Alejandra Stehr | MTI University (original) (raw)
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Papers by Alejandra Stehr
Hydrological Sciences Journal
Water scarcity is influencing environmental and socioeconomic development on a global scale. Paki... more Water scarcity is influencing environmental and socioeconomic development on a global scale. Pakistan is ranked third among the countries facing water scarcity. This situation is currently generating intra-provincial water disputes and could lead to transboundary water conflicts. This study assessed the future water resources of Astore basin under representative concentration pathways (RCP) 4.5 and 8.5 scenarios using fully distributed TOPographic Kinematic APproximation and Integration (TOPKAPI) model. TOPKAPI model was calibrated and validated over five years from 1999-2003 with a Nash coefficient ranging from 0.93-0.97. Towards the end of the 21 st century, the air temperature of Astore will increase by 3°C and 9.6 °C under the RCP4.5 and 8.5 scenarios, respectively. The rise in air temperature can decrease the snow cover with Mann Kendall trend of-0.12%/yr and-0.39%/yr (p ≥ 0.05) while annual discharge projected to be increased 11% (p ≤ 0.05) and 37% (p ≥ 0.05) under RCP4.5 and RCP8.5, respectively. Moreover, the Astore basin showed a different pattern of seasonal shifts, as surface runoff in summer monsoon season declined further due to a reduction in precipitation. In the spring season, the earlier onset of snow and glacier melting increased the runoff due to high temperature, regardless of the decreasing trend of precipitation. This increased surface runoff from snow/glacier melt of Upper Indus Basin (UIB) can potentially be utilized to develop water policy and planning new water harvesting and storage structures, to reduce the risk of flooding.
Limnologica, Mar 1, 2020
The seasonal nature of the stream thermal regime has been recognized as an important factor for t... more The seasonal nature of the stream thermal regime has been recognized as an important factor for the structure of benthic macroinvertebrate communities. In this study, we show the importance of temperature and the potential implications of global warming on the composition of benthic macroinvertebrate communities in Andean watersheds. Here we show that thermal factors (mean temperature and monthly range) partially explain the seasonal variability of macroinvertebrates in Andean streams. Different thermal requirements were observed for macroinvertebrate families. Optimal monthly mean temperatures estimated for Gripopterygidae (Plecoptera), Hydrobiidae (Gastropoda) and Helicophidae (Trichoptera) were lower than 7°C, while temperatures for Ameletopsidae, Baetidae (Ephemeroptera), Ecnomidae, Limnephilidae, Hydropsychidae, Leptoceridae (Trichoptera), Elmidae (Coleoptera) and Notonemouridae (Plecoptera) were close to 9.5°C. According to our estimations, future global warming could cause important changes in the macroinvertebrate composition of Andean watersheds. Gripopterygidae, Austroperlidae, Diamphipnoidae (Plecoptera), Hydrobiidae and Helicophidae (Trichoptera) would be the most vulnerable families under the 2090 temperature predictions due to their preference for low temperature.
The 2022-2023 Chilean summer showed increased temperatures and similar burned area, compared to t... more The 2022-2023 Chilean summer showed increased temperatures and similar burned area, compared to the 2016-2017 season, where more than 500,000 hectares were compromised, mainly in the rural areas. After a brief review, it is revealed that the effects of forest fires on soil and hydrological properties are barely debated in Chile. Here, we showed a climatological analysis where temperature records in the 2016-2017 season were unusual, as well as another unexpected increase in the summer of 2022-2023, resulting in high-severity fires known as ‘mega-fires’ or “storm-fires”. Mega-fires affect forest plantations and native forests mainly from 33º S (Maule Region) to 39º S (Los Ríos Region) and they are expected to become frequent due to climate change, moving from the north to the south. We present an overview of the influence of wildfires on soil components in the most affected areas (inland, Coastal, and Andes ranges), their hydrological impacts, and potential erosion risk due to high w...
