Afstroom

Afstroom is a Dutch term used in hydrology and water management to describe the discharge, or outflow, of water from a system. It denotes the portion of water that exits a body of water, reservoir, drainage basin, or treatment facility, typically measured in terms of volume per unit time (for example cubic meters per second).

In rivers and lakes, afstroom is the outflow component opposite to inflow. In reservoir operation, it is the target discharge that determines water level, hydroelectric generation, and downstream supply. Monitoring afstroom is essential for flood risk assessment, water allocation, and ecological management.

In urban drainage and wastewater management, afstroom describes the treated effluent leaving a facility or the outflow from a stormwater system. The quality of afstroom, including nutrient and pollutant loads, influences downstream ecosystems and compliance with environmental standards.

In groundwater and irrigation contexts, afstroom can refer to seepage, pumped discharge, or drainage flow that exits soils or fields. It is often modeled together with inflow and evapotranspiration to understand hydrological balance.

The term is Dutch; its English equivalents include outflow or discharge. It is used in technical reports, hydrological models, and environmental impact assessments.