Browsing by Autor "Patrick Willems"

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A Novel Downscaling Approach to Improve Local-Scale Assessment of Future Precipitation Changes in the Tropical-Subtropical Andes–Lowland Transition Region
(RELX Group (Netherlands), 2025) Santiago Mendoza Paz; Mariella Carbajal; Jhan Carlo Espinoza; Kevin Campos; Patrick Willems
Adapting to Climate Change with Machine Learning: The Robustness of Downscaled Precipitation in Local Impact Analysis
(Multidisciplinary Digital Publishing Institute, 2024) Santiago Mendoza Paz; Mauricio Villazón; Patrick Willems
The skill, assumptions, and uncertainty of machine learning techniques (MLTs) for downscaling global climate model’s precipitation to the local level in Bolivia were assessed. For that, an ensemble of 20 global climate models (GCMs) from CMIP6, with random forest (RF) and support vector machine (SVM) techniques, was used on four zones (highlands, Andean slopes, Amazon lowlands, and Chaco lowlands). The downscaled series’ skill was evaluated in terms of relative errors. The uncertainty was analyzed through variance decomposition. In most cases, MLTs’ skill was adequate, with relative errors less than 50%. Moreover, RF tended to outperform SVM. Robust (weak) stationary (perfect prognosis) assumptions were found in the highlands and Andean slopes. The weakness was attributed to topographical complexity. The downscaling methods were shown to be the dominant source of uncertainties. This analysis allowed the derivation of robust future projections, showing higher annual rainfall, shorter dry spell duration, and more frequent but less intense high rainfall events in the highlands. Apart from the dry spell’s duration, a similar pattern was found for the Andean slopes. A decrease in annual rainfall was projected in the Amazon lowlands and an increase in the Chaco lowlands.
Assessment of Rainfall Variability and Its Relationship to ENSO in a Sub-Andean Watershed in Central Bolivia
(Multidisciplinary Digital Publishing Institute, 2018) Andres Gonzales Amaya; Mauricio Villazón; Patrick Willems
Climate change and variability are likely to increase in most parts of the world, leading to more extreme events, which may increase the stress on already threatened water resources. This study focuses on the effects of the El Niño Southern Oscillation in the rainfall of Pucara basin and in the groundwater levels of the Punata alluvial fan in the Bolivian sub-Andes. Climate change and variability were assessed using the Quantile Perturbation Method, by detecting anomalous temporal changes in extreme quantiles of annual precipitation in the Pucara watershed and the correlation with groundwater levels in the Punata fan. The results show oscillatory behavior over periods of 28 to 33 years for the occurrence of wet and dry extremes at all studied meteorological stations. This suggests a similar oscillatory behavior of the groundwater levels; however, longer groundwater level observations are needed in order to confirm the link between precipitation variability and groundwater fluctuations. Local actors such as water managers, farmers and decision makers must take into consideration this climate variability in order to plan for these multi-decadal variations in response to the changes.
Development of a semi-automated model identification and calibration tool for conceptual modelling of sewer systems
(Pergamon Press, 2013) Vincent Wolfs; Mauricio Villazón; Patrick Willems
Applications such as real-time control, uncertainty analysis and optimization require an extensive number of model iterations. Full hydrodynamic sewer models are not sufficient for these applications due to the excessive computation time. Simplifications are consequently required. A lumped conceptual modelling approach results in a much faster calculation. The process of identifying and calibrating the conceptual model structure could, however, be time-consuming. Moreover, many conceptual models lack accuracy, or do not account for backwater effects. To overcome these problems, a modelling methodology was developed which is suited for semi-automatic calibration. The methodology is tested for the sewer system of the city of Geel in the Grote Nete river basin in Belgium, using both synthetic design storm events and long time series of rainfall input. A MATLAB/Simulink(®) tool was developed to guide the modeller through the step-wise model construction, reducing significantly the time required for the conceptual modelling process.
Impacts of climate change on the hydropower potential of a multipurpose storage system project in Bolivian Andes
(Elsevier BV, 2025) I. Flores; Santiago Mendoza Paz; Mauricio Villazón; Patrick Willems; Anne Gobin
Andean Region, Bolivia. Rositas is a multipurpose storage system designed to enhance hydropower generation, agricultural production, and flood mitigation downstream in the Rio Grande basin. This study evaluates the climate resilience of the project by analysing changes in its hydropower potential. Using regional climate models from the Coordinated Regional Climate Downscaling Experiment (CORDEX) for the near (2040–2069) and far (2070–2099) future, river flow impacts were analysed under three future scenarios (RCP 2.6, 4.5, 8.5). K-means clustering was applied to 101 stations with similar climatic features to perform statistical downscaling (quantile perturbation, and delta change) at the catchment scale. The hydrological models SWAT+ and HEC-HMS were used to estimate changes in water availability and hydropower potential. Projections indicate that river discharges will increase in the wet season and decrease in the dry season, exacerbating severity of droughts. While annual hydropower potential increases by up to 11 % in the near future and 9 % for the far future, seasonal variations are significant. Energy potential decreases by up to 30 % in June to September but increases by up to 25 % in November to February. Calibration focused on seasonal transitions enhances analysis, since hydrological models significantly contribute to uncertainty. These results highlight climate risks faced by the Rositas project and the need for adaptative water management strategies to mitigate potential water conflicts. • Climate change impacts water availability and hydropower potential. • K-means clustering identified climate patterns. • Statistical downscaling was applied to an ensemble of six RCMs. • Model calibration should focus more on seasonal transitions. • Dry season hydropower potential is projected to decrease in the Rositas project.
