Green roof for sustainable urban flash flood control via cost benefit approach for local authority

Abstract

People migration to urban region have created dense opaque urban landscape which generates high volume of storm water runoff and frequent flash flood episodes. This has caused tremendous damages and loss to the nation. Local authority has to spend greatly to repair damages caused by this disaster. Studies have proven that green roof acts as an efficient green infrastructure to control storm water runoff and hindrance flash flood occurrences. However, the worth of implementing green roof for the local authority remains unrevealed. This study prompts to assess the economic worth of implementing green roof for the local authority using costs benefits analysis. Overall, extensive green roof provides better cost benefits ratio than intensive green roof whereby the benefit is 1.2–3.5 times larger than green roof cost. Roof slope contributes the highest benefit ratio for intensive green roof at 2 times higher than minimum cost. Meanwhile, vegetation provides the largest benefit ratio for extensive green roof at 4.2 times larger than minimum cost. Green roof has proven to be worthy for local authority from the economic and environment aspects. This is significant in creating a new pathway to encourage sustainable practice among local authority thus serve national sustainable development agenda.