Development of a 3D groundwater model based on scarce data: the Wadi Kafrein catchment/Jordan

In this work, a 3D groundwater flow model integrating all important geological features of the hydrogeological system is developed to investigate hydrological processes in the Wadi Kafrein area of Jordan. A large amount of available geological and hydrological data is integrated to construct a 3D groundwater flow model for the Wadi Kafrein area. Using the newly developed mapping approach, the translation of the highly detailed geological formations to an unstructured finite element grids, can be accomplished with high precision. The existing data set for model calibration is scarce, which is a typical situation for many hydrogeological case studies. At first, the steady state calibration of the groundwater model is carried out based on the observation wells. Then, the time and space-dependent recharge from precipitation are applied at the top surface of the finite element model. The transient simulation is conducted during the period of 1996–2008 considering the abstraction rates of the production wells and discharge of the springs. The calculated water levels are close to the observed values. The difference is partly caused by return flows from irrigation and the groundwater inflow from the adjacent aquifers which are not taken into consideration so far. Since the Wadi Kafrein area is an important agricultural area in the semiarid region of the Lower Jordan Valley, the model developed in this study can be regarded as a useful tool for analyzing the hydrological processes and improving groundwater management practices elsewhere affected by similar geological and hydrogeological conditions.     

Wild and farmed salmon in Norway—A review

The Salmon industry in Norway includes three sectors, namely sea and river fishing for wild salmon, and salmon farming, or aquaculture. The three sectors provide different social, economic and cultural benefits to society, but also face many problems and challenges. They have different interests, practices, traditions and audiences, and are also administered by different authorities and regulated under varying management regimes and legislations. On the one hand, they complement each other in terms of product supply, employment creation and income; on the other hand, they face conflicts over management objectives and strategies. This paper provides an overview of the salmon sectors associated with their status, challenges and management regimes. It further analyzes their interests and conflicts over economic contribution and management. Finally, some potential solutions are suggested in an attempt to solve these conflicts.     

Stratigraphic correlation of late Palaeocene sand deposits in the Søgne Basin area of the Danish and Norwegian central North Sea

A stratigraphic analysis of late Palaeocene sands of the Søgne Basin and the western part of the Norwegian–Danish Basin shows that the sand bodies are of differenct ages. The geographic distribution of the sand deposits shows that they are related to underlying Mesozoic structures suggesting a controlling effect of Tertiary tectonics on the deposition of sand during the late Palaeocene. However, the structural setting of various sand bodies varies from reactivation of older faults and reactivation of salt structures. The local character of the structures active during the late Palaeocene introduces minor depressions with no lateral connection. The sand bodies, which are interpreted as having been deposited in these depressions, are thus in general separate bodies with no lateral connection. The Fennoscandian shield and eroded Mesozoic sediments along the Fennoscandian Border Zone are suggested as source area for the late Palaeocene sand deposits.     

Gamma-ray source stacking analysis at low galactic latitudes

We studied the problematic of uncertainties in the diffuse gamma radiation apparent in stacking analysis of EGRET data at low Galactic latitudes. Subsequently, we co-added maps of counts, exposure and diffuse background, and residuals, in varying numbers for different sub-categories of putatively and known source populations (like PSRs). Finally we tested for gamma-ray excess emission in those maps and attempt to quantify the systematic biases in such approach. Such kind of an analysis will help the classification processes of sources and source populations in the GLAST era.     

The Greenland 8200 cal. yr BP event detected in loss‐on‐ignition profiles in Norwegian lacustrine sediment sequences

High‐resolution loss‐on‐ignition analyses of lacustrine sediment cores from both proglacial and non‐glacial lakes in southern Norway have revealed a specific pattern characterised by a significant, two‐peaked reduction of the loss‐on‐ignition values in the basal half of the cores. In non‐glacier‐fed lakes, the loss‐on‐ignition variations are interpreted to reflect mainly lake productivity and hence variability in surface summer air temperature. Sediments deposited in proglacial lakes, however, reflect mainly the glacier activity in the lake catchment. Bulk AMS radiocarbon dates from the core sequences and the loss‐on‐ignition curve pattern suggest that this event correlates with the ‘8200 cal. yr BP event’ recorded in the GRIP and GISP2 Greenland ice‐cores, termed the Finse event in southern Norway. Copyright © 2001 John Wiley & Sons, Ltd.     

Late Quaternary lake-level changes of Lake El'gygytgyn, NE Siberia

Lake El'gygytgyn is situated in a 3.6 Ma old impact crater in northeastern Siberia. Presented here is a reconstruction of the Quaternary lake-level history as derived from sediment cores from the southern lake shelf. There, a cliff-like bench 10 m below the modern water level has been investigated. Deep-water sediments on the shelf indicate high lake levels during a warm Mid-Pleistocene period. One period with low lake level prior to Marine Oxygen Isotope Stage (MIS) 3 has been identified, followed by a period of high lake level (10 m above present). In the course of MIS 2 the lake level dropped to − 10 m. At the end of MIS 2 the bench was formed and coarse beach sedimentation occurred. Subsequently, the lake level rose rapidly to the Holocene level. Changes in water level are likely linked to climate variability. During relatively temperate periods the lake becomes free of ice in summer. Strong wave actions transport sediment parallel to the coast and towards the outlet, where the material tends to accumulate, resulting in lake level rise. During cold periods the perennial lake ice cover hampers any wave activity and pebble-transport, keeping the outlet open and causing the lake level to drop.     

