The characteristics of hyporheic water and its influence on surface water quality

The effect of hyporheic water on wetland ecological habitat is important. The hyporheic processes not only impact physical and chemical characteristics of water but also provide needs to organisms in stream ecosystems. The exchange between surface water and hyporheic water was quantified by measuring the vertical hydraulic gradient (VHG) and streambed hydraulic conductivity (K) in minipiezometers by using the slug test in Wu Gou Shui spring-fed wetland area. Physical and chemical characteristics of the surface water and hyporheic water were measured and analyzed. Most upwelling sites wereobserved in the upper reach at Xing Sheng Bridge. On a small scale, few downwelling sites contained large sediment in the streambed. The magnitude of downwelling sites was significantly higher than the magnitude of upwelling sites because of gravity and good permeability. Some neutral sites were observed with frequent interactions between surface water and hyporheic water in small areas. There were no differences in water quality characteristics of surface water and hyporheic water between upwelling sites and downwelling sites. By using multidimensional scaling analysis (MDS) and principal component analysis (PCA), we could distinguish upwelling and downwelling sites and find the main factors of water quality characteristics by analyzing water quality characteristics of surface water. © 2016, Taiwan Agricultural Engineers Society. All rights reserved.