The Draft Framework Law on Climate Change establishes the necessary procedures to elaborate Chile... more The Draft Framework Law on Climate Change establishes the necessary procedures to elaborate Chile's Long Term Climate Strategy (LTCS). Article 5 states that the LTCS must include a prior report by the Scientific Advisory Committee on Climate Change. In this context, the Committee prepares this report to be submitted to the Chilean Ministry of Environment to be used as an input in the elaboration of the LTCS. The Committee members took over one or more chapters for review and comment, according to their experience and expertise.<br>
This study presents the main results of the project “Economic Evaluation of Climatic Change Impac... more This study presents the main results of the project “Economic Evaluation of Climatic Change Impacts on Water Resources at River Basin Scale”. We evaluate the economic consequences of climate change at river basin scale using a hydroeconomic model, which includes two water demand sectors: residential and agricultural. The main quantitative results are complemented with a qualitative social and vulnerability analysis. According to our results, climate change will have minor overall impacts on the basin economy with large distributional consequences. Moreover, subsistence agricultural communities, seem to be the most vulnerable groups to climate change.
Water
Flash floods, produced by heavy seasonal rainfall and characterized by high speeds and destructiv... more Flash floods, produced by heavy seasonal rainfall and characterized by high speeds and destructive power, are among the most devastating natural phenomena and are capable of causing great destruction in very little time. In the absence of hydrological data, morphometric characterization can provide important information on preventive measures against flash floods. A priority categorization of hydrographic units in the Cañete River basin was carried out using morphometric analysis together with a weighted sum analysis (WSA) based on a statistical correlation matrix. The delineation of the drainage network was performed based on Digital Elevation Model (DEM) data from the Shuttle Radar Topography Mission (SRTM). The Cañete River basin was subdivided into 11 sub-basins, and 15 morphometric parameters were selected. The priority category (very high, high, and moderate) of each sub-basin was assigned according to the value of the composite factor obtained through WSA. The results of this...
Water
As precipitation is a fundamental component of the global hydrological cycle that governs water r... more As precipitation is a fundamental component of the global hydrological cycle that governs water resource distribution, the understanding of its temporal and spatial behavior is of great interest, and exact estimates of it are crucial in multiple lines of research. Meteorological data provide input for hydroclimatic models and predictions, which generally lack complete series. Many studies have addressed techniques to fill gaps in precipitation series at annual and monthly scales, but few have provided results at a daily scale due to the complexity of orographic characteristics and in some cases the non-linearity of precipitation. The objective of this study was to assess different methods of filling gaps in daily precipitation data using regression model (RM) and machine learning (ML) techniques. RM included linear regression (LRM) and multiple regression (MRM) algorithms, while ML included multiple regression algorithms (ML-MRM), K-nearest neighbors (ML-KNN), gradient boosting tree...
Aqua-LAC, 2019
Se analizan los modelos de gestión del agua y la utilidad de la mediación ambiental en los casos ... more Se analizan los modelos de gestión del agua y la utilidad de la mediación ambiental en los casos de conflictividad sobre los recursos hídricos de España y Brasil y su aplicabilidad a Chile. Se parte de la experiencia de España, que establece las cuencas hidrográficas como las bases territoriales de la administración. En España, se crean en 1926 por Real Decreto las Confederaciones Sindicales Hidrográficas, instituciones adscritas al Ministerio de Fomento para “el aprovechamiento intensivo, máximo de los recursos hidráulicos de las cuencas de nuestros grandes ríos”, que establece las cuencas hidrográficas como las bases territoriales de la administración. La trasposición de la Directiva Marco del Agua conservó la Demarcación Hidrográfica como base territorial de gestión, incorporando la participación social activa e integra de los implicados como principio crucial para la gestión sostenible. Brasil y Chile están entre los 14 países del mundo con más disponibilidad de agua. Sin embarg...
