bluuebunny/crossref_metadata_2025 huggingface dataset:
Phreatic surface fluctuations within the tropical floodplain paddy field of the Yom River, Thailand
Authors: Chuenchooklin S. , Ichikawa T. , Patamatamkul S. , Sriboonlue V. , Kerdpitaksa C.
Published: April 2010

Abstract. The fluctuation of phreatic surfaces in tropical floodplain was studied for the lower part of the Yom's river basin at Phichit Province in Thailand. The simple water balance budget model was applied to estimate the groundwater recharge. The hydrologic components i.e. average rainfall, surface runoff, and deep percolation were calculated by using climatologically recorded and measured data. The Penman-Monteith's evapotranspiration method was used to estimate potential evapotranspiration for crop water requirement based on climatic data. The 49-points of field infiltration and theirs distribution over the floodplain were measured using ring-infiltrometers. The surface water and phreatic surface deviations from the existing 22-observation wells nearby the Yom River daily observed continuously for 3 years. The observed river water levels and phreatic surface water levels were agreed very well with R2 approx. 0.90. The rising or recessing of those fluctuations was depended on the inundated depth over floodplain or the amount of groundwater withdrawal for crop consuming. Understanding and quantifying the phreatic surface fluctuations in lowland paddy field is crucial for further floodplain management.
Satellite data interpretation of causes and controls on groundwater-seawater flow directions, Merseyside, UK: implications for assessing saline intrusions
Authors: Mukherjee S. , Mohammad E. A. , Worden R. H.
Published: April 2010

Abstract. Groundwater in the Triassic Sherwood Sandstone aquifer, Liverpool, UK, has locally elevated chloride concentrations (~4000 mg/l) in parts of the coastal region although there is freshwater right up to the coast line in other areas. The aquifer is cut my numerous faults with vertical displacements of as much 300 m. SPOT satellite data have been used for the Merseyside area of Liverpool. The satellite data revealed and confirmed the location of some of the main faults since the fault zones of the aquifer have low permeability (due to grain crushing, cataclasis, and clay smearing). Where fault zones outcrop at the surface, below the well-developed regolith, there is locally elevated soil water and thus anomalous vegetation patterns in comparison to unfaulted and highly porous aquifer. The ability to identify fault zones by this satellite-based method strongly suggests that they are at least partially sealing, sub-vertical features in the aquifer. Digitally enhanced and processed satellite data were used to define the relative proportions of sand and clay in the near-coastal (inter-tidal) part of the Mersey estuary. Sand-dominated sediment has higher pixel values in comparison with clay deposits in the near infrared spectral region (NIR). Where open and weathered fault rocks crop out at the surface near the intertidal zone, water movement in these potential surface water conduits is limited where the intertidal zone is clay-dominated since clay will plug the conduit. Where these weathered and open fault-rocks crop out against sand-dominated parts of the coastline, fresh water outflux into the seawater has been imaged using the satellite data. Furthermore, the high and low chloride concentration parts of the aquifer are separated by major, sub-vertical fault zones and have allowed a very steep water table gradient to remain in the aquifer.
Nonlinear estimation of aquifer parameters from surficial resistivity measurements
Authors: Singh K. P.
Published: April 2010

Abstract. The present study is focused on an examination of the correlation relationships for hydraulic permeability and transmissivity with electrical resistivity in a range of fractured and alluvial aquifers. The observed permeability data for fractured rock aquifers at some locations is correlated nonlinearly with electrical resistivity of the aquifers estimated from resistivity sounding data and it is found that the permeability of the aquifer in this region exponentially decreases with increase in resistivity. Permeability of the hard rock aquifer within the weathered zone and alluvium aquifers increases exponentially with increase in resistivity, and transmissivity decreases exponentially. However, in case of fracture rock and sandwiched aquifers, transmissivity increases exponentially with increase in resistivity. An attempt has been made to find general functional relationship between hydraulic parameters and resistivity of the aquifer, and therefore, published and observed data from India and other parts of the world has been taken under consideration. It is found that for fracture rock and alluvium aquifers, permeability and the transmissivity are best defined as the exponential functions of aquifer resistivity. The application of electrical parameters obtained from resistivity data for evaluation of hydraulic parameters has been demonstrated in detail within the Osmania University Campus, Hyderabad (India). The empirical relations between aquifer parameters and resistivity are established for transforming resistivity distribution into permeability and transmissivity of the aquifer. The information thus obtained from resistivity data on permeability of the aquifer and transmissivity distribution in the study area can be used for optimal use and assessment of water resources.
Application of fuzzy representation of geographic boundary to the soil loss model
Authors: Lee G.-S. , Lee K.-H.
Published: April 2010

