The hydraulic properties of faults in unconsolidated sediments and their impact on groundwater flow : A study in the Roer Valley Rift System and adjacent areas in the Lower Rhine Embaymant

Cloetingh, S.A.P.L. [Promotor]Vries, J.J. de [Promotor]Balen, R.T. van [Copromotor

Using Distributed Temperature Sensing to monitor field scale dynamics of ground surface temperature and related substrate heat flux

We present one of the first studies of the use of Distributed Temperature Sensing (DTS) along fibre-optic cables to purposely monitor spatial and temporal variations in ground surface temperature (GST) and soil temperature, and provide an estimate of the heat flux at the base of the canopy layer and in the soil. Our field site was at a groundwater-fed wet meadow in the Netherlands covered by a canopy layer (between 0-0.5 m thickness) consisting of grass and sedges. At this site, we ran a single cable across the surface in parallel 40 m sections spaced by 2 m, to create a 40×40 m monitoring field for GST. We also buried a short length (≈10 m) of cable to depth of 0.1±0.02 m to measure soil temperature. We monitored the temperature along the entire cable continuously over a two-day period and captured the diurnal course of GST, and how it was affected by rainfall and canopy structure. The diurnal GST range, as observed by the DTS system, varied between 20.94 and 35.08◦C; precipitation events acted to suppress the range of GST. The spatial distribution of GST correlated with canopy vegetation height during both day and night. Using estimates of thermal inertia, combined with a harmonic analysis of GST and soil temperature, substrate and soil-heat fluxes were determined. Our observations demonstrate how the use of DTS shows great promise in better characterising area-average substrate/soil heat flux, their spatiotemporal variability, and how this variability is affected by canopy structure. The DTS system is able to provide a much richer data set than could be obtained from point temperature sensors. Furthermore, substrate heat fluxes derived from GST measurements may be able to provide improved closure of the land surface energy balance in micrometeorological field studies. This will enhance our understanding of how hydrometeorological processes interact with near-surface heat fluxes

Hydrogeological and temperature data Renkum Brooke Valley, Netherlands

Data used to prepare research article 'Inferring aquitard hydraulic conductivity using transient temperature-depth profiles impacted by ground surface warming' to be published in Water Resources Research

Hydrogeological and temperature data Renkum Brooke Valley, Netherlands

Data used to prepare research article 'Inferring aquitard hydraulic conductivity using transient temperature-depth profiles impacted by ground surface warming' to be published in Water Resources Research

Tracking the Subsurface Signal of Decadal Climate Warming to Quantify Vertical Groundwater Flow Rates

Sustained ground surface warming on a decadal time scale leads to an inversion of thermal gradients in the upper tens of meters. The magnitude and direction of vertical groundwater flow should influence the propagation of this warming signal, but direct field observations of this phenomenon are rare. Comparison of temperature-depth profiles in boreholes in the Veluwe area, Netherlands, collected in 1978-1982 and 2016 provided such direct measurement. We used these repeated profiles to track the downward propagation rate of the depth at which the thermal gradient is zero. Numerical modeling of the migration of this thermal gradient "inflection point" yielded estimates of downward groundwater flow rates (0-0.24 m a-1) that generally concurred with known hydrogeological conditions in the area. We conclude that analysis of inflection point depths in temperature-depth profiles impacted by surface warming provides a largely untapped opportunity to inform sustainable groundwater management plans that rely on accurate estimates of long-term vertical groundwater fluxes

Hydrogeological and temperature data Renkum Brooke Valley, Netherlands

Data used to prepare research article 'Inferring aquitard hydraulic conductivity using transient temperature-depth profiles impacted by ground surface warming' to be published in Water Resources Research

Hydrogeological aspects of fault zones on various scales in the Roer Valley Rift System.

The impact of faults on the groundwater flow system in the Roer Valley Rift System (RVRS) is demonstrated with examples from outcrop scale to regional scale. Faults in the RVRS can form strong barriers to horizontal groundwater flow as well as enhanced vertical groundwater flow paths at the same location. The strongly anisotropic hydraulic conductivity distribution within fault zones has important implications for the modeling of groundwater flow in sedimentary aquifer systems that are cut by faults. In this study, the hydraulic behavior of fault zones is studied at different scales. An outcrop study over the Geleen Fault zone shows deformation mechanisms as particulate flow and clay smearing in great detail. Qualitative and quantitative image analysis allows for an estimate of the micro-scale variation of the hydraulic properties within a fault zone. Additional core-plug measurements indicate that the damage zone around fault zones may form preferential flow paths. On a larger scale, observations over the Peel Boundary fault near the village of Uden also indicate that vertical groundwater flow close to the fault is enhanced, which results in a discharge of the underlying aquifers at the location of the fault zone. Finally, on a regional scale, hydraulic head patterns around the lignite mining areas in Germany show the importance of faults and the variation of their hydraulic properties to regional groundwater flow patterns. © 2003 Elsevier Science B.V. All rights reserved

Hydrologische en hydraulische randvoorwaarden voor natuurontwikkeling en -behoud in uiterwaarden : Methodiek ontwikkeling en toepassing op Gelderse Poort

Doelstelling van dit rapport is het bepalen van hydrologische en hydraulische condities die nodig zijn voor diverse ecotopen in de uiterwaarden. Er wordt hierbij een vertaalslag gemaakt van ecologische vereisten naar hydrologische en hydraulische randvoorwaarden die gebruikt kunnen worden als richtlijn voor rivierinrichting. Bijkomend doel is de ontwikkeling van een methodiek waarmee de effecten van klimaatverandering en zomerbedverlaging op terrestrische ecotooptypen kan worden bepaald