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Search Results: 1 - 10 of 406308 matches for " Chris M.Mannaerts "
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Participatory Approach for Integrated Basin Planning with Focus on Disaster Risk Reduction: The Case of the Limpopo River
Mathias Spaliviero,Morgan De Dapper,Chris M.Mannaerts,Antonio Yachan
Water , 2011, DOI: 10.3390/w3030737
Abstract: This paper defends the idea that a participatory approach is a suitable method for basin planning integrating both water and land aspects. Assertions made are based on scientific literature review and corroborated by field experience and research carried out in the Limpopo River basin, a transboundary river located in southern Africa which is affected by periodical floods. The paper explains how a basin strategic plan can be drafted and disaster risk reduction strategies derived by combining different types of activities using a bottom-up approach, despite an institutional context which operates through traditional top-down mechanisms. In particular, the “Living with Floods” experience in the lower Limpopo River, in Mozambique, is described as a concrete example of a disaster adaptation measure resulting from a participatory planning exercise. In conclusion, the adopted method and obtained results are discussed and recommendations are formulated for potential replication in similar contexts of the developing world.
Untangling hydrological pathways and nitrate sources by chemical appraisal in a stream network of a reservoir catchment
M. A. Yevenes ,C. M. Mannaerts
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2012,
Abstract: The knowledge of water source contributions to streamflow is important for understanding chemical contamination origins and the status of biogeochemical cycling in stream networks of catchments. In this study, we evaluated whether a limited number of spatially distributed geochemical tracer data sampled during different hydrological seasons were sufficient to quantify water flow pathways and nitrate sources in a catchment. Six geochemical water constituents (δ2H, δ18O, Cl , SO2 4, Na+, NO 3 and K+) of precipitation, stream water, alluvial sediment pore water and shallow groundwater of a 352 km2 agricultural catchment in the Alentejo region of Portugal were analysed. Exploratory data analysis and end-member mixing analysis (EMMA) were performed to estimate the water source mixing proportions. Residual analysis of principal components was used to identify the appropriate geochemical tracers and the number of end-members (water sources and flow paths), and their proportional contributions to streamflow were quantified. Spearman's rank correlation analysis was further used to identify nitrate origins in the streamflow. Results showed that, when using data from both wet and dry seasons, streamflow chemistry was strongly influenced by shallow groundwater. When only wet season data were modelled, streamflow chemistry was controlled and generated by three end-members: shallow groundwater, alluvial sediment pore water and precipitation. Isotope signatures of stream water were located mostly below the local meteoric water line (LMWL) and plotted along a local evaporation line (LEL), reflecting the permanence in the streamflow of shallow groundwater subjected to prior evaporation. Interpretation of isotope signatures during summer showed an isotopic enrichment in both streamflow and shallow groundwater. Measured and historical stream nitrate concentrations appeared to be strongly related to shallow groundwater. In addition, two hydrochemical data outliers for almost every solute from two sample points were identified by the analysis and could be related to local waste water outfalls. The results of this study have improved our understanding of water source contributions to streamflow in the catchment, and also yielded indications of nitrate consumption related to biogeochemical processes in the streamflow network. Moreover, we could conclude that the relatively limited geochemical spatial sample database used in this study was an adequate input for the end-member mixing analysis and diagnostic tools to quantify water sources and nitrate origins in the streamflow of the catchment.
