Infiltration into fractured bedrock

Abstract

[1] One potential consequence of global climate change and rapid changes in land use is an increased risk of flooding. Proper understanding of floodwater infiltration thus becomes a crucial component of our preparedness to meet the environmental challenges of projected climate change. In this paper, we present the results of a long-term infiltration experiment performed on fractured ash flow tuff. Water was released from a 3 Â 4 m 2 infiltration plot (divided into 12 square subplots) with a head of $0.04 m, over a period of $800 days. This experiment revealed peculiar infiltration patterns not amenable to current infiltration models, which were originally developed for infiltration into soils over a short duration. In particular, we observed that in part of the infiltration plot, the infiltration rate abruptly increased a few weeks into the infiltration tests. We suggest that these anomalies result from increases in fracture permeability during infiltration, which may be caused by swelling of clay fillings and/or erosion of infill debris. Interaction of the infiltration water with subsurface natural cavities (lithophysal cavities) could also contribute to such anomalies. This paper provides a conceptual model that partly describes the observed infiltration patterns in fractured rock and highlights some of the pitfalls associated with direct extension of soil infiltration models to fractured rock over a long period.

Splitting Dynamics of Liquid Slugs at a T‐Junction

“…Water infiltration through fractured rock vadose zone has received extensive attention owing to its great influence on the application of hydrological cycle, contaminant treatment, geothermal energy production, and radioactive waste disposal (e.g., Berkowitz, 2002; Dobson et al, 2012; Essaid et al, 2015; Liu et al, 2003; Salve et al, 2008; Tsang et al, 2015). Field evidences show that focused, rapid, and deep infiltration along preferential pathways within fracture networks commonly occur (e.g., Dahan et al, 1999; Nimmo, 2012).…”

Modelling Debris Flow Runout: A Case Study on the Mesilau Watershed, Kundasang, Sabah

“…The 2015 Ranau earthquake altered the hydrological processes within the watershed area. Water infiltrating the soil and fracturing the bedrock drained rapidly, causing large rapid flow [61]. Therefore, the initial and continuous losses were set from 1 to 5 mm based on the impervious properties of geological and land use of the watershed area.…”

Liquid Breakthrough Time in an Unsaturated Fracture Network

“…Water infiltration in unsaturated fractured rocks is an important topic in a wide variety of subsurface engineering applications, including contaminant transport, nuclear waste disposal, and seepage control in water conservancy and hydropower projects (e.g., Berkowitz, 2002; Chen et al., 2020; Hartmann et al., 2021; Lee & Song, 2003; Scanlon et al., 1997). Previous studies have shown that focused, rapid and preferential flow occurs in unsaturated fracture networks with the preferential pathways exhibiting complex unsteady behaviors (e.g., Dahan et al., 1999; Dobson et al., 2012; Faybishenko et al., 2000; Glass, Nicholl, Ramirez, & Daily, 2002; Liu et al., 1998; Nimmo, 2012; Podgorney et al., 2000; Salve et al., 2008; Zhou et al., 2006). Although these studies have greatly advanced our understanding of unsaturated flow in fracture networks and have qualitatively explained the complexity of temporal and spatial characteristics of unsaturated flow in fracture networks, the progress in development of predictive models remains relatively slow.…”