Estimating runoff quality and quantity : from selected urban road rehabilitation projects

Abstract

Malta is a densely populated island that is characterised by water scarcity and conversely by flooding issues. Stormwater management for the Maltese islands has up to date been taken into consideration into a number of fragmented projects. A Stromwater Master Plan for the Maltese islands is currently being formulated as an option that can help Malta solve both its flooding and water scarcity issues. Stormwater harvesting is to be seen as an integral part of stormwater management. The reuse of harvested stormwater depends mainly on the availability of such water, on the demand by end users and on the quality constraints. This study was focused on the determination of the quality of stormwater runoff from the Birkirkara-Msida catchment with a strive to promote the possibility of stormwater harvesting and reuse for the different consuming sectors in the Maltese islands. Possible ways to harness urban stormwater runoff were identified. Also corrective measures and treatment processes required to treat the stormwater runoff to a quality that would enable its reuse were proposed. Through comparison with international quality guidelines and with local legislation and directives, it was determined that the quality of the stormwater from the Birkirkara-Msida catchment is such that there is high potential to use the stormwater for irrigation. Further testing is required to ensure safety of use, however the study gives a first indication that there is also high potential to use the stormwater for potable supply, groundwater recharge and industry.