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Over the last decades, Chile has experienced a long-term drought with significant consequences for water availability, forest productivity, and soil degradation, ultimately dramatically increasing the surface of burned area. Here, we quantify the Palmer Drought Severity Index (PDSI) to ascertain the extent of "moisture deficiency" across the central-southern region of Chile from 2000 to 2023 to assess the drought's relationship with the frequency of wildfires focusing on the impact of native forests. Our methodology quantifies the PDSI from the burned area data using MODIS MCD64A1 satellite imagery, validated by in situ wildfire occurrence records. The findings indicate that 85.2% of fires occurred under moderate to severe drought conditions. We identified 407,561 ha showing varying degrees of degradation due to wildfires, highlighting the critical areas for targeted conservation efforts. A significant increase in both the frequency of wildfires and the extent of the affected area in native forests was observed with the intensification of drought conditions in the 21st century within mesic to humid Mediterranean climatic zones where drought explains up to 41% of the variability in the burned area (r2 = 0.41; p < 0.05). This study highlights the relationship between drought conditions and wildfire frequency, showing the paramount need to adopt comprehensive wildfire mitigation management in native forests. [ABSTRACT FROM AUTHOR]

Chile is particularly vulnerable to climate change due to its geomorphology, ecological wealth and economic dependence on water resources, and has been facing a severe drought since 2010. The objective of this work is to propose a methodology able to project and evaluate changes in the magnitude, duration and frequency of meteorological and hydrological droughts, as a decision-making tool to support adaptation to climate change. Four basins were assessed using different downscaled General Circulation Models (GCM) and the Soil & Water Assessment Tool (SWAT) model. Results were evaluated using Standardized Precipitation Index (SPI) and Standardized Streamflow Index (SSFI) comparing drought events over two periods of time. An increase in magnitude and duration of meteorological droughts is projected, especially in the Andes Mountain range. Regarding hydrological drought, greater increases in magnitude and duration are projected for the Itata River Basin. In both types of droughts, an increase in frequency is expected. [ABSTRACT FROM AUTHOR]

The growth of traditional crops could be a primary resource for adapting to climate change and strengthening agrosystems' resilience. However, these crops tend to be replaced by non-traditional crops with higher productivity, higher market values, and higher short-term income. In this context, smallholders face trade-offs between maximizing short-term income and ensuring resilience to face likely future climate adversities. The economic assessment of such trade-offs has been commonly neglected in the literature. Most studies are conducted using agronomic or anthropological frameworks to recognize the value of traditional agriculture to increase adaptive capacity and reduce vulnerability. This study fills this gap by assessing economic and agronomic trade-offs between traditional and non-traditional crops triggered by climate-induced changes in water availability. We also simulate the effectiveness of a water policy. Our results suggest that farmers growing traditional crops may get lower profits, but their portfolio is more resilient to climate change, whereas the water policy proves to be an effective adaptation strategy to climate change. However, the policy implementation could hinder the development of traditional crops. Based on our results, we suggest implementing smart agricultural policies to balance economic, cultural, and adaptation goals. [ABSTRACT FROM AUTHOR]

Understanding past climate variability is important for obtaining better predictions of future changes. Documentary records are high temporal resolution proxies that can be used to reconstruct aspects of the climate, such as precipitation. Vicuña Mackenna developed a compilation of historical climatic events between the 16th and 19th centuries using chronicles from Spanish colonizers and town council records. The objective of this work was to classify dry and wet periods beginning in the 16th century using records from Vicuña Mackenna by generating a precipitation index based on events in the documentary evidence (e.g., epidemics, "pro pluvia" rogations, and infrastructural damage) into a simple annual precipitation index on an ordinal scale. The index used a three‐term classification scale, with 0 representing normal years, 1 representing wet years, and −1 representing dry years. The documentary records were not substantial enough to identify wet/dry periods during the 16th and 17th centuries. However, it was possible to identify dry and wet years described by conquerors and settlers that first arrived in the study area. During the 18th century, two long periods of drought were identified: 1705 to 1718 and 1770 to 1797. During these droughts, people organized rogations to the Virgen and different saints in desperation due to the lack of water. Finally, during the 19th century, technological improvements in measuring precipitation made it possible to identify intermittent dry and wet periods with higher resolution and precision, and these events could be related to the El Niño–Southern Oscillation (ENSO). The objective of this work was to classify dry and wet periods since the 16th century using Vicuña Mackenna's records by generating a precipitation index based on the transformation of documentary evidence into a simple annual precipitation index. The classification scale used was 0 for normal years, 1 for wet years, and −1 for dry years. During the 18th century it identified two long periods of droughts that are not fully recorded in literature. [ABSTRACT FROM AUTHOR]

