Variações multidecenais da precipitação na Colômbia e na Bacia do Prata e suas relações com os jatos de baixos níveis

The hypothesis investigated in this Thesis is that low frequency natural variations associated with the Atlantic Multidecadal Oscillation (AMO) can have a strong influence on the average behavior of precipitation and streamflow rates over the Colombian Biogeographic Choco (CBC) basins, and in extreme precipitation events over the La Plata Basin (LPB) driven by changes in low-level jets (LLJ) of South America. For this, spatial interpolations and cross-validation, trend and homogeneity tests, principal component analysis (PCA), extreme precipitation indices, and composite analysis were used. The main contributions of this research were: i) the interpolations allowed to examine the data and characteristics of annual and seasonal mean precipitation for the two study areas; through the cross-validation of multivariate geostatistical methods and deterministic methods, Cokriging was identified with the spherical (Gaussian) model as the best precipitation interpolator in the CBC region (in the LPB), using elevation as a secondary variable; ii) regarding the influence of the Atlantic Multidecadal Oscillation (AMO) on the variability of the Chocó Jet (CJ) and the Caribbean Low-Level Jet (CLLJ), there is an increase in the zonal wind in the center of the CJ during September-November (SON), reinforced after 1997, associated with negative sea surface temperature (SST) anomalies in the tropical Pacific Ocean and positive ones in the Caribbean Sea and Tropical North Atlantic (TNA), strengthen the CJ and weaken the CLLJ, enhanced the moisture transport to central and western Colombia, increasing the rainfall there. The results indicate that the combination of the cold phase of the PDO (CPDO) and the warm phase of the AMO (WAMO) defines a low-frequency medium state, which affects the interannual climate variability and can affect the CJ variability and the precipitation In Colombia; iii) the variations in the streamflow of the Atrato River Basin (ARB) during the 1965-2015 period, considering the cold (1965-1994) and warm (1995-2015) phases of the AMO, showed an increase after 1994. The warm tropical Atlantic during WAMO intensified the Walker circulation, causing an upward movement in the north and northwestern South America, which contributed to the positive rainfall anomalies and increased streamflow in the ARB; iv) the seasonal validation of the CHIRPS (Climate Hazards Group Infrared Precipitation with Stations) precipitation dataset for the LPB, through the PCA, indicated that the CHIRPS v.2 dataset captures the spatial patterns and variability at different time scales in the LPB; v) an increase in total wet-day precipitation (PRCPTOT) and number of heavy precipitation days (R10mm) in the southern LPB (S-LPB) during SON, and an increase in the consecutive dry days (CDD) in northern LPB (N-LPB) during June-August (JJA) were observed. An upward change in R10mm after 1999 is identified during SON in S-LPB, associated with: teleconnections with the positive Indian Ocean Dipole (IOD), drives an extratropical southern Rossby wave disturbance extending towards southeastern South America and configures a barotropic cyclone over the south of the continent, and favor the moisture transport from the northwestern and central Amazon to southern and western LPB; and increased moisture flow to LPB due to warming in the southwestern Atlantic. An important aspect discussed here is that the low-frequency background conditions are modulated by the Atlantic Multidecadal Oscillation (AMO). The results, as well as the proposed methods, are of interest for low-frequency climate monitoring and forecasting, for water resources management and hydrometeorological risk in two regions of particular environmental and