On subwatersheds of the Walnut Gulch Experimental Watershed measurements of precipitation and runoff showed extreme variation in the rainfall-runoff relation. This variation is attributed to irregularity of amount, intensity, and dislribution of the precipitation and to unmeasured differences among the subwatersheds. To ascertain effects of soil on infiltration, rain gages and Bouyoucos moisture blocks were installed on a 4.5-acre, grass-covered drainage area of igneous soil and on a 3.0-acre drainage area of calcareous soil supporting a shrub cover. Soil in the grassland area showed greater and more abrupt responses to rainfall at the 6- and 18-inch depths. Moisture depletion at the 6-inch depth was more rapid in the grassland area, [...]