Simulación de la producción de quinua en el altiplano boliviano con el modelo de Aquacrop con escenarios futuros generados por LARS-WG y QPM
(2015) Gavi Alavi; Jan Diels; Patrick Willems; Magali García Cárdenas
El Altiplano de Bolivia es una región semiárida a árida con condiciones adversas para la agricultura (4000 msnm). La quínoa (Chenopodium quinoa Willd.), alimento altamente nutritivo, está bien adaptado a las condiciones desfavorables del Altiplano. El presente estudio tiene como objetivo determinar el impacto del cambio climático sobre la quinua en tres localidades del Altiplano boliviano (Viacha, Patacamaya y Río Mulatos). Dos métodos de downscaling se emplearon para generar escenarios climáticos futuros (SREs y RCPs): LARS (escenarios B1, A1B y A2 para SRE) y QPM (escenarios 4.5 y 8.5 para RCP). Precipitación, temperatura máxima y mínima fueron generados para tres diferentes periodos (2030s, 2050s y 2090s). Para estimar la productividad de la quinua se utilizó el modelo AquaCrop. Entre los resultados se tiene que las temperaturas máximas y mínimas se incrementan más en RCPs que en SREs, para los años 2030s y 2090s. La precipitación mensual no mostró cambios significantes durante la época seca. El número de días con heladas se reducen. Asimismo, las probabilidades de periodos de helada que pueden dañar a la quinua (-3ºC) se reduciría. AquaCrop estima que el ciclo promedio se reduciría en todas las localidades y escenarios. Además, indicaron que si las condiciones de manejo en el campo (riego a secano, poca fertilidad, etc.) son similares a las actuales la producción no varía mucho para SRE. Sin embargo para RCPs, en Patacamaya y Rio Mulatos la producción se reduciría en un rango de 0,1 a 0,2 Mg ha-1. Finalmente, en Patacamaya y Río Mulatos se espera que la pérdida de producción por el estrés hídrico se incremente y en Viacha se presente un leve decremento en el estrés hídrico. Efectos positivos y negativos en la quinua son esperados en el Altiplano boliviano.
Soil organic carbon in Andean high-mountain ecosystems: importance, challenges, and opportunities for carbon sequestration
(Springer Science+Business Media, 2022) Gavi Alavi-Murillo; Jan Diels; Jere L. Gilles; Patrick Willems
Understanding the water-ecosystem nexus in the Inter-Andean region of Bolivia – a synergistic, historical and complex connection
(2026) I. Flores; Santiago Mendoza Paz; Andres Saul Gonzales Amaya; Mauricio Florencio Villazon Gomez; Santiago Núñez Mejía; Patrick Willems; Anne Gobin
Climate change poses a major threat to vulnerable regions, necessitating the development of adaptive strategies to ensure a sustainable future. To achieve sustainability, a deeper understanding of ecosystems and their nexus with climate is needed. Moreover, the interconnection between mountains and valleys demonstrate the synergies of water services in these two zones. Mountain regions, which function as critical water sources for downstream users, are particularly vulnerable and should be prioritized in adaptation strategies. These areas play a central role in water production, storage, and distribution, rendering their resilience essential for regional sustainable water management. Remote sensing products, such as MODIS and GMET, provide valuable tools for monitoring ecosystem dynamics and their interconnection with climatic variables. Precipitation emerges as the key driver influencing ecosystem responses. Our analysis reveals that vegetation indicators, NDVI and EVI, exhibit a lag by approximately one month in response to changes in precipitation. Seasonal-Trend decomposition (STL) confirms a strong correlation in the trend component: wet events typically trigger ecosystem responses after about one month. Furthermore, both wet and dry extreme events, significantly influence ecosystem development and their capacity to deliver services. Climate change scenarios indicate that future extremes will predominantly be wet rather than dry. This suggests an increase in the frequency and intensity of precipitation events by 2050, raising the risk of flooding and associated socio-ecological challenges. Such extremes can disrupt vegetation dynamics in EVI and NDVI indicators which may reflect a reduction in plant productivity and altering the dynamics of ecosystem services. Understanding these dynamics is crucial for designing resilient integrated water and ecosystem management strategies that safeguard both human and environmental well-being in the Inter - Andean region of Bolivia.