Conceptualizing catchment storage dynamics and nonlinearities          下载免费PDF全文

Marco P. Maneta  Chris Soulsby  Sylvain Kuppel  Doerthe Tetzlaff 《水文研究》2018,32(21):3299-3303

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Spatial aggregation of time‐variant stream water ages in urbanizing catchments          下载免费PDF全文

C. Soulsby  C. Birkel  J. Geris  D. Tetzlaff 《水文研究》2015,29(13):3038-3050

We calibrated an integrated flow–tracer model to simulate spatially distributed isotope time series in stream water in a 7.9‐km² catchment with an urban area of 13%. The model used flux tracking to estimate the time‐varying age of stream water at the outlet and both urbanized (1.7 km²) and non‐urban (4.5 km²) sub‐catchments over a 2.5‐year period. This included extended wet and dry spells where precipitation equated to >10‐year return periods. Modelling indicated that stream water draining the most urbanized tributary was youngest with a mean transit time (MTT) of 171 days compared with 456 days in the non‐urban tributary. For the larger catchment, the MTT was 280 days. Here, the response of urban contributing areas dominated smaller and more moderate runoff events, but rural contributions dominated during the wettest periods, giving a bi‐modal distribution of water ages. Whilst the approach needs refining for sub‐daily time steps, it provides a basis for projecting the effects of urbanization on stream water transit times and their spatial aggregation. This offers a novel approach for understanding the cumulative impacts of urbanization on stream water quantity and quality, which can contribute to more sustainable management. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Spatial multi-criteria analysis for selecting potential sites for aquifer recharge via harvesting and infiltration of surface runoff in north Jordan     

Anke Steinel  Klaus Schelkes  Ali Subah  Thomas Himmelsbach 《Hydrogeology Journal》2016,24(7):1753-1774

In (semi-)arid regions, available water resources are scarce and groundwater resources are often overused. Therefore, the option to increase available water resources by managed aquifer recharge (MAR) via infiltration of captured surface runoff was investigated for two basins in northern Jordan. This study evaluated the general suitability of catchments to generate sufficient runoff and tried to identify promising sites to harvest and infiltrate the runoff into the aquifer for later recovery. Large sets of available data were used to create regional thematic maps, which were then combined to constraint maps using Boolean logic and to create suitability maps using weighted linear combination. This approach might serve as a blueprint which could be adapted and applied to similar regions. The evaluation showed that non-committed source water availability is the most restricting factor for successful water harvesting in regions with <200 mm/a rainfall. Experiences with existing structures showed that sediment loads of runoff are high. Therefore, the effectiveness of any existing MAR scheme will decrease rapidly to the point where it results in an overall negative impact due to increased evaporation if maintenance is not undertaken. It is recommended to improve system operation and maintenance, as well as monitoring, in order to achieve a better and constant effectiveness of the infiltration activities.  相似文献   

Application of a spectral correction method for measurements of covariances with fast-response sensors in the atmospheric boundary layer up to a height of 130 m and testing of the corrections   总被引：1，自引：0，他引：1  

Jürgen Rißmann  Gerd Tetzlaff 《Boundary-Layer Meteorology》1994,70(3):293-305

Measurement of meteorological quantities with fast-response sensors by means of the eddycorrelation technique allows calculation of turbulent transport without too severe demands with regard to stationarity and homogeneity. However, the measurement system causes frequency-dependent errors due to measuring height, averaging interval, sampling rate and mean wind speed. A correction method (Moore, 1986) was applied to measurements taken on a 130 m tower located at the German North Sea coast. The errors for 10-min averages, obtained at a height of 10 m were between 20 and 30%, mainly caused by the inertia of the sensors, increasing to between 30 and 60% at 130 m height due to a loss of low-frequency parts of the spectra because of the averaging interval. The corrections to the obtained data were validated by comparing the cospectra calculated from the data with the spectra used for the computation of the correction factors.  相似文献   

Density-dependent dispersion in heterogeneous porous media Part I: A numerical study   总被引：1，自引：0，他引：1  

Anke Jannie Landman  K. Johannsen  Ruud Schotting   《Advances in water resources》2007,30(12):2467-2480

In this paper, we describe carefully conducted numerical experiments, in which a dense salt solution vertically displaces fresh water in a stable manner. The two-dimensional porous media are weakly heterogeneous at a small scale. The purpose of these simulations, conducted for a range of density differences, is to obtain accurate concentration profiles that can be used to validate nonlinear models for high-concentration-gradient dispersion. In this part we focus on convergence of the computations, in numerical and statistical sense, to ensure that the uncertainty in the results is small enough.Concentration variances are computed, which give estimates of the uncertainty in local concentration values. These local variations decrease with increasing density contrast. For tracer transport, obtained longitudinal dispersivities are in accordance with analytical findings. In the case of high-density contrasts, stabilizing gravity forces counteract the growth of dispersive fingers, decreasing the effective width of the transition zone. For small log-permeability variances, the decrease of the apparent dispersivity that is found is in agreement with laboratory results for homogeneous columns.  相似文献   

GIS-based determination of the mean long-term groundwater recharge in Lower Saxony     

F.?WendlandEmail author  R.?Kunkel  B.?Tetzlaff  G.?D?rh?fer 《Environmental Geology》2003,45(2):273-278