economic importance in South America.A hipótese investigada nessa Tese é que variações naturais de baixa frequência, associadas à Oscilação Multidecenal do Atlântico (AMO) podem ter uma forte influência sobre o comportamento médio da precipitação e vazão sobre as bacias do Choco Biogeográfico Colombiano (CBC) e sobre os eventos extremos de precipitação sobre a Bacia do Prata (LPB) impulsionadas por mudanças nos jatos de baixos níveis (LLJs) na América do Sul. Para isso, foram utilizadas interpolações espaciais e validação cruzada, testes de tendência e homogeneidade, Análises de Componentes Principais (PCA), índices extremos de precipitação e análises de composições. As principais contribuições de esta investigação foram: i) as interpolações permitiram examinar os dados e características da precipitação média anual e sazonal para as duas áreas de estudo; através da validação cruzada de métodos geoestatísticos multivariados e determinísticos, Cokriging com o modelo esférico (Gaussiano) foi identificado como o melhor interpolador da precipitação na região do CBC (na LPB), usando a elevação como variável secundária; ii) sobre a influência da Oscilação Multidecenal do Atlântico (AMO) na variabilidade do Jato do Choco (CJ) e do Caribe (CLLJ), se observa o aumento do vento zonal no centro do CJ durante Setembro-Novembro (SON), reforçado após de 1997, associado as anomalias negativas da temperatura da superfície do mar (TSM) no Oceano Pacífico tropical e positivas no Mar do Caribe e no Atlântico Norte Tropical (TNA) que enfraquecem (intensificam) o CLLJ (CJ), aprimorando o transporte de umidade para a região central e oeste da Colômbia e aumentando as precipitações. Os resultados indicam que a combinação da fase fria da PDO (CPDO) e a quente da AMO (WAMO), definem um background de baixa frequência, o que afeta a variabilidade climática interanual, e podem influenciar o CJ e as precipitações na Colômbia; iii) variações da vazão na Bacia do Rio Atrato (ARB) durante o período de 1965-2015, considerando as fases fria (1965-1994) e quente (1995-2015) mostraram o aumentou após 1994. O Atlântico tropical quente durante a WAMO intensifica a circulação de Walker, causando movimento ascendente no norte e noroeste da América do Sul, o que contribuiu para as anomalias positivas de chuva e aumento da vazão na ARB; iv) a validação sazonal do conjunto de dados de precipitação de CHIRPS (Climate Hazards Group Infrared Precipitation with Stations) para a LPB, através de PCA, indicou que o conjunto de dados CHIRPS v.2 captura os padrões espaciais e a variabilidade em diferentes escalas de tempo na LPB; v) foram observadas tendências positivas na precipitação total em dias úmidos (PRCPTOT) e no número de dias de precipitação intensa (R10mm) na região sul da LPB (S-LPB) durante SON, e tendências positivas de dias secos consecutivos (CDD) no norte da LPB (N-LPB) durante Junho-Agosto (JJA). Uma mudança positiva no R10mm após de 1999 é identificada durante SON em S-LPB, associada com: teleconexões com o dipolo positivo do Oceano Indico (IOD), que gera uma perturbação extratropical de onda de Rossby no hemisfério sul que se estende em direção ao sudeste da América do Sul e configura um ciclone barotrópico sobre o sul do continente, favorecendo o transporte de umidade do noroeste e centro da Amazônia para o sul e oeste da LPB; e aumento do fluxo de umidade para a LPB devido ao aquecimento no Atlântico sudoeste. Um aspecto importante discutido aqui é que as condições do estado médio da baixa frequência são moduladas pela Oscilação Multidecenal do Atlântico (AMO). Os resultados, bem como os métodos propostos, são de interesse para o monitoramento e previsão climática de baixa frequência, a gestão dos recursos hídricos e o risco hidrometeorológico em duas regiões de especial interesses ambiental e econômico na América do Sul

