Differences in the amount of sand cover explain the sharply contrasting colors on the western and eastern shores of Lake Egypt.

An astronaut aboard the International Space Station took this photo of a short 30 kilometers (20 miles) section of Lake Nasser, one of the largest man-made lakes in the world. The approximately 500 kilometers (300 mi) long reservoir was created after the construction of the Aswan High Dam on the Nile River in Aswan, Egypt.

The northern two-thirds of Egypt’s lake are named after the country’s former president, Gamal Abdel Nasser, who was largely responsible for starting construction of the dam. The Sudanese part is also known as Lake Nubia.

One of the notable features of this image is the dichotomy of the landscape on either side of the lake. The geology of this region is characterized by medium to coarse sandstone. The color difference between the west and east coasts is due to the dark brown sand covering the bedrock on that coast towards the west from the springs.

In contrast, the east coast is characterized by exposed rocky surfaces with little or no sand cover. This is because wind transport is not sufficient to transport the sand across the Nile Valley. Source