La cuenca hidrológica Lerma-Chapala-Santiago que drena hacia el Lago de Chapala ha sido intensamente impactada por las actividades humanas, lo cual ha alterado el ciclo hidrológico y afectado la recuperación anual del mismo. Para determinar la fluctuación histórica de sus volúmenes se desarrolló una red de nueve cronologías de poblaciones de Taxodium mucronatum distribuidas en bosques de galería de dicha cuenca. Las series de tiempo se analizaron mediante Componentes Principales y ello derivó en una cronología regional de 547 años (1462-2008). La asociación entre los índices dendrocronológicos y los datos del restablecimiento de los niveles del lago del año previo fue significativo, por lo que se creó un modelo de regresión para su reconstrucción. Los valores reconstruidos mostraron una alta variabilidad interanual y multianual que se asocia con sucesos extremos de El Niño-Oscilación del Sur. No obstante, el cambio de uso del suelo y el aprovechamiento indiscriminado del agua para diversos fines, en las últimas décadas, han enmascarado su efecto. Sequías de alta intensidad se detectaron en los períodos 1508-1560, 1581-1608, 1685-1725, 1770-1840, 1916-1924 y 1988-2000. De igual manera, algunas etapas húmedas notables ocurrieron en 1561-1578, 1610-1616, 1760-1769, 1842-1850, 1863-1893 y 1926-1963. De 1960 a la fecha, la recuperación anual del lago disminuyó a causa de la influencia humana. El entendimiento de las oscilaciones históricas en la profundidad del lago permitirá fundamentar acciones para un mejor uso del agua y la conservación de los ecosistemas rivereños que dependen de los recursos hídricos generados en la cuenca Lerma-Chapala-Santiago para su supervivencia.
Irrigation is expanding in the tropics and could make an important contribution to the intensification of production in those tropical areas where a dry season limits productivity. A study was carried out to characterize irrigation performance and the yield gaps of a tropical irrigation scheme that covers more than 41 000 ha in northern Costa Rica. The study covered a 5-year period, from 2014 to 2018. The performance indicator relative irrigation supply (RIS) ranged between 2.48 and 3.78, values higher than those typically observed in schemes of temperate areas, but in the low range of those documented in the tropics. Despite the excess of water usage, it was found that there were farms with water shortages, especially in the canal tails during the dry season, but there was also damage caused by excess of water in the rainy season. The potential yield of the two main crops (rice and sugar cane) was determined with the AquaCrop simulation model. Actual yields were determined via a farmers' survey that also inquired about irrigation management issues. Yield gaps were determined for each of the two sectors that make up the irrigation scheme (South and West canals). The mean yield gap of rice in the South Canal sector (3.34 t ha À1 ) was smaller than that of the West Canal sector (4.84 t ha À1 ). The highest yield gap of rice occurred in the rainy season in the West canal sector. The yield gap of sugar cane in the West canal sector was significantly larger than that in the South canal sector (170 and 148 t ha À1 , respectively). A farmers' survey, combined with an examination of soil maps, revealed that poor drainage through the heavy soils that predominate in the West canal sector is one of the main causes of the large yield gap, in both rice and sugar cane. While users are relatively satisfied with the provision of irrigation water and its cost, several opportunities (e.g. water delivery, amount of fertilizer in sugar cane, water supply and irrigation system on farms) for improving scheme performance and for closing the yield gaps are discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.