Modelo para el monitoreo y seguimiento de indicadores de sostenibilidad del recurso hídrico en el sector agrícola

El sistema de monitoreo y seguimiento permite identificar, a través de indicadores e índices, la sostenibilidad del recurso hídrico en el sector agrícola de la microcuenca Centella (Dagua-Valle del Cauca). Este modelo de monitoreo permite evaluar continua y sistemáticamente el progreso y los cambios ocasionados por la ejecución de un conjunto de actividades en un período de tiempo determinado. De igual manera, a través de este sistema es posible realizar un seguimiento y verificar en qué medida se cumplen las metas propuestas de sostenibilidad del recurso hídrico en el sector agrícola a nivel: biofísico, tecnológico, político-institucional y socioeconómico

Análisis de sequías meteorológicas para la cuenca del río Dagua, Valle del Cauca, Colombia

Context: Extreme climatic events causes great challenges for social, economic and environmental sustainability of a region. Droughts affect agricultural activities significantly thus endangering the livelihoods and food security of rural populations, this is especially crucial for developing countries. The objective of this study is to characterize meteorological drought in Dagua river basin, Valle del Cauca.Method:  Intensity, magnitude, duration and frequency of drought events was estimated using the Standardized Precipitation Index (SPI), for semi-annual and annual groupings with records of 19 stations, during the period 1982-2011Results: At least one drought was identified in each series; the area near to the subxerofític Basin region, exhibits more frequency of extremely strong drought and lower threshold of minimum precipitation; the largest percentage of spatial coverage of drought coincides with El Niño phenomena events, such as those that occurred in 91-92 to 09-10.Conclusions: The results obtained provide an approach for prediction and characterization of drought, and offer inputs to generate strategies for planning and mitigation of their impacts.Contexto: Los eventos climáticos extremos ocasionan grandes retos para la sostenibilidad social, económica y medioambiental, de una región, como es el caso de las sequías que afectan significativamente las actividades agrícolas, aumentando el riesgo de la subsistencia y la seguridad alimentaria de la población rural, principalmente de países en desarrollo.  Este estudio tuvo como objetivo caracterizar  las sequías meteorológicas en la cuenca del río Dagua,  Valle del Cauca.Método: Se estimó la intensidad, magnitud, duración y frecuencia de eventos de sequía mediante el uso del Índice Estandarizado de Precipitación (SPI) para agrupaciones semestrales y anuales, usando el registro de 19 estaciones en el período comprendido entre 1982-2011Resultados: Al menos una sequía fue identificada en cada serie, mientras el área próxima a la región subxerofítica de la cuenca,  presentó mayor frecuencia de sequías extremadamente fuertes y los menores umbrales de precipitación mínima; el mayor porcentaje de cobertura espacial coincidió con la ocurrencia de eventos del fenómeno El Niño, tales como los ocurridos en 91-92 y 09-10.Conclusiones: Los resultados obtenidos sirven como aproximación para la predicción y caracterización de las sequías, y ofrecen insumos para generar estrategias de planificación y mitigación de sus impactos

Índice estandarizado de precipitación (SPI) para la caracterización de sequías meteorológicas en la cuenca del río Dagua-Colombia

The Standardized Precipitation Index (SPI) characterizes meteorological droughts of a place, by quantifying the deficit of rainfall in different time periods. Negative SPI values represents drought, while positive values indicate wet periods. The results suggest that negative SPI periods coincide with El Niño years: 82-83, 91-92 and 97-98. The 91-92 event had the largest impact on the region. These results indicate that the most severe droughts in the basin of Dagua, were presented at the quarters of Dec- Jan-Feb, Jan-Feb-Mar, Jun-Jul-Aug and Jul-Aug-Sep. The results have been obtained with geostatistical techniques, and are a basic input to formulate adaptation strategies and ensure food sovereignty of small farmers against drought.El Índice Estandarizado de Precipitación (SPI) caracteriza las sequías meteorológicas de un lugar, mediante la cuantificación del déficit de precipitación en diferentes períodos de tiempo. Valores negativos del SPI representan sequías, mientras valores positivos indican periodos húmedos. Los resultados muestran que los períodos SPI negativos, coinciden con años clasificados como El Niño: 82-83, 91-92 y 97-98, de los cuales, el evento 91-92 presentó los mayores impactos en la región. En general, los resultados indican que las sequías más intensas en la cuenca del Dagua, se presentaron en los trimestres de Dic-Ene-Feb, Ene-Feb-Mar, Jun-Jul-Ago y Jul-Ago-Sep; estos resultados se espacializaron con técnicas geoestadísticas, y son insumo básico para formular estrategias de adaptación y garantizar la soberanía alimentaria de los pequeños agricultores frente a las sequías. [fr] L’Indice de précipitations normalisé (SPI) caractérise les sécheresses météorologiques d’un lieu, en quantifiant le déficit de précipitations à différentes périodes de temps. Les valeurs négatives de SPI indiquent périodes sécheresse, tandis que les positives indiquent des périodes humides. Les résultats montrent que les périodes SPI négatifs obtenus coïncident avec les années «El Niño». Les années en question sont: 82-83, 91-92 et 97-98. L’événement 91-92 montre le plus grand impact sur la région. Ces résultats suggèrent que les sécheresses les plus sévères touchant le bassin de Dagua ont eu lieu lors des trimestres de décembre-janvier-février, janvier-février-mars, juin-juillet- août et juin-août-septembre. Les résultats ont été obtenus à l’aide des techniques géostatistiques et fournissent des outils de base pour l’élaboration des stratégies d’adaptation afin d’assurer la souveraineté alimentaire des petits agriculteurs contre la sécheresse