Untangling hydrological pathways and nitrate diffusive sources by chemical appraisal in a stream network of a reservoir catchment
M. A. Yevenes-Burgos,C. M. Mannaerts
Hydrology and Earth System Sciences Discussions , 2011, DOI: 10.5194/hessd-8-2289-2011
Abstract: Stable water isotopes and water hydrochemistry of a catchment in the Alentejo region, south Portugal, were analysed to investigate source origins of water and nitrate flows towards a reservoir. The 353 km2 headwater catchment of Roxo river, is strongly influenced by agricultural impacts, and high variations in water and chemical inflows into an important drinking and irrigation water supply (108 m3) are observed. This leads to regular disputes on water quantity and quality amongst local authorities and population. Three sampling campaigns in different seasons were used to address the temporal and spatial variations in stream and groundwater hydrochemistry and water isotopic signatures. A total of 27 sampling points from the stream network, shallow groundwater and reservoir were used. Isotopic signatures and chemistry of precipitation were obtained from local data of the Global Network of Isotopes in Precipitation (GNIP) and the Global Atmosphere Watch (GAWSIS) network. Other meteorological, hydrological and environmental datasets were obtained from local authorities. The stable water isotopes deuterium (δ2H), oxygen-18 (δ18O) together with chloride (Cl–) and sulphate (SO42–) were used as environmental tracers in the hydrological pathways. Water pathways were then related with nitrate concentrations to elucidate potential relationships between the water and nutrient sources. Interpretation of isotope signatures showed a high degree of isotope enrichment in both surface (stream flow) and shallow groundwater. For the entire period, most of stream waters were located right of the global meteoric water line or GMWL and plotted along a local evaporation line (LEL) established for the study area. The LEL showed slopes similar to stream systems in other dry environments. Monthly stream flow and precipitation, seasonal isotope compositions and major ion chemistry data were used for an evaluation of the relative contribution of water sources using an end-member mixing analysis. An extensive PCA or principal component analysis preceded the mixing analysis. Contributions of the three water end-members in the catchment: groundwater, surface runoff and precipitation to stream flow could be identified based on their 2H, 18O and Cl– signatures. Also two hydro chemical data outliers for Cl– and NO3– from two sample points were identified by the analysis and could be related to local waste water outfalls, giving the method also diagnostic value for pollution source allocation. The shallow groundwater source could be related to stream nitrate concentrations during the wet
Deriving inherent optical properties and associated uncertainties for the Dutch inland waters during the Eagle Campaign
M. S. Salama,Z. Su,C. M. Mannaerts,W. Verhoef
Hydrology and Earth System Sciences Discussions , 2009,
Abstract: During the Eagle 2006 campaign intensive in-situ and air/space borne measurements were carried out over the Wolderwijd and Veluwemeer natural waters in the Netherlands. In this paper, we modify the GSM semi-analytical inversion model for these lakes to derive inherent optical properties (IOPs) and their spectral dependencies from air and space borne data. Uncertainties of the derived IOPs are estimated using a nonlinear regression technique. The modified model succeeded in deriving accurate estimates of IOPs with R2 higher than 0.9 and RMSE values equal to 0.12 and 0.05 for absorption and scattering coefficients, respectively. Finally, we show that the uncertainty of derived absorption coefficients is slightly independent of absorption's magnitude. While the uncertainty of all derived IOPs increases with water turbidity.
Changes in land cover and stream flows in Gilgel Abbay catchment, Upper Blue Nile basin – Ethiopia
T. H. M. Rientjes,A. T. Haile,C. M. M. Mannaerts,E. Kebede
Hydrology and Earth System Sciences Discussions , 2010, DOI: 10.5194/hessd-7-9567-2010
Abstract: We evaluated the land cover change in the Upper Gilgel Abbay catchment in the Upper Blue Nile basin through classification analysis of remote sensing based land cover data and through assessing the changes in the hydrological regime by statistical analysis of stream flow observations. Results of the land cover classification analysis indicated that 50.9% and 16.7% of the catchment area was covered by forest in 1973 and 2001, respectively. This significant decrease in forest cover is mainly due to expansion of agricultural land. A comparison of stream flow time series of the Upper Gilgel Abbay catchment to stream flow time series from two neighbouring catchments shows a different trend and a statistically significant change over time. In 1986–2001, the annual and the high flows of the catchment increased by 13% and 46%, respectively while the low flows decreased by 35%. Generally, the results indicate significant changes in land cover and the hydrological regimes of the Upper Gilgel Abbay catchment over the past 30 years.
Deriving inherent optical properties and associated inversion-uncertainties in the Dutch Lakes
M. S. Salama, A. Dekker, Z. Su, C. M. Mannaerts,W. Verhoef
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2009,
Abstract: Remote sensing of water quality in inland waters requires reliable retrieval algorithms, accurate atmospheric correction and consistent method for uncertainty estimation. In this paper, the GSM semi-analytical inversion model is modified for inland waters to derive inherent optical properties (IOPs) and their spectral dependencies from air and space borne data. The modified model was validated using two data sets from the Veluwe and the Vecht Dutch lakes. For the Veluwe lakes, the model was able to derive a linear relationship between measured concentrations and estimated IOPs with R2 values above 0.7 for chlorophyll-a (Chl-a) and up to 0.9 for suspended particulate matters (SPM). In the Vecht lakes, the modified model derived accurate values of IOPs. The R2 values were 0.89 for Chl-a and up to 0.95 for SPM. The RMSE values were 0.93 mg m 3 and 0.56 g m 3 for Chl-a and SPM respectively. Finally, the IOPs of the Veluwe lakes are derived from multi-spectral, ocean color and hyperspectral airborne data. Inversion-uncertainties of the derived IOPs were also estimated using a standard nonlinear regression technique. The study shows that inversion-uncertainties of remote sensing derived IOPs are proportional to water turbidity.
Changes in land cover, rainfall and stream flow in Upper Gilgel Abbay catchment, Blue Nile basin – Ethiopia
T. H. M. Rientjes, A. T. Haile, E. Kebede, C. M. M. Mannaerts, E. Habib,T. S. Steenhuis
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2011,
Abstract: In this study we evaluated changes in land cover and rainfall in the Upper Gilgel Abbay catchment in the Upper Blue Nile basin and how changes affected stream flow in terms of annual flow, high flows and low flows. Land cover change assessment was through classification analysis of remote sensing based land cover data while assessments on rainfall and stream flow data are by statistical analysis. Results of the supervised land cover classification analysis indicated that 50.9 % and 16.7 % of the catchment area was covered by forest in 1973 and 2001, respectively. This significant decrease in forest cover is mainly due to expansion of agricultural land. By use of a change detection procedure, three periods were identified for which changes in rainfall and stream flow were analyzed. Rainfall was analyzed at monthly base by use of the Mann-Kendall test statistic and results indicated a statistically significant, decreasing trend for most months of the year. However, for the wet season months of June, July and August rainfall has increased. In the period 1973–2005, the annual flow of the catchment decreased by 12.1 %. Low flow and high flow at daily base were analyzed by a low flow and a high flow index that is based on a 95 % and 5 % exceedance probability. Results of the low flow index indicated decreases of 18.1 % and 66.6 % for the periods 1982–2000 and 2001–2005 respectively. Results of high flows indicated an increase of 7.6 % and 46.6 % for the same periods. In this study it is concluded that over the period 1973–2005 stream flow has changed in the Gilgel Abbay catchment by changes in land cover and changes in rainfall.
Effect of Nitrogen Removal Simulated by RIP-N Model to a Riparian Zone in Guangting Reservoir Catchment
RIP-N模型对官厅水库库滨带去氮效应的流域尺度模拟分析

WANG Xue-lei,LIU Chang-ming,YANG Sheng-tian,Mannaerts C M,GAO Yun-fei,LI Qian,
王雪蕾
,刘昌明,杨胜天,Mannaerts C M,高云飞,李茜

环境科学 , 2009,
Abstract: An eco-hydrological model system(RIP_N) was constructed to simulate the nitrogen(N) removal by riparian zone in reservoir catchment scale.As a case study,the N removal in Guanting Reservoir riparian zone from March to September in 2007 was estimated.At same time,the field simulated experiment was carried out in Yanqing experimental station,which lies in the northeast part of the catchment.With the experimental data and previous studies,the RIP_N model was calibrated.RIP_N model was consisted with two parts,...
Extending cell cycle synchrony and deconvolving population effects in budding yeast through an analysis of volume growth with a structured Leslie model  [PDF]
Chris C. Stowers, Asmita M. Boczko
Journal of Biomedical Science and Engineering (JBiSE) , 2010, DOI: 10.4236/jbise.2010.310129
Abstract: Budding yeast are a fundamental organism at the center of systems biology research. Understanding the physiology and kinetics of their growth and division is fundamental to the design of models of gene regulation and the interpretation of experimental measurements. We have developed a Leslie model with structured volume and age classes to understand population growth and cell cycle synchrony in budding yeast. The model exhibits broad agreement with a variety of experimental data. The model is easily annotated with volume milestones and cell cycle phases and at least three distinct goals are realizable: 1) One can investigate how any single cell property manifests itself at the population level. 2) One can deconvolve observed population averages into individual cell signals structured by volume and age. 3) One can investigate controllability of the population dynamics. We focus on the latter question. Our model was initially designed to answer the question: Can continuous volume filtration extend synchrony? To date, most general experimental methods can produce an initially synchronous population whose synchrony decays rapidly over three or four cell cycles. Our model predicts that continuous volume filtration can extend this maintenance of synchrony by an order of magnitude. Our data inform the development of simple fluidic devices to extend synchrony in continuous culture at all scales from nanophysiometers to bioreactors.
An Ultradiscrete Matrix Version of the Fourth Painlev Equation
Chris M. Field,Chris M. Ormerod
Advances in Difference Equations , 2007, DOI: 10.1155/2007/96752
Abstract: This paper is concerned with the matrix generalization of ultradiscrete systems. Specifically, we establish a matrix generalization of the ultradiscrete fourth Painlev equation (ud-PIV). Well-defined multicomponent systems that permit ultradiscretization are obtained using an approach that relies on a group defined by constraints imposed by the requirement of a consistent evolution of the systems. The ultradiscrete limit of these systems yields coupled multicomponent ultradiscrete systems that generalize ud-PIV. The dynamics, irreducibility, and integrability of the matrix-valued ultradiscrete systems are studied.
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