Geography of Kazakhstan the water in Kazakhstan is polluted by industrial effluents, pesticide and fertilizer residue, and, in some places, radioactive elements. The most visible damage has been to the Aral Sea, which as recently as the 1970s was larger than any of the Great Lakes of North America save Lake Superior. The sea began to shrink rapidly when sharply increased irrigation and other demands on the only significant tributaries, the Syr Darya and the Amu Darya (the latter reaching the Aral from neighboring Uzbekistan), all but eliminated inflow. During the Soviet Era, Kazakhstan received water from Tajikistan and Kyrgyzstan, and Uzbekistan, Turkmenistan,
Kazakhstan–Uzbekistan border sparsely populated and traverse largely desert areas, in stark contrast to the western third which is densely populated, containing some of the largest towns in Uzbekistan and southern Kazakhstan. The eastern-most section is mountainous and contains a series of national parks (Sayram-Ugam National Park and Aksu-Zhabagly Nature Reserve in Kazakhstan and Ugam-Chatkal National Park in Uzbekistan. Uzbekistan’s Jizzakh to Sirdaryo railway crosses through Kazakhstan briefly, a legacy of the Soviet era where infrastructure was built without regard to what were then internal boundaries. Russia had conquered Central Asia in the 19th century by annexing the formerly independent Khanates of Kokand