Metodología para determinar la disponibilidad de aguas subterráneas en el secano interior de Ninhue
Loading...
Date
2002
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Universidad de Concepción
Abstract
El secano interior de la VIII región de Chile es una zona de suelos derivados de rocas graníticas y cuyo clima es de tipo mediterráneo, donde la escasez de agua es la principal limitante para el desarrollo integral de la zona. En el área de estudio, la escasa agua obtenida de pozos-norias está destinada principalmente al consumo doméstico. El presente trabajo se realizó en la cuenca San José (36º24’ S y 72º30’ W), comuna de Ninhue, provincia de Ñuble, VIII Región del Bio-Bio, Chile, la cual es considerada como representativa del secano interior de la provincia. El objetivo del trabajo fue el desarrollar y aplicar una metodología para determinar la disponibilidad de aguas subterráneas como fuente de abastecimiento con fines de riego y de uso doméstico. Para este fin se utilizó la metodología de Rupp (2001) con la cual se determinaron valores de conductividad hidráulica (Ks).
La información de las subcuencas y pozos-norias fue manejada con Sistemas de Información Geográficos (SIG). La recarga se estimó mediante balances hidrológicos en dos sub-cuencas del Estero San José aplicando una modificación del método de Thornhwaite (1957, en Scozzafava, 2001), para lo cual se utilizaron datos de escorrentía superficial, precipitación, humedad del suelo y estimaciones de la evapoptranspiración potencial (ETo) mediante la ecuación de Penman- Montheith (González de Aguilar, 1997). Adicionalmente, se determinó la recarga del acuífero a través de la variación estacional de niveles freáticos medidos en 35 pozos noria.
De acuerdo a los resultados obtenidos, la conductividad hidráulica (Ks) de los acuíferos estudiados es baja, con una media de 107 cm/día, que varía entre 4 y 514 cm/día, con una desviación estandard de 136.4 cm/día. Según este estudio, la disponibilidad de agua en el área es de 20 mm/año, de los cuales 8 mm/año podrían ser extraídos con la infraestructura existente. Sin embargo, menos de 2 mm/año están siendo extraídos por los agricultores, por 2 lo cual es necesario desarrollar la tecnología apropiada para que los agricultores puedan mejorar el nivel de obtención de agua subterránea.
The central drylands of Chile has granite soils and the climate has been described as Mediterranean. Water scarcity is the main constrain to an integral development. Water is obtained from shallow wells in little quantity, available only for domestic consumption. This study was conducted at the San José watershed (36º24’ S y 72º30’ W), located in Ninhue County, Region of Bío-Bío, which is considered as representative of the drylands. The objective of the study was to develop a methodology to determine groundwater availability for irrigation and domestic consumption. Metodology developed by Rupp (2001) was used to determine hydraulic conductivity (Ks). The information of the micro-basins and shallow wells were managed with Geographic Information Systems (GIS). The aquifer recharge was estimated by hydrological balances in two micro-basins of the San Jose’s creeks applying a variation of Thornhwaite method (1957, in Scozzafava, 2001), using in situ measurements of water flow, precipitation, soil humidity and estimations of potencial evapotranspiration using Penman-Montheith ecuation (González de Aguilar, 1997). Also, recharge was also considered through the variation of ground water levels measured in 35 shallow wells. Results indicates that hydraulic conductivity (Ks) is low and highly variable, with a mean of 107 mm/day (4 to 514 mm/day) and a standard deviation of 136.4 mm/day. Water availability is 20 mm/year, 8 of which can be extracted with the actual technology. However, lessthan 2 mm/year are extracted by farmers. That means, that appropriate technology should be develop to improve groundwater uptake.
The central drylands of Chile has granite soils and the climate has been described as Mediterranean. Water scarcity is the main constrain to an integral development. Water is obtained from shallow wells in little quantity, available only for domestic consumption. This study was conducted at the San José watershed (36º24’ S y 72º30’ W), located in Ninhue County, Region of Bío-Bío, which is considered as representative of the drylands. The objective of the study was to develop a methodology to determine groundwater availability for irrigation and domestic consumption. Metodology developed by Rupp (2001) was used to determine hydraulic conductivity (Ks). The information of the micro-basins and shallow wells were managed with Geographic Information Systems (GIS). The aquifer recharge was estimated by hydrological balances in two micro-basins of the San Jose’s creeks applying a variation of Thornhwaite method (1957, in Scozzafava, 2001), using in situ measurements of water flow, precipitation, soil humidity and estimations of potencial evapotranspiration using Penman-Montheith ecuation (González de Aguilar, 1997). Also, recharge was also considered through the variation of ground water levels measured in 35 shallow wells. Results indicates that hydraulic conductivity (Ks) is low and highly variable, with a mean of 107 mm/day (4 to 514 mm/day) and a standard deviation of 136.4 mm/day. Water availability is 20 mm/year, 8 of which can be extracted with the actual technology. However, lessthan 2 mm/year are extracted by farmers. That means, that appropriate technology should be develop to improve groundwater uptake.
Description
Tesis presentada para optar al grado de Magíster en Ingeniería Agrícola con mención en Riego y Drenaje
Keywords
Recursos hidrológicos - Chile, Aguas subterráneas - Chile, Cultivos de secano - Chile