Use of a particle-tracking model for predicting entrainment at power plants on the Hudson River

A major assumption of the Empirical Transport Model (ETM), widely adopted by both electric utilities and regulatory agencies for estimating the effects of entrainment mortality on fish populations in estuaries, is that the fraction of ichthyoplankton entrained varies only in response to changes in water withdrawals, not to changes in freshwater flow. We evaluated this assumption using a particle-tracking model to estimmate the probability of entrainment at power plants on the Hudson River during low and high freshwater flow periods and comparing those probabilities with estimates calculated from the ETM. We found that freshwater flow had a profound effect on the probability of entrainment. Both the number of river regions from which particles were entrained and the probabilities of entrainment for particles in those river regions differed between low-flow and high-flow periods. During high flow, particles spent less time in the grid box next to the intakes, reducing the probability of entrainment for particles released in the river region of each power plant and the average probability of entrainment across all regions at three power plants. The reduced probability of entrainment for particles released in the river regions of two power plants was offset by higher entrainment for particles upriver of these power plants. Although the average probabilities of entrainment across all river regions estimated with the particle-tracking model and the ETM were relatively similar for some power plants at high flow, low flow, or both, the probabilities for each river region differed considerably between the models. The number of river regions from which particles were entrained using the ETM was consistently undersestimated, resulting in probabilities for regions where entrainment occurred that were biased high compared with the particle-tracking model.     

Remarks on erratic period fluctuations of detached close binaries and the constancy of the orbital period of XY UMa

It is shown that the erratic changes of the orbital period, which are observed in some detached eclipsing binary systems, cannot be interpreted as real if their light curves show changing anomalies with asymmetric minimum profiles. In this case the photometrically determined times of the minima do not coincide with the ideal geometric ones, which are unobservable. This fact and the applied reduction methods for deriving the photometric times of minima cause systematic period errors of cumulative character. The discussion of six photoelectrically-determined minima obtained within the last 20 yr, and earlier photographic ones of the 0^d.479 period eclipsing binary XY UMa yields a constant period. The long cyclic light curve variations due to starspot activity of the larger and hotter component of this system are reflected in corresponding period oscillations. Dedicated to Dr. Ida Noddack on the occasion of her eightieth birthday.     

Assessment of key transport parameters in a karst system under different dynamic conditions based on tracer experiments: the Jeita karst system,Lebanon

Artificial tracer experiments were conducted in the mature karst system of Jeita (Lebanon) under various flow conditions using surface and subsurface tracer injection points, to determine the variation of transport parameters (attenuation of peak concentration, velocity, transit times, dispersivity, and proportion of immobile and mobile regions) along fast and slow flow pathways. Tracer breakthrough curves (TBCs) observed at the karst spring were interpreted using a two-region nonequilibrium approach (2RNEM) to account for the skewness in the TBCs’ long tailings. The conduit test results revealed a discharge threshold in the system dynamics, beyond which the transport parameters vary significantly. The polynomial relationship between transport velocity and discharge can be related to the variation of the conduit’s cross-sectional area. Longitudinal dispersivity in the conduit system is not a constant value (α?=?7–10 m) and decreases linearly with increasing flow rate because of dilution effects. Additionally, the proportion of immobile regions (arising from conduit irregularities) increases with decreasing water level in the conduit system. From tracer tests with injection at the surface, longitudinal dispersivity values are found to be large (8–27 m). The tailing observed in some TBCs is generated in the unsaturated zone before the tracer actually arrives at the major subsurface conduit draining the system. This work allows the estimation and prediction of the key transport parameters in karst aquifers. It shows that these parameters vary with time and flow dynamics, and they reflect the geometry of the flow pathway and the origin of infiltrating (potentially contaminated) recharge.     

Estimating groundwater recharge using the chloride mass-balance method in the West Bank,Palestine

Abstract

The quantification of natural recharge rate is a prerequisite for efficient and sustainable groundwater resources management. Since groundwater is the only source of water supply in the West Bank, it is of utmost importance to estimate the rate of replenishment of the aquifers. The chloride mass-balance method was used to estimate recharge rates at different sites representing the three groundwater basins of the Mountain Aquifer in the West Bank. The recharge rate for the Eastern Basin was calculated as between 130.8 and 269.7 mm/year, with a total average replenishment volume of 290.3 × 10⁶ m³/year. For the Northeastern Basin, the calculated recharge rate ranged between 95.2 and 269.7 mm/year, with a total average recharge volume of 138.5 × 10⁶ m³/year. Finally, the recharge rate for the Western Basin was between 122.6 and 323.6 mm/year, with a total average recharge volume of 324.9 × 10⁶ m³/year. The data reveal a replenishment potential within the estimated replenishment volumes of previous studies for the same area. Also, the range was between 15 and 50% of total rainfall, which is still within the range of previous studies. The geological structure and the climate conditions of the western slope were clearly play an important role in the increment of total volume. In some cases, such as the geological formations in the Northeastern Basin, the interaction between Eocene and Senonian chalk formations result in minimum recharge rates.

Citation Marei, A., Khayat, S., Weise, S., Ghannam, S., Sbaih, M. & Geyer, S. (2010) Estimating groundwater recharge using the chloride mass-balance method in the West Bank, Palestine. Hydrol. Sci. J. 55(5), 780–791.     

Water quality deterioration at a karst spring (Gallusquelle,Germany) due to combined sewer overflow: evidence of bacterial and micro-pollutant contamination

The concurrent use of karst aquifers as drinking water resources and receptors of combined sewer overflow lacking appropriate pre-treatment may cause conflicts between drinking water supply and storm water management. A storm water tank (SWT) for combined wastewater is identified as the source of sporadic contamination of a karst spring (Gallusquelle, “Schwäbische Alb”, SW Germany) used for public water supply. Spring water quality was examined by routine and event sampling and by evaluating physicochemical and microbiological parameters. The total number of microbial colonies growing at 20°C and the number of Escherichia coli colonies rose to values up to four orders of magnitude higher than background, 2–5 days after overflow of the SWT. High concentrations of chloride, sodium, and total organic carbon (TOC) and high values of turbidity coincide with this increase. However, high bacterial contamination is also observed while turbidity and TOC are low. Several wastewater-related organic micro-pollutants such as chlorinated and non-chlorinated organophosphates were detected in the SWT and, depending on their K_ow values and their biodegradability, in lower concentrations at the spring.     

Geometrie der Raum-Zeit der Maßbestimmung von KOTTLER,WEYL und TREFFTZ

The space-time manifold with the metric tensor of KOTTLER , WEYL and TREFFTZ (KWT) is analytically extended for all the three ranges 2m/a ⩽ 2/3^3/2 and the transformations into Kruskal-coordinates are given. The conformal infinity is represented by Penrose-diagrams. Finally embeddings in three-space are shown of surfaces with KWT-metric in cylindrical and spherical coordinates.