A multi-proxy approach to assessing isolation basin stratigraphy from the Lofoten Islands, Norway

This study takes a comprehensive approach to characterizing the isolation sequence of Heimerdalsvatnet, a coastal lake in the Lofoten Islands, northern Norway. We use established methods and explore new techniques to assess changes in marine influence. Bathymetric and sub-bottom profiles were acquired to examine basin-wide sedimentation and a 5.8 m sediment core spanning the last 7800 cal yr BP was analyzed. We measured magnetic susceptibility, bulk organic matter properties, molecular biomarkers, diatom assemblages, and elemental profiles acquired by scanning X-ray fluorescence. These characteristics of the sediment reflect detailed changes in salinity and water column conditions as the lake was progressively isolated. Three distinct litho/chemo-stratigraphic units represent a restricted marine phase (7800-6500 cal yr BP), a transitional phase characterized by intermittent marine influence (6500-4900 cal yr BP), and complete isolation and freshwater sedimentation (4900 cal yr BP to present). Although there are uncertainties in the estimate of the threshold elevation of the lake, the timing of these phases generally corresponds with previous interpretations of the local relative sea-level history. This record captures sea-level regression following the Tapes transgression and supports the interpretation of a subsequent sea-level stillstand, dated in Heimerdalsvatnet from 6500 to 4900 cal yr BP.     

Recharge and discharge controls on groundwater travel times and flow paths to production wells for the Ammer catchment in southwestern Germany

Travel times and flow paths of groundwater from its recharge area to drinking-water production wells will govern how the quality of pumped groundwater responds to contaminations. Here, we studied the 180 km² Ammer catchment in southwestern Germany, which is extensively used for groundwater production from a carbonate aquifer. Using a 3-D steady-state groundwater model, four alternative representations of discharge and recharge were systematically explored to understand their impact on groundwater travel times and flow paths. More specifically, two recharge maps obtained from different German hydrologic atlases and two plausible alternative discharge scenarios were tested: (1) groundwater flow across the entire streambed of the Ammer River and its main tributaries and (2) groundwater discharge via a few major springs feeding the Ammer River. For each of these scenarios, the groundwater model was first calibrated against water levels, and subsequently travel times and flow paths were calculated for production wells using particle tracking methods. These computed travel times and flow paths were indirectly evaluated using additional data from the wells including measured concentrations of major ions and environmental tracers indicating groundwater age. Different recharge scenarios resulted in a comparable fit to observed water levels, and similar estimates of hydraulic conductivities, flow paths and travel times of groundwater to production wells. Travel times calculated for all scenarios had a plausible order of magnitude which were comparable to apparent groundwater ages modelled using environmental tracers. Scenario with groundwater discharge across the entire streambed of the Ammer River and its tributaries resulted in a better fit to water levels than scenario with discharge at a few springs only. In spite of the poorer fit to water levels, flow paths of groundwater from the latter scenario were more plausible, and these were supported by the observed major ion chemistry at the production wells. We concluded that data commonly used in groundwater modelling such as water levels and apparent groundwater ages may be insufficient to reliably delineate capture zones of wells. Hydrogeochemical information relating only indirectly to groundwater flow such as the major ion chemistry of water sampled at the wells can substantially improve our understanding of the source areas of recharge for production wells.     

On-line fluorometry of multiple reactive and conservative tracers in streams

Performing tracer tests using artificial tracer compounds is a common practice to characterize natural streams regarding their (reactive) transport properties. Recently, the fluorescent compound resazurin was introduced as a reactive stream tracer to quantify hyporheic exchange and metabolic activity of streams. This tracer, together with its reaction product resorufin and a conservative tracer (in our case fluorescein), provides additional information about transport properties of the stream and its hyporheic zone and can therefore overcome restrictions that are commonly affiliated with the use of conservative tracers alone. However, all previously published studies using this tracer system were based on manual sampling of the water. This usually limits the number of measurements and thus the achievable temporal resolution, and potentially endangers data quality due to inadequate handling of samples. In this paper, a modified version of the GGUN-FL30 on-line fluorometer is presented in which the optics have been modified to allow measuring the concentrations of all three tracers simultaneously at intervals of 10 s. Experiments under controlled and natural conditions showed that the performance of the on-line fluorometer regarding tracer separation efficiency and practical detection limits is comparable to a high-performance laboratory spectrofluorometer. Furthermore, suggestions are given on how to correct tracer signal fluctuations caused by temporal changes in temperature and pH that might occur during a field tracer test.