Cambio en el patrón espacial del paisaje y su efecto en los procesos hidrológicos. Hacia soluciones basadas en la naturaleza para la gestión de cuencas bajo un contexto de cambio climático.
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Date
2025
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Universidad de Concepción
Abstract
El cambio climático es uno de los principales impulsores de los cambios en el ciclo hidrológico. En muchas regiones del mundo la disminución considerable de las precipitaciones y el aumento de las temperaturas extremas ha repercutido en la disminución del caudal y cambios en diversos procesos hidrológicos, como almacenamiento en la cubierta vegetal, infiltración y evapotranspiración. Sin embargo, numerosas investigaciones han demostrado como los cambios de cobertura y uso del suelo afectan también importantes componentes hidrológicos como régimen de sedimento, alteraciones de la calidad del agua y las afectaciones a la zona ribereña. Sin embargo, aún existen grandes contradicciones en torno a como los cambios del paisaje influyen en el ciclo del agua, fundamentalmente asociada con la inclusión de especies forestales exóticas y la pérdida de la superficie de bosques nativo. Algunos autores aseguran que la inclusión de las plantaciones forestales ejerce un rol estabilizador en los procesos hidrológicos, mientras que otros aseguran que la pérdida de bosques nativos repercute en la estabilidad y capacidad de regulación de las cuencas. Chile no se encuentra ajena a esta problemática, pues tanto el cambio climático como el desordenado aumento de las actividades económicas urbano-forestal están llevando a fuertes cambios en los componentes del ciclo del agua en numerosas cuencas del territorio. Esta problemática se agrava especialmente en la región centro y sur del país, donde se proyecta una disminución considerable de las precipitaciones en el futuro. Numerosas cuencas están siendo fuertemente intervenidas para el desarrollo de plantaciones forestales, lo que implica la ocupación de grandes extensiones de superficie nativa. Es por ello que, el objetivo principal de esta investigación es evaluar los efectos de la configuración y composición del paisaje sobre componentes del ciclo del agua en las cuencas Quino y Muco del centro sur de Chile.
El modelo hidrológico distribuido TETIS se implementó con el propósito de analizar cómo la combinación de dos principales forzantes el cambio climático y las transformaciones en la composición y configuración del paisaje afecta la respuesta hidrológica de las cuencas. El análisis se llevó a cabo tanto para el período histórico (1980–2018) como para proyecciones futuras (2030–2060 y 2061–2091). Los cambios en la cobertura y uso del suelo fueron analizados en dos etapas. En la primera, se utilizaron cuatro clasificaciones temporales (1986, 2001, 2011 y 2017) para caracterizar la evolución del paisaje. A partir de estas, y mediante el software Fragstats, se obtuvieron métricas espaciales que permitieron describir los patrones del paisaje y su influencia sobre los componentes del ciclo hidrológico. En la segunda etapa, se generaron cinco escenarios futuros de LUCC a partir del año 2017, construidos bajo criterios ambientales, sociales y económicos. Estos escenarios se combinaron con proyecciones climáticas para evaluar su impacto conjunto sobre los procesos hidrológicos.
Los resultados, obtenidos a través de análisis de correlación y regresión de mínimos cuadrados parciales (PLSR), indican que paisajes con mayor diversidad, fragmentación y menor conectividad espacial tienden a alterar significativamente la dinámica hidrológica. En particular, un paisaje altamente fragmentado afecta negativamente los flujos horizontales y verticales del agua. Asimismo, la expansión de plantaciones forestales en patrones agregados modifica los procesos verticales, como la infiltración y la evapotranspiración. La pérdida de contigüidad espacial de los bosques nativos, junto con la reducción en el número de parches, se asocia directamente con una disminución de procesos hidrológicos y en los caudales generados. Adicionalmente, los escenarios de LUCC simulados bajo el escenario climático RCP 8.5 revelan que el aumento en la superficie boscosa incrementa la evapotranspiración real en aproximadamente +20 mm. Este efecto es particularmente pronunciado en los escenarios que consideran recuperación mediante plantaciones forestales, con aumentos entre +30 y +40 mm. Por otro lado, los escenarios que promueven la reforestación con especies nativas muestran una mayor capacidad de retención hídrica en el sistema, especialmente durante períodos secos.
