About EULER
EULER is a lake eutrophication modelling system developed by Longline Environment Ltd. It provides researchers, environmental consultants, and water managers with tools to understand, predict, and manage nutrient enrichment in freshwater systems.
The framework supports multiple model types, from empirical steady-state relationships suitable for rapid assessment, to process-based dynamic models that capture seasonal patterns and stratification dynamics.
Model Types
EULER offers a hierarchy of models to match the complexity of your system and the questions you need to answer.
Steady-State Models
Empirical relationships like Vollenweider and Dillon-Rigler models. Predict equilibrium phosphorus and chlorophyll concentrations from loading, hydrology, and basic lake characteristics.
Use for: Rapid screening, management scenarios, data-limited situations.
Box Models
Process-based simulation treating the lake as a single well-mixed box. Resolves temporal changes in nutrients, phytoplankton, and oxygen through mechanistic equations.
Use for: Shallow polymictic lakes, seasonal dynamics, process understanding.
Stratified Models
Vertically resolved simulation capturing thermocline development, hypolimnetic oxygen depletion, and internal nutrient loading from anoxic sediments.
Use for: Deeper stratified lakes, oxygen dynamics, internal loading assessment.
Spatially Distributed
Horizontal grid models with optional vertical layers. Wind-driven circulation, multiple inflows, and complex bathymetry. Full spatial resolution of water quality gradients.
Use for: Large lakes, spatial heterogeneity, complex management questions.
Understanding Eutrophication
What is Eutrophication?
Eutrophication is the enrichment of water bodies with nutrients, primarily nitrogen and phosphorus. While a natural process occurring over geological timescales, human activities have dramatically accelerated nutrient loading to lakes worldwide.
Causes
Major sources of nutrient loading include agricultural runoff (fertilisers, livestock waste), urban stormwater, wastewater discharges, and atmospheric deposition. Phosphorus is typically the limiting nutrient in freshwater systems, making it the primary management target.
Consequences
Excess nutrients stimulate algal growth, leading to blooms that reduce water clarity, deplete oxygen during decomposition, and can produce toxins harmful to humans and wildlife. Severe eutrophication degrades ecosystem services including drinking water supply, recreation, and fisheries.
Recovery
Lake recovery requires reducing external nutrient loads through catchment management. However, internal loading from nutrient-rich sediments can delay recovery for years or decades. Understanding these dynamics through modelling helps set realistic expectations and evaluate intervention options.
Contact
EULER is developed and maintained by Longline Environment Ltd., specialists in aquatic ecosystem modelling since 2005.
For more information about EULER, our other technological applications, and business intelligence services, please visit longline.co.uk or contact us at info@longline.co.uk