Abstract. The polygon boundaries on the digital map of land surface characteristic are conventionally represented as a sharp change (categorical format), which results in discrepancy between real world phenomena and the information presented by boundaries on map, and it is especially true for soil properties. This paper presents a probable impact of the representation of geographic boundary for the soil loss model. To do this, the Revise Universal Soil Loss Equation (RUSLE) model is facilitated at a small basin in Korea and then the fuzzy representation of geographic boundary, which is presumably better description of soil properties in nature, was introduced into the soil factors in the RUSLE. The model results were compared to the conventional representation of sharp change in relative terms. The model results show the impact of the fuzzy representation on the RUSLE model is considerable and the soil loss model is expected to use more realistic description for geographic boundaries of land surface characteristics. The method suggested herein is relatively simple and has wide applicability.
Uncertainties in river basin data at various support scales – Example from Odense Pilot River Basin
Authors: Refsgaard J. C. , van der Keur P. , Nilsson B. , Müller-Wohlfeil D.-I. , Brown J.
Published: April 2010

Abstract. In environmental modelling studies field data usually have a spatial and temporal scale of support that is different from the one at which models operate. This calls for a methodology for rescaling data uncertainty from one support scale to another. In this paper data uncertainty is assessed for various environmental data types collected for monitoring purposes from the Odense river basin in Denmark by use of literature information, expert judgement and simple data analyses. It is demonstrated how such methodologies can be applied to data that vary in space or time such as precipitation, climate variables, discharge, surface water quality, soil parameters, groundwater abstraction, heads and groundwater quality variables. Data uncertainty is categorised and assessed in terms of probability density functions and temporal or spatial autocorrelation functions. The autocorrelation length scales are crucial when support scale is changing and it is demonstrated how the assumption used when estimating the autocorrelation parameters may limit the applicability of these autocorrelation functions.
A statistical post-processor for accounting of hydrologic uncertainty in short-range ensemble streamflow prediction
Authors: Seo D.-J. , Herr H. D. , Schaake J. C.
Published: April 2010

Abstract. In addition to the uncertainty in future boundary conditions of precipitation and temperature (i.e. the meteorological uncertainty), parametric and structural uncertainties in the hydrologic models and uncertainty in the model initial conditions (i.e. the hydrologic uncertainties) constitute a major source of error in hydrologic prediction. As such, accurate accounting of both meteorological and hydrologic uncertainties is critical to producing reliable probabilistic hydrologic prediction. In this paper, we describe and evaluate a statistical procedure that accounts for hydrologic uncertainty in short-range (1 to 5 days ahead) ensemble streamflow prediction (ESP). Referred to as the ESP post-processor, the procedure operates on ensemble traces of model-predicted streamflow that reflect only the meteorological uncertainty and produces post-processed ensemble traces that reflect both the meteorological and hydrologic uncertainties. A combination of probability matching and regression, the procedure is simple, parsimonious and robust. For a critical evaluation of the procedure, independent validation is carried out for five basins of the Juniata River in Pennsylvania, USA, under a very stringent setting. The results indicate that the post-processor is fully capable of producing ensemble traces that are unbiased in the mean and in the probabilistic sense. Due primarily to the uncertainties in the cumulative probability distributions (CDF) of observed and simulated flows, however, the unbiasedness may be compromised to a varying degree in real world situations. It is also shown, however, that the uncertainties in the CDF's do not significantly diminish the value of post-processed ensemble traces for decision making, and that probabilistic prediction based on post-processed ensemble traces significantly improves the value of single-value prediction at all ranges of flow.
A time delay artificial neural network approach for flow routing in a river system
Authors: Diamantopoulou M. J. , Georgiou P. E. , Papamichail D. M.
Published: April 2010

