Browsing by Author "Strappa García de la Huerta, Valentina"

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    Economic modelling of water storage, irrigation and crop choice under water scarcity
    (2023) Strappa García de la Huerta, Valentina; Melo Contreras, Óscar; Pontificia Universidad Católica de Chile. Facultad de Agronomía y Sistemas Naturales
    In the context of climate change's impact on water resources, this thesis investigates three adaptive strategies for water use in agriculture: - Changing the irrigation policy: Examining farmers' responses to water availability uncertainty, especially for permanent crops, the study employs a dynamic economic model considering intertemporal effects. The results emphasize the tradeoff between water dose and crop area under water restrictions, crucial for optimal irrigation decisions.- Water storage policies: Addressing the need for efficient water management, the research focus on dam operating rules. Integrating rational expectations, the study develops optimal storage policies based on expected future water resources. Findings underscore the importance of bounded capacity in mitigating the effects of decreased mean water inflows.- Changing the crop mix: Exploring water scarcity's impact on crop choice in low- to medium-income nations, the study proposes an economic model where water, not land, is the primary decision variable for farmers. The research employs a multinomial logistic structure to analyze water allocations for crop choices in Peru.This interdisciplinary research integrates dynamic economic modeling to provide insights into optimal irrigation, water storage, and crop choice strategies, contributing to understanding adaptive responses amid changing climatic conditions and resource pressures.
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    Importance of the Population Exposure Model in the Impact of PM and Daily Mortality
    (2009) Strappa García de la Huerta, Valentina; Cifuentes Lira, Luis Abdón; Jorquera, Héctor
    Background and Objectives: A usual critique of ecological studies is the poor characterization of the population exposure to air pollution. In this work, the impact of population exposure modeling to particulate matter (PM10 and PM2.5) on the risk estimates is analyzed for the inhabitants of Santiago (Chile), for the years 1997 to 2005. Methods: All cause mortality risks were computed using a simple exposure model (average of several monitors) and a more detailed one, based on the results of an atmospheric photochemical model for four weeks, and extrapolated to the rest of the year. Results: Significant contributions to the risk estimates were found when the detailed exposure model was considered. The elderly showed the biggest increase on risk due to PM2.5 exposure, from 2.7% (CI 95%: 1.8–3.6) to 3% (1.9–4.1). For all ages, the increase was smaller, from 1% (0.4–1.7) to 1.2% (0.3–2.1). Even though the increases in risk were higher for the cold season, the incorporation of the proposed exposure wasn’t statistically significant. Conclusion: Health risks found were consistent with the evidence of previous national and international studies. The relative risks estimations using the proposed model were greater than using the average of the monitors, as usual in ecological studies. Even though the difference between the two models was not statistically significant, the RR increase is important for policy applications. The model based on photochemical estimations is a contribution in the exposure assessment, but its influence has to be explored with more detail.
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    Mortality Effects of PM10 and O-3 in Chilean Cities: Results from the ESCALA Project
    (Oxford University Press, 2009) Cifuentes Lira, Luis Abdón; Strappa García de la Huerta, Valentina
    ESCALA (Estudio de Salud y Contaminación del Aire en Latinoamérica) is a study that examines the association between outdoor air pollution (PM10 and O3) and health effects in Brazil, Mexico and Chile, in all causes, all ages mortality and in subgroups defined by cause, age and gender. We report the results for Santiago, a 5 M people city, Concepcion, a 600,000 people industrial city, and Temuco, a city of 360,000 people dominated by wood-burning pollution in winter. Poisson regression was used to fit a model to the time-series data (1997–2005), adjusting for seasonality and meteorology. Distributed lag models were fitted considering a 2nd degree polynomial with exposure lagged up to 5 days. In Santiago, in most of the age groups and causes studied, PM10 had a signficant impact on daily mortality. The risk percentage change (RPC) for 10 μg/m3 PM10 ranged from 0.12% (cardiopulmonary, all ages) to 0.46% (respiratory, all ages). Ozone also had significant impacts for all causes, cardiopulmonary causes. The biggests effects were found for cerebrovascular/stroke (CEV) deaths (RPC 0.56 to 0.66 for all ages and elder). The only significant effects in Concepcion were found for the elder population for respiratory causes (RPC 1.65%) and COPD (RPC 2.6 to 2.9%). In Temuco, COPD had the higher risk for the whole population (RPC 2.7 to 4%) and CEV also had a high risk (RPC 1.2 for all ages, 1.1 to 1.5 for elder). These results provide further evidence of the adverse health effects of PM10 and O3 in cities of the developing world. The higher effects were found for two relatively small cities, with different mixtures of air pollution. Possible differential effects by socioeconomic characteristics of the exposed populations may explain much of the differences and are being currently investigated.