This paper presents the findings of a collaborative research project of the Geological Survey of Lower Saxony (NLfB) and the Programme Group Systems Analysis and Technology Evaluation (STE) of Research Centre Jülich on the GIS-based determination of the mean long-term groundwater recharge in Lower Saxony using high-resolution digital data (Dörhöfer and others 2001). The model calculations were performed on the basis of the water-balance model GROWA (Kunkel and Wendland 2002) with a spatial resolution of 100x100 m². The accuracy of the calculated groundwater recharge values for the period 1961–1990 was verified on the basis of data from gauging stations and displayed a good agreement between observed runoff values and model results.  相似文献   

Ammonium in aqueous fluids to 600 °C, 1.3 GPa: A spectroscopic study on the effects on fluid properties, silica solubility, and K-feldspar to muscovite reactions     

Christian Schmidt  Anke Watenphul 《Geochimica et cosmochimica acta》2010,74(23):6852-6866

The behavior of ammonium, NH₄⁺, in aqueous systems was studied based on Raman spectroscopic experiments to 600 °C and about 1.3 GPa. Spectra obtained at ambient conditions revealed a strong reduction of the dynamic three-dimensional network of water with addition of ammonium chloride, particularly at small solute concentrations. The differential scattering cross section of the ν₁-NH₄⁺ Raman band in these solutions was found to be similar to that of salammoniac.The Raman band of silica monomers at ∼780 cm⁻¹ was present in all spectra of the fluid at high temperatures in hydrothermal diamond-anvil cell experiments with H₂O ± NH₄Cl and quartz or the assemblage quartz + kyanite + K-feldspar ± muscovite/tobelite. However, these spectra indicated that dissolved silica is less polymerized in ammonium chloride solutions than in comparable experiments with water. Quantification based on the normalized integrated intensity of the H₄SiO₄⁰ band showed that the silica solubility in experiments with H₂O + NH₄Cl was significantly lower than that in equimolal NaCl solutions. This suggests that ammonium causes a stronger decrease in the activity of water in chloridic solutions than sodium.The Raman spectra of the fluid also showed that a significant fraction of ammonium was converted to ammonia, NH₃, in all experiments at temperatures above 300 °C. This indicates a shift towards acidic conditions for experiments without a buffering mineral assemblage. The estimated pH of the fluid was ∼2 at 600 °C, 0.26 GPa, 6.6 m initial NH₄Cl, based on the ratio of the integrated ν₁-NH₃ and ν₁-NH₄⁺ intensities and the HCl⁰ dissociation constant. The NH₃/NH₄⁺ ratio increased with temperature and decreased with pressure. This implies that more ammonium should be retained in K-bearing minerals coexisting with chloridic fluids upon high-P low-T metamorphism. At 500 °C, 0.73 GPa, ammonium partitions preferentially into the fluid, as constrained from infrared spectroscopy on the muscovite and from mass balance.The conversion of K-feldspar to muscovite proceeded much faster in experiments with NH₄Cl solutions than in comparable experiments with water. This is interpreted as being caused by enhancement of the rate-limiting alumina solubility, suggesting complexation of Al with NH₄. Nucleation and growth of mica at the expense of K-feldspar and NH₄⁺/K⁺ exchange between fluid and K-feldspar occurred simultaneously, but incorporation of NH₄⁺ into K-feldspar was distinctly faster than K-feldspar consumption.  相似文献   

Ductile to brittle fault zone evolution in Austroalpine units to the southeast of the Tauern Window (Eastern Alps)     

Andreas Wölfler  Wolfgang Frisch  Harald Fritz  Martin Danišik  Anke Wölfler 《Swiss Journal of Geoscience》2015,108(2-3):239-251

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Scaling up and out in runoff process understanding: insights from nested experimental catchment studies     

C. Soulsby  D. Tetzlaff  S. M. Dunn  S. Waldron 《水文研究》2006,20(11):2461-2465

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Identification of mid-latitudinal regional and urban temperature variabilities based on regional reanalysis data     

Woonsup Choi  Anke Keuser  Stefan Becker 《Theoretical and Applied Climatology》2012,107(1-2):87-98

The objective of the study is to detect geographical and temporal variations of near surface air temperatures over Minnesota and Wisconsin, USA derived from the North American Regional Reanalysis (NARR) dataset. In addition, the study serves to assess the usefulness of NARR temperature data to analyze regional and local temperature variations. Particular emphasis was placed on the analyses on the temperature-modifying effects of the Great Lakes and large urban environments. We analyzed annual mean, daily maximum and minimum, and January minimum and July maximum temperatures for the period 1979–2006 by using methods such as ordinary kriging, principal component analysis, and the Mann–Kendall test. On a regional scale, we found significant effects of the latitude and the Great Lakes on the spatial variability of the data. Furthermore, we found clearly identifiable effects of large urban areas in the study region (Minneapolis—Saint Paul and Milwaukee), which are more evident in the principal component scores than in the temperature data themselves. While we failed to detect significant July maximum temperature trends, we detected significantly increasing trends in January minimum and mean annual temperature datasets in the eastern part of the region. Overall, the present study has demonstrated the potential of using NARR data for urban climate research.  相似文献