Modelling Phosphorus Retention in Lakes and Reservoirs

• Published in: Water, air & soil pollution: Focus Vol. 6; no. 5-6; pp. 487 - 494
• Main Authors: Hejzlar, J, Šámalová, K, Boers, P, Kronvang, B
• Format: Journal Article
• Language: English
• Published: Dordrecht : Kluwer Academic Publishers 01.12.2006
• Subjects: Freshwater; lakes; mass-balance model; phosphorus; reservoirs; retention; statistical optimization; OECD
• ISSN: 1567-7230; 1573-2940
• DOI: 10.1007/s11267-006-9032-7

Steady-state models for the prediction of P retention coefficient (R) in lakes were evaluated using data from 93 natural lakes and 119 reservoirs situated in the temperate zone. Most of the already existing models predicted R relatively successfully in lakes while it was seriously under-estimated in reservoirs. A statistical analysis indicated the main causes of differences in R between lakes and reservoirs: (a) distinct relationships between P sedimentation coefficient, depth, and water residence time; (b) existence of significant inflow-outflow P concentration gradients in reservoirs. Two new models of different complexity were developed for estimating R in reservoirs: [graphic removed] , where τ is water residence time (year), was derived from the Vollenweider/Larsen and Mercier model by adding a calibrated parameter accounting for spatial P non-homogeneity in the water body, and is applicable for reservoirs but not lakes, and [graphic removed] , where [Pin] is volume-weighted P concentration in all inputs to the water body (μg l-¹), was obtained by re-calibrating the OECD general equation, and is generally applicable for both lakes and reservoirs. These optimised models yield unbiased estimates over a large range of reservoir types.