Journal of Paleolimnology, 2013
Patagonia is commonly seen as an exceptionally pristine area because of its wildlife and practica... more Patagonia is commonly seen as an exceptionally pristine area because of its wildlife and practically unpolluted waters. However, during the twentieth century the burning of natural forests was one of the most important human activities in Northern Chilean Patagonia. Some estimations indicate that three million hectares were burned during the first three decades of the century being its impacts rarely assessed. Hence the objective of this study was to evaluate the impacts of the historical fires in Lake Burgos (45º42'S) and Lake Thompson (45º38'S) in Chilean Patagonia. The impact was measured by evaluating chironomid assemblage since they are sensitive enough to be used as an indicator of aquatic ecosystem health. Fires have a direct and drastic effect on a lake watershed but also indirectly affect a lake ecosystem, changing sedimentation patterns or increasing nutrient inputs. In the studied lakes the periods with higher prevalence of fires were identified by charcoal analysis, while organic matter and magnetic susceptibility allowed to confirm the pre-fire and post-fire periods. The chironomid composition was evaluated through a PCA and an analysis of similarity (ANOSIM) to test the significance among periods while a DCA was applied to the chironomid assemblage downcore to assess compositional structure and taxa turnover. In Lake Burgos the ANOSIM test indicated significant differences between the pre-fire and fire periods (p<0.05), while in Lake Thompson differences were not significant. However, in Lake Thompson the PCA clearly separated the pre-fire from the fire period but not the fire from the post-fire periods. In both lakes chironomid composition changed in relation to the period of higher prevalence of fires, which in turn implies catchment changes, pollution, and other anthropogenic impacts. Particularly a marked change in mesotrophic/eutrophic taxa was detected, reflecting an increase in nutrient input due to deforestation. Our findings point out that the lacustrine ecosystems are still affected by the impact of fires and the subsequent increase in nutrient supply that occurred almost fifty years ago. No sign of reverting to predisturbance conditions was observed, which makes these lakes highly sensitive to current human-induced impacts.
SSRN Electronic Journal, 2016
This paper analyzes the economic impacts of changes in water availability due to climate change. ... more This paper analyzes the economic impacts of changes in water availability due to climate change. We develop a new modeling approach as an alternative to include water as a production factor within a global CGE model. We tailor the structure of the ICES model to characterize the key features of the world economy with a detailed representation of the agricultural sector. In order to reach this objective, a new database has been built to explicitly consider water endowments, precipitation changes, and unitary irrigation costs. Results suggest different economic consequences of climate change depending on the specific region. Impacts are related to change in crop production, endowment demands, and international trade.
Hydrological Sciences Journal
Water scarcity is influencing environmental and socioeconomic development on a global scale. Paki... more Water scarcity is influencing environmental and socioeconomic development on a global scale. Pakistan is ranked third among the countries facing water scarcity. This situation is currently generating intra-provincial water disputes and could lead to transboundary water conflicts. This study assessed the future water resources of Astore basin under representative concentration pathways (RCP) 4.5 and 8.5 scenarios using fully distributed TOPographic Kinematic APproximation and Integration (TOPKAPI) model. TOPKAPI model was calibrated and validated over five years from 1999-2003 with a Nash coefficient ranging from 0.93-0.97. Towards the end of the 21 st century, the air temperature of Astore will increase by 3°C and 9.6 °C under the RCP4.5 and 8.5 scenarios, respectively. The rise in air temperature can decrease the snow cover with Mann Kendall trend of-0.12%/yr and-0.39%/yr (p ≥ 0.05) while annual discharge projected to be increased 11% (p ≤ 0.05) and 37% (p ≥ 0.05) under RCP4.5 and RCP8.5, respectively. Moreover, the Astore basin showed a different pattern of seasonal shifts, as surface runoff in summer monsoon season declined further due to a reduction in precipitation. In the spring season, the earlier onset of snow and glacier melting increased the runoff due to high temperature, regardless of the decreasing trend of precipitation. This increased surface runoff from snow/glacier melt of Upper Indus Basin (UIB) can potentially be utilized to develop water policy and planning new water harvesting and storage structures, to reduce the risk of flooding.
