elvesystemer

Elvesystemer, in hydrology, are networks of rivers and waterways that drain a landscape, forming a drainage basin or watershed. They include the main river and its tributaries, plus lakes, wetlands, and connected groundwater systems. The boundaries of an elvesystem are defined by the watershed divide, the highest topographic line that separates it from neighboring basins.

Formation and functioning:

They collect water from precipitation, snowmelt, and groundwater, delivering discharge downstream. The discharge is influenced by rainfall patterns, geology, soil, vegetation, and human use. Sediment and nutrient transport shape channel morphology and create features such as floodplains, deltas, and meanders. Ecological connectivity supports aquatic and riparian ecosystems.

Human interaction:

Humans alter elvesystems through dam construction, water withdrawals, irrigation, flood control, navigation, and pollution. Management aims include sustaining water supply, reducing flood risk, preserving ecosystems, and supporting hydropower.

Ecology and threats:

River systems host diverse habitats and migratory species but face threats from climate change, droughts, pollution, invasive species, and fragmentation. Restoration efforts focus on restoring natural flow regimes, reconnecting floodplains, and improving water quality.

Examples:

Major global elvesystems include the Amazon River basin, the Nile, the Mississippi–Missouri, the Yangtze, and the Rhine. In Norway and much of northern Europe, smaller river networks feed into fjords and coastal systems.