Monitoring the water surface dynamics of four Mediterranean mountain lakes in the Middle Atlas (Morocco) using Landsat imagery in a global change context

Abstract

Study region

Morocco's Middle Atlas, the wettest region in the country, hosts diverse water sources, including springs, rivers, and lakes. This study focuses on four representative mountain lakes—Azigza (LaZ), Ouiouan (LaO), the central lake of Tiglmamine (c-LaT), and Abakhan (LaB)—over the period from 1984 to 2023. These lakes are critical components of local hydrosystems, providing both ecological services and socioeconomic support in a region highly sensitive to climatic variability and increasing anthropogenic pressures.

Study focus

The research investigates the long-term surface water dynamics using multi-temporal Landsat imagery and spectral indices, complemented by field observations. The Modified Normalized Difference Water Index (MNDWI) was used to delineate lake surfaces, achieving an accuracy of 83 %. In parallel, the Normalized Difference Vegetation Index (NDVI) and field data were employed to evaluate the influence of human activities. Particular emphasis was placed on understanding the role of climate variability and agricultural intensification in altering lake dynamics.

New hydrological insights for the region

Findings reveal substantial reductions in lake surface areas, particularly between 2010 and 2023. LaB experienced a dramatic 95 % loss, nearing desiccation, while LaZ, c-LaT, and LaO declined by 52 %, 35 %, and 4 %, respectively. Around LaB, cultivated land expanded by over 300 %, indicating a pronounced anthropogenic impact. These results emphasize the urgent need for sustainable water and land management practices to safeguard these vulnerable high-altitude hydrosystems.