Índice estandarizado de precipitación (SPI) para la caracterización de sequías meteorológicas en la cuenca del río Dagua-Colombia

The Standardized Precipitation Index (SPI) characterizes meteorological droughts of a place, by quantifying the deficit of rainfall in different time periods. Negative SPI values represents drought, while positive values indicate wet periods. The results suggest that negative SPI periods coincide with El Niño years: 82-83, 91-92 and 97-98. The 91-92 event had the largest impact on the region. These results indicate that the most severe droughts in the basin of Dagua, were presented at the quarters of Dec- Jan-Feb, Jan-Feb-Mar, Jun-Jul-Aug and Jul-Aug-Sep. The results have been obtained with geostatistical techniques, and are a basic input to formulate adaptation strategies and ensure food sovereignty of small farmers against drought.<br><br>El Índice Estandarizado de Precipitación (SPI) caracteriza las sequías meteorológicas de un lugar, mediante la cuantificación del déficit de precipitación en diferentes períodos de tiempo. Valores negativos del SPI representan sequías, mientras valores positivos indican periodos húmedos. Los resultados muestran que los períodos SPI negativos, coinciden con años clasificados como El Niño: 82-83, 91-92 y 97-98, de los cuales, el evento 91-92 presentó los mayores impactos en la región. En general, los resultados indican que las sequías más intensas en la cuenca del Dagua, se presentaron en los trimestres de Dic-Ene-Feb, Ene-Feb-Mar, Jun-Jul-Ago y Jul-Ago-Sep; estos resultados se espacializaron con técnicas geoestadísticas, y son insumo básico para formular estrategias de adaptación y garantizar la soberanía alimentaria de los pequeños agricultores frente a las sequías. [fr] L’Indice de précipitations normalisé (SPI) caractérise les sécheresses météorologiques d’un lieu, en quantifiant le déficit de précipitations à différentes périodes de temps. Les valeurs négatives de SPI indiquent périodes sécheresse, tandis que les positives indiquent des périodes humides. Les résultats montrent que les périodes SPI négatifs obtenus coïncident avec les années «El Niño». Les années en question sont: 82-83, 91-92 et 97-98. L’événement 91-92 montre le plus grand impact sur la région. Ces résultats suggèrent que les sécheresses les plus sévères touchant le bassin de Dagua ont eu lieu lors des trimestres de décembre-janvier-février, janvier-février-mars, juin-juillet- août et juin-août-septembre. Les résultats ont été obtenus à l’aide des techniques géostatistiques et fournissent des outils de base pour l’élaboration des stratégies d’adaptation afin d’assurer la souveraineté alimentaire des petits agriculteurs contre la sécheresse

Spatio-temporal analysis of the droughts in Cali, Colombia and their primary relationships with the El Nino-Southern Oscillation (ENSO) between 1971 and 2011

