RESUMEN. El delta del Patía ha experimentado grandes variaciones morfológicas en las últimas cuatro décadas debido a presiones antrópicas. El transvase del río Patía al río Sanquianga, debido a la construcción del canal Naranjo en 1973, y la posterior formación del brazo Patianga, han derivado en complejas problemáticas ambientales que se evidencian en la reactivación del lóbulo norte del delta y el abandono de la anterior desembocadura en el lóbulo sur. En este artículo se analizan las principales alteraciones que se presentan en el delta del Patía como producto del desvío del río y las consecuentes variaciones en el aporte fluvial y de sedimentos. Estas alteraciones se reflejan en: (1) cambios drásticos en la línea de costa, con tasas de erosión de hasta 70 m año -1 ; (2) dulcificación de los estuarios del lóbulo norte del delta, cambio hidrológico que ha ocasionando la migración de la zona alta estuarina (salinidad <1) 15 km aguas abajo; y (3) alteraciones en la cobertura vegetal del Parque Nacional Natural Sanquianga, con incrementos en la vegetación de agua dulce de hasta 42%, y disminución en la cobertura de manglar de hasta 31% en un período de 15 años. Las condiciones actuales del delta del Patía son ejemplo de la importancia de las actividades humanas como agentes de cambio dentro de la evolución de los sistemas deltaicos, y revelan la necesidad de profundizar el estudio de este delta para establecer estrategias adecuadas de manejo y conservación. Palabras clave: río Patía, río Sanquianga, deltas tropicales, erosión costera, manglares, Pacífico colombiano.The environmental collapse in the Patía River, Colombia: morphological variations and impacts on mangrove ecosystems ABSTRACT. The Patía River delta has experienced major morphological variations in the last four decades due to anthropogenic pressures. The diversion of the Patía River to the Sanquianga River as a result of the construction of the Canal Naranjo in 1973, and the former development of the Patianga River, has generated complex environmental issues that are evidenced by the reactivation of the northern delta lobe and the abandonment of the previous river mouth in the southern lobe. This paper analyzes the main alterations taking place in the Patia delta as a result of the river diversion and the consequent variations in the water and sediment discharge. This alterations are reflected in: (1) drastic changes in coastline, with erosion rates up to 70 m y -1 ; (2) freshening conditions in the Sanguianga distributary channel, a hydrologic change that has shifted the upper estuarine region (salinity <1) 15 km downstream; and (3) alterations in the Sanquianga National Park land cover with increase in freshwater vegetation up to 42%, and decrease in mangrove cover up to 31% for a 15 years period. The current conditions of the Patía River delta are a clear example of the importance of human activities as change agents in the evolution of deltaic systems, and also reveal the need of deepen in the studies of this delta and establish appropriate manag...

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Global demand for vegetable oil and high oil palm yield have driven the rapid expansion of oil palm plantations in tropical countries. The research literature widely recognizes the effects of forest cover conversion into oil palm on biodiversity, deforestation, and carbon dynamics. However, research on the ecohydrological impacts of oil palm plantations is sparse, despite studies indicating that oil palm development may reshape land-water interactions and the availability and movement of water at different spatial and temporal scales. We address this gap by conducting a systematic literature review on oil palm development and its relation to ecohydrological processes. We found 139 relevant papers up to the year 2021, addressing different ecohydrological processes related to oil palm. We reviewed their spatiotemporal scales, geographic distribution, oil palm species and age, and the effects of land conversion from forest, cropland, and pastures. We also incorporated societal aspects regarding community perceptions of water. Our review highlights the effects of oil palm plantations on three main components of the water cycle: i) land-atmosphere, ii) fluvial systems, and iii) soils and groundwater. Most studies include analyses of the Indo-Malayan and Australasian biogeographical regions (113), followed by the Neotropics (49) and the Afrotropics (15). Compared to rainforests, oil palm monocultures are warmer and drier. They have higher evapotranspiration rates, lower runoff regulation and infiltration capacity, and lower soil organic carbon. Although less often implemented, alternative oil palm management practices, including oil palm agroforestry, can help to mitigate some of these effects. Forest to oil palm conversion is the most studied land transition, while conversions from croplands, pastures, and grasslands are less studied. Overall, we identify gaps in understanding the long-term effects of management on ecohydrological processes under different land conversions, especially in the Neotropics and the Afrotropics, precluding research-informed policy to manage impacts of this expanding crop.