yfirvatninu

Yfirvatnið, or surface water, refers to water that occurs on the Earth's surface. It includes rivers and streams, lakes and reservoirs, wetlands, and other bodies of water exposed to the atmosphere. It is distinct from groundwater, which lies beneath the surface in soil and rock. Surface water systems are organized into drainage networks that transport water from high to low elevations and connect inland waters with oceans.

Hydrologically, surface water is driven by the balance of precipitation, evaporation, runoff, and infiltration. When rain or snowmelt adds water to a landscape, some of it runs over the surface to streams, while some infiltrates the soil to replenish groundwater. Water bodies store and regulate runoff, influence local climate, and provide habitat for a wide range of organisms. Surface water interacts with groundwater through recharge and seepage, creating a dynamic exchange between the two reservoirs.

Surface water is a major source for drinking water, agriculture, industry, and energy, particularly in hydropower systems. It supports diverse ecosystems and offers recreational opportunities such as boating, fishing, and swimming. The health of surface-water systems often reflects land use, pollution controls, and climate conditions across catchment areas.

Quality and protection: Surface-water quality is affected by nutrients, pathogens, sediments, toxic chemicals, and temperature changes. Pollution from agriculture, industry, and urban runoff can degrade habitats and water usability. Climate change can alter the timing and volume of flows, affecting water availability and ecosystem resilience. Management approaches include monitoring and standards, watershed or river-basin planning, pollution controls, habitat protection, and cooperation across administrative boundaries.