Abstract. River flow routing provides basic information on a wide range of problems related to the design and operation of river systems. In this paper, three layer cascade correlation Time Delay Artificial Neural Network (TDANN) models have been developed to forecast the one day ahead daily flow at Ilarionas station on the Aliakmon river, in Northern Greece. The networks are time lagged feed-formatted with delayed memory processing elements at the input layer. The network topology is using multiple inputs, which include the time lagged daily flow values further up at Siatista station on the Aliakmon river and at Grevena station on the Venetikos river, which is a tributary to the Aliakmon river and a single output, which are the daily flow values at Ilarionas station. The choice of the input variables introduced to the input layer was based on the cross-correlation. The use of cross-correlation between the ith input series and the output provides a short cut to the problem of the delayed memory determination. Kalman's learning rule was used to modify the artificial neural network weights. The networks are designed by putting weights between neurons, by using the hyperbolic-tangent function for training. The number of nodes in the hidden layer was determined based on the maximum value of the correlation coefficient. The results show a good performance of the TDANN approach for forecasting the daily flow values, at Ilarionas station and demonstrate its adequacy and potential for river flow routing. The TDANN approach introduced in this study is sufficiently general and has great potential to be applicable to many hydrological and environmental applications.
Energy balance closure and footprint analysis using Eddy Covariance measurements in Eastern Burkina Faso, West Africa
Authors: Bagayoko F. , Yonkeu S. , van de Giesen N. C.
Published: April 2010

Abstract. The quality and the representativeness of the first long-term Eddy Covariance measurements in the savanna zone of West Africa were investigated using the energy balance closure and the footprint analysis. The quality and representativeness of the first long-term Eddy Covariance measurements over the West African savanna were investigated using the energy balance closure and the footprint analysis. The analysis covered four contrasting periods such as the complete dry season (January to March 2004), the dry to wet transition period (April to May 2004), the rainy season (June to September 2004) and the wet to dry transition period (October to November 2004). The results show that the overall energy balance closure can be considered as satisfactory over the whole dataset. The regression fit between (Rn−G) and (H+λE) was significant (P<0.05) with a coefficient of determination (r2) of 0.80 and a slope of 0.88, while the intercept was 25W/m2. The energy balance closure was affected by rain during the rainy season (r2=0.69), and by sampling problems during the transition periods (R2 were 0.80 and 0.86, respectively). The footprint analysis shows that the fetch ranged between 20 m (daytime) and 800 m (nighttime). This range showed that the fetch was adequate and fluxes sampled were representative, especially during the rainy season when the vegetal cover was dominated by crops and grasses with scale length of a few meters. During the dry season when the surface is free from crops and grasses, the measurements were also representative as about 60% of the trees around the station were contributing to the measured fluxes. However, during the transition periods some sampling problems appeared, less than 30% of the trees were contributing to the measured fluxes. The relevance of the dominant wind direction in the representativeness of the measurements was also discussed.
Mapping mean and variance of runoff in a river basin
Authors: Gottschalk L. , Krasovskaia I. , Leblois E. , Sauquet E.
Published: April 2010

Abstract. The study presents an approach to depict the two first order moments of runoff as a function of area (and thus on a map). The focal point is the mapping of the statistical properties of runoff q=q(A,D) in space (area A) and time (time interval D). The problem is divided into two steps. Firstly the first order moment (the long term mean value) is analysed and mapped applying an interpolation procedure for river runoff. In a second step a simple random model for the river runoff process is proposed for the instantaneous point runoff normalised with respect to the long term mean. From this model theoretical expressions for the time-space variance-covariance of the inflow to the river network are developed, which then is used to predict how the second order moment vary along rivers from headwaters to the mouth. The observation data are handled in the frame of a hydrological information system HydroDem, which allows displaying the results either in the form of area dependence of moments along the river branches to the basin outlet or as a map of the variation of the moments across the basin space. The findings are demonstrated on the example of the Moselle drainage basin (French part).
Hydrological parameter estimation for ungauged basin based on satellite altimeter data and discharge modeling. A simulation for the Caqueta River (Amazonian Basin, Colombia)
Authors: Leon J. G. , Seyler F. , Calmant S. , Bonnet M.-P. , Cauhopé M.
Published: April 2010

