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- Persson, Magnus, et al.
(författare)
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A profiling TDR probe for water content and electrical conductivity measurements of soils
- 2010
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Ingår i: European Journal of Soil Science. - : Wiley. - 1365-2389 .- 1351-0754. ; 61:6, s. 1106-1112
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Tidskriftsartikel (refereegranskat)abstract
- Measurements of water content profiles are of great interest in hydrology and soil science. Time domain reflectometry (TDR) is a well-established method for water content measurements; however, most TDR probe designs are suitable for measurements in only a small soil volume. In this article, a 1-m long TDR profiling probe with five measurement sections is described. Unlike most other previous profiling probes, our probe allows for both dielectric permittivity (e) and electrical conductivity (sa) measurements. The accuracy of the e and sa measurements was excellent; the precision of the measurements was, however, significantly poorer than with a 0.20-m long standard three rod TDR probe. The new probe was installed in a field and successfully measured water content profiles during the growing season of 2009. During an infiltration experiment it was shown that because of its geometry, the profiling probe over-estimated the wetting-front velocity. At a 0.10-m depth, the over-estimation was almost 30%. The over-estimate will be less significant at greater depths.
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| 2. |
- Persson, Magnus, et al.
(författare)
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A small-scale matric potential sensor based on time domain reflectometry
- 2006
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Ingår i: Soil Science Society of America Journal. - 0361-5995. ; 70:2, s. 533-536
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Tidskriftsartikel (refereegranskat)abstract
- Measurements of soil matric potential (Psi) are needed in many soil science applications. In the present study, a small matric potential sensor having a length of 30 mm and a diameter of 9.6 mm was developed. The sensor consists of two coils made of lacquer-coated copper wires embedded in gypsum. The dielectric constant of the gypsum (K-gypsum) was measured with time domain reflectometry (TDR). The gypsum probes were tested in a sandy loam soil using a pressure extractor to obtain the relationship between K-gypsum and Psi, allowing inference of the soil Psi in equilibrium with the sensor. It was shown that the gypsum probe could give Psi estimates with a root mean square error (RMSE) of around 50 kPa in the range of -20 to -1500 kPa. Most of the sensitivity of the sensor was in the -50- to -1000-kPa range.
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| 3. |
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| 4. |
- Aronsson, Pär, et al.
(författare)
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Treatment of landfill leachate by irrigation of willow coppice - Plant response and treatment efficiency
- 2010
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Ingår i: Environmental Pollution. - : Elsevier BV. - 0269-7491 .- 1873-6424. ; 158:3, s. 795-804
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Tidskriftsartikel (refereegranskat)abstract
- Landfill leachates usually need to be treated before discharged. and using soil-plant systems for this has gained substantial interest in Sweden and in the UK A three-year field study was conducted in central Sweden to quantify plant response, treatment efficiency and impact on groundwater quality of landfill leachate irrigation of short-rotation willow coppice (Salix) Two willow varieties were tested and four irrigation regimes in sixteen 400-m(2) plots. The willow plants did not react negatively, despite very high annual loads of nitrogen (<= 2160 kg N/ha), chloride (<= 8600 kg Cl/ha) and other elements. Mean annual growth was 15. 98 and 12.6 tonnes DM/ha during years 1-3 For one of two willow varieties tested. relative leaf length accurately predicted growth rate. Irrigation resulted in elevated groundwater concentrations of all elements applied. Treatment efficiency varied considerably for different elements, but was adequate when moderate loads were applied. (C) 2009 Elsevier Ltd All rights reserved.
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| 5. |
- Arvidsson, Kristina, et al.
(författare)
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A hydrogeological study of the Nhandugue River, Mozambique - A major groundwater recharge zone
- 2010
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Ingår i: Procs. WaterNet 2010.
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Konferensbidrag (refereegranskat)abstract
- The Nhandugue River flows over the western margin of the Urema Rift, the southernmost extension of the East African Rift System, and marks the north-western border of Gorongosa National Park, Mozambique. It constitutes one of the major indispensable water resources for the ecosystem that the park protects. Our study focused on the hydrogeological conditions at the western rift margin by resistivity measurements, soil sampling and discharge measurements. The resistivity results suggest that the area is heavily faulted and constitutes a major groundwater recharge zone. East of the rift margin the resistivity indicate that solid gneiss is fractured and weathered, and is overlain by sandstone and alluvial sediments. The top 10-15 m of the alluvial sequence is interpreted as sand. The sand layer extends back to the rift margin thus also covering the gneiss. The sandstone outcrops a few kilometers from the rift margin and dips towards east/south-east. Further into the rift valley, the sand is underlain by lenses of silt and clay on top of sand mixed with finer matter. In the lower end of the investigated area the lenses of silt and clay appears as a more or less continuous layer between the two sand units. The topmost alluvial sand constitutes an unconfined aquifer under which the solid gneiss forms a hydraulic boundary and the fractured gneiss an unconfined aquifer. The sandstone is an unconfined aquifer in the west, becoming semi-confined down dip. The lenses of silt and clay forms an aquitard and the underlying sand mixed with finer matter a semi-confined aquifer. The surface runoff decreases downstream and it is therefore concluded that surface water infiltrates as recharge to the aquifers and moves as groundwater in an east/south-eastward direction. (C) 2011 Elsevier Ltd. All rights reserved.
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| 9. |
- Bernstone, Christian, et al.
(författare)
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DC resistivity mapping of internal landfill structures: two pre-excavation surveys.
- 2000
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Ingår i: Environmental Geology. - : Springer Science and Business Media LLC. - 0943-0105 .- 1432-0495. ; 39:3-4, s. 360-371
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Tidskriftsartikel (refereegranskat)abstract
- Geophysical investigations using 2-D DC resistivity were carried out on old parts of two similar landfills, with waste of different ages. The data sets, which included high data density in both vertical and horizontal directions, were interpreted with 2-D smoothness constrained inversion. The landfills were excavated after the surveying. The objective was to test the capability of the resistivity method as a pre-characterization technique. The objectives were only partially fulfilled. First, the moisture content was the parameter that appeared to exert the dominant control over the resistivity distribution of the landfill. The most important potential information that can be recovered is, therefore, an indication of the waste piles hydraulics. Second, it was neither possible to estimate the amount of recoverable soils, nor to correlate the type of waste with the resistivity models. However, discrete anomalies were identified, and if specific materials are searched for, the resistivity models indicate possible places to search.
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