A study of K variability and its effect on solute transport in subsurface-flow sand filters by measurement and modelling.
Hydraulics of subsurface flow filters (SSF) was studied by measurement of soil hydraulic conductivity (K) variation and performing tracer tests in two SSF filters consisting of 1-4 mm Ca rich sand (shell sand). Soil samples were carefully taken at several locations in Filter I. A tracer experiment was conducted in the undisturbed Filter II using KI. The measured K variability in Filer I was used to analyze the variations in tracer breakthrough. The spatially distribution of K was obtained by fitting a variogram to observed data and interpolation using Kriging. The tracer residence probability density function (PDF) was determined by modelling the tracer movement with a 3-D groundwater model. The observed and simulated tracer arrival was compared for cases with constant K, constant K and dispersion (D), and for spatially variable K and dispersion. The results show that groundwater models were well suited to simulate solute movement in the SSF system studied. An almost perfect fit to observed tracer PDF was obtained when variable K and dispersion was included in the model. This indicates that information on K variability and dispersion is important for studying solute movement in SSF constructed wetlands.
Kløve
Bjørn
B
Norwegian Centre for Soil and Environmental Research (Jordforsk), As, Norway. bjorn.klove@oulu.fi
Xu
Shulan
S
Lindahl
Anna
A
Wörman
Anders
A
Søvik
Anne-Kristine
AK
D002118:Calcium; D004553:Electric Conductivity; D005374:Filtration; D008962:Models, Theoretical; D012822:Silicon Dioxide; D012995:Solubility; D014867:Water / Q000737:chemistry; D014872:Water Movements
D014867:Water; D012822:Silicon Dioxide; D002118:Calcium