Why are salt evaporation ponds usually shallow and separated by dikes?

Salt evaporation ponds are designed to be shallow and separated by dikes to optimize the production of sodium chloride through solar evaporation.

• Shallow depth: Shallow ponds allow for more efficient heat absorption from sunlight, which accelerates the evaporation process. In some operations, dyes are added to the brine to further increase heat absorption in these thin layers.1
• Dikes and compartmentalization: Dikes are essential to retain the brine and manage its flow through a series of ponds. This system allows producers to move the brine through different stages of concentration. As the solution becomes more concentrated, impurities such as sand, clay, calcium carbonate, and calcium sulfate are removed. By separating the process into multiple ponds or crystallizing pans, producers can control the specific gravity of the solution, ensuring the harvested salt remains pure and free from other dissolved constituents that reach saturation at different rates.21