Limnologica, Mar 1, 2020
The seasonal nature of the stream thermal regime has been recognized as an important factor for t... more The seasonal nature of the stream thermal regime has been recognized as an important factor for the structure of benthic macroinvertebrate communities. In this study, we show the importance of temperature and the potential implications of global warming on the composition of benthic macroinvertebrate communities in Andean watersheds. Here we show that thermal factors (mean temperature and monthly range) partially explain the seasonal variability of macroinvertebrates in Andean streams. Different thermal requirements were observed for macroinvertebrate families. Optimal monthly mean temperatures estimated for Gripopterygidae (Plecoptera), Hydrobiidae (Gastropoda) and Helicophidae (Trichoptera) were lower than 7°C, while temperatures for Ameletopsidae, Baetidae (Ephemeroptera), Ecnomidae, Limnephilidae, Hydropsychidae, Leptoceridae (Trichoptera), Elmidae (Coleoptera) and Notonemouridae (Plecoptera) were close to 9.5°C. According to our estimations, future global warming could cause important changes in the macroinvertebrate composition of Andean watersheds. Gripopterygidae, Austroperlidae, Diamphipnoidae (Plecoptera), Hydrobiidae and Helicophidae (Trichoptera) would be the most vulnerable families under the 2090 temperature predictions due to their preference for low temperature.
The 2022-2023 Chilean summer showed increased temperatures and similar burned area, compared to t... more The 2022-2023 Chilean summer showed increased temperatures and similar burned area, compared to the 2016-2017 season, where more than 500,000 hectares were compromised, mainly in the rural areas. After a brief review, it is revealed that the effects of forest fires on soil and hydrological properties are barely debated in Chile. Here, we showed a climatological analysis where temperature records in the 2016-2017 season were unusual, as well as another unexpected increase in the summer of 2022-2023, resulting in high-severity fires known as ‘mega-fires’ or “storm-fires”. Mega-fires affect forest plantations and native forests mainly from 33º S (Maule Region) to 39º S (Los Ríos Region) and they are expected to become frequent due to climate change, moving from the north to the south. We present an overview of the influence of wildfires on soil components in the most affected areas (inland, Coastal, and Andes ranges), their hydrological impacts, and potential erosion risk due to high w...
The Draft Framework Law on Climate Change establishes the necessary procedures to elaborate Chile... more The Draft Framework Law on Climate Change establishes the necessary procedures to elaborate Chile's Long Term Climate Strategy (LTCS). Article 5 states that the LTCS must include a prior report by the Scientific Advisory Committee on Climate Change. In this context, the Committee prepares this report to be submitted to the Chilean Ministry of Environment to be used as an input in the elaboration of the LTCS. The Committee members took over one or more chapters for review and comment, according to their experience and expertise.<br>
This study presents the main results of the project “Economic Evaluation of Climatic Change Impac... more This study presents the main results of the project “Economic Evaluation of Climatic Change Impacts on Water Resources at River Basin Scale”. We evaluate the economic consequences of climate change at river basin scale using a hydroeconomic model, which includes two water demand sectors: residential and agricultural. The main quantitative results are complemented with a qualitative social and vulnerability analysis. According to our results, climate change will have minor overall impacts on the basin economy with large distributional consequences. Moreover, subsistence agricultural communities, seem to be the most vulnerable groups to climate change.
Water
Flash floods, produced by heavy seasonal rainfall and characterized by high speeds and destructiv... more Flash floods, produced by heavy seasonal rainfall and characterized by high speeds and destructive power, are among the most devastating natural phenomena and are capable of causing great destruction in very little time. In the absence of hydrological data, morphometric characterization can provide important information on preventive measures against flash floods. A priority categorization of hydrographic units in the Cañete River basin was carried out using morphometric analysis together with a weighted sum analysis (WSA) based on a statistical correlation matrix. The delineation of the drainage network was performed based on Digital Elevation Model (DEM) data from the Shuttle Radar Topography Mission (SRTM). The Cañete River basin was subdivided into 11 sub-basins, and 15 morphometric parameters were selected. The priority category (very high, high, and moderate) of each sub-basin was assigned according to the value of the composite factor obtained through WSA. The results of this...