Abstract. The main objective of this paper is to review the usefulness of altimetric data in ungauged or very poorly monitored basin. It is shown that altimetric measurements can be combined with a single in-situ gauge to derive a reliable stage-discharge relationship upstream from the gauge. The Caqueta River in the Colombian Amazon Basin was selected to simulate a poorly monitored basin. Thus it was possible to derive the stage-discharge relationship for 13 "virtual gauge stations'' defined at river crossing with radar altimetric ground tracks. Stage measurements are derived from altimetric data following the methodology developed by Leon et al. (2006). Discharge is modeled using PROGUM – a flow routing model based on the Muskingum Cunge (M-C) approach considering a diffusion-cum-dynamic wave propagation (Leon et al., 2006) using a single gauge located downstream from the basin under study. Rating curve parameters at virtual stations are estimated by fitting with a power law the temporal series of water surface altitude derived from satellite measurements and the modelled discharges. The methodology allows the ellipsoidal height of effective zero flow to be estimated. This parameter is a good proxy of the mean water depth from which the bottom slope of the reaches can be computed. Validation has been conducted by comparing the results with stages and discharges measured at five other gauges available on the Caqueta basin. Outflow errors range from 10% to 20% between the upper basin and the lower basin, respectively. Mean absolute differences less than 1.10 m between estimated equivalent water depth and measured water depth indicates the reliability of the proposed method. Finally, a 1.2×10−4 mm−1 mean bottom slope has been obtained for the 730 km long reach of the Caqueta main stream considered.
Time dependent dispersivity behavior of non-reactive solutes in a system of parallel fractures
Authors: Suresh Kumar G. , Sekhar M. , Misra D.
Published: April 2010

Abstract. In order to obtain meaningful predictions of contaminant transport, an accurate way of quantifying dispersivity needs to be developed. Results from the theoretical studies suggest that dispersion and the associated dispersivity is non-fickian near the source of contaminant and it grows with travel time and distance. In most tests of a limited duration it is quite probable that the asymptotic regime is not reached, and a proper interpretation of the test should be based on the time-dependent results due to the difficulty associated with the expensive experimental setups added to the marked scarcity of field data. An attempt has been made using spatial moment analysis to evaluate the time dependent dispersivity for a system of parallel fractures with matrix diffusion. The study is limited to non-reactive solutes, having a constant continuous source. An empirical relation to evaluate the dispersivity was developed by us based on the sensitivity analysis, when distinct parallel fractures have constant aperture width and is found to be functions of matrix porosity, matrix diffusion coefficient and injected fracture velocity at pre-asymptotic stage. The system becomes more complex when the aperture widths of the distinct parallel fractures are varied, as it appears that the initial development period of non-fickian behavior may be long due to the continuous lateral mixing of the solute body. It is found that dispersivity at pre-asymptotic regime increases with the coefficient of variation for distinct parallel fractures with varying aperture widths.
Temporal stability of soil moisture spatial variability at two scales and its implication for optimal field monitoring
Authors: Zhou X. , Lin H. , Zhu Q.
Published: April 2010

Abstract. Soil moisture spatial distribution is a key component in characterizing and modeling water movement at multiple scales. The temporal stability of soil moisture spatial distribution at multiple depths was investigated at the 7.9-ha Shale Hills Catchment in central Pennsylvania with a year-round monitoring of 77 sites distributed across the catchment. For this catchment with heterogeneous soils and landforms, integration of soils information into the temporal stability assessment provided a more accurate location of representative monitoring sites for capturing mean soil moisture. The temporal stability pattern of soil moisture at the swale scale was similar to that at the catchment scale, suggesting that the swale could be used as a representative unit in the catchment study in terms of mean soil moisture dynamics. The temporal stability of soil moisture variability in this catchment varied over space and seasons. Temporally stable sites were found in the northwestern and southeastern parts of the catchment, while the areas near the stream and some swale areas had lower temporal stability. The spatial distribution of soil moisture was more stable over time during wet seasons, but less stable during transitional periods (i.e. drying or recharging periods). The temporal stability concept helps the optimal design of field monitoring sites and sampling strategies. On the other hand, the temporally unstable sites provide insights regarding the hydrological processes behind the spatial variability of soil moisture.
Unsupervised classification of saturated areas using a time series of remotely sensed images
Authors: DeAlwis D. A. , Easton Z. M. , Dahlke H. E. , Philpot W. D. , Steenhuis T. S.
Published: April 2010

