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Camila Alvarez-Garreton

Bio: Camila Alvarez-Garreton is an academic researcher from University of La Frontera. The author has contributed to research in topics: Streamflow & Surface runoff. The author has an hindex of 11, co-authored 22 publications receiving 845 citations. Previous affiliations of Camila Alvarez-Garreton include Austral University & University of Melbourne.

Papers
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Journal ArticleDOI
TL;DR: In this article, the authors investigated the nature and biophysical impacts of the megadrought in central Chile and reported some of the measures taken by the central government to relieve the effects and the public perception of this event.
Abstract: . Since 2010 an uninterrupted sequence of dry years, with annual rainfall deficits ranging from 25 to 45 %, has prevailed in central Chile (western South America, 30–38° S). Although intense 1- or 2-year droughts are recurrent in this Mediterranean-like region, the ongoing event stands out because of its longevity and large extent. The extraordinary character of the so-called central Chile megadrought (MD) was established against century long historical records and a millennial tree-ring reconstruction of regional precipitation. The largest MD-averaged rainfall relative anomalies occurred in the northern, semi-arid sector of central Chile, but the event was unprecedented to the south of 35° S. ENSO-neutral conditions have prevailed since 2011 (except for the strong El Nino in 2015), contrasting with La Nina conditions that often accompanied past droughts. The precipitation deficit diminished the Andean snowpack and resulted in amplified declines (up to 90 %) of river flow, reservoir volumes and groundwater levels along central Chile and westernmost Argentina. In some semi-arid basins we found a decrease in the runoff-to-rainfall coefficient. A substantial decrease in vegetation productivity occurred in the shrubland-dominated, northern sector, but a mix of greening and browning patches occurred farther south, where irrigated croplands and exotic forest plantations dominate. The ongoing warming in central Chile, making the MD one of the warmest 6-year periods on record, may have also contributed to such complex vegetation changes by increasing potential evapotranspiration. We also report some of the measures taken by the central government to relieve the MD effects and the public perception of this event. The understanding of the nature and biophysical impacts of the MD helps as a foundation for preparedness efforts to confront a dry, warm future regional climate scenario.

392 citations

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TL;DR: In this paper, the effect of forest management on streamflow in two watersheds in the Valdivian Andes (600-650 m of elevation; 39837 0S), and fish abundance as a function of forest cover in 17 watersheds located in the Coastal Range and the Central Depression (39850 0 -42830 0 S).

174 citations

Journal ArticleDOI
TL;DR: In this article, satellite soil moisture data (SM-DA) is used to correct bias in soil moisture and streamflow in the ensemble generation process, and for seasonal biases and errors in the satellite data.
Abstract: Assimilation of remotely sensed soil moisture data (SM-DA) to correct soil water stores of rainfall-runoff models has shown skill in improving streamflow prediction. In the case of large and sparsely monitored catchments, SM-DA is a particularly attractive tool. Within this context, we assimilate satellite soil moisture (SM) retrievals from the Advanced Microwave Scanning Radiometer (AMSR-E), the Advanced Scatterometer (ASCAT) and the Soil Moisture and Ocean Salinity (SMOS) instrument, using an Ensemble Kalman filter to improve operational flood prediction within a large (> 40 000 km 2 ) semi-arid catchment in Australia. We assess the importance of accounting for channel routing and the spatial distribution of forcing data by applying SM-DA to a lumped and a semi-distributed scheme of the probability distributed model (PDM). Our scheme also accounts for model error representation by explicitly correcting bias in soil moisture and streamflow in the ensemble generation process, and for seasonal biases and errors in the satellite data. Before assimilation, the semi-distributed model provided a more accurate streamflow prediction (Nash–Sutcliffe efficiency, NSE = 0.77) than the lumped model (NSE = 0.67) at the catchment outlet. However, this did not ensure good performance at the "ungauged" inner catchments (two of them with NSE below 0.3). After SM-DA, the streamflow ensemble prediction at the outlet was improved in both the lumped and the semi-distributed schemes: the root mean square error of the ensemble was reduced by 22 and 24%, respectively; the false alarm ratio was reduced by 9% in both cases; the peak volume error was reduced by 58 and 1%, respectively; the ensemble skill was improved (evidenced by 12 and 13% reductions in the continuous ranked probability scores, respectively); and the ensemble reliability was increased in both cases (expressed by flatter rank histograms). SM-DA did not improve NSE. Our findings imply that even when rainfall is the main driver of flooding in semi-arid catchments, adequately processed satellite SM can be used to reduce errors in the model soil moisture, which in turn provides better streamflow ensemble prediction. We demonstrate that SM-DA efficacy is enhanced when the spatial distribution in forcing data and routing processes are accounted for. At ungauged locations, SM-DA is effective at improving some characteristics of the streamflow ensemble prediction; however, the updated prediction is still poor since SM-DA does not address the systematic errors found in the model prior to assimilation.

