral Sea has directly caused as the entire Central Asian region has seen an increase in air temperature, but two studies on the area have arrived at the conclusion that the shrinking of the Sea directly accounts for 50-66% of the temperature increase around the Sea. The temperature hasn't only changed for the summer - temperatures have also decreased during the winter. The total result of the change in the weather in accordance with the desiccation of the Aral Sea is that there are shorter and hotter summers, longer and colder winters, and a decrease in precipitations.