Andean watersheds present important snowfall accumulation mainly during the winter, which melts during the spring and part of the summer. The effect of snowmelt on the water balance can be critical to sustain agriculture activities, hydropower generation, urban water supplies and wildlife. In Chile, 25% of the territory between the region of Valparaiso and Araucanía comprises areas where snow precipitation occurs. As in many other difficult-to-access regions of the world, there is a lack of hydrological data of the Chilean Andes related to discharge, snow courses, and snow depths, which complicates the analysis of important hydrological processes (e.g. water availability). Remote sensing provides a promising opportunity to enhance the assessment and monitoring of the spatial and temporal variability of snow characteristics, such as the snow cover area (SCA) and snow cover dynamic (SCD).With regards to the foregoing questions, the objective of the study is to evaluate the spatiotemporal dynamics of the SCA at five watersheds (Aconcagua, Rapel, Maule, Biobío and Toltén) located in the Chilean Andes, between latitude 32.0 and 39.5° S, and to analyse its relationship with the precipitation regime/pattern and El Niño- Southern Oscillation (ENSO) events. Those watersheds were chosen because of their importance in terms of their number of inhabitants, and economic activities depending on water resources. The SCA area was obtained from MOD10A2 for the period 2000-2016, and the SCD was analysed through a number of statistical tests to explore observed trends. In order to verify the SCA for trend analysis, a validation of the MOD10A2 product was done, consisting of the comparison of snow presence predicted by MODIS with ground observations. Results indicate that there is an overall agreement of 81 to 98% between SCA determined from ground observations and MOD10A2, showing that the MODIS snow product can be taken as a feasible remote sensing tool for SCA estimation in southern-central Chile. Regarding SCD, no significant reduction in SCA for the period 2000-2016 was detected, with the exception of the Aconcagua and Rapel watersheds. In addition to that, an important decline in SCA in the five watersheds for the period of 2012 and 2016 was also evident, which is coincidental with the rainfall deficit for the same years. Findings were compared against ENSO episodes that occurred during 2010-2016, detecting that Niña years are coincident with maximum SCA during winter in all watersheds. [ABSTRACT FROM AUTHOR]

Andean watersheds present important snowfall accumulation mainly during the winter which is later melted during spring and part of the summer. The effect of snowmelt on the water balance can be critical to sustain agriculture activities, hydropower generation, urban water supply and wildlife. In Chile 25% of the territory between the Valparaiso and Araucanía Regions comprise areas where snow precipitation occurs. As in many other difficult-to-access regions of the world, in the Chilean Andes there is a lack of hydrological data like discharge, snow courses, snow depths, which complicate the analysis of important hydrological processes (e.g. water availability). Remote sensing provides a promising opportunity to enhance the assessment and monitoring of the spatial and temporal variability of snow characteristics, like Snow Cover Area (SCA) and Snow Cover Dynamic (SCD). In the above mentioned context the objectives of this study are to evaluate the suitability of MOD10A2 to estimate SCA and to assess SCD at five watersheds (Aconcagua, Rapel, Maule, Biobío and Toltén) located in the Chilean Andes, between latitude 32.0º S and 39.5º S. Those watershed were chosen because their importance in terms of number of inhabitants, and dependence of economic activities on water resources. SCA area was obtained from MOD10A2 for the period 2000-2013 and SCD was analysed through a number of statistical tests to explore observed trends. Prior of obtaining SCA for trend analysis, a validation of MOD10A2 product was done; comparing presence of snow predicted by MODIS with ground observations. Results indicate that there is an overall agreement from 81 to 98% between SCA-determined from ground observations, and MOD10A2, showing that MODIS snow product can be taken as a feasible remote sensing tool for SCA estimation in South-Central Chile. Regarding SCD no significant reduction in SCA area for 2000-2013 was detected, with the exception of the Aconcagua and Rapel watersheds, although an important decline in SCA for the period of 2012 and 2013 was also evident, which is coincident with the rainfall deficit for the same years. Findings were compared against ENSO episodes occurring during 2010-2013, detecting that Niña years are coincident with maximum SCA during winter in all watersheds. [ABSTRACT FROM AUTHOR]

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Copyright of Tecnología y Ciencias del Agua is the property of Instituto Mexicano de Tecnologia del Agua (IMTA) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)