Characteristic regimes for in‐situ bioremediation of aquifers by injecting water containing an electron acceptor     

H. Keijzer  S.E.A.T.M. van der Zee  A. Leijnse 《Computational Geosciences》1998,2(1):1-22

A onedimensional model is developed for simulating insitu bioremediation. The modeled processes are advective and dispersive transport, biotransformation and microbial growth. The biodegradation of the contaminant is limited by the supply of electron acceptor or microbial mass. We distinguish three regimes of oxygen consumption, a low oxygen consumption regime, an intermediate regime and a fast oxygen consumption regime. Parameter variation reveals the influence of the dimensionless numbers on the duration of the three regimes.  相似文献   

DISCUSSION OF "Theis Parameter Evaluation from Pumping Tests by Sensitivity Analysis", by Carl D. McElwee, January-February 1980 issue, v. 18, no. 1, pp. 56–60     

A. Leijnse 《Ground water》1981,19(1):104-105

  相似文献   

The effect of differences between rainfall measurement techniques on groundwater and discharge simulations in a lowland catchment          下载免费PDF全文

Claudia C. Brauer  Aart Overeem  Hidde Leijnse  Remko Uijlenhoet 《水文研究》2016,30(21):3885-3900

Several rainfall measurement techniques are available for hydrological applications, each with its own spatial and temporal resolution and errors. When using these rainfall datasets as input for hydrological models, their errors and uncertainties propagate through the hydrological system. The aim of this study is to investigate the effect of differences between rainfall measurement techniques on groundwater and discharge simulations in a lowland catchment, the 6.5‐km² Hupsel Brook experimental catchment. We used five distinct rainfall data sources: two automatic raingauges (one in the catchment and another one 30 km away), operational (real‐time and unadjusted) and gauge‐adjusted ground‐based C‐band weather radar datasets and finally a novel source of rainfall information for hydrological purposes, namely, microwave link data from a cellular telecommunication network. We used these data as input for the, a recently developed rainfall‐runoff model for lowland catchments, and intercompared the five simulated discharges time series and groundwater time series for a heavy rainfall event and a full year. Three types of rainfall errors were found to play an important role in the hydrological simulations, namely: (1) Biases, found in the unadjusted radar dataset, are amplified when propagated through the hydrological system; (2) Timing errors, found in the nearest automatic raingauge outside the catchment, are attenuated when propagated through the hydrological system; (3) Seasonally varying errors, found in the microwave link data, affect the dynamics of the simulated catchment water balance. We conclude that the hydrological potential of novel rainfall observation techniques should be assessed over a long period, preferably a full year or longer, rather than on an event basis, as is often done. Copyright © 2016 The Authors. Hydrological Processes. Published by John Wiley & Sons Ltd.  相似文献   

Prediction uncertainty of plume characteristics derived from a small number of measuring points   总被引：1，自引：0，他引：1  

H. K. French  S.E.A.T.M van der Zee  A. Leijnse 《Hydrogeology Journal》2000,8(2):188-199

A small number of measuring points may inflict a bias on the characterisation of flow and transport based on field experiments in the unsaturated zone. Simulation of pure advective transport of a Gaussian plume through a setup of 30 regularly placed measuring points revealed regular temporal fluctuations about the real spatial moments. An irregular setup predicted both irregular fluctuations and larger discrepancies from the real value. From these considerations, a regular setup is recommended. Spatial moments were sensitive to the plume size relative to the distance between individual measuring points. To reduce prediction errors of the variance, the distance between the measuring points should be less than twice the standard deviation of the examined plume. The total size of the setup should cover several standard deviations of the plume to avoid mass being lost from the monitored area. Numerical simulations of a dispersing plume (comparing calculations based on 9000 nodes with 30 measuring points) revealed that vertical and horizontal centres of mass were predicted well at all degrees of heterogeneity, and the same was the case for horizontal variances. Vertical variances were more susceptible to prediction errors, but estimates were of the same order of magnitude as the real values. Received, October 1998/Revised, June 1999, October 1999/Accepted, November 1999  相似文献   

Differences in gravity‐dominated unsaturated flow during autumn rains and snowmelt     

H. K. French  S. E. A. T. M. van Der Zee  A. Leijnse 《水文研究》1999,13(17):2783-2800

Five tracer experiments have been performed in a coarse‐textured soil near the new main airport at Gardermoen, Norway. In two lysimeter walls, 30 and 40 measuring points form the basis for spatial moment calculations. Although experiments were performed under different meteorological conditions (autumn and snowmelt) and at two different sites, the ratios of centres of vertical mass over cumulative infiltration were of the same order of magnitude, indicating a gravity‐dominated flow. Two‐dimensional transport simulations with SUTRA (Voss, 1984), with a priori estimated input parameters and random fields of soil hydraulic properties revealed a relatively good agreement with the experimental results. Three possible sources of heterogeneity affecting the vertical displacement of solute during snowmelt were identified: variability of soil physical properties, soil surface elevations and variability of ground frost during the melting period. To obtain accurate predictions, soil heterogeneity was the most important factor to characterize for the coarse‐textured soil under consideration. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献