Contemporary biogeomorphological landscape dynamics in northern Algeria: Case study of the Oued Atteba in the Ighil Emda watershed

Abstract

The Mediterranean region is facing profound ecological changes. The Ighil Emda watershed in Northeast Algeria, located within the Tellian region, illustrates these changes, yet relatively few studies have been devoted to this area. Over the last 60 years, the Ighil Emda watershed has undergone significant transformations, during which a new eco-geomorphological landscape has been established, clearly reflected in one of its tributaries. In this study, we aim to reconstruct the hydromorphological and biogeomorphological dynamics of the Oued Atteba over the last 60 years using transition matrices and landscape metrics, combined with field observations. The results show that the watercourse’s hydromorphological system has evolved through three phases. The first phase, between 1960 and 2002, is marked by intense hydromorphological activity, as indicated by the Number of Patches (NP) and the Landscape Shape Index (LSI). The second phase, from 2002 to 2012, is characterized by biogeomorphological construction and the genesis of riparian vegetation cover, as reflected by minimal changes in the values of NP and the Aggregation Index (AI). The third phase, from 2012 to 2022, is marked by the establishment of a stable biogeomorphological structure, signaled by the transition from a post-pioneer ecological stage to an alluvial forest dominated by Tamarix africana and Populus alba. These results provide important insights into the genesis of alluvial forests. LSI, NP, and AI indices are more suitable for studying hydromorphological dynamics, while SHDI and SHEI indices are more appropriate for examining biogeomorphological evolution. We believe that this study, aligned with similar research conducted in other geographic contexts, offers a relevant perspective on the deterministic relationship between geomorphological dynamics and the development of riparian ecosystems. Field monitoring has enabled a clearer understanding of the mechanisms behind biogeomorphological landscape construction.