The Aras River, as a transboundary meandering river system, has experienced pronounced morphodynamic and riparian land-use changes driven by the combined effects of natural processes and human interventions. This study aimed to conduct a quantitative spatial analysis of riverbed dynamics and riparian land-use changes along the Aras River during the period 2010–2024, and to predict future trends up to the 2031 horizon within Ardabil Province, Iran. To this end, multi-temporal Landsat 5 TM (2010), Landsat 8 OLI (2017) and Sentinel-2 satellite imagery were integrated with field observations related to changes in riverbed and land-use, along with GIS techniques, to detect spatiotemporal patterns of channel migration and land-use transformation. Future changes were predicted using an integrated Cellular Automata and Markov model. The results reveal a substantial reduction in the riverbed area, declining from 1,821.6 ha in 2010 to 939.47 ha in 2024, whereas agricultural lands (31,968 ha) and residential areas (829.99 ha) exhibited the highest spatial persistence. Concurrently, tree-shrubland expanded markedly, increasing from 921.6 to 1,684.7 ha over the study period. Model validation confirmed the high predictive capability of the CA–Markov model, with an overall accuracy of 99%, a Kappa coefficient of 0.97, and an AUC value of 0.926. Model projections indicate that by 2031 approximately 25.5% of the riverbed will be converted into tree and shrubland and 2.92% into agricultural land, reflecting continued lateral channel migration, riverbed morphological alteration, and a tendency toward relative channel desiccation. The intensification of bank erosion and channel displacement poses increasing risks to agricultural lands and human settlements. These findings highlight the need for integrated riparian land-use management, bank stabilization strategies, and flood risk mitigation in transboundary river systems.
Introduction
Rivers, as dynamic geomorphological systems, play a crucial role in sediment transport, floodplain formation, and the stability of surrounding ecosystems. Meandering rivers, due to the complexity of hydrodynamic and sedimentary processes, have long been a focus of scientific research. Their morphological changes are influenced by hydrological, tectonic, and human-induced factors, and understanding them requires a multi-scale approach. Remote sensing technologies and geographic information systems (GIS) enable tracking river course changes and quantifying morphometric indices over decades. The Aras River, with its meandering course and numerous bends in the northern part of Ardabil Province, is a prominent example of this dynamism. Its channel migration has led to bed changes, lateral erosion, and the threat to agricultural lands, natural resources, and settlements. Land-use changes and unsustainable exploitation of natural resources further intensify these hydrodynamic processes. This study aims to analyze the morphological changes of the Aras River from 2010 to 2024 and predict future trends until 2031. Using multi-temporal satellite imagery combined with spatiotemporal CA–Markov modeling, dynamic changes in river morphology and surrounding land-use were quantified, and hazard maps identifying high-risk areas in agricultural lands, rangelands, woody and shrub vegetation, shrublands and residential zones were produced. The findings provide valuable insights for sustainable water and soil resource management, mitigation of flood and erosion hazards, and enhancement of environmental and economic security in border regions.
Material and Methods
To analyze the morphological and land-use dynamics of the Aras River and predict future trends up to 2031, an integrated modeling approach was applied using the TerrSet environment. The study area covers a 73-km reach of the Aras River in the Moghan Plain, Ardabil Province, characterized by high fluvial dynamism and geomorphological sensitivity. Multitemporal satellite imagery, including Landsat 5 TM (2010), Landsat 8 OLI (2017), and Sentinel-2 (2024) with 10–30 m spatial resolution, served as the primary dataset. Supplementary data from Google Earth and field surveys were used for validation and accurate delineation of land-use boundaries. Classification accuracy was assessed through overall accuracy, Kappa coefficient and the ROC curve. The CA–Markov hybrid model was employed as the core predictive framework. The transition probability matrix was computed using 2010–2017 data to simulate the 2024 scenario, which was validated against the actual 2024 map. Upon confirming model reliability, the 2031 land-use projection was generated. The model integrates Markov analysis (temporal transitions) with Cellular Automata (spatial dynamics), enabling detailed simulation of landscape evolution. Finally, the simulated changes in land-use, as well as in the extent and channel of the Aras River, were integrated with the potential economic losses to examine the bidirectional interactions between natural fluvial processes and human activities, along with their associated economic impacts on agricultural lands, natural resources, and infrastructures. This methodological framework provides a scientific foundation for sustainable land management and flood-risk mitigation in the Moghan Plain located along the northern border of Ardabil Province.
