Topics:
- Fluvial geomorphology
- Biodiversity
- Hazards
- Conservation
1. Fluvial geomorphology
Rivers in the Amazon basin evolve through time and space at different scales depending on several conditions. The planform shapes and morphodynamic modes of evolution are highly dependent on the type of rivers: meandering and anabranching. Meandering rivers have higher planform migration rates than anabranching rivers, producing abundant oxbow lakes and paleochannels along the floodplain. Conversely, anabranching rivers present primary and secondary channels linked by islands. Anabranching rivers tend to have larger water and sediment fluxes than meandering rivers.
2. Biodiversity
The connectivity between Amazonian forests and rivers is vital for terrestrial and aquatic life yield. For instance, algae growth in the Amazon relies on the phosphorus and nitrogen carried out from the main rivers to the floodplains, thus the magnitude of the flood determines the number of algae produced and thus the amount of fish that feed on these algae. Additionally, inundation timing enables the lateral migration of fish and other aquatic life and the movement of nutrients from these rivers to one another or nearby streams whereas the flood pulse plays a key role in structuring and differentiating communities in terra firme (unflooded) and seasonally-flooded forests, supporting unique adaptations due to intense hydrologic cycles.
3. Hazards
The Amazon basin is under several threads that can impact not only the forest but also, the river itself. Nowadays, more infrastructure projects are projected and several hazards are occurring that can impact the basin. For instance: 1) hydropower dams are planned especially in the Andes region where the production of sediments occurs for the entire basin, 2) waterways are executed or planned where dredging is required, 3) illegal and informal mining operations produce deforestation along the floodplain and dredging along the river, 4) oil spills produce water contamination and affect the fauna and flora surrounding it, 5) roads promote deforestation, among others. The figure below shows a combined heat map of hazards presented along the Marañón, Ucayali, and Napo Rivers.
4. Conservation
Seasonal flooding patterns of hydrological and hydraulic regimes create a diverse mosaic of vegetation and habitats, which support ecosystem functioning. Gradients in land cover that form due to flooding and subsequent vegetation succession are often associated with animal functional diversity and biomass in Amazonian floodplains. Therefore, conservation strategies in the Amazon basin must incorporate both ecological systems and the geomorphological dynamics of rivers; that is, a comprehensive system that combines the dynamism and synergy of biotic and abiotic systems.
