Evaluating the suitability of sustainable urban drainage systems in the context of the Maltese Islands

Abstract

The Maltese Islands have no natural fresh water resources except for precipitation and ground water aquifers which are recharged by rainfall infiltration. Precipitation rates are low, infrequent and when intense, result in large volumes of runoff. This is exacerbated by an increase in impermeable surfaces due to widespread urbanisation brought about by population growth and an increased standard of living. Impermeable surfaces reduce infiltration to ground water aquifers, with the result that these are over-abstracted and increasingly saline. Gradually, stormwater is globally being considered as an alternative source of non-potable water and in the Maltese Islands an estimated 24 million m3 is discharged to the sea annually. The semi-arid characteristics of these islands dictate an urgent need for a more sustainable management of such an important resource. Therefore recent local policy objectives have pointed towards the implementation of Sustainable Urban Drainage Systems which are designed to collect runoff at upstream sites of a catchment area for infiltration or storage purposes. This study has outlined a methodology for the identification of characteristic features found ubiquitously in Maltese towns and villages that can be applied to the implementation of SUDS. A review of the benefits and criteria for different SUDS typologies revealed those designs more suited to the local urban context and matched them to the features where they could be implemented. Results show that there are numerous instances of features where SUDS can be applied. This study has also suggested changes to policy, building regulations and development permits to ensure that the recharge area is not decreased any further. The study was limited to qualitative observations, therefore it is suggested that further research and site specific investigations be carried out to enable the initiation of implementing this more sustainable urban water management strategy.