Results and Discussion
The Aras River, located in the northern part of Ardabil Province, exhibits a highly dynamic and meandering course that plays a crucial role in shaping floodplains and controlling sediment deposition. Continuous erosion along concave banks and deposition on convex ones have resulted in channel migration and significant local morphological changes. Fertile agricultural lands and diverse vegetation have developed along the river margins, which, although productive, remain highly vulnerable to natural river dynamics and land loss. To mitigate erosion and protect infrastructure, several embankments have been constructed; however, these structures, while effective in the short term, often modify natural flow regimes and intensify downstream erosion.
Land-use analyses from 2010, 2017, and 2024 reveal a clear expansion of human-modified zones—especially agricultural, residential, and industrial areas—while the riverbed area has shrunk significantly by 2024. Between 2010 and 2017, the main river channel migrated primarily northward, affecting around 373.35 hectares. Some of the abandoned river areas were converted to tree and shrub cover, while the riverbed width decreased by approximately 64.78 hectares. Agricultural and residential lands showed the highest persistence (≈99%), while rangelands experienced the most substantial changes. From 2010 to 2024, agricultural and residential areas remained largely stable (99% and nearly 100%, respectively), whereas the riverbed underwent the most drastic transformations, retaining only 734 out of 1,868 hectares. Some of these transformed zones were converted to agricultural, rangeland, or tree/shrub areas. These results emphasize the stability of anthropogenic land-uses and the high dynamism of riverine environments over the 14-year period.
Using the CA–Markov model, the 2024 land-use simulation based on 2010–2017 data showed high predictive accuracy (Overall accuracy = 99%, Kappa = 0.97, AUC = 0.926). The model predicted that by 2031, agricultural (99.89%), residential (98.86%), and tree/shrub (97.66%) areas will remain highly stable, while the riverbed will continue to be the most dynamic feature, with only a 68.33% probability of persistence. Around 25.5% of the riverbed is expected to convert to tree/shrub cover and 2.9% to agriculture, indicating continued channel adjustment and further desiccation in the future.
The economic assessment estimated total losses of about 22,971 billion rials by 2031, mainly due to riverbed conversion to natural cover (19,193 billion rials). Changes in agricultural (60 ha; 1,811 billion rials) and residential (18 ha; 530 billion rials) lands also contributed substantially. Based on the estimated value of 30 billion rials per hectare in 2025, agricultural and residential zones represent the highest economic risk, whereas rangelands and natural covers serve critical ecological functions. Among the six studied reaches, reaches 3 and 5 are most vulnerable, with estimated losses of 7,106 and 6,145 billion rials, respectively. Therefore, priority management should focus on these sectors through channel stabilization, protective vegetation, and adaptive land-use planning. Historical floods in Parsabad and Aslanduz (Modarres, Sarhadi & Burn, 2016; Khoshnoodmotlagh et al., 2020) confirm recurring flood hazards.
Conclusion
The Aras River in Ardabil Province is experiencing active morphological and functional transformation driven by meandering channel migration, bank erosion, and sediment deposition. Analysis of satellite imagery and CA–Markov modeling (2010–2024) revealed that agricultural and residential lands remain largely stable, whereas the riverbed is highly dynamic, with significant portions transforming into vegetated and agricultural areas. Model validation (Overall accuracy = 99%, Kappa = 0.97, AUC = 0.926) confirmed its reliability, and predictions for 2031 indicate continued riverbed contraction alongside high stability of cultivated and settled areas.
These results highlight the strong interaction between fluvial processes and surrounding land-use dynamics, demonstrating that channel migration directly influences the stability of agricultural and residential lands. Without integrated management, ongoing morphological evolution may intensify economic losses and ecological degradation. Therefore, implementing targeted floodplain planning, riverbank stabilization, and systematic monitoring especially in high-risk reaches is essential for ensuring long-term sustainability. This study provides a scientific basis for sustainable water and soil management, erosion and flood risk mitigation, and rational land-use planning in the transboundary Moghan Plain.