Scale invariance of daily runoff time series in agricultural watersheds X. Zhou, N. Persaud, and H. Wang Department of Crop and Soil Sciences, The Pennsylvania State University, University Park, PA 16802, USA Department of Crop and Soil Environmental Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA Soil and Water Science Department, University of Florida,...

Four decades after conversion from chaparral to grass, zero-order watersheds were compared to identify differences in topography and its relation to soil characteristics. Three watersheds of each vegetation type were topographically mapped and sampled at random points for depth to weathered bedrock and soil water content. Stepwise regression was used to explain spatial variability in terms of t...

The major drawback of watershed transformation is over-segmentation. It also has a significant advantage: very good edge extraction. Thresholding methods usually utilize only global information such as an image histogram; however, they have the ability to group pixels into clusters by their value. The method presented in this paper combines the advantages of watershed segmentation and multileve...

Many conservation programs under the 2002 Farm Act address resource concerns such as water quality and aquatic communities in streams. Analyzing two such programs, simulated changes in agricultural practices decreased field-edge sediment losses by 25S31% in two geophysically distinct Minnesota watersheds. However, while in-stream sediment concentrations and lethal fisheries events decreased sig...

We present an I/O-efficient algorithm that decomposes a grid-based terrain model into a hierarchy of watersheds. Each watershed gets a unique label, a Pfafstetter label, and each grid cell is labeled with the labels of all (nested) watersheds it belongs to. The algorithm runs in O(sort(T )) I/Os, where T is the total length of the computed cell labels. Our algorithm is simple and practical. We ...

Prior Converted Croplands (PCCs) are historic wetlands that were transformed (drained, dredged, filled or leveled) to support production of agricultural crops prior to “Swampbuster” provisions of the 1985 Food Security Act. Our research suggests that PCCs can substantially reduce nitrate export from agricultural watersheds in the region, an ecosystem function shared with natural and restored we...