107 citations

Journal ArticleDOI
01 Jan 2018
TL;DR: In this article, an analysis of long-term records (50+ years) of precipitation and streamflow in central-southern Chile (30-48°S) confirmed a tendency toward a dryer condition.
Abstract: The socio-ecological sensitivity to water deficits makes Chile highly vulnerable to global change. New evidence of a multi-decadal drying trend and the impacts of a persistent drought that since 2010 has affected several regions of the country, reinforce the need for clear diagnoses of the hydro-climate changes in Chile. Based on the analysis of long-term records (50+ years) of precipitation and streamflow, we confirm a tendency toward a dryer condition in central-southern Chile (30–48°S). We describe the geographical and seasonal character of this trend, as well as the associated large-scale circulation patterns. When a large ensemble of climate model simulations is contrasted to observations, anthropogenic forcing appears as the leading factor of precipitation change. In addition to a drying trend driven by greenhouse gas forcing in all seasons, our results indicate that the Antarctic stratospheric ozone depletion has played a major role in the summer rainfall decline. Although average model results agree well with the drying trend’s seasonal character, the observed change magnitude is two to three times larger than that simulated, indicating a potential underestimation of future projections for this region. Under present-day carbon emission rates, the drying pathway in Chile will likely prevail during the next decades, although the summer signal should weaken as a result of the gradual ozone layer recovery. The trends and scenarios shown here pose substantial stress on Chilean society and its institutions, and call for urgent action regarding adaptation measures.

104 citations

Journal ArticleDOI
TL;DR: The authors introduced a set of global high-resolution (0.05°) precipitation (P) climatologies corrected for bias using streamflow (Q) observations from 9372 stations worldwide.
Abstract: We introduce a set of global high-resolution (0.05°) precipitation (P) climatologies corrected for bias using streamflow (Q) observations from 9372 stations worldwide. For each station, we ...

99 citations


Cited by
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01 Apr 2003
TL;DR: The EnKF has a large user group, and numerous publications have discussed applications and theoretical aspects of it as mentioned in this paper, and also presents new ideas and alternative interpretations which further explain the success of the EnkF.
Abstract: The purpose of this paper is to provide a comprehensive presentation and interpretation of the Ensemble Kalman Filter (EnKF) and its numerical implementation. The EnKF has a large user group, and numerous publications have discussed applications and theoretical aspects of it. This paper reviews the important results from these studies and also presents new ideas and alternative interpretations which further explain the success of the EnKF. In addition to providing the theoretical framework needed for using the EnKF, there is also a focus on the algorithmic formulation and optimal numerical implementation. A program listing is given for some of the key subroutines. The paper also touches upon specific issues such as the use of nonlinear measurements, in situ profiles of temperature and salinity, and data which are available with high frequency in time. An ensemble based optimal interpolation (EnOI) scheme is presented as a cost-effective approach which may serve as an alternative to the EnKF in some applications. A fairly extensive discussion is devoted to the use of time correlated model errors and the estimation of model bias.

2,975 citations

01 Jan 2016

803 citations

Journal ArticleDOI
TL;DR: A template and checklist of information needed for those beginning an ecosystem service modelling and mapping study will reduce the uncertainty associated with quantifying ecosystem services and thereby help to close the gap between theory and practice.
Abstract: The inconsistency in methods to quantify and map ecosystem services challenges the development of robust values of ecosystem services in national accounts and broader policy and natural resource management decision-making. In this paper we develop and test a blueprint to give guidance on modelling and mapping ecosystem services. The primary purpose of this blueprint is to provide a template and checklist of information needed for those beginning an ecosystem service modelling and mapping study. A secondary purpose is to provide, over time, a database of completed blueprints that becomes a valuable information resource of methods and information used in previous modelling and mapping studies. We base our blueprint on a literature review, expert opinions (as part of a related workshop organised during the 5th ESP conference2 ) and critical assessment of existing techniques used to model and map ecosystem services. While any study that models and maps ecosystem services will have its unique characteristics and will be largely driven by data and model availability, a tool such as the blueprint presented here will reduce the uncertainty associated with quantifying ecosystem services and thereby help to close the gap between theory and practice.

635 citations

01 Jan 2012
TL;DR: In this paper, the authors used the RAPID-watch 26˚N observations of the AMOC strength and vertical structure, reviewed by scientific panels such as the IPCC, inform studies of impacts of climate change on both national and international levels.
Abstract: The UK has passed legislation that introduces the world’s first long-term legally binding framework to tackle the dangers of climate change (The Climate Change Act 20084). The act requires Government to set carbon budgets, which are limits on greenhouse gas emissions in the UK for consecutive five year periods. Models analysed in IPCC AR4 have a range of 0-60% for an AMOC decrease over the next 100 years. The RAPID-WATCH 26˚N observations provide the only continuous measurements of the AMOC strength and vertical structure, and are thus a vital monitoring tool for this key climate variable'. Analysis of the PSMSL data set, reviewed by scientific panels such as the IPCC, inform studies of impacts of climate change on both national and international levels (e.g. UK Marine Climate Change Impacts Partnership (MCCIP), UK Climate Impacts Programme (UKCIP), UK Foresight Flood and Coastal Defence Review, Charting Progress and Charting Progress 2, IPCC Working Group II).

579 citations