Rainfall–runoff simulations to assess the potential of SuDS for mitigating flooding in highly urbanized catchments

Sustainable Urban Drainage Systems (SuDS) constitute an alternative to conventional drainage when managing stormwater in cities, reducing the impact of urbanization by decreasing the amount of runoff generated by a rainfall event. This paper shows the potential benefits of installing different types of SuDS in preventing flooding in comparison with the common urban drainage strategies consisting of sewer networks of manholes and pipes. The impact of these systems on urban water was studied using Geographic Information Systems (GIS), which are useful tools when both delineating catchments and parameterizing the elements that define a stormwater drainage system. Taking these GIS-based data as inputs, a series of rainfall–runoff simulations were run in a real catchment located in the city of Donostia (Northern Spain) using stormwater computer models, in order to compare the flow rates and depths produced by a design storm before and after installing SuDS. The proposed methodology overcomes the lack of precision found in former GIS-based stormwater approaches when dealing with the modeling of highly urbanized catchments, while the results demonstrated the usefulness of these systems in reducing the volume of water generated after a rainfall event and their ability to prevent localized flooding and surcharges along the sewer network

Behaviour of geotextiles designed for pervious pavements as a support for biofilm development

Runoff is one of the main sources of contamination in urban areas, since water can transport pollutants from many different media, among which the hydrocarbons generated by vehicles have an especially significant relevance. Under this premise, the study of geotextiles used as water purification layers within pervious pavement structures becomes a crucial issue, since these fabrics have proved to be a suitable environment for the development of biofilms, which are groups of microorganisms capable of reducing the presence of hydrocarbons. For this reason, this paper proposes a first test to assess the capacity of ten different geotextiles by immersing them in a culture medium prepared to favour the growth of a microbial community. The results showed the major importance of geotextile thickness in the generation of biomass and its relationship to the manufacturing process of the fabric, either heat-sealing or needlepunching. Consequently, a second test was developed to measure the mechanical behaviour of a geotextile of each type when buried in a microbially active soil under different conditions. The comparison between exposed and control samples revealed the maintenance of strength-related properties of geotextiles in the presence of microorganisms.This study was financed by the Spanish Ministry of Economy and Competitiveness through the research projects FIDICA (Ref. REN2003-05278/TECNO) and RHIVU (Ref. BIA2012-32463) with funds from the State General Budget (PGE) and the European Regional Development Fund (FEDER)

Review of seasonal heat storage in large basins: water tanks and gravel-water pits

In order to respond to climatic change, many efforts have been made to reduce harmful gas emissions. According to energy policies, an important goal is the implementation of renewable energy sources, as well as electrical and oil combustion savings through energy conservation. This paper focuses on an extensive review of the technologies developed, so far, for central solar heating systems employing seasonal sensible water storage in artificial large scale basins. Among technologies developed since the late 70s, the use of underground spaces as an energy storage medium - Underground Thermal Energy Storage (UTES) - has been investigated and closely observed in experimental plants in many countries, most of them, as part of government programmes. These projects attempt to optimise technical and economic aspects within an international knowledge exchange; as a result, UTES is becoming a reliable option to save energy through energy conservation. Other alternatives to UTES include large water tanks and gravel-water pits, also called man-made or artificial aquifers. This implies developing this technology by construction and leaving natural aquifers untouched. The present article reviews most studies and results obtained in this particular area to show the technical and economical feasibility for each system and specifics problems occurred during construction and operation. Advantages and disadvantages are pointed out to compare both alternatives. The projects discussed have been carried out mainly in European states with some references to other countries