Browsing by Author "Isidoro, Jorge"
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- An assessment of forest fires and CO2 gross primary production from 1991 to 2019 in Mação (Portugal)Publication . Fernandez, Helena Maria; Granja-Martins, Fernando M.; Pedras, Celestina M. G.; Fernandes, Patrícia; Isidoro, JorgeForest-fire rates have increased in Southern European landscapes. These fires damage forest ecosystems and alter their development. During the last few decades, an increase in fast-growing and highly fuel-bearing plant species such as bush, Eucalyptus globulus Labill., and Pinus pinaster Ait. has been observable in the interior of Portugal. This study aims to verify this assumption by the quantification of the biomass carbon sink in the forests of the Mação municipality. Maps of fire severity and forest biomass evolution after a wildfire event were produced for the period of 1991 to 2019. To quantify carbon retention in this region, this evolution was correlated with gross primary production (GPP) on the basis of satellite imagery from Landsat 5, Landsat 8, and MODIS MYD17A2H. Results show that wildfires in Mação increased in area and severity with each passing decade due to the large accumulation of biomass promoted by the abandonment of rural areas. Before the large fires of 2003, 2017, and 2019, carbon rates reached a daily maximum of 5.4, 5.3, and 4.7 gC/m2/day, respectively, showing a trend of forest-biomass accumulation in the Mação municipality.
- Assessment of climate change impacts on rainfall and streamflow in the Alto Paranapanema Basin, BrazilPublication . Hucke, André Teixeira da Silva; Menegaz, Mateus Nardini; Isidoro, Jorge; Tiezzi, Rafael de OliveiraClimate change has the potential to fundamentally transform landscapes on a global scale. Leveraging advanced predictive modeling to enhance water resource management within the Alto Paranapanema Basin (Brazil), holds the potential to proactively anticipate challenges and alleviate the impacts and conflicts arising from this phenomenon. This is particularly important in a region boasting over 1,600 center-pivot irrigation systems. This study employs the Soil Moisture Accounting Procedure, a physical model, to simulate long-term climate datasets and flows. Future climate scenarios, rooted in the Representative Concentration Pathways, are developed through the downscaling of Global Climate Models. The findings reveal a temporal shift in rainfall patterns, characterized by a reduction during the wet season of up to -40% compared to the average historical rainfall, and an increase throughout the dry season up to 40% compared to the same historical, estimated by the Eta-BESM model. These changes present challenges regarding to water availability, hydroelectric generation, and agricultural sustainability. By fostering collaboration among different governmental entities responsible for the managements of basins and harnessing the potential of predictive models, this research advocates for the adoption of proactive strategies in management of water resources. These strategies are imperative to effectively counteract the far-reaching effects of climate change. HIGHLIGHTS center dot Impacts of climate change, with four Regional Climate Models and two Representative Concentration Pathways, in rainfall and river flow utilizing Soil Moisture Accounting Procedure as an analytical tool. center dot Watershed has a major impact on society around the river and downstream. center dot River flow changes could disrupt energy and water for those communities.
- Characterization of artificial rainfall produced by a portable rainfall simulator using a rotating dynamic rainfall gauge systemPublication . Costa, Antônio Reynaldo de Sousa; Alvarenga, Lívia Alves; Thebaldi, Michael Silveira; Lima, Luiz Antonio; Colombo, Alberto; Green, Daniel; Isidoro, JorgeRainfall properties and drop spectra characterization is essential when designing and using rainfall simulators to properly replicate natural rainfall characteristics. This study considered a small-scale rainfall simulator operating under varying nozzle, pressure and rotating disc scenarios. A dynamic rainfall gauge system developed at the Federal University of Lavras was used to quantify the impact velocity of rainfall droplets and kinetic energy, and to conduct radial uniformity analyses. The results showed that the rainfall intensity, impact velocity of droplets, kinetic energy, and uniformity of distribution of rainfall are influenced by effects of the spray nozzle, operating pressure and the rotating disc opening of the rainfall simulator. Lower values of simulated rainfall kinetic energy were observed compared to the empirical natural rainfall kinetic energy at equivalent rainfall intensities. This paper highlights the influence of rainfall simulator design specifications on resultant rainfall spectra and validates simulated rainfall against empirically based natural rainfall characteristics.