Abstract. The spatial distribution of saturated areas is an important consideration in numerous applications, such as water resource planning or sighting of management practices. However, in humid well vegetated climates where runoff is produced by saturation excess processes on hydrologically active areas (HAA) the delineation of these areas can be difficult and time consuming. Much of the non-point source pollution in these watersheds originates from these HAAs. Thus, a technique that can simply and reliably predict these areas would be a powerful tool for scientists and watershed managers tasked with implementing practices to improve water quality. Remotely sensed data is a source of spatial information and could be used to identify HAAs, should a proper technique be developed. The objective of this study is to develop a methodology to determine the spatial variability of saturated areas using a temporal sequence of remotely sensed images. The Normalized Difference Water Index (NDWI) was derived from medium resolution LANDSAT 7 ETM+ imagery collected over seven months in the Town Brook watershed in the Catskill Mountains of New York State and used to characterize the areas that were susceptible to saturation. We found that within a single landcover type, saturated areas were characterized by the soil surface water content when the vegetation was dormant and leaf water content of vegetation during the growing season. The resulting HAA map agreed well with both observed and spatially distributed computer simulated saturated areas. This methodology appears promising for delineating saturated areas in the landscape.
Experimental analysis of drainage and water storage of litter layers
Authors: Guevara-Escobar A. , Gonzalez-Sosa E. , Ramos-Salinas M. , Hernandez-Delgado G. D.
Published: April 2010

Abstract. Leaf litter overlying forested floors are important for erosion control and slope stability, but also reduces pasture growth in silvopastoral systems. Little information exists regarding the value of percolation and storage capacity parameters for litter layers. These estimates are needed for modelling better management practices for leaf litter. Therefore, this work measured the effect of four rainfall intensities: 9.8, 30.2, 40.4 and 70.9 mm h−1 on the hydrological response of layers of three materials: recently senesced poplar leaves, fresh grass and woodchips. Maximum storage (Cmax), defined as the detention of water immediately before rainfall cessation, increased with rainfall intensity. The magnitude of the increment was 0.2 mm between the lowest and highest rainfall intensities. Mean values of Cmax were: 1.27, 1.51, 1.67 and 1.65 mm for poplar leaves; 0.63 0.77, 0.73 and 0.76 for fresh grass and; 1.64, 2.23, 2.21 and 2.16 for woodchips. Drainage parameters were: 9.9, 8.8 and 2.2 mm−1 for poplar, grass and woodchips layers. An underlying soil matrix influenced the drainage flow from poplar leaf layers producing pseudo-Hortonian overland flow, but this occurred only when the rainfall intensity was 40.4 and 70.9 mm h−1 and accounted for 0.4 and 0.8‰ of total drainage. On the other hand, the presence of a poplar leaf layer had a damping effect on the drainage rate from the underlying soil matrix, particularly at intermediate rainfall intensities: 30.2 or 40.4 mm h−1.
Assessing winter storm flow generation by means of permeability of the lithology and hydrological soil processes
Authors: Hellebrand H. , Hoffmann L. , Juilleret J. , Pfister L.
Published: April 2010

