A river diverted
The glittering white terrain of the Syr Darya floodplain is a modern geological feature, created in just a few decades. This vast salt-crusted terrain is caused by one of the most ambitious agricultural endeavors of the 20th century. Beginning in the 1960s, Soviet planners sought to transform the arid plains of Central Asia into a major producer of cotton and rice. To do this, they engineered massive irrigation networks, diverting colossal amounts of water from the region's two main arteries, the Amu Darya and the Syr Darya rivers.
These rivers were the sole sources of inflow for the Aral Sea, which at the time was the world's fourth-largest inland lake. The irrigation canals, many of them unlined and inefficient, bled water into the desert soil through leakage and evaporation long before it reached the crops. Before 1965, the Aral Sea received 20-60 cubic kilometers of fresh water annually; by the early 1980s, it received almost none. The consequences were twofold. First, the Aral Sea began to shrink at a catastrophic rate, its surface area eventually declining to just 10% of its original size. Second, the Syr Darya's flow was too diminished to flush naturally occurring salts from the floodplain soils, led to widespread salinization.
The chemistry of a crisis
With the freshwater supply choked off, a complex environmental process began. The groundwater level in the floodplain, fed by decades of inefficient irrigation, began to rise. This rising water dissolved ancient salt deposits within the soil and brought them toward the surface. In the arid climate, the water quickly evaporated, leaving behind an ever-thickening crust of salt. This process, known as secondary salinization, has rendered huge areas of formerly fertile land useless for agriculture. In the Kyzylorda Region alone, more than 73,000 hectares of irrigated land suffer from severe salinity, with some reports indicating that up to 85% of agricultural lands are affected to some degree.
The chemical composition of the land changed dramatically. Dominated by sodium, sulfate, and chloride ions, the soil became toxic to most native plant life. The once-common tugai riparian forests began to die off, replaced by hardy, salt-tolerant plants known as halophytes. The problem is compounded by dust storms. The exposed bed of the former Aral Sea, now called the Aralkum Desert, is a 60,000-square-kilometer source of salt and dust storms. These storms pick up an estimated 15 to 75 million tons of salt-laden dust annually, depositing it on the surrounding landscape and further contaminating the soil.