Mauricio Zambrano-Bigiarini

Validation of Satellite-Based Precipitation Products over Sparsely Gauged African River Basins

AbstractSix satellite-based rainfall estimates (SRFE)—namely, Climate Prediction Center (CPC) morphing technique (CMORPH), the Rainfall Estimation Algorithm, version 2 (RFE2.0), Tropical Rainfall Measuring Mission (TRMM) 3B42, Goddard profiling algorithm, version 6 (GPROF 6.0), Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN), Global Satellite Mapping of Precipitation moving vector with Kalman filter (GSMap MVK), and one reanalysis product [the interim ECMWF Re-Analysis (ERA-Interim)]—were validated against 205 rain gauge stations over four African river basins (Zambezi, Volta, Juba–Shabelle, and Baro–Akobo). Validation focused on rainfall characteristics relevant to hydrological applications, such as annual catchment totals, spatial distribution patterns, seasonality, number of rainy days per year, and timing and volume of heavy rainfall events. Validation was done at three spatially aggregated levels: point-to-pixel, subcatchment, and river basin for ...

Standard Particle Swarm Optimisation 2011 at CEC-2013: A baseline for future PSO improvements

In this work we benchmark, for the first time, the latest Standard Particle Swarm Optimisation algorithm (SPSO-2011) against the 28 test functions designed for the Special Session on Real-Parameter Single Objective Optimisation at CEC-2013. SPSO-2011 is a major improvement over previous PSO versions, with an adaptive random topology and rotational invariance constituting the main advancements. Results showed an outstanding performance of SPSO-2011 for the family of unimodal and separable test functions, with a fast convergence to the global optimum, while good performance was observed for four rotated multimodal functions. Conversely, SPSO-2011 showed the weakest performance for all composition problems (i.e. highly complex functions specially designed for this competition) and certain multimodal test functions. In general, a fast convergence towards the region of the global optimum was achieved, requiring less than 10E+03 function evaluations. However, for most composition and multimodal functions SPSO2011 showed a limited capability to “escape” from sub-optimal regions. Despite this limitation, a desirable feature of SPSO-2011 was its scalable behaviour, which observed up to 50-dimensional problems, i.e. keeping a similar performance across dimensions with no need for increasing the population size. Therefore, it seems advisable that future PSO improvements be focused on enhancing the algorithms ability to solve non-separable and asymmetrical functions, with a large number of local minima and a second global minimum located far from the true optimum. This work is the first effort towards providing a baseline for a fair comparison of future PSO improvements.

Particle Swarm Optimization for inverse modeling of solute transport in fractured gneiss aquifer.

Particle Swarm Optimization (PSO) has received considerable attention as a global optimization technique from scientists of different disciplines around the world. In this article, we illustrate how to use PSO for inverse modeling of a coupled flow and transport groundwater model (MODFLOW2005-MT3DMS) in a fractured gneiss aquifer. In particular, the hydroPSO R package is used as optimization engine, because it has been specifically designed to calibrate environmental, hydrological and hydrogeological models. In addition, hydroPSO implements the latest Standard Particle Swarm Optimization algorithm (SPSO-2011), with an adaptive random topology and rotational invariance constituting the main advancements over previous PSO versions. A tracer test conducted in the experimental field at TU Bergakademie Freiberg (Germany) is used as case study. A double-porosity approach is used to simulate the solute transport in the fractured Gneiss aquifer. Tracer concentrations obtained with hydroPSO were in good agreement with its corresponding observations, as measured by a high value of the coefficient of determination and a low sum of squared residuals. Several graphical outputs automatically generated by hydroPSO provided useful insights to assess the quality of the calibration results. It was found that hydroPSO required a small number of model runs to reach the region of the global optimum, and it proved to be both an effective and efficient optimization technique to calibrate the movement of solute transport over time in a fractured aquifer. In addition, the parallel feature of hydroPSO allowed to reduce the total computation time used in the inverse modeling process up to an eighth of the total time required without using that feature. This work provides a first attempt to demonstrate the capability and versatility of hydroPSO to work as an optimizer of a coupled flow and transport model for contaminant migration.

DESARROLLO FORESTAL, ESCASEZ HÍDRICA, Y LA PROTESTA SOCIAL MAPUCHE POR LA JUSTICIA AMBIENTAL EN CHILE

From a theoretical approach based on political ecology and environmental justice, we assess how forestry development has generated socio-spatial dynamics of...

Forestry development, water scarcity, and the Mapuche protest for environmental justice in Chile

Com um enfoque baseado na ecologia politica e na justica ambiental, avaliamos como o desenvolvimento florestal silvicola tem gerado dinâmicas socio-espaciais de degradacao ambiental e escassez hidrica no sul do Chile. Atraves de metodos historico-geografico e etnografico, discutimos como e porque o avanco e a consolidacao do setor florestal tem influenciado significativamente na crescente degradacao social e ambiental das condicoes de vida dos Mapuches. Em resposta a isto, durante as ultimas decadas se observa a articulacao politica do movimento social Mapuche, cujas demandas sao terra, autonomia, respeito de direitos e possibilidades de guiar seu proprio desenvolvimento. Dentro da diversidade interna desse movimento, se destaca a ideia de reverter o avanco da degradacao ambiental, que implica recuperar a mata nativa e seu ciclo natural de agua, interrompidos significativamente pelos avancos dos monocultivos florestais. Estas dinâmicas do movimento Mapuche sao exploradas desde o ponto de vista da justica ambiental.