Water
As precipitation is a fundamental component of the global hydrological cycle that governs water r... more As precipitation is a fundamental component of the global hydrological cycle that governs water resource distribution, the understanding of its temporal and spatial behavior is of great interest, and exact estimates of it are crucial in multiple lines of research. Meteorological data provide input for hydroclimatic models and predictions, which generally lack complete series. Many studies have addressed techniques to fill gaps in precipitation series at annual and monthly scales, but few have provided results at a daily scale due to the complexity of orographic characteristics and in some cases the non-linearity of precipitation. The objective of this study was to assess different methods of filling gaps in daily precipitation data using regression model (RM) and machine learning (ML) techniques. RM included linear regression (LRM) and multiple regression (MRM) algorithms, while ML included multiple regression algorithms (ML-MRM), K-nearest neighbors (ML-KNN), gradient boosting tree...
Aqua-LAC, 2019
Se analizan los modelos de gestión del agua y la utilidad de la mediación ambiental en los casos ... more Se analizan los modelos de gestión del agua y la utilidad de la mediación ambiental en los casos de conflictividad sobre los recursos hídricos de España y Brasil y su aplicabilidad a Chile. Se parte de la experiencia de España, que establece las cuencas hidrográficas como las bases territoriales de la administración. En España, se crean en 1926 por Real Decreto las Confederaciones Sindicales Hidrográficas, instituciones adscritas al Ministerio de Fomento para “el aprovechamiento intensivo, máximo de los recursos hidráulicos de las cuencas de nuestros grandes ríos”, que establece las cuencas hidrográficas como las bases territoriales de la administración. La trasposición de la Directiva Marco del Agua conservó la Demarcación Hidrográfica como base territorial de gestión, incorporando la participación social activa e integra de los implicados como principio crucial para la gestión sostenible. Brasil y Chile están entre los 14 países del mundo con más disponibilidad de agua. Sin embarg...
Journal of Paleolimnology, 2013
Patagonia is commonly seen as an exceptionally pristine area because of its wildlife and practica... more Patagonia is commonly seen as an exceptionally pristine area because of its wildlife and practically unpolluted waters. However, during the twentieth century the burning of natural forests was one of the most important human activities in Northern Chilean Patagonia. Some estimations indicate that three million hectares were burned during the first three decades of the century being its impacts rarely assessed. Hence the objective of this study was to evaluate the impacts of the historical fires in Lake Burgos (45º42'S) and Lake Thompson (45º38'S) in Chilean Patagonia. The impact was measured by evaluating chironomid assemblage since they are sensitive enough to be used as an indicator of aquatic ecosystem health. Fires have a direct and drastic effect on a lake watershed but also indirectly affect a lake ecosystem, changing sedimentation patterns or increasing nutrient inputs. In the studied lakes the periods with higher prevalence of fires were identified by charcoal analysis, while organic matter and magnetic susceptibility allowed to confirm the pre-fire and post-fire periods. The chironomid composition was evaluated through a PCA and an analysis of similarity (ANOSIM) to test the significance among periods while a DCA was applied to the chironomid assemblage downcore to assess compositional structure and taxa turnover. In Lake Burgos the ANOSIM test indicated significant differences between the pre-fire and fire periods (p<0.05), while in Lake Thompson differences were not significant. However, in Lake Thompson the PCA clearly separated the pre-fire from the fire period but not the fire from the post-fire periods. In both lakes chironomid composition changed in relation to the period of higher prevalence of fires, which in turn implies catchment changes, pollution, and other anthropogenic impacts. Particularly a marked change in mesotrophic/eutrophic taxa was detected, reflecting an increase in nutrient input due to deforestation. Our findings point out that the lacustrine ecosystems are still affected by the impact of fires and the subsequent increase in nutrient supply that occurred almost fifty years ago. No sign of reverting to predisturbance conditions was observed, which makes these lakes highly sensitive to current human-induced impacts.
SSRN Electronic Journal, 2016
This paper analyzes the economic impacts of changes in water availability due to climate change. ... more This paper analyzes the economic impacts of changes in water availability due to climate change. We develop a new modeling approach as an alternative to include water as a production factor within a global CGE model. We tailor the structure of the ICES model to characterize the key features of the world economy with a detailed representation of the agricultural sector. In order to reach this objective, a new database has been built to explicitly consider water endowments, precipitation changes, and unitary irrigation costs. Results suggest different economic consequences of climate change depending on the specific region. Impacts are related to change in crop production, endowment demands, and international trade.