Long-term effects of watershed management on surface runoff and sediment loss in the Ethiopian Highlands

Data on rainfall, runoff and sediment loss from different land use types have been collected by the Soil Conservation Research Programme in seven small catchments (73-673 hectares) throughout the Ethiopian Highlands since the early 1980s. Monitoring was carried out on a storm-to-storm basis for extended periods of 10-20 years, and the data are analysed here to assess long-term effects of changes. Soil and water conservation technologies were introduced in the early years in the catchments in view of their capacity to reduce runoff and sediment yield. Results indicate that rainfall did not substantially change over the observation periods. Land use changes and land degradation, however, altered runoff, as shown by the data from small test plots (30 m2), which were not altered by conservation measures during the monitoring periods. Sediment delivery from the catchments may have decreased due to soil and water conservation, while runoff rates did not change significantly. Extrapolation of the results in the highlands, however, showed that expansion of cultivated and grazing land induced by population growth may have increased the overall surface runoff. Watershed management in the catchments, finally, had beneficial effects on ecosystem services by reducing soil erosion, restoring soil fertility, enhancing agricultural production, and maintaining overall runoff to the benefit of lowland areas and neighbouring countries.

Micropreparative isoelectric focusing protein separation in a suspended drop

IEF protein binary separations were performed in a 12-μL drop suspended between two palladium electrodes, using pH gradients created by electrolysis of simple buffers at low voltages (1.5-5 V). The dynamics of pH gradient formation and protein separation were investigated by computer simulation and experimentally via digital video microscope imaging in the presence and absence of pH indicator solution. Albumin, ferritin, myoglobin, and cytochrome c were used as model proteins. A drop containing 2.4 μg of each protein was applied, electrophoresed, and allowed to evaporate until it splits to produce two fractions that were recovered by rinsing the electrodes with a few microliters of buffer. Analysis by gel electrophoresis revealed that anode and cathode fractions were depleted from high pI and low pI proteins, respectively, whereas proteins with intermediate pI values were recovered in both fractions. Comparable data were obtained with diluted bovine serum that was fortified with myoglobin and cytochrome c.

Monitoring and Modeling of the Hydraulic and Sediment Processes at In-Stream Restoration Structures in the Vicinity of a Bridge Crossing

The long-term performance of infrastructure depends on reliable and sustainable designs. Many of Pennsylvania’s streams experience sediment transport problems that increase maintenance costs and lower structural integrity of bridge crossings. A stream restoration project is one common mitigation measure used to correct such problems at bridge crossings. Specifically, in an attempt to alleviate aggradation problems with the Old Route 15 Bridge crossing on White Deer Creek, in White Deer, PA, two in-stream structures (rock cross vanes) and several bank stabilization features were installed along with a complete channel redevelopment. The objectives of this research were to characterize the hydraulic and sediment transport processes occurring at the White Deer Creek site, and to investigate, through physical and mathematical modeling, the use of instream restoration structures. The goal is to be able to use the results of this study to prevent aggradation or other sediment related problems in the vicinity of bridges through improved design considerations. Monitoring and modeling indicate that the study site on White Deer Creek is currently unstable, experiencing general channel down-cutting, bank erosion, and several local areas of increased aggradation and degradation of the channel bed. An in-stream structure installed upstream of the Old Route 15 Bridge failed by sediment burial caused by the high sediment load that White Deer Creek is transporting as well as the backwater effects caused by the bridge crossing. The in-stream structure installed downstream of the Old Route 15 Bridge is beginning to fail because of the alignment of the structure with the approach direction of flow from upstream of the restoration structure.

Hydrologic and Water Quality Assessment of Miller Run: A Study of Bucknell University’s Impact

Human development causes degradation of stream ecosystems due to impacts on channel morphology, hydrology, and water quality. Urbanization, the second leading cause of stream impairment, increases the amount of impervious surface cover, thus reducing infiltration and increasing surface runoff of precipitation, which ultimately affects stream hydrologic process and aquatic biodiversity. The main objective of this study was to assess the overall health of Miller Run, a small tributary of the Bull Run and Susquehanna River watersheds, through an integrative hydrologic and water quality approach in order to determine the degree of Bucknell University’s impact on the stream. Hydrologic conditions, including stage and discharge, and water quality conditions, including total suspended solids, ion, nutrient, and dissolved metal concentrations, specific conductivity, pH, and temperature, were measured and evaluated at two sampling sites (upstream and downstream of Bucknell’s main campus) during various rain events from September 2007 to March 2008. The primary focus of the stream analysis was based on one main rain event on 26 February 2008. The results provided evidence that Miller Run is impacted by Bucknell’s campus. From a hydrologic perspective, the stream’s hydrograph showed the exact opposite pattern of what would be expected from a ‘normal’ stream. Miller run had a flashier downstream hydrograph and a broader upstream hydrograph, which was more than likely due to the increased amount of impervious surface cover throughout the downstream half of the watershed. From a water quality perspective, sediment loads increased at a faster rate and were significantly higher downstream compared to upstream. These elevated sediment concentrations were probably the combined result of sediment runoff from upstream and downstream construction sites that were being developed over the course of the study. Sodium, chloride, and potassium concentrations, in addition to specific conductivity, also significantly increased downstream of Bucknell’s campus due to the runoff of road salts. Calcium and magnesium concentrations did not appear to be impacted by urbanization, although they did demonstrate a significant dilution effect downstream. The downstream site was not directly affected by elevated nitrate concentrations; however, soluble reactive phosphorus concentrations tended to increase downstream and ammonium concentrations significantly peaked partway through the rain event downstream. These patterns suggest that Miller Run may be impacted by nutrient runoff from the golf course, athletic fields, and/or fertilizers applications on the main campus. Dissolved manganese and iron concentrations also appeared to slightly increase downstream, demonstrating the affect of urban runoff from roads and parking lots. pH and temperature both decreased farther downstream, but neither showed a significant impact of urbanization. More studies are necessary to determine how Miller Run responds to changes in season, climate, precipitation intensity, and land-use. This study represents the base-line analysis of Miller Run’s current hydrologic and water quality conditions; based on these initial findings, Bucknell should strongly consider modifications to improve storm water management practices and to reduce the campus’s overall impact on the stream in order to enhance and preserve the integrity of its natural water resources.