Luís Filipe Sanches Fernandes

Rainwater harvesting systems for low demanding applications

A rainwater harvesting system (RHS) was designed for a waste treatment facility located near the town of Mirandela (northern Portugal), to be used in the washing of vehicles and other equipment, the cleaning of outside concrete or asphalt floors, and the watering of green areas. Water tank volumes representing 100% efficiency (Vr) were calculated by the Ripple method with different results depending on two consumption scenarios adopted for irrigation. The RHS design was based on a precipitation record spanning a rather long period (3 decades). The calculated storage capacities fulfilled the water demand even when prolonged droughts occurred during that timeframe. However, because the drought events have been rather scarce the Vr values were considered oversized and replaced by optimal volumes. Notwithstanding the new volumes were solely half of the original Vr values, the projected RHS efficiency remained very high (around 90%) while the probability of system failure (efficiency<100%) stayed very low (in the order of 5%). In both scenarios, the economic savings related to the optimization of Vr were noteworthy, while the investments return periods decreased substantially from the original to the optimized solutions. A high efficiency with a low storage capacity is typical of low demanding applications of rainwater harvesting, where water availability (Vw) largely exceeds water demand (Cw), that is to say where demand fractions (Cw/Vw) are very low. Based on the results of a literature review covering an ample geographic distribution and describing a very large number of demand fraction scenarios, a Cw/Vw=0.8 was defined as the threshold to generally distinguish the low from the high demanding RHS applications.

Climate change impacts in the design of drainage systems: case study of Portugal

AbstractThis paper aims to assess the necessity of updating the intensity-duration-frequency (IDF) curves used in Portugal to design building storm-water drainage systems. A comparative analysis of the design was performed for the three predefined rainfall regions in Portugal using the IDF curves currently in use and estimated for future decades. Data for recent and future climate conditions simulated by a global and regional climate model chain are used to estimate possible changes of rainfall extremes and its implications for the drainage systems. The methodology includes the disaggregation of precipitation up to subhourly scales, the robust development of IDF curves, and the correction of model bias. Obtained results indicate that projected changes are largest for the plains in southern Portugal (5–33%) than for mountainous regions (3–9%) and that these trends are consistent with projected changes in the long-term 95th percentile of the daily precipitation throughout the 21st century. The authors concl...

DRASTIC and GOD vulnerability maps of the Cabril River Basin, Portugal

The main purpose of this study is to compare two methodologies, DRASTIC and GOD, applied to the basin of the Cabril River in determining groundwater vulnerability to pollution. The justification for the research work in this area relates to the fact that we are facing a basin adjoining the town of Vila Real (Portugal), with a propensity to expand into this area, and where there are many springs, both near the base of the basin and in hillside areas. As a result of the application, the GOD and DRASTIC maps were obtained. To better com-pare these final vulnerability maps, the conversion of the ranges of DRAS TIC indices to a normal-ized scale from 0.0 to 1.0 value was performed, staying in the same rating scale as the GOD meth-od. It was observed, through the GOD method, that the area of the basin has mostly low or negligi-ble vulnerability, related to the high depth of the groundwater level and also to the low degree of confinement. Moreover, the results of the DRASTIC method indicate that most of the basin pre-sents medium to low vulnerability, especially in areas of higher altitude. However, both methods make high vulnerability correspond to areas covered by alluvium. It may be concluded from this study that the production of results using different methods of analysis, although with similar objectives, may differ in certain locations. Thus, the outlook for the future is that the vulnerability mapping techniques ought to include physical methods, improving the credibility of these studies.

Diagnosis on Transport Risk Based on a Combined Assessment of Road Accidents and Watershed Vulnerability to Spills of Hazardous Substances

Roads play an important role in the economic development of cities and regions, but the transport of cargo along highways may represent a serious environmental problem because a large portion of transported goods is composed of dangerous products. In this context, the development and validation of risk management tools becomes extremely important to support the decision-making of people and agencies responsible for the management of road enterprises. In the present study, a method for determination of environmental vulnerability to road spills of hazardous substances is coupled with accident occurrence data in a highway, with the purpose to achieve a diagnosis on soil and water contamination risk and propose prevention measures and emergency alerts. The data on accident occurrences involving hazardous and potentially harmful products refer to the highway BR 050, namely the segment between the Brazilian municipalities of Uberaba and Uberlândia. The results show that many accidents occurred where vulnerability is high, especially in the southern sector of the segment, justifying the implementation of prevention and alert systems. The coupling of vulnerability and road accident data in a geographic information system proved efficient in the preparation of quick risk management maps, which are essential for alert systems and immediate environmental protection. Overall, the present study contributes with an example on how the management of risk can be conducted in practice when the transport of dangerous substances along roads is the focus problem.