Phosphorus and sediment are major nonpoint source pollutants that degrade water quality. Streambank erosion can contribute a significant percentage of the phosphorus and sediment load in streams. Riparian land-uses can heavily influence streambank erosion. The objective of this study was to compare streambank erosion along reaches of row-cropped fields, continuous, rotational and intensive rotational grazed pastures, pastures where cattle were fenced out of the stream, grass filters and riparian forest buffers, in three physiographic regions of Iowa. Streambank erosion was measured by surveying the extent of severely eroding banks within each riparian land-use reach and randomly establishing pin plots on subsets of those eroding banks. Based on these measurements, streambank erosion rate, erosion activity, maximum pin plot erosion rate, percentage of streambank length with severely eroding banks, and soil and phosphorus losses per unit length of stream reach were compared among the riparian land-uses. Riparian forest buffers had the lowest streambank erosion rate (15-46 mm ⁄ year) and contributed the least soil (5-18 tonne ⁄ km ⁄ year) and phosphorus (2-6 kg ⁄ km ⁄ year) to stream channels. Riparian forest buffers were followed by grass filters (erosion rates 41-106 mm ⁄ year, soil losses 22-47 tonne ⁄ km ⁄ year, phosphorus losses 9-14 kg ⁄ km ⁄ year) and pastures where cattle were fenced out of the stream (erosion rates 22-58 mm ⁄ year, soil losses 6-61 tonne ⁄ km ⁄ year, phosphorus losses 3-34 kg ⁄ km ⁄ year). The streambank erosion rates for the continuous, rotational, and intensive rotational pastures were 101-171, 104-122, and 94-170 mm ⁄ year, respectively. The soil losses for the continuous, rotational, and intensive rotational pastures were 197-264, 94-266, and 124-153 tonne ⁄ km ⁄ year, respectively, while the phosphorus losses were 71-123, 37-122, and 66 kg ⁄ km ⁄ year, respectively. The only significant differences for these pasture practices were found among the percentage of severely eroding bank lengths with intensive rotational grazed pastures having the least compared to the continuous and rotational grazed pastures. Row-cropped fields had the highest streambank erosion rates (239 mm ⁄ year) and soil losses (304 tonne ⁄ km ⁄ year) and very high phosphorus losses (108 kg ⁄ km ⁄ year).(KEY TERMS: riparian areas; streambank erosion; soil and phosphorus losses; best management practices; grazing practices; nonpoint source pollution.) Zaimes, George N., Richard C. Schultz, and Thomas M. Isenhart, 2008. Streambank Soil and Phosphorus Losses Under Different Riparian Land-Uses in Iowa. Journal of the American Water Resources Association (JAWRA) 44(4):935-947.

Human alterations to the Iowa landscape, such as elimination of native vegetation for row crop agriculture and grazing, channelization of streams, and tile and ditch drainage, have led to deeply incised channels with accelerated streambank erosion. The magnitude of streambank erosion and soil loss were compared along Bear Creek in central Iowa. The subreaches are bordered by differing land uses, including reestablished riparian forest buffers, row crop fields, and continuously grazed riparian pastures. Erosion pins were measured from June 1998 to July 2002 to estimate the magnitude of streambank erosion. Total streambank soil loss was estimated by using magnitude of bank erosion, soil bulk density, and severely eroded bank area. Significant seasonal and yearly differences in magnitude of bank erosion and total soil loss were partially attributed to differences in precipitation and associated discharges. Riparian forest buffers had significantly lower magnitude of streambank erosion and total soil loss than the other two riparian land uses. Establishment of riparian forest buffers along all of the nonbuffered subreaches would have reduced stream‐bank soil loss by an estimated 77 to 97 percent, significantly decreasing sediment in the stream, a major water quality problem in Iowa.

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Stream velocity and flow are very important parameters that must be measured accurately to develop effective water resource management plans. There are various methods and tools to measure the velocity but, nowadays, image-based methods are a promising alternative that does not require physical contact with the water body. The current study describes the application of a low cost unmanned aerial vehicle that was selected in order to capture a video over a specific reach of Aggitis River in Greece. The captured frames were analyzed by three different software (PIVlab, PTVlab, and KU-STIV) in order to estimate accurately the surface water velocity. These three software also represent three different image-based methodologies. Although there are differences among these three methods, the analysis produced similar trends for all. The velocity ranged between 0.02 and 3.98 m/s for PIVlab, 0.12 and 3.44 m/s for PTVlab, and 0.04 and 3.99 m/s for KU-STIV software. There were parts, especially in the existing vegetation, where differences were observed. Further applications will be examined in the same or different reaches, to study the parameters affecting the analysis. Finally, the image-based methods will be coupled with verification measurements by a current meter to produce more rigorous results.