Mensuração e modelagem da interceptação vegetal em uma microbacia perene de vertente

Abstract

Knowledge of the hydrological behaviour of a given region is of fundamental importance for the management of water resources. However, in Brazil and in several other regions of the world, the real influence of vegetation on the interception of rainwater is still not understood. In this context, the present work aimed at evaluating, on a scale of individual events, the plant interception and the other partitioning of rainwater, in addition to testing the main mathematical models for their estimates. The area of study is an area of relevant ecological interest (ARIE) located within the microbasin of the spout in the municipality of Portalegre, situated in the Highland region of the west of the state of Rio Grande do Norte. The losses by interception of the vegetation in ARIE were measured in the period from January to December 2017 in an experimental site with area of 10 x 20 m, where the composition floristic presents predominance of Caatinga and occurrence of vegetation of the Atlantic forest. The losses by interception were quantified by the difference between the total precipitation and the sum of the portions of internal precipitation (under the vegetation) and runoff by the trunks. For the measurement of the total precipitation, a gauge installed in an unfielded area was used, the internal precipitation estimated by the arithmetic mean of the daily records of ten gauges randomly distributed under the vegetation and repositioned every two Weeks. The measurement of the flow through the trunks was in six trees of varying diameters in which the plastic mass gutters were constructed, which directed the flow of water from the trunks to the collectors. In the monitored period the analysis of 20 rainy events in ARIE indicates that the interception, internal precipitation and flow by the trunks correspond to 44.9%, 52.8% and 2.2% of the total precipitation, respectively. Studying the characteristics of rainfall, the maximum intensities in 15, 20, 30 and 45 minutes (I15, I20, I30 and I45) presented the largest factorials weights indicating that more attention is needed in hydrological studies for this variable in the Brazilian semi-arid region. The interception loss models used in this work have pretold the forest intercept in a satisfactory manner. The Rutter model obtained the smallest error value relative to the accumulated I at the end of the monitored period, with a value of 10% followed by the Gash model that presented a relative error of 12%