Coupling SVM classification and CA-Markov simulation: four decades of land cover evolution and 2056 projection in Egypt’s northern Nile Delta — dual-dimensional analysis of aquaculture expansion and agricultural land loss

Résumé

Introduction This study provides the first spatially explicit, multi-decadal modeling of land use and land cover (LULC) dynamics in El-Hamoul District, Egypt—the largest district in Kafr El-Sheikh Governorate and a critical transition zone between intensive agriculture and the globally protected Lake Burullus Ramsar wetland. Methods Using Landsat 5, 7, 8, and 9 imageries from five benchmark years (1986–2025), classified via Support Vector Machine on Google Earth Engine (overall accuracy: 87–98%; Kappa: 0.83–0.97), six LULC classes were mapped: Agricultural Lands, Bare Lands, Fish Farms, Lake Burullus, Natural Vegetation, and Urban Areas. Results Between 1986 and 2025, 192.5 km 2 (29.97% of the district) underwent net transition. Fish farms expanded by 359% (from 24.9 to 114.4 km 2 ; +2.24 km 2 /year), primarily converting agricultural lands (59.0 km 2 ) and bare lands (34.5 km 2 ). Agricultural lands declined by 34.1 km 2 (−7.0%), while urban areas grew by 189% to 33.1 km 2 . Bare lands were nearly eliminated (−99.9%), removing the spatial buffer that once absorbed conversion pressures. A CA-Markov model, calibrated using the 1986–2025 transition matrix and validated against 2025 actual maps (difference: 0.1 km 2 , 0.017%), simulated LULC up to 2056. Results indicate continued aquaculture expansion to 143.9 km 2 (+25.8%), agricultural decline to 408.0 km 2 (−9.6%), and urban growth to 42.3 km 2 (+27.6%). Natural vegetation would increase modestly (to 33.7 km 2 ; +13.4%), driven by reed bed establishment in shallow lake margins, alongside limited bare land regeneration (2.8 km 2 ) from cyclical fish farm abandonment. Critically, Lake Burullus’s portion within El-Hamoul would shrink to 11.6 km 2 (−14.95% from 2025; −45.9% since 1986). Conclusion These findings reveal an accelerating loss of the lake–agriculture interface, direct encroachment on a Ramsar site, and the elimination of fallow buffers—pointing to urgent needs for spatially explicit land-use planning that balances aquaculture economics with wetland conservation and agricultural sustainability in one of Egypt’s most ecologically sensitive deltas.

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