Determination of streambed hydraulic conductivity is of great importance in the analysis of stream-aquifer interactions and stream ecosystems. In this paper, in situ falling-head standpipe permeameter tests were conducted to determine streambed vertical hydraulic conductivity (K v ) of two connected layers of sediments at 60 test locations from eight sites in the Elkhorn River, Nebraska. Our results show that the K v values for the upper layer of sediments are generally larger than those in their respective lower layer of sediments. The individual K v value for the upper layer of sediments from all test locations of the eight sites range from 2.7 to 104.9 m/d, and the average value is 26.6 m/d. The individual K v value ranges from 0.4 to 73.4 m/d and the average value is 16.1 m/d for the lower layer of sediments. We believe that hyporheic processes can enhance larger streambed K v in the upper layer of sediments. Inflow and outflow through hyporheic zone produce more porous and permeable sediments and further result in an increasing of streambed K v . Moreover, we observe that bioturbation activities can destroy the clogging layer of the exposed sediments and create pore spaces in the sediments, which also further increases streambed K v . streambed vertical hydraulic conductivity, permeameter test, depth of streambed sediment, hyporheic processes, bioturbation Citation: Song J X, Chen X H, Cheng C, et al. Variability of streambed vertical hydraulic conductivity with depth along the Elkhorn River, Nebraska, USA. Chinese Sci Bull, 2010, 55: 992−999,
Weihe River Watershed above Linjiacun Section is taken as the research objective in this paper and NH3-N is chosen as the water quality parameter. According to the discharge characteristics of point source pollutions and non-point source pollutions, a new method to estimate pollution loads-characteristic section load method is suggested and point source pollution and non-point source pollution loads of Weihe River Watershed above Linjiacun Section are calculated in the rainy, normal and dry season in the year 2007. The results show that the monthly point source pollution loads of Weihe River Watershed above Linjiacun Section are discharged stably, the monthly non-point source pollution loads of Weihe River Watershed above Linjiacun Section change greatly, the non-point source pollution load proportions of total pollution load of NH3-N are gradually decreased in the rainy, normal and wet periods.
Guanzhong Segment of Wei River was studied in this article. Based on water quality observational data (ammonia-nitrogen) and hydrology observational data (flow of the sections) of Guanzhong Segment of Wei River in the rainy, normal and wet season in 2006, improved one-dimensional steady-state river water quality model was calibrated. River water quality was predicted in the normal season which were compared with the observational data in 2005. The results show that the water quality computed by improved one-dimensional steady-state river water quality model is grossly consistent with the observational water quality data and the model may provide the technical supports for the response relationships of water quality and water quantity of Guanzhong Segment of Wei River.
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