Development of an empirical formula for estimation of bioretention outflow rate

• Published in: Water S. A. Vol. 45; no. 2; pp. 209 - 215
• Main Authors: Gulbaz, Sezar, Kazezyilmaz-Alhan, Cevza Melek, Temur, Rasim
• Format: Journal Article
• Language: English
• Published: Gezina Water Research Commission (WRC) 01.04.2019; Water Research Commission
• Subjects: Algorithms; Analysis; Bioretention; Coefficients; Depression; Depression storage; Design optimization; Empirical analysis; Empirical formula; Evapotranspiration; Excess runoff; Flooding; Floods; Flow rates; Flow velocity; Groundwater; Groundwater recharge; Groundwater storage; Heuristic; Heuristic methods; Hydrogeology; Hydrology; Infiltration; Infiltration (Hydrology); Low impact development (LID); Mathematical analysis; Moisture content; Optimization algorithms; Outflow; Pollutants; Ponding; Porosity; Rain; Rainfall; Reliability analysis; Retention basins; Runoff; Runoff volume; Soil; Soil mixtures; Soil moisture; Soil porosity; Soil suction; Storm runoff; Storms; Stormwater; Stormwater management; Stormwater quality; Stormwater runoff; Surface runoff; Surface water; Surface-groundwater relations; Urbanization; Water; Water content; Water quality; Water quality management; Water resource management; Water resources; Water shortages; Watersheds; North Carolina; Istanbul Turkey; Turkey; United States > US
• ISSN: 0378-4738; 1816-7950
• DOI: 10.4314/wsa.v45i2.07

Urbanization of a watershed affects both surface water and groundwater resources. When impervious area increases, the excess runoff and volume of water collected at the downstream end of the watershed also increases, due to the decrease in groundwater recharge, depression storage, infiltration and evapotranspiration. Low-impact development (LID) methods have been developed in order to diminish adverse effects of excess stormwater runoff. Bioretention is one of the LID types which is used to prevent flooding by decreasing runoff volume and peak flow rate, and to manage storm-water by improving water quality. In this study, an empirical formula is derived to predict the peak outflow out of a bioretention column as a function of the ponding depth on bioretention, hydraulic conductivity, porosity, suction head, initial moisture content and height of the soil mixture used in the bioretention column. Coefficients of the empirical formula are determined by using metaheuristic algorithms. For analyses, the experimental data obtained from rainfall-watershed-bioretention (RWB) system are used. The reliability of the empirical formula is evaluated by calculating the absolute per cent error between the peak value of the measured outflow and the calculated outflow of the bioretention columns. The results show that the performance of the empirical formula is satisfactory.