Green roofs and rain gardens at packhouses to reduce runoff in Emilia–Romagna

¹ Aarhus University, Aarhus, Denmark
² Technical University of Denmark, Kongens Lyngby, Denmark
³ Bukhara State Medical Institute, Bukhara, Uzbekistan
⁴ Kuban State Agrarian University, Krasnodar, Russian Federation

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract

Large fruit-and-vegetable packhouses in Emilia-Romagna present extensive impervious surfaces that accelerate stormwater runoff, elevate combined sewer loads, and concentrate first-flush pollutants. This article evaluates nature-based retrofits—extensive green roofs and ground-level rain gardens—designed for hydrologic source control at logistics sites. The objective is to quantify runoff volume retention, peak attenuation, and water-quality co-benefits under Mediterranean-subcontinental rainfall, and to compare levelized costs per cubic metre managed. Using open statistics for 2012-2024, we parameterize a functional unit of ten thousand square metres of roof area and assess three configurations: extensive green roof retrofit, bioretention rain gardens sized as ten percent of contributing area, and a combined system with partial green roof and downsized rain gardens. Indicators include annual retained volume, reduction in event peak discharge, first-flush total suspended solids removal, runoff coefficients, and normalized costs. Results indicate that combined systems achieve the highest hydrologic performance and robust pollutant control at moderate incremental cost relative to single-technology retrofits, supporting scalable flood-risk mitigation at agri-logistics hubs.