Potential (ETp) and actual (ETr) evapotranspiration for different land uses in a watershed in southern Brazil
DOI:
https://doi.org/10.6008/CBPC2179-6858.2018.008.0010Keywords:
Use of the soil, Hydric balance, EvapotranspirationAbstract
Evapotranspiration can be determined by direct or indirect methods, and its verification is performed by comparison with the measured data. This study aimed to determine the actual evapotranspiration (ETr) for different land uses that make up the agricultural landscape of the Ribeirão Concórdia watershed, compared with the potential evapotranspiration (ETp). The land uses analyzed were: agriculture, native forest, pasture and reforestation. ETp was estimated by the Penman-Monteith method (FAO-56) from surface weather station data, and ETr determined by field-installed equipment such as volumetric lysimeters, runoff gutters and below-canopy rainfall interceptors. vegetation in native forest and reforestation areas. The precipitation in the region was uneven and with values above the regional precipitation, due to the orographic rainfall occurred in the region. The native forest area had an interception volume of 11.2% greater than the reforestation area. Rainfalls up to 6.5mm were totally intercepted by the vegetative canopy, while in reforestation this value was only 2.1mm. The Penman-Monteith method overestimated evapotranspiration values in all land uses. Soil water storage had little variation as the hydrological cycle is a dynamic system and comes into balance over time. The runoff was high in the agricultural areas due to the soil management adopted by the producers. The water balance method proved to be efficient in the determination of ETr in a decendial time scale.
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