Manejo de cuencas en Argentina : conceptos, diagnóstico y aspectos institucionales

Fil: Vich, Alberto I. J.Fil: Cobos, Daniel R..Fil: Lenzano, Luis E.

Dinámica de las tierras irrigadas en el centro-oeste de Argentina durante el período 1986-2018: análisis a partir de la anomalía del índice de vegetación mejorado

Los cambios en las áreas de riego de zonas áridas tienen fuertes implicancias para la producción de alimentos, la demanda de agua, la sustentabilidad de los cultivos y los acuíferos subterráneos. Los oasis del Centro-Oeste de Argentina constituyen una de las mayores áreas de riego en zonas áridas de Sudamérica. El objetivo del presente trabajo es estudiar la dinámica espacial y temporal de las áreas irrigadas del Centro-Oeste de Argentina en el período 1986-2018, su relación con la evolución del sistema agrícola-productivo y los factores impulsores de cambio en los usos de la tierra. Para el análisis de las áreas de riego se utilizó un modelo empírico que permite estimar las anomalías de evapotranspiración a partir del índice EVI, implementado en la plataforma Google Earth Engine. El área irrigada se incrementó un 17%, impulsada por el crecimiento en las cuencas de los ríos Tunuyán Superior (36%), San Juan (19%) y Mendoza (10,4%). El crecimiento de las áreas irrigadas comprende, principalmente, la expansión hacia el pedemonte mediante el aprovechamiento de aguas subterráneas y nuevas zonas de reúso de efluentes cloacales. El abandono de sitios de riego se asocia al avance urbano sobre áreas irrigadas y el abandono en áreas marginales, donde se produce una profunda transformación en el uso de la tierra y del agua. Los resultados encontrados sugieren un aporte sostenido de agua de riego en sitios abandonados para la producción agrícola y una disminución del área irrigada y cultivada durante la última década. Las transformaciones encontradas en los patrones de riego, tipo de cultivos y el área irrigada total tienen fuertes implicancias para los balances hídricos, por lo que deben ser consideradas para la planificación territorial y la gestión sustentable del agua en las cuencas del Centro-Oeste de Argentina.Irrigated cropland changes in arid regions have strong implications for food production, water demand, crop and groundwater sustainability. The oases of Central-Western Argentina constitute one of the largest irrigated areas across South America. The aim of this paper is to study the spatial and temporal dynamics of the irrigated lands in Central-Western Argentina in the period 1986-2018, their relationship with the evolution of the agricultural-productive system and the drivers of land use change. For the analysis of irrigated areas, an empirical model was used to estimate evapotranspiration anomalies based on the EVI index, implemented in the Google Earth Engine cloud-computing platform. The irrigated area increased by 17%, driven by growth in the Upper Tunuyán (36%), San Juan (19%) and Mendoza (10.4%) river basins. The growth of irrigated areas mainly includes expansion into the foothills through the use of groundwater and new sewage effluent reuse areas. The abandonment of irrigated plots is associated with urban sprawling over irrigated croplands and abandonment in marginal areas, where a deep transformation in land and water use occurs. The results suggest an irrigation water supply sustained in plots abandoned for agricultural production and a decrease in irrigated and cultivated area during the last decade. The transformations found in irrigation patterns, crop choices and total irrigated area have strong implications for water balances and should be considered for territorial planning and sustainable water management in the Central-Western Argentina basins.Asociación Argentina de Geofísicos y Geodesta

Vegetation influence on runoff and sediment yield in the Andes region: Observation and modelling

The Precordillera of the Andes Mountains (Mendoza, Argentina) is prone to severe flash floods, caused by heavy rainfall events of short duration and high intensities. Two catchments were instrumented in order to study the rainfall-runoff process and soil management impact on runoff and/or sediment yield. In the first catchment (Divisadero Largo, DL, 5.47 km2), characterized by a large heterogeneity of surface geology, a data set of about 50 rainfall-runoff events covering the 1983-1994 period was available. Vegetation cover changed significantly after the catchment was enclosed in 1989-1990. This change was successfully mapped using Landsat TM image analysis. The second catchment (Cuenca Aluvional Piloto, CAP, 35 ha), the soil of which was homogeneous, was instrumented in 1992 for total runoff and sediment yield measurements. Three small plots of 3 × 10 m2 (bare soil, 42 and 60% vegetation cover) and three sub catchments (2-4.5 ha) were delimited with different average vegetation cover. Data analysis showed the difficulty in relating runoff volume and sediment yield to simple descriptors of the catchments such as the average slope and/or the average vegetation cover. The DL and CAP catchments were modelled using the Areal Non Point Source Watershed Environment Response Simulation (ANSWERS) model with contrasting results. Good agreement between model and observation could be achieved after calibration on the 3 × 10 m2 plots, but the model failed to correctly reproduce runoff on the three 2-4.5 ha CAP sub-catchments using the values calibrated on the small plots. Better results were obtained on the larger and heterogeneous DL basin, where surface geology variations and rainfall variability seemed to be the most influential factors. In this case, no sensitivity to vegetation coverage changes, induced when enclosing the catchment, was found. On the other hand, the model proved sensitive to differences in vegetation cover at smaller scales when the geology was homogeneous. © 2001 Elsevier Science B.V. All rights reserved.Fil: Braud. I.. LTH; FranciaFil: Vich, Alberto Ismael Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Zuluaga, J. INA-CRA; ArgentinaFil: Fornero, Luis Alberto Tomás. Instituto Nacional del Agua; ArgentinaFil: Pedrani, A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentin