Application of linear and nonlinear techniques in river flow forecasting in the Kilombero River basin,Tanzania / Application de techniques linéaires et non-linéaires à la prévision des débits dans le bassin de la Rivière Kilombero,en Tanzanie     

《水文科学杂志》2013,58(5)

Abstract

Modelling of the rainfall–runoff transformation process and routing of river flows in the Kilombero River basin and its five sub-catchments within the Rufiji River basin in Tanzania was undertaken using three system (black-box) models—a simple linear model, a linear perturbation model and a linear varying gain factor model—in their linear transfer function forms. A lumped conceptual model—the soil moisture accounting and routing model—was also applied to the sub-catchments and the basin. The HEC-HMS model, which is a distributed model, was applied only to the entire Kilombero River basin. River discharge, rainfall and potential evaporation data were used as inputs to the appropriate models and it was observed that sometimes the system models performed better than complex hydrological models, especially in large catchments, illustrating the usefulness of using simple black-box models in datascarce situations.  相似文献   

Evaluating infiltration losses in a Mediterranean wetland: Las Tablas de Daimiel National Park,Spain     

S. Castaño‐Castaño  P. Martínez‐Santos  P. E. Martínez‐Alfaro 《水文研究》2008,22(26):5048-5053

Las Tablas de Daimiel National Park is a series of wetlands which naturally originated from groundwater discharges from the Mancha Occidental aquifer, Spain. Despite the relatively large size of this aquifer, 30 years of intensive groundwater pumping have significantly depleted the water table. As a result, wetlands only remain functional due to artificial inflows. Infiltration loss is therefore a key parameter to evaluate how much water is needed to maintain ecosystem functionality. Although yearly infiltration estimates existed prior to this work, these did not take into account key parameters such as the temporal evolution of the flooded area. This paper presents a more concrete estimate of the average infiltration losses. Infiltration is calculated as the closure term of daily water balances during a period of time where all other elements were known to an acceptable accuracy. A validation mechanism is provided to check the potential utility of the calculated infiltration in wetland management practices. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

The status of artisanal fishing in El Salvador     

《Marine Policy》2015

El Salvador is one of the most environmentally degraded nations in Latin America, but the declining fishing industry is under-studied compared with deforestation and landuse. This paper examines the reactions to fish stock decline of two generations of fishers in La Union, El Salvador on the Golfo de Fonseca, one of the most important fishing areas in Latin America, using face to face interviews and questionaires. Both older (>35 years) and younger (<36 years) fishers supplemented their income with trading, farming and loans from their relatives in the United States. All older fishers reported larger fish catches five and ten years previously than at present. Previously, fishers caught more fish, but significantly more younger fishers than older fishers reported their fathers caught more fish than they did, indicating an increasing gap in fish catches in recent decades. More younger fishers than older fishers had fathers or male kin who were also fishers, indicating young men were less likely to join fishing without a parent or kin already involved. Minorities of both older and younger fishers engaged in supplementary activities. Environmental degradation disuaded fishers from switching to farming or hunting. The findings are similar to findings elsewhere on the decline of fish resources and generational gaps in environmental knowledge, but differ in that some other studies report fewer opportunities for fishers to access alternative or complementary activities. These findings are relevant to Latin American studies, considering the great value of the Golfo de Fonseca to the livelihoods of Central America.  相似文献   

Définition et datation de la Formation de Venaco (Corse) : dépôt d’origine gravitaire d’âge Priabonien     

Jean Ferrandini  Michelle Ferrandini  Philippe Rossi  Brengre Savary-Sismondini 《Comptes Rendus Geoscience》2010,342(12):921-929

Priabonian age is highlighted for the first time in Corsica in the Venaco Formation using the presence of specific microfauna (in particular some representatives of Turborotalia cerroazulensis lineage). This silicoclastic formation is mainly represented by coarse facies. It is composed of three members from south to north and from oldest towards youngest: member of Uboli, Cardo and Orsu. The sedimentologic analysis reveals a gravity depositional environment, involving different type of currents. Sedimentologic and chronologic characteristics make the Venaco Formation and the Annot Formation (p.p.) equivalent. Dating the Venaco Fm. brings confirmation that the green schist metamorphism of the Variscan batholith and the related deformation are from the pre-Priabonian period.  相似文献   

Evaluation of a Quality Control Monitor Material for the Routine Electron Probe Microanalysis of Kimberlite Exploration Garnets     

Deon De Bruin 《Geostandards and Geoanalytical Research》2010,34(3):257-264

Election probe microanalysis of indicator minerals is extensively used in the exploration for kimberlite deposits, the evaluation of specific kimberlite occurrences for their diamond bearing potential and to classify grains into different chemical and lithological mantle associations. Kimberlite exploration programmes can involve several tens of thousands of indicator mineral analyses. Procedures for monitoring data quality and consistency of analyses across large data sets are commonly absent. Suitable monitor minerals should be used to verify the data quality of kimberlite exploration and evaluation data sets. This material should have a suitable composition, be homogenous, be available in sufficient quantities and have a similar appearance to the unknown samples. Garnet P1, a megacryst garnet from the Premier kimberlite, was found to have a suitable composition as a monitor for kimberlite garnet analyses. Data were collected on the monitor material at regular intervals during routine analyses, over an extended period, both as a fixed grain mounted on the sample holder and as separate grains set within batches of routine samples. The data were evaluated to assess the quality and consistency in the analyses of large data sets over time. The monitor material was also analysed at independent laboratories using their routine analytical set-up and calibration procedures for comparative purposes. Values are given for the mean ± 2s range, which can serve as guide values for acceptable analyses for all elements.  相似文献   

Accurate and Precise Elemental Abundance of Zinc in Reference Materials by an Isotope Dilution Mass Spectrometry TIMS Technique     

Osama Y. Ghidan  Robert D. Loss 《Geostandards and Geoanalytical Research》2010,34(2):185-191

A thermal ionisation mass spectrometric technique enabled the abundance of Zn in geological and biological reference materials and water samples to be measured by double spiking isotope dilution mass spectrometry enriched in the ⁶⁷Zn and ⁷⁰Zn isotopes. In the past, thermal ionisation mass spectrometry proved to be difficult for low-level zinc isotopic measurements. The size of Zn samples used for isotopic determination, in particular the biological RMs, represents an important breakthrough. These results represent the most accurate and precise concentrations measured for Zn in these samples. The maximum fractional uncertainty was that for TILL-3 (2%), while the minimum fractional uncertainty was 0.7% for both BCR-1 and W-2. The inhomogeneity of Zn in HISS-1 was revealed while other reference materials appeared homogeneous at the 95% confidence uncertainty. The certified concentration of Zn in HISS-1 and IMEP-19 by their producers are 28% and 3.8% higher than the values measured in this work. These are the first Zn concentration measurements in these materials by the isotope dilution-TIMS technique, except for BCR-1, NIES N^o 9 and IMEP-19. Reducing the blank enabled accurate measurement in water at the ng g^-1 level demonstrating the applicability of the technique for low-level Zn samples.  相似文献   

Calcium,Na, K and Mg Concentrations in Seawater by Inductively Coupled Plasma‐Atomic Emission Spectrometry: Applications to IAPSO Seawater Reference Material,Hydrothermal Fluids and Synthetic Seawater Solutions     

Philippe Besson  Jefferson Degboe  Benjamin Berge  Valérie Chavagnac  Sébastien Fabre  Gilles Berger 《Geostandards and Geoanalytical Research》2014,38(3):355-362

We report a measurement procedure to determine simultaneously the major cation concentrations (Na, Ca, K and Mg) of seawater‐derived solutions by inductively coupled plasma‐atomic emission spectrometry. The best results were obtained when the IAPSO (‘standard’) seawater reference material was diluted by thirty times with Milli‐Q^® water. We obtained an average reference value r_K (the ratio of the mass fraction of potassium to that of chlorine, i.e., (g kg^?1)/(g kg^?1)) for IAPSO seawater of 0.0205 ± 0.0006 (2.9% RSD), not significantly different from 0.0206 ± 0.0005 (2.4% RSD) for seawater composition reported in the literature. The measured Na, Ca and Mg concentrations correspond to r_Na, r_Ca and r_Mg values of 0.5406 ± 0.0026 (0.5% RSD), 0.02192 ± 0.00048 (2.2% RSD) and 0.06830 ± 0.00047 (0.7% RSD), respectively, in line with previous values measured by wet‐chemistry and atomic absorption spectrophotometry or wet‐chemical titration. Our measurement procedure was used successfully on synthetic seawater solutions and high‐temperature hydrothermal fluids.  相似文献   

Sulfur Concentration in Geochemical Reference Materials by Solution Inductively Coupled Plasma‐Mass Spectrometry     

Monica E. Erdman  Cin‐Ty A. Lee  Wenbo Yang  Lynn Ingram 《Geostandards and Geoanalytical Research》2014,38(1):51-60

With implications for the origin of ore deposits, redox state of the atmosphere, and effects of volcanic outgassing, understanding the sulfur cycle is vital to our investigation of Earth processes. However, the paucity of sulfur concentration measurements in silicate rocks and the lack of well‐calibrated reference materials with concentrations relevant to the rocks of interest have hindered such investigations. To aid in this endeavour, this study details a new method to determine sulfur concentration via high mass resolution solution inductively coupled plasma‐mass spectrometry (ICP‐MS). The method is based on an aqua regia leach, involving relatively rapid sample preparation and analysis, and uses small test portion masses (< 50 mg). We utilised two independently prepared standard solutions to calibrate the analyses, resulting in 4% accuracy, and applied the method to eight geochemical reference materials. Measurements were reproducible to within ~ 10%. Sulfur concentrations and isotopes of six reference materials were measured additionally by elemental analyser‐combustion‐isotope ratio mass spectrometry to independently evaluate the accuracy of the ICP‐MS method. Reference materials that yielded reproducible measurements identical to published values from other laboratories (JGb‐1, JGb‐2 and MAG‐1) are considered useful materials for the measurement of sulfur. Reference materials that varied between studies but were reproducible for a given test portion perhaps suffer from sample heterogeneity and are not recommended as sulfur reference materials.  相似文献   

Precise and Accurate In Situ Determination of Lead Isotope Ratios in NIST,USGS, MPI‐DING and CGSG Glass Reference Materials using Femtosecond Laser Ablation MC‐ICP‐MS     

Chen Kaiyun  Yuan Honglin  Bao Zhian  Zong Chunlei  Dai Mengning 《Geostandards and Geoanalytical Research》2014,38(1):5-21

Lead isotope ratio data were obtained with good precision and accuracy using a 266 nm femtosecond laser ablation (fLA) system connected to a multi‐collector ICP‐MS (MC‐ICP‐MS) and through careful control of analytical procedures. The mass fractionation coefficient induced by 266 nm femtosecond laser ablation was approximately 28% lower than that by 193 nm excimer laser ablation (eLA) with helium carrier gas. The exponential law correction method for Tl normalisation with optimum adjusted Tl ratio was utilised to obtain Pb isotopic data with good precision and accuracy. The Pb isotopic ratios of the glass reference materials NIST SRM 610, 612, 614; USGS BHVO‐2G, BCR‐2G, GSD‐1G, BIR‐1G; and MPI‐DING GOR132‐G, KL2‐G, T1‐G, StHs60/80‐G, ATHO‐G and ML3B‐G were determined using fLA‐MC‐ICP‐MS. The measured Pb isotopic ratios were in good agreement with the reference or published values within 2s measurement uncertainties. We also present the first high‐precision Pb isotopic data for GSE‐1G, GSC‐1G, GSA‐1G and CGSG‐1, CGSG‐2, CGSG‐4 and CGSG‐5 glass reference materials obtained using the femtosecond laser ablation MC‐ICP‐MS analysis technique.  相似文献   

Statistical and geostatistical investigations into the effects of the Gabcikovo hydropower plant on the groundwater resources of northwest Hungary / Analyses statistiques et géostatistiques des effets de la centrale hydroélectrique de Gabcikovo sur les ressources en eaux souterraines du Nord-Ouest de la Hongrie     

《水文科学杂志》2013,58(4)

Abstract

Abstract The construction of the Gabcikovo hydropower plant and the diversion of the Danube River over 25 km into an artificial channel in 1992 influenced the groundwater regime of the region considerably. Statistical and geostatistical methods are used to quantify changes of different groundwater characteristics on the Hungarian side of the river based on observations in the time period 1960–2000. External drift kriging was used to interpolate groundwater levels and the other related variables. While mean groundwater levels did not change appreciably, there are significant changes in the variability. Standard deviations of the groundwater levels and the amplitude of the annual cycle decreased near the old river bed of the Danube. The water-level fluctuations of the Danube have a decreased influence on the groundwater dynamics. Interrelationships between water levels in wells have also changed.  相似文献