Climate change is one of the primary drivers of alterations in the hydrological cycle. In many regions worldwide, a significant decrease in precipitation combined with rising extreme temperatures has led to reduced streamflow and disruptions in key hydrological processes such as vegetation canopy storage, infiltration, and evapotranspiration. However, numerous studies have also demonstrated that land use and land cover changes (LUCC) significantly affect hydrological components such as sediment regimes, water quality, and riparian zone dynamics. Despite these findings, considerable controversy remains regarding how landscape changes influence the water cycle, particularly in relation to the introduction of exotic forest species and the loss of native forest cover. Some authors argue that forest plantations play a stabilizing role in hydrological processes, while others contend that the loss of native forests compromises watershed stability and regulatory capacity. Chile is not exempt from this issue. Both climate change and the unregulated expansion of urban and forestry economic activities are driving significant alterations in hydrological components across numerous watersheds. This situation is particularly critical in the central-southern region of the country, where a substantial decrease in precipitation is projected for the future. Many catchments in this region are undergoing intense land transformation due to the expansion of forest plantations, often at the expense of native forest ecosystems. In this context, the primary objective of this study is to evaluate the effects of landscape composition and configuration on hydrological cycle components in the Quino and Muco catchments in south-central Chile. The distributed hydrological model TETIS was implemented to analyze how the combined influence of climate change and landscape transformation affects watershed hydrological responses. The analysis covers both historical conditions (1980–2018) and future projections (2030–2060 and 2061–2091). LUCC was assessed in two stages. First, four land cover classifications (1986, 2001, 2011, and 2017) were used to characterize landscape evolution. Spatial metrics were derived using the Fragstats software to quantify landscape patterns and their influence on hydrological components. Second, five future LUCC scenarios were generated from the 2017 baseline, based on environmental, social, and economic criteria. These were combined with climate projections to evaluate their joint impact on the water cycle. Results obtained through correlation analyses and partial least squares regression (PLSR) indicate that landscapes with higher diversity, greater fragmentation, and reduced spatial connectivity tend to significantly disrupt hydrological dynamics. Highly fragmented landscapes negatively affect both horizontal and vertical water fluxes. Furthermore, the expansion of forest plantations in aggregated spatial patterns alters vertical hydrological processes such as infiltration and evapotranspiration. The reduction in spatial contiguity of native forests, along with a decrease in the number of patches, is directly associated with diminished hydrological functioning and reduced streamflow. Additionally, LUCC scenarios simulated under the RCP 8.5 climate projection reveal that increasing forested area leads to an approximate rise of +20 mm in actual evapotranspiration. This effect is particularly marked in scenarios involving recovery through forest plantations, with increases ranging from +30 to +40 mm. In contrast, scenarios promoting reforestation with native species show greater water retention capacity in the system, particularly during dry periods, highlighting their relevance as an adaptive strategy for hydrological regulation under climate change.
Climate change is one of the primary drivers of alterations in the hydrological cycle. In many regions worldwide, a significant decrease in precipitation combined with rising extreme temperatures has led to reduced streamflow and disruptions in key hydrological processes such as vegetation canopy storage, infiltration, and evapotranspiration. However, numerous studies have also demonstrated that land use and land cover changes (LUCC) significantly affect hydrological components such as sediment regimes, water quality, and riparian zone dynamics. Despite these findings, considerable controversy remains regarding how landscape changes influence the water cycle, particularly in relation to the introduction of exotic forest species and the loss of native forest cover. Some authors argue that forest plantations play a stabilizing role in hydrological processes, while others contend that the loss of native forests compromises watershed stability and regulatory capacity. Chile is not exempt from this issue. Both climate change and the unregulated expansion of urban and forestry economic activities are driving significant alterations in hydrological components across numerous watersheds. This situation is particularly critical in the central-southern region of the country, where a substantial decrease in precipitation is projected for the future. Many catchments in this region are undergoing intense land transformation due to the expansion of forest plantations, often at the expense of native forest ecosystems. In this context, the primary objective of this study is to evaluate the effects of landscape composition and configuration on hydrological cycle components in the Quino and Muco catchments in south-central Chile. The distributed hydrological model TETIS was implemented to analyze how the combined influence of climate change and landscape transformation affects watershed hydrological responses. The analysis covers both historical conditions (1980–2018) and future projections (2030–2060 and 2061–2091). LUCC was assessed in two stages. First, four land cover classifications (1986, 2001, 2011, and 2017) were used to characterize landscape evolution. Spatial metrics were derived using the Fragstats software to quantify landscape patterns and their influence on hydrological components. Second, five future LUCC scenarios were generated from the 2017 baseline, based on environmental, social, and economic criteria. These were combined with climate projections to evaluate their joint impact on the water cycle. Results obtained through correlation analyses and partial least squares regression (PLSR) indicate that landscapes with higher diversity, greater fragmentation, and reduced spatial connectivity tend to significantly disrupt hydrological dynamics. Highly fragmented landscapes negatively affect both horizontal and vertical water fluxes. Furthermore, the expansion of forest plantations in aggregated spatial patterns alters vertical hydrological processes such as infiltration and evapotranspiration. The reduction in spatial contiguity of native forests, along with a decrease in the number of patches, is directly associated with diminished hydrological functioning and reduced streamflow. Additionally, LUCC scenarios simulated under the RCP 8.5 climate projection reveal that increasing forested area leads to an approximate rise of +20 mm in actual evapotranspiration. This effect is particularly marked in scenarios involving recovery through forest plantations, with increases ranging from +30 to +40 mm. In contrast, scenarios promoting reforestation with native species show greater water retention capacity in the system, particularly during dry periods, highlighting their relevance as an adaptive strategy for hydrological regulation under climate change.
Description
Tesis presentada para optar al grado de Doctor en Ciencias Ambientales con mención en Sistemas Acuáticos Continentales.
Keywords
Cuencas hidrográficas, Ciclo hidrológico, Restauración ecológica