Variaciones de la conductividad hidráulica vertical en el cauce de un río antes y después de una estación de inundaciones

The change of vertical hydraulic conductivity (K_v) before and after a flood season is crucial in understanding the long-term temporal variation of streambed permeability. Therefore, in this study, a detailed K_vfield investigation was conducted at an in-channel site within the Dawen River, China, before and after a flood season. In-situ falling-head permeameter tests were performed for the determination of K_v. The tests were conducted using a 10 × 10 grid, at five different depths. In total, 871 valid K_vvalues from layers 1–5 were obtained. The Kruskal-Wallis test on these K_vvalues before and after the flood season shows they belonged to different populations. The sediments before the flood season primarily consisted of sand and gravel, whereas after the flood season, patchy distribution of silt/clay occurred in the sandy streambed and silt/clay content increased with the increasing depth; under the losing condition during flooding, downward movement of water brought fine particles into the coarse sediments, partially silting the pores. Accordingly, the K_vvalues after the flood season had a smaller mean and median, and a higher level of heterogeneity, compared to those before the flood season. Additionally, the distribution pattern in K_vacross the stream differed before and after flood season; after the flood season, there was an increasing trend in K_vfrom the south bank to the north bank. Overall, the contrasts of K_vbefore and after the flood season were predominantly subject to the infiltration of fine particles.