Fast Flow in Unsaturated Coarse Sediments

Tokunaga,Tetsu K. ; Wan, Jiamin

Lawrence Berkeley National Laboratory

关键词: Management;    Flow Rate;    Sediments;    Hydraulics;    Transport;   

DOI  :  10.2172/833510
RP-ID  :  EMSP-70069--2000
RP-ID  :  833510

美国|英语

来源: UNT Digital Library

【 摘 要 】

Unsaturated flow in very coarse sediments is a critical area for improving our basic understanding of vadose zone flow and transport because it contains important aspects that are beyond the realm predictable by classical Miller-Miller scaling analyses. In particular, very coarse-textured (>1 mm grain-size) media can sustain high flow rates at relatively low saturations, doing so via film flow rather than by flow through an interconnected network of saturated pores. Thus, the physics of fast flow processes in unsaturated very coarse media is fundamentally different from that traditionally recognized in finer textured sediments. Our general objectives are (i) to quantify the macroscopic hydraulic properties of very coarse textured sediments in the near-zero (-10 to 0 kPa) matric potential region, and (ii) determine the microscale basis for fast unsaturated flow. Through these macroscopic and microscale studies, we intend to develop appropriate scaling relations for unsaturated flow in coarse-granular sediments. Gaining improved understanding of unsaturated flow in coarse granular sediments is important for practical concerns. Effective remediation and management of contaminated coarse-grained sediments such as those found at the Hanford Site requires knowledge of unsaturated fast flow. A better understanding of the failure mode for natural and engineered capillary barriers is also needed. This research proposal was developed to improve our understanding of the physics of unsaturated flow in coarse- to very coarse-textured sediments, and through this meet practical needs related to contaminant transport in such vadose environments.