Aral Sea is located in the Central Asian Republics of Uzbekistan and Kazakhstan, with the southern section located in the Autonomous Republic of Karapakalstan. Aral Sea is a large inland sea that has no outlets. The Sea is connected to two rivers that supply the sea with water. These two rivers consist of water that is from glaciers. One river is called Amu Darya and the other Syr Darya. Amu Darya is 2,580 km long and flows northwest from the sources in the snow-capped Pamirs. The waters from this river are used for irrigation in Turkmenistan and Uzbekistan. Syr Darya is 2,220 km long and it is also used extensively for irrigation.
It is formed in the Fergana Valley by the confluence of the Naryn and Kara Darya rivers. When combining the two rivers we see that it is quite large with a combined annual flow of 111 cubic km, this is higher than the river Nile which is only 90 cubic km. The fresh water from these two rivers held the Aral’s water and salt levels in perfect balance. Even though much of the water in the river is lost to evaporation, transpiration and seepage as the river flow across the desert. There is still enough water in the river to maintain the Aral Sea normal surface area. But more recently due to human intervention not enough water is entering the sea.
This is because locals tried using the rivers as an economy advantage and started many irrigation schemes to produce cotton. But this lead to the shrinking of the Aral Sea and it was shrinking so fast nothing could be done to prevent it. So in this case study I will be looking at how the whole surrounding was affected by the Shrinking of Aral Sea. The Biophysical Environment “The area around Aral sea consists of dry, flat plain with few rivers. Aral Sea is situated in the middle of the Asian land. So the area around it experience hot, dry climates which have the land similar to that of a desert or steppe grassland.
The Average annual precipitation rarely exceeds 150mm per year. The range between the minimum and maximum temperature is a huge difference. The maximum temperature is 47 degree centigrade in the summer and in the winter it falls to -20 degrees centigrade. The air around the Aral sea is very dry. In the summer the humidity by day is less than 25% and my midday it can fall below 10%. In winter the humidity averages to 40 to 65% during the day. It is has also been noticed that many parts of Kazakhstan and Uzbekistan experiences hot, dry winds called the sukhoveya, these winds can cause severe damage to crops.
The soil around this region is quite sandy this means that they do not retain the moisture that falls on them. And because of the winds it picks up the salt from the area where the sea has retreated backwards and blows them over the soil. When salt settles on the top of the soil it does not allow water to seep through the soil and water evaporates from the surface of the soil. Therefore the plants then die out. As they’re not getting enough water. This destroys the present crops and also in the near future the land will be suitable to grow crops.
This process of the wind blowing salt over the land is called salt deflation. edited from the book Planet Geography by Stephen Codrington Change in Climate Conditions & the impact to the surroundings During the last five to ten years the drying of the Aral Sea, has bought many changes in the climate conditions. Before the drying of the Aral Sea it was a regulator mitigating cold winds from Siberia and reducing the summer heat. But as of now the climate has change this is because evaporation has decreased due to low volume of water in the rivers and in Aral sea. Thus the climate change has led to a dryer and shorter summer in the region, and longer and colder winters.
The vegetative season has reduced to 170 days. This result in the pasture productivity has decreased by half, and meadow vegetation has decreased by 10 times. The Air temperature during winter has fallen, and summer temperature has increase by 2 to 3 degree centigrade. There has also been frequent occurrence of long dust storms and ground winds. Strong winds blowing the area now, there most intensive on the western coast, with around 50 days of storms per year. The maximum wind velocity reaches around 20- 25 m/s. And now by looking at this we can see that in these climate conditions agriculture without irrigation is not possible.
But in this dry climate people started making cotton through irrigation instead of food. So even when the people knew that due to irrigation the Aral Sea is shrinking they cannot stop the scheme as there using this to grow cottons. So if they do stop they will lose their jobs and money. So this led to an increase in irrigated land in Uzbekistan. Below is a diagram that shows the change in climatic conditions. And we can clearly see the difference from the two. The above one is from before the drying of the Aral Sea and the second one is after the drying of the Aral Sea.