A photopoint soil erosion study of gilman sandy loam in Organ Pipe Cactus National Monument

Marsh, Terrence

Data were gathered on the nature and extent of gullies in Gilman sandy loam at two study areas in Organ Pipe Cactus National Monument. Some increases in the widths of gullies and relatively large increases in the lengths of the gullies were evident. Gully development cannot be correlated to rainfall due to a lack of data. The lengthening of the gullies is due to a waterfall affect in which the soil at the bottom of the face of the gully head is washed away and the waterfall is undercut and subsequently falls. This report uses photopoint monitoring to document the rate of erosion at severely eroded sites in Gilman sandy loam soil at two locations, near Armenta Well and Dos Lomitas. In 1977, the author and a group of students measured and photographed three gullies at each site (for a total of 6) and installed permanent marking stakes. In 1979, the author and more students returned and remeasured and photographed the gullies. A variety of gully erosion patterns was selected, so that a qualitative evaluation of the erosion rates according to gully shape could be made. Evidently the gullies were the result of cattle trailing. Comparison of measurements from the two years' work reveals some increases in the widths of gullies and consistent increases in the length of gullies. The photo album contains 9 tables of data (gully measurements, precipitation records), and photo records of each gully (1977-1987).