Cloud-Based Scenario Assessment of Environmental Flow for Sustainable Transboundary Water Resources Management in the Luapula Basin

Environmental flow assessment is essential for sustaining riverine ecosystems, yet data scarcity limits the application of conventional methods in many transboundary African basins. This study developed a cloud-based, scenario-driven framework for assessing environmental flows in the Luapula River Basin, using Google Earth Engine and multi-source Earth observation datasets. The framework integrated SRTM, HydroSHEDS, JRC Global Surface Water, and CHIRPS datasets to establish a long-term hydrological baseline (1981–2025), assess spatial variability in hydrological connectivity under different environmental flow scenarios, and identify the hydrological connectivity threshold point. Model performance was evaluated using gauge-station discharge, hydrological consistency analysis, and comparison with GLDAS runoff products. Mean annual precipitation was 1,180.250 mm, generating an average runoff depth of 165.235 mm yr⁻¹ and an estimated runoff volume of 27.408 billion m³ yr⁻¹. Connectivity increased progressively with environmental flow allocation. Scenario-based analysis identified a hydrological connectivity threshold at 50% of the environmental flow requirement, beyond which river–floodplain pathways became activated. Above this threshold, connected areas expanded rapidly, indicating a nonlinear increase in river–floodplain connectivity. This finding suggests that environmentalists should focus on maintaining flow levels sufficient to preserve longitudinal and lateral connectivity rather than relying on minimum flow requirements. Validation demonstrated strong agreement between Connectivity Index and observed discharge (R² = 0.82) and moderate agreement with GLDAS runoff (R² = 0.56). The proposed framework provides a scalable, reproducible, and cost-effective approach for environmental flow assessment in data-scarce transboundary basins, supporting adaptive water allocation, ecosystem conservation, and evidence-based transboundary water resources management.