This paper analyzed the spatio-temporal variability of droughts in Cali, Colombia and their primary relations to the El Nino Southern Oscillation (ENSO). The Standardized Precipitation Index (SPI) was used to detect drought events from monthly rainfall data of 24 stations well spread over Cali during 1971-2011. The SPI provided the drought intensity, magnitude, frequency, and the minimum rainfall thresholds, mainly on an annual scale (SPI-12). Eighty percent of the stations reported four events with dry conditions in Cali: 1976-1977, 1983-1984, 1990-1992 and 2009-2010. The ENSO influence was evaluated using the correlation and wavelet transform analyses. Significant (non-significant) negative correlations between SPI-12 in the northern (southern) part of Cali, the multivariate ENSO Index (MEI), and Sea Surface Temperature (SST) Nino 3.4 and Nino 4 indices were observed. The wavelet coherence analysis showed significant coherencies between ENSO and SPI-12: at interannual scale (4-6 years), the phase difference of-135o generates a lag of 6-9 months between the minimum peak of the SPI-12 and the maximum peak of the indices. On the quasi-biennial scale (2-3 years), the phase difference of-180o suggests that the maximum wet (dry) conditions coincide with the mature stage of the La Nina (El Nino) event; and on the decadal scale (8-16 years), the decreases (increases) in rainfall precede the El Nino (La Nina) mature stage by approximately 10-18 months. These results are relevant for seasonal forecasting, since changes in SST in the equatorial Pacific may take place 6-18 months ahead of the dry conditions in Cali. © 2020 Universidad Nacional Autonoma de Mexico

Streamflow Variability in Colombian Pacific Basins and Their Teleconnections with Climate Indices

[EN] Oceanic-atmospheric phenomena of different time scales concurrently might affect the streamflow in several basins around the world. The Atrato River Basin (ARB) and Pa-Ha River Basin (PRB) of the Colombian Pacific region are examples of such basins. Nevertheless, the relations between the streamflows in the ARB and PRB and the oceanic-atmospheric factors have not been examined considering different temporal scales. Hence, this article studies the relations of the climate indices and the variability of the streamflows in the ARB and PRB at interannual and decadal timescales. To this, the streamflow variability modes were obtained from the principal component analysis (PCA); furthermore, their linear dependence with indices of the El Nino/Southern Oscillation (ENSO), precipitation (PRP), the Choco low-level jet (CJ), and other indices were quantified through (a) Pearson and Kendall's tau correlations, and (b) wavelet transform. The PCA presented a single significant mode for each basin, with an explained variance of around 80%. The correlation analyses between the PC1s of the ARB and PRB, and the climate indices showed significant positive (negative) high correlations with PRP, CJ, and Southern Oscillation Index (SOI) (ENSO indices). The wavelet coherence analysis showed significant coherencies between ENSO and ARB: at interannual (2-7 years) and decadal scale (8-14), preferably with the sea surface temperature (SST) in the east and west Tropical Pacific Ocean (TPO). For PRB with the SST in the central and western regions of the TPO in the interannual (4-8 years) and decadal (8-14 years) scales, the decreases (increases) in streamflow precede the El Nino (La Nina) events. These results indicate multiscale relations between the basins' streamflow and climate phenomena not documented in previous works, relevant to forecast the extreme flow events in the Colombian Pacific rivers and for planning and implementing strategies for the sustainable use of water resources in the basins studied.The first author was supported by the Program for Strengthening Regional Capacities in Research, Technological Development and Innovation in the department of Naritio and the CEIBA foundation for doctoral studies. The second author was supported by the Doctoral Scholarship of the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior Brazil (CAPES) Finance Code 001 and Universidad del Valle (Cali-Colombia). The Conselho Nacional de Desenvolvimento Cientifico e TecnolOgico (CNPq) of Brazil partially supported the fifth and sixth authors under grants 305942/2015-8 and 302322/2017-5, respectively. This research was done partially during an internship of the first two authors at the Research Institute of Water and Environmental Engineering of the Universitat Politecnica de Valencia. This work was also supported by the Spanish Ministry of Science and Innovation through Project TETISCHANGE (RTI2018-093717-B-I00). We are thankful to the research groups IREHISA and PSI of the Universidad del Valle. The authors thank the anonymous reviewers for their useful suggestions.Canchala, T.; Cerón, WL.; Francés, F.; Carvajal-Escobar, Y.; Andreoli, RV.; Kayano, MT.; Alfonso-Morales, W.... (2020). Streamflow Variability in Colombian Pacific Basins and Their Teleconnections with Climate Indices. Water. 12(2):1-23. https://doi.org/10.3390/w12020526S12312