- Design and characterisation of customised-roughness beds for open-channel flow experimentsPublication . Isidoro, Jorge; Martins, Ricardo; Pereira, Luísa Gomes; de Lima, João L.M.P.The use of laboratory channels or flumes for open-channel flow research is widespread. However, this type of equipment is often expensive, susceptible to damage, and require regular maintenance. In open-channel flow, the roughness of the channel bed is a critical property in governing the flow characteristics. Unfortunately, changing the bed properties, particularly its roughness, proves to be a challenging and time-consuming task in most laboratory channels. To address these limitations, this stud introduces a novel and cost-effective technique to build laboratory channel beds with tailored roughness. Additionally, we describe a precise photogrammetric based method for quantifying the absolute roughness of the bed. These engineered beds can be seamlessly in tegrated into various laboratory channels without posing any risk of equipment damage. In addition, they offer the flexibility to be modified to meet specific roughness conditions, thus advancing the capabilities of experi mental setups in hydraulic studies Furthermore, these specially designed beds can find utility in other facilities where control of surface properties is necessary.
- Development of a large-scale rainfall simulator for urban hydrology researchPublication . Isidoro, Jorge; Silveira, Alexandre; Lima, Bruno OliveiraThis work presented the development and testing of a large-scale rainfall simulator (LSRS) to be used as a research tool on rainfall-runoff and associated transport processes in urban areas. The rainfall simulator consists of a pressurized water supply system which supplies a set of 16 full-cone nozzles. Artificial rainfall with different rainfall intensities can be produced over an area of 100 m2 in a V shape. The assembly is housed in a tailor-made acrylic structure to eliminate the influence of wind and natural rainfall. Runoff is measured and collected at the outlet of the drainage basin, from where it is pumped to a storage tank that enables the reuse of water. Runoff hydrographs and pollutographs are presented as examples of possible outcomes from this facility. The LSRS is showed to be able to reproduce the rainfall-runoff and pollutant transport processes under simulated rainfall events with intensity and spatial uniformity similar to other experiments described in the literature.
- Estimation of evaporation in Andalusian reservoirs: proposal of an index for the assessment and classification of damsPublication . García-López, Santiago; Salazar-Rojas, Marcia; Vélez-Nicolás, Mercedes; Isidoro, Jorge; Ruiz-Ortiz, VerónicaStudy region: This study focuses on Andalusia (Southern Spain), a mediterranean region of 87,270 km2. Andalusia experiences significant water stress, making effective water management crucial. Study focus: Evaporation is a key element of the water budget, particularly in arid and semi-arid climates, where losses from reservoirs represent a significant fraction of the volume annually regulated and compromise the efficiency of these infrastructures. This study aims to (i) estimate the annual volume of water evaporated from large dams (> 5 hm3) in Andalusia and (ii) propose an index to classify reservoirs based on evaporative losses. New hydrological insights for the region: Data from 76 large dams in Andalusia, including their descriptive characteristics, morphometric details, and hydrological information, were retrieved from institutional sources. The monthly average flooded area was calculated from the AreaVolume-Elevation (AVE) curve, while monthly average evaporation rate was calculated through the FAO Penman-Monteith equation using meteorological data. The combination of both variables has allowed to estimate the mean monthly volume of water evaporated in each reservoir. Results were validated with isotopic content (18O and 2H) from selected reservoirs. The annual average volume evaporated from Andalusian reservoirs was estimated at 547 hm3/year (8.0 % of the inflows). Evaporative losses represent 1.1 % of inflows in the most efficient reservoirs, while in others, losses exceed 30 %, reaching 54 % in the most extreme case.
