Papers by Gabriel Mancilla
Watershed Management Conference 2010: Innovations in Watershed Management under Land Use and Climate Change, 2010
ABSTRACT The key objective of this paper is to develop a mechanistic, 1-D hydrodynamic and sedime... more ABSTRACT The key objective of this paper is to develop a mechanistic, 1-D hydrodynamic and sediment transport model namely, RILL1D, that handles transcritical flows over abrupt changes and predicts changes in rill bed elevation, without violating the flow continuity equation. Replication of rill conditions necessitated the use of an enhanced TVD-MacCormack scheme with implementation of Tseng's surface gradient method, to provide an oscillation free solution over formed pool crests. The performance of the model is ...
Journal of Hydrology
This paper reviews the current knowledge of hydrological processes in Chilean temperate forests w... more This paper reviews the current knowledge of hydrological processes in Chilean temperate forests which extend along western South America from latitude 29 • S to 56 • S. This geographic region includes a diverse range of natural and planted forests and a broad sweep of vegetation, edaphic, topographic, geologic, and climatic settings which create a unique natural laboratory. Many local communities, endangered freshwater ecosystems, and downstream economic activities in Chile rely on water flows from forested catchments. This review aims to (i) provide a comprehensive overview of Chilean forest hydrology, to (ii) review prior research in forest hydrology in Chile, and to (iii) identify knowledge gaps and provide a vision for future research on forest hydrology in Chile. We reviewed the relation between native forests, commercial plantations, and other land uses on water yield and water quality from the plot to the catchment scale. Much of the global understanding of forests and their relationship with the water cycle is in line with the findings of the studies reviewed here. Streamflow from
Biodiversity and Conservation
Water
Drought has been, is and most likely will remain one of the most significant socio-natural disast... more Drought has been, is and most likely will remain one of the most significant socio-natural disasters affecting society and the environment worldwide. One priority objective in the adoption of national drought policies is to promote standardized approaches to vulnerability assessment. To reach this objective, however, there is a need to address the noticeable lack of reconciliation between the two major epistemic frameworks that have been used to determine who is vulnerable and why: the so-called outcome and contextual frameworks. This study presents a novel procedure called the convergent approach to assess drought vulnerability under an integral framework. The procedure has been applied to the study of the vulnerability of water security to drought in water-use sectors in a basin located in north-central Chile. The study is justified by the role that drought plays as the major threat to water security in a context of global water crisis. The results show that the convergent approach outperforms traditional procedures such as those based on composite indicators, showing sound robustness and reaching sufficient levels of reliability and validity. The potential expansion of this approach to other applications, such as those related to global estimations of vulnerability to drought, is also discussed.
Influencia de la hojarasca y el riego sobre la germinación de semillas de la especie vulnerable B... more Influencia de la hojarasca y el riego sobre la germinación de semillas de la especie vulnerable Beilschmiedia miersii: Un experimento de campo Belloto del norte (Beilschmiedia miersii) es una especie arbórea endémica de la zona central de Chile (estado conservación vulnerable). La predación de sus semillas y plántulas por el ganado y a la desecación del hábitat son amenazas que enfrentan las poblaciones naturales. La hojarasca modifica la humedad del suelo y podría afectar la germinación de semillas y la supervivencia de plantas de regeneración. El objetivo del estudio es analizar la germinación de semillas de belloto del norte respecto a variación de la humedad y profundidad de hojarasca. Éste se llevó a cabo en tres condiciones boscosas, con una variación desde alta a nula presencia de belloto del norte en el estrato arbóreo, en la Cordillera de la Costa de la ×ȋ͵͵͑ͷͳǯǡͳ͑ͲǯȌǤ
instalaron 24 parcelas cubiertas con casetas de malla metálica (42x49 cm). En...
2005 Tampa, FL July 17-20, 2005, 2005
The key objective of this paper is to develop a 1-D hydrodynamic and sediment transport model, na... more The key objective of this paper is to develop a 1-D hydrodynamic and sediment transport model, namely, RILL1D, that handles transcritical flows over abrupt changes (e.g., formation of pool crests and width change) in a single rill and also predicts changes in rill bed elevation. Replication of rill conditions in terms of flow and bed evolution changes necessitated the use of an enhanced TVD-MacCormack scheme with implementation of Tseng's surface gradient method, to provide an oscillation free solution over formed pool crests. The model at the end of each time step calculates the flow depth, velocity, and bed shear stress and provides changes in bed elevation and grain size distribution within a cell. The hydrodynamic performance of RILL1D is evaluated by comparing its results with either analytical solutions or experimental observations from various benchmark tests with rigid bed conditions that include (1) formation of a hydraulic jump in a rectangular channel, (2) steady subcritical and transcritical flow (without a shock) over a hump, (3) formation of a hydraulic jump in a converging-diverging frictionless channel, and (4) flows over step-pools. It is shown that the enhanced TVD-MacCormack scheme adequately simulates transcritical flows by preserving the mass conservation and reducing the artificial numerical error. The scheme also approximates satisfactorily depth and velocity for a single rill, with a fixed bed consisting of steps and pools, except near the pool headwalls where a backroller forms with negative velocities. The sediment component of RILL1D is evaluated by two field investigations of single rills with mobile beds. With the field data the code is tested for its ability to reproduce measured values of sediment transport rates. A sensitivity analysis is performed to assess the effects of cell size and critical erosional strength in the predictive ability of the model. RILL1D performs reasonably well in these simulations in terms of sediment prediction rates and fared adequately in terms of replicating rill bed morphology.
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Papers by Gabriel Mancilla