The construction industry must meet current environmental requirements, mostly those pertaining to the reduction in construction and demolition waste and the consumption of raw materials. The use of recycled concrete aggregates can be part of the solution, but one question that arises is how many times recyclables can be recycled. This unknown involves other related queries regarding the properties and possible uses of repeated recycled concrete aggregates. This research is derived from the precast concrete industry, where multi-recycling is a pressing need. From good-quality parent concretes, three cycles of recycled concrete aggregates were produced and analysed. The final results are promising due to the good quality of the recycled and multi-recycled concrete aggregates obtained. Not only can they be used in low-level applications (backfilling) as usual, but they can also be used for more demanding purposes, such as graded aggregates, cement-treated road bases and concrete pavements. Their use in structural concrete is feasible, but it will be dependent on the water absorption level and the amount of recycled aggregate substitution. This research proves the viability of multi-recycled concrete aggregates with all of the associated environmental benefits.

The treatment of wastewater from small towns supposes problems of economic efficiency, leading to very high environmental costs in areas with low population density. Constructed wetlands (CW) seems to be the more suitable solution for this kind of situation, but further investigations are needed regarding their efficiency under different climatic conditions. This work presents the results concerning urban wastewater treatment by means of two different constructed wetlands using macrophytes: horizontal subsurface flow (HSSF) and free water surface (FWS). The systems are located in a Mediterranean continental climate area and are fed by a by-pass at the entrance of a wastewater treatment plant. A four-year sampling campaign at the outlet of the CW allowed verifying their relative effectiveness in removing pollutants in the different seasons of the year. BOD₅, COD, and TSS were significantly removed (with average reductions of 55%, 60%, and 57%, respectively) by these natural phytodepuration systems, with HSSF being more efficient during plants’ dormancy than FWS, but the concentrations of nutrients indicated that cumulative effects occur in CW with the need of adequate annual maintenance. It was found that the main factors controlling the efficiency of such systems throughout the year are the period of vegetative development, the presence/absence of a solid substrate, and the pollutant load of the wastewater inlet.

This study aims to analyse the effect of partially clogged inlets on the behaviour of urban drainage systems at the city scale, particularly regarding intercepted volumes and flood depths. The main challenges were to represent the inlet network in detail at a rather large scale and to avoid the effect of sewer network surcharging on the draining capacity of inlets. This goal has been achieved through a 1D/2D coupled hydraulic model of the whole urban drainage system in La Almunia de Doña Godina (Zaragoza, Spain). The model focuses on the interaction between grated drain inlets and the sewer network under partial clogging conditions. The model is fed with data obtained on field surveys. These surveys identified 948 inlets, classified into 43 types based on geometry and grouped into 7 categories for modelling purposes. Clogging patterns were derived from field observations or estimated using progressive clogging trends. The hydrological model combines a semi-distributed approach for micro-catchments (buildings and courtyards) and a distributed “rain-on-grid” approach for public spaces (streets, squares). The model assesses the impact of inlet clogging on network performance and surface flooding during four rainfall scenarios. Results include inlet interception volumes, flooded surface areas, and flow hydrographs intercepted by single inlets. Specifically, the reduction in intercepted volume ranged from approximately 7% under a mild inlet clogging condition to nearly 50% under severe clogging conditions. Also, the model results show the significant influence of the 2D mesh detail on flood depths. For instance, a mesh with high resolution and break lines representing streets curbs showed a 38% increase in urban areas with flood depths above 1 cm compared to a scenario with a lower-resolution 2D mesh and no curbs. The findings highlight how inlet clogging significantly affects the efficiency of urban drainage systems and increases the surface flood hazard. Further novelties of this work are the extent of the analysis (city scale) and the approach to improve the 2D mesh to assess flood depth.

The present paper examines the use of optical fiber as a distributed temperature sensor to detect leaks in earth dams. This real-time data acquisition technique complements current auscultation systems and improves monitoring of these critical infrastructures. The aim of this paper is to provide a practical illustration of this novel and promising technique and, particularly, of the precautions to consider to correctly deploy the sensor elements. For this last purpose, this document describes the field tests carried out on the Yesa dam in February 2017 and propose best practices concerning the implementation of the system. Keywords: Dam auscultation; Distributed temperature sensor; DTS; leak detection; earth dams

This work presents the hydraulic characterization of the existing surface drainage system of the town of La Almunia de Doña Godina (Spain). This is a preliminary activity before the modeling tasks simulate the functioning of urban drainage system during extreme rainfall events. It is well known that, during these types of meteorological events, urban drainage systems partially lose their efficiency and that this performance reduction is also influenced by the clogging phenomenon of surface grated inlets. Therefore, it is clear the need to simulate urban pluvial flooding scenarios considering the inlets hydraulic efficiency and the related effects of clogging phenomena to achieve reliable results in terms of hazard assessment. In this work, data collection was carried out on all the existing grated inlets of the municipal urban drainage system. This activity included the identification of the type of grates, their exact geographic location, their geometry and dimensions, as well as their state of maintenance with special regard on the percentage of the clogged area and the related shape pattern. Thus, five clogging patterns were defined, which allowed the estimation of hydraulic efficiency and clogging coefficient according to an experimental methodology recently developed by the Universitat Politècnica de Catalunya. These results will allow, in a subsequent phase of the research, to model the hydraulic behavior of the drainage system under different grated inlets clogging conditions, as such as different rainfall intensity events, with particular emphasis on extreme ones. Keywords: Urban drainage, surface drainage, inlet, grate, hydraulic efficiency, clogging, clogging coefficient, clogging patterns, maintenance, field activity, modeling, extreme events.

Different hydroclimatology researchers apply eigenvectors-based techniques to compress large volumes of information while preserving the invariant structure of the original data. This research developed a methodology applying one of these techniques, Principal Component Analysis, on the elements of variability in hydroclimatic time series, and then to identify clusters with the "k-means" method. The result is a regionalized map by variable. Finally, these maps are intersected, obtaining areas with a homogeneous hydroclimatic structure, because the variables have similarity in their variance structure. In the case study, 8 variables were evaluated for Colombia (9268 time series), obtaining as a result 26 hydroclimatic regions. Obtaining hydroclimatically homogeneous regions The progressive increment of impervious areas in many of our cities contributes to the increase of surface runoff volumes that, moreover, reach the drainage network or, directly, the receiving water bodies without any type of filter provided by the vegetation. In this context, that in several sites could be exacerbated by the effects of climate change that are determining a drastic increase of maximum rainfall intensities, Sustainable Urban Drainage Systems (SUDS) suppose a valid alternative to address these kinds of problems, and providing, at the same time, a long series of other co-benefits at environmental and social level. The objective of this study is to propose the implementation of green roofs in a new urbanization of the city of Zaragoza and assess their hydraulic, environmental and socioeconomic benefits. The analysis of the hydraulic and environmental benefits has been performed through the USEPA-SWMM5 software that includes a specific module for SUDS simulations with special regard to green roofs, allowing to define and fully characterize their main layers and to simulate their effects at local or catchment scale. The hydrological simulations carried out for extreme rainfall events (return periods of 2, 5 and 10 years), indicate that the reduction of the hydrograph peaks can be between 31 y 38%, while the reduction in terms of runoff volumes is ranged from 17 up to 27 %. Concerning the simulation of a continuous annual rainfalls' series, the reduction in runoff volumes would vary approximately between 30% and 37% depending on the type of green roof used. Finally, regarding the water quality parameters of the sewer discharged overflows, the reduction of pollutants would be very significant, varying from 92% to 99% depending on the type of pollutant and the type of roof.