- Fluorescent quinine-based tracking techniques for measurement of open-channel surface flow velocities under low luminosity conditions using a UASPublication . Zehsaz, Soheil; L. M. P. de Lima, João; Isidoro, Jorge; de Lima, M. Isabel P.; Martins, RicardoThis study presents techniques based on the use of fluorescent quinine as a visual tracer for surface flows, to assess surface flow velocities in channels and streams under low luminosity conditions. Fieldwork was conducted in three open channels, with different hydraulic characteristics. A quinine solution, in both liquid and solid (ice cube) forms, was applied on the water flow surface and an Unmanned Aerial System (UAS) was used to record the movement of the fluorescent quinine. The results were compared to the velocities estimated using the thermal tracer technique and flowmeter-based velocity maps. The findings show that the quinine solution, in both liquid and solid forms, can be used to estimate open-channel surface flow velocities under low luminosity conditions. While the solid form of the quinine tracer was applied in a smaller volume than the liquid tracer, its fluorescence effect persisted longer. By comparison, the liquid tracer had the advantage of continual availability and was devoid of the constraint of melting.
- High spatiotemporal resolution free surface detection using cost-effective video equipment and computer vision techniques in nearly stationary flow along a transparent wall in the laboratoryPublication . Martins, Ricardo; Isidoro, Jorge; Lima, João L. M. P. deThe identification of the air-water interface in free surface flows traditionally involves intrusive techniques or costly equipment. Non-intrusive alternatives, such as computer vision, are emerging as highly effective substitutes or supplements for more invasive techniques in laboratory measurements, thanks to their straightforward implementation and cost efficiency. This research specifically delves in the conjunction of various naive techniques, exploring their collective precision in detecting the air-water interface along transparent walls in laboratory. A detection technique based on the double gradient of the image is applied and thoroughly examined. The study progresses through multiple refinement stages, culminating in a method that is both cost effective and easy to implement. This methodology allows for large-scale, high resolution measurements (200 mm x 1800 frames per video at a 0.25 mm, 50 Hz resolution), offering both spatial and temporal measurements by adeptly detecting the free surface along transparent walls.
- A high-frequency low-cost technique for measuring small-scale water level fluctuations using computer visionPublication . Isidoro, Jorge; Martins, Ricardo; Carvalho, Rita F.; de Lima, João L.M.P.Measuring and monitoring the water depth/level is a key issue when studying free-surface flows. These tasks are usually expensive in terms of time and money; however, even that expenditure is sometimes not enough to assure reliable and/or accurate results. Free-surface flows are complicated to deal with, as the instability caused by e.g., turbulence, wind, or air-entrainment, can cause important spatial and temporal fluctuations at the surface level. This work presents a non-intrusive, computer vision-based image treatment and segmentation technique that assures the detection and measurement of the free-surface water fluctuations along space and time. The labo-ratory physically based tests under steady flow conditions, and different channel bed roughness and slopes, showed a very good fit with manually direct measurements carried out with a point-gauge micrometre. Under unsteady flow conditions this technique also showed to successfully deal with applications requiring high spatiotemporal resolution of water depth/level measurements.
- A multimethod interpolation approach for mapping the spatial distribution of rainfall in southwest Iberian PeninsulaPublication . Ruiz-Ortiz, Verónica; Maria Neto Paixão Vazquez Fernandez Martins, Helena; Granja Martins, Fernando Miguel; Vélez-Nicolás, Mercedes; Isidoro, Jorge; García-López, SantiagoEight spatial interpolation models were used to map the spatial distribution of precipitation in the southwestern sector of the Iberian Peninsula (22330 km2) over 40 years (1980/1981-2019/2020). Rainfall data from 103 meteorological stations were used to generate the interpolation models, namely inverse distance weight (IDW) with 6, 12 and 24 points, regression spline (RS), thin spline (TS), universal kriging with spherical and Gaussian variogram (UK_Sphe and UK_gauss, respectively) and multilinear regression (MR), based on physiographic and geographic variables. Furthermore, 32 rainfall stations were used to assess the performance of the previous methods through 7 statistical metrics Ordinary Least Squares (OLS), Root Mean Square Error (RMSE), Normalized root mean square error (NRMSE), Coefficient of determination (R2), Nash-Sutcliffe efficiency coefficient (NSE), Mean Absolute Error (Bias and MAE). Based on these metrics, UK_gauss and IDW_6 provided the best adjustments, whereas MR presented the highest errors. All methods were suitable to predict the spatial distribution of rainfall, but adjustments are conditioned by the features of the study area, gauge density and gauge spatial distribution.