Examinando por Autor "Udías, Angel"

Mostrando 1 - 3 de 3

Integrating multiple land cover maps through a multi-criteria analysis to improve agricultural monitoring in Africa
(Elsevier, 2020) Pérez-Hoyos, Ana; Udías, Angel; Rembold, Francois
Monitoring agricultural land cover is highly relevant for global early warning systems such as ASAP (Anomaly hot Spots of Agricultural Production), because it represents the basis for detecting production deficits in food security assessment. Given the significant inconsistencies among existing land cover datasets, there is a need to obtain a more accurate representation of the spatial distribution and extent of agricultural area in Africa. In this research, we explore a fusion approach that combines the strength of individual datasets and minimises their limitations. Specifically, a semi-automatic method is developed, relying on multi-criteria analysis (MCA) complemented with manual fine-tuning using the best-rated datasets, to generate two hybrid and static agricultural masks – one for cropland and another for grassland. Following a comprehensive selection of land cover maps, each dataset is evaluated at country level according to five criteria: timeliness, spatial resolution, comparison with FAO statistics, accuracy assessment and expert evaluation. A sensitivity analysis is performed, based on an evaluation of the impact of weight settings on the resulting land cover. The proposed methodology is capable of improving agricultural characterisation in Africa. As a result, two static masks at 250 m spatial resolution for the nominal year 2016 are provided
Robust multi criteria wastewater treatment alternative selection - a case study
(Universidad Rey Juan Carlos, 2010) Udías, Angel; Efremov, Roman; Galbiati, Lorenzo; Coscera, Giuliana; Ghiang, Gisella
Urban heat island mitigation by green infrastructure in European Functional Urban Areas
(Elsevier, 2022-02) Marando, Federica; P. Heris, Mehdi; Zulian, Grazia; Udías, Angel; Mentaschi, Lorenzo; Chrysoulakis, Nektarios; Parastatidis, David; Maes, Joachim
The Urban Heat Island (UHI) effect is one of the most harmful environmental hazards for urban dwellers. Climate change is expected to increase the intensity of the UHI effect. In this context, the implementation of Urban Green Infrastructure (UGI) can partially reduce UHI intensity, promoting a resilient urban environment and contributing to climate change adaptation and mitigation. In order to achieve this result, there is a need to systematically integrate UGI into urban planning and legislation, but this process is subject to the availability of widely applicable, easily accessible and quantitative evidence. To offer a big picture of urban heat intensity and opportunities to mitigate high temperatures, we developed a model that reports the Ecosystem Service (ES) of microclimate regulation of UGI in 601 European cities. The model simulates the temperature difference between a baseline and a no-vegetation scenario, extrapolating the role of UGI in mitigating UHI in different urban contexts. Finally, a practical, quantitative indicator that can be applied by policymakers and city administrations has been elaborated, allowing to estimate the amount of urban vegetation that is needed to cool summer temperatures by a certain degree. UGI is found to cool European cities by 1.07 °C on average, and up to 2.9 °C, but in order to achieve a 1 °C drop in urban temperatures, a tree cover of at least 16% is required. The microclimate regulation ES is mostly dependent on the amount of vegetation inside a city and by transpiration and canopy evaporation. Furthermore, in almost 40% of the countries, more than half of the residing population does not benefit from the microclimate regulation service provided by urban vegetation. Widespread implementation of UGI, in particular in arid regions and cities with insufficient tree cover, is key to ensure healthy urban living conditions for citizens. Keywords: Ecosystem services; Urban green infrastructure; Urban heat island; Microclimate regulation; Nature-based solutions