Streamflow Intensification Driven by the Atlantic Multidecadal Oscillation (AMO) in the Atrato River Basin, Northwestern Colombia

[EN] The impact of the Atlantic Multidecadal Oscillation (AMO) on the variations in the streamflow in the Atrato River Basin (ARB) during the 1965-2016 period was analyzed here by considering the cold (1965-1994) and warm (1995-2015) phases of this oscillation. The mean streamflow increased after 1994 (AMO phase change). This increase is related to the strengthening of the zonal gradients of the sea surface temperature (SST) and sea level pressure (SLP) between the tropical central Pacific and the tropical Atlantic after 1994 (warm AMO phase). These gradients contributed to strengthen the Walker cell related upward movement over northern and northwestern South America, in particular during November-December (ND). Consistently, the frequency (R20 mm) and intensity (SDII) of extreme daily rainfall events increased during the 1995-2015 period. Our results show a connection between the AMO and the increase in the streamflow in the ARB during the last five decades. These results contribute to the studies of resilience and climate adaptation in the region.The first author was supported by the Doctoral Scholarship of the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior-Brazil (CAPES), Finance Code 001 and Universidad del Valle (Cali-Colombia). The Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq) of Brazil partially supported the second and third authors under grants 302322/2017-5 and 305942/2015-8, respectively. The fourth author was supported by the CAPES-Brazil and Universidade Federal de Vicosa for doctoral studies. The fifth author was supported by the Program for Strengthening Regional Capacities in Research, Technological Development and Innovation in the department of Narino and the CEIBA Foundation for doctoral studies. The seventh author was supported by the CAPES-Brazil. This research was done partially during an internship of the first and fifth author at the Research Institute of Water and Environmental Engineering of the Universitat Politecnica de Valencia. This work was also supported by the Spanish Ministry of Science and Innovation through Project TETISCHANGE (RTI2018-093717-B-I00).Cerón, WL.; Kayano, MT.; Andreoli, RV.; Avila, A.; Canchala, T.; Francés, F.; Rivera, IA.... (2020). Streamflow Intensification Driven by the Atlantic Multidecadal Oscillation (AMO) in the Atrato River Basin, Northwestern Colombia. Water. 12(1):1-23. https://doi.org/10.3390/w12010216S12312

Distribución espacial del índice de propensión al homicidio (IPH) en las comunas de Cali, Colombia

La violencia por homicidios, es el resultado de una práctica social establecida a partir de los conflictos que se originan en las generaciones que se suceden y los distintos grupos sociales que se enfrentan. En la ciudad de Cali, los homicidios se han constituido como la principal causa de muerte de los habitantes, producto de dinámicas (narcotráfico, robos, seguridad pública) que han ocasionado el agravamiento de este delito. Con este contexto del área estudio, desde la geografía, se determinó la localización espacial del índice de propensión al homicidio (IPH). Los resultados por comunas muestran que a medida que la ciudad se extiende hacia las periferias, la probabilidad de ocurrencia va aumentando hacia las laderas en el occidente y las márgenes del río Cauca en el oriente, logrando constituir una herramienta que permitió diferenciar las zonas con los mayores problemas de violencia en Cali

Distribución espacial del índice de propensión al homicidio (IPH) en las comunas de Cali, Colombia

La violencia por homicidios, es el resultado de una práctica social establecida a partir de los conflictos que se originan en las generaciones que se suceden y los distintos grupos sociales que se enfrentan. En la ciudad de Cali, los homicidios se han constituido como la principal causa de muerte de los habitantes, producto de dinámicas (narcotráfico, robos, seguridad pública) que han ocasionado el agravamiento de este delito. Con este contexto del área estudio, desde la geografía, se determinó la localización espacial del índice de propensión al homicidio (IPH). Los resultados por comunas muestran que a medida que la ciudad se extiende hacia las periferias, la probabilidad de ocurrencia va aumentando hacia las laderas en el occidente y las márgenes del río Cauca en el oriente, logrando constituir una herramienta que permitió diferenciar las zonas con los mayores problemas de violencia en Cali.