Pressure head spatial distribution center pivot lateral line based digital elevation model

Abstract

The spatial distribution of pressure head values along a 432,6m long center pivot lateral line was determined using measured values, taken at the inlet and end sections of the lateral line, and combined with topographic elevation data from a SRTM (Shuttle Radar Topography Mission) image. Data furnished by SRTM describes topographic elevation values along the wheel tracks of each one of the eight towers used for the sustentation of the center pivot lateral line. For validation purposes of the process used for the determination of the pressure head distribution along the lateral line length, on 18 angular positions equally spaced along a complete turn of the lateral line, values of pressure head were also measured on 6 distinct points of the lateral line. Differences, on a 5% signiï¬cance level for the student t means test, were observed when measured values were compared to pressure head values estimated based on SRTM's altitude data. After the creation of thematic maps, there was a coincidence in the positioning of the regions of occurrence of the highest of pressure head, also, the lower pressure head values. The study demonstrates that the use of elevation data from SRTM images is acceptable only for the elaboration of thematic maps destined to delimit within the irrigated area the occurrence of regions where different pressure head values prevailed.