[Paper Review] The decreasing level of Toshka Lakes seen from space

Amelia Carolina Sparavigna|arXiv (Cornell University)|Jul 22, 2011

Historical and Architectural Studies2 references3 citations

TL;DR

This study analyzes the shrinking of Toshka Lakes in Egypt's Sahara Desert using satellite imagery and astronaut observations from 2006 onward. It documents a significant reduction in surface area of the easternmost lake, indicating a decline in water levels due to changes in water supply from the Nile via the Toshka Canal, highlighting the vulnerability of man-made desert lakes to hydrological shifts.

ABSTRACT

Toshka Lakes are lakes recently formed in the Sahara Desert of Egypt, by the water of the Nile, conveyed from the Nasser Lake through a canal in the Toshka Depression. From space, astronauts noticed the growing of a first lake, the easternmost one, in 1998. Then additional lakes grew in succession due west, the westernmost one between 2000 and 2001. In fact, sources of precious information on Toshka Lakes are the pictures takes by the crews of space missions and the satellite imagery. They show that, from 2006, the lakes started shrinking. A set of recent images displays that the surface of the easternmost lake is strongly reduced.

Motivation & Objective

• To monitor the temporal evolution of Toshka Lakes, newly formed in the Sahara Desert, using space-based observations.
• To assess changes in lake surface area and water levels from 2006 onward, particularly focusing on the easternmost lake.
• To evaluate the impact of reduced water flow from the Nile via the Toshka Canal on the sustainability of these artificial lakes.
• To provide a remote sensing-based assessment of the hydrological dynamics of man-made lakes in arid environments.

Proposed method

• Utilization of satellite imagery and astronaut photography from multiple space missions to track changes in lake extent over time.
• Analysis of image sequences from 1998 to 2011 to document the formation and subsequent decline of Toshka Lakes.
• Comparison of lake surface area across different time periods using visual and digital image interpretation techniques.
• Use of temporal image stacks to identify trends in water level reduction, particularly from 2006 onward.
• Reliance on publicly available data from space missions and Earth observation platforms to ensure reproducibility and transparency.

Experimental results

Research questions

• RQ1 How has the surface area of the Toshka Lakes changed from 2006 to 2011 based on satellite observations?
• RQ2 What factors contributed to the observed decline in water levels in the Toshka Lakes after 2006?
• RQ3 To what extent do changes in water supply from the Nile via the Toshka Canal correlate with lake shrinkage?
• RQ4 How do the spatial patterns of lake formation and retreat reflect hydrological and climatic dynamics in the region?

Key findings

• The Toshka Lakes began shrinking visibly in satellite imagery from 2006, with a marked reduction in surface area of the easternmost lake.
• The easternmost lake, first observed in 1998, showed strong signs of desiccation by 2011, indicating a significant decline in water levels.
• The shrinking trend was confirmed through sequential analysis of satellite and crew-sourced images, showing a consistent retreat of water boundaries.
• The decline in lake levels is attributed to reduced water flow from the Nile through the Toshka Canal, suggesting instability in the artificial hydrological system.