Abstract. In this study two approaches are used to predict winter storm flow coefficients in meso-scale basins (10 km2 to 1000 km2) with a view to regionalization. The winter storm flow coefficient corresponds to the ratio between rainfall and direct discharge caused by this rainfall. It is basin specific and supposed to give an integrated response to rainfall. The two approaches, which used the permeability of the substratum and soil hydrological processes as basin attributes are compared. The study area is the Rhineland Palatinate and the Grand Duchy of Luxembourg and the study focuses on the Nahe basin and its 16 sub-basins (Rhineland Palatinate). For the comparison, three statistical models were derived by means of regression analysis. The models used the winter storm flow coefficient as the dependent variable in the models; the independent variables were the permeability of the substratum, preliminary derived hydrological soil processes and a combination of both. It is assumed that the permeability and the preliminary derived hydrological soil processes carry different layers of information. Cross-validation and a statistical test were used to determine and evaluate model differences. The cross-validation resulted in a best model performance for the model that used both parameters, followed by the model that used the preliminary hydrological soil processes. From the statistical test it was concluded that the models come from different populations, carrying different information layers. Analysis of the residuals of the models indicated that the permeability and hydrological soil processes did provide complementary information. Simple linear models appeared to perform well in describing the winter storm flow coefficient at the meso-scale when a combination of the permeability of the substratum and soil hydrological processes served as independent parameters.
Computationally efficient calibration of WATCLASS Hydrologic models using surrogate optimization
Authors: Kamali M. , Ponnambalam K. , Soulis E. D.
Published: April 2010

Abstract. In this approach, exploration of the cost function space was performed with an inexpensive surrogate function, not the expensive original function. The Design and Analysis of Computer Experiments(DACE) surrogate function, which is one type of approximate models, which takes correlation function for error was employed. The results for Monte Carlo Sampling, Latin Hypercube Sampling and Design and Analysis of Computer Experiments(DACE) approximate model have been compared. The results show that DACE model has a good potential for predicting the trend of simulation results. The case study of this document was WATCLASS hydrologic model calibration on Smokey-River watershed.
Local δ18O and δ²H variability in UK rainfall
Authors: Jones M. D. , Leng M. J. , Arrowsmith C. , Deuchars C. , Hodgson J. , Dawson T.
Published: April 2010

Abstract. Rainfall collected twice weekly from 3 nearby UK stations between November 2004 and October 2006 allows local differences in δ18O and δ2H to be observed. Local gradients in δ18Op appear to be of the same order of magnitude as national trends, suggesting the spatial δ18Op picture is more complicated than the one currently available from sparse GNIP coverage. Comparing data from this study with previous work we find that average δ18Op has changed in the UK over the last 20 years concurrent with an average temperature increase although inter-annual controls on the values remain seasonal temperature and the amount of precipitation in each rain event. Climate-isotope relationships observed from the weekly data do not explain the observed decadal scale shifts.
Analysis of effective resistance calculation methods and their effect on modelling evapotranspiration in two different patches of vegetation in semi-arid SE Spain
Authors: Were A. , Villagarcía L. , Domingo F. , Alados-Arboledas L. , Puigdefábregas J.
Published: April 2010

Abstract. Effective parameters are of major importance in modelling surface fluxes at different scales of spatial heterogeneity. Different ways to obtain these effective parameters for their use in meso-scale and GCM models have been studied. This paper deals with patch-scale heterogeneity, where effective resistances were calculated in two patches with different vegetation (Retama sphaerocarpa (L.) Boiss shrubs, and herbaceous plants) using different methods: aggregating soil and plant resistances in parallel, in series or by an average of both. Effective aerodynamic resistance was also calculated directly from patch fluxes. To assess the validity of the different methods used, the Penman-Monteith equation was used with effective resistances to estimate the total λ E for each patch. The λ E estimates found for each patch were compared to Eddy Covariance system measurements. Results showed that for effective surface resistances, parallel aggregation of soil and plant resistances led to λ E estimates closer to the measured λ E in both patches (differences of around 10%). This may be due to the fact that in semi-arid areas, with very sparse vegetation, soil resistances are much higher than plant resistances, and therefore parallel aggregation attenuates the effect of the high soil resistances on λ E modelling. Results for effective aerodynamic resistances differed depending on the patch considered and the method used to calculate them. The use of effective aerodynamic resistance calculated from fluxes provided less accurate estimates of λ E compared to the measured λ E, than the use of effective aerodynamic resistances aggregated from soil and plant resistances. The results reported in this paper show that the best way of aggregating soil and plant resistances depend on the type of resistance, and the type of vegetation in the patch.
Statistical distribution of series of 12 monthly concentration samples for environmental classification of rivers
Authors: Eliasson J. , Thordarson T.
Published: April 2010

Abstract. Environmental monitoring and classification of rivers in the northern hemisphere is frequently hampered by lack of infrastructure in the scarcely populated areas of the north. Carefully designed economical methods are important. Analysis of 15 constituents in 14 rivers in Iceland show that monthly samples for a period of 1 year are sufficient for classification provided that the correct statistical distribution is known. Normalizing and plotting all the constituents in each river by rank shows systematic deviations from both the normal and lognormal distributions. When the constituents are pooled by river the result is one distribution for each river, all very similar. A new cumulative distribution function (DoC) is formed as the average of these. It has a long tail similar to that of the lognormal distribution but below the 60% quantile, the DoC differs a lot from the lognormal so if it is to be used, an unbiased estimate of the scale and location parameters will in most cases be difficult to obtain if more than 30–40% of the highest points is used. The influence of the DoC on the classification result is very strong when the 90% quantile is used for classification, but fades out at the 60% quantile. It is shown that the storage effect in rivers with a lake that holds some weeks flow in storage, can have a great influence on the classification result.
Multi-method geophysical measurements for soil science investigations in the vadose zone
Authors: Weihnacht B. , Börner F.
Published: April 2010

Abstract. We studied the changes of geophysical parameters on a soil wall of the testfield Grenzhof (University of Heidelberg). The unsaturated materials investigated range from coarse-grain gravel to sandy loam. Ground-penetrating radar, ultrasound transmission and complex conductivity measurements were applied as geophysical methods. The measured parameters were used to calculate soil parameters such as porosity, water content, density and grain surface area necessary to obtain geohydraulic parameters such as hydraulic conductivity, field capacity and retention parameters. Soil samples were taken and analysed regarding porosity, apparent density, true density and internal surface. The comparison between petrophysical data from the laboratory and from geophysical measurements showed good correlations for the majority of the data.
Water quality limits for Atlantic salmon (Salmo salarL.) exposed to short term reductions in pH and increased aluminum simulating episodes
Authors: Kroglund F. , Rosseland B. O. , Teien H.-C. , Salbu B. , Kristensen T. , Finstad B.
Published: April 2010

Abstract. Acidification has caused the loss or reduction of numerous Atlantic salmon (Salmo salar L.) populations on both sides of the North Atlantic. Acid deposition peaked in the 1980's and resulted in both chronically and episodically acidified rivers. At present, water quality is improving in all affected rivers due to reduced acid deposition. However, spring snow melt, heavy rainfall and sea salt episodes can still cause short term drops in pH and elevated concentrations of bioavailable aluminum. Technical malfunction in lime dozers will cause short termed episodic spates in the limed rivers. The current situation has prompted a need for dose-response relationships based on short term exposures of Atlantic salmon to assess the potential population effects of episodic acidification. Water quality guidelines for salmon have been lacking, despite a large number of experiments, all demonstrating dose-response relationships between water chemistry and fish health. We have summarized results from 347 short-term (<14 days) exposures of salmon parr and smolt performed between 1990 and 2003 in Norway. The experiments have been performed as bioassays, where fish have been exposed in tanks fed river water, in tanks where the river water quality has been manipulated (added H+ and Al) and as Carlin-tagged smolt releases after preexposure to moderately acidic waters. The results from the various bioassays are compared to water quality limits proposed on basis of the relationship between water quality and population status/health in Norwegian rivers. The focus of this article is placed on chemical-biological interactions that can be drawn across experiments and exposure protocols. We propose dose-response relationships for acid neutralizing capacity (ANC), pH, cationic Al and gill accumulated Al, versus mortality in freshwater, effects on hypo-osmoregulatory capacity in seawater challenge tests and on smolt to adult survival in release experiments. The "no effect" dose depends on the life history stage tested and on the sensitivity of the biomarkers. Parr are more tolerant than smolt. Concentrations of Al that have no significant impact on freshwater life history stages can still have major population effects if they occur prior to smolt migration. While smolt can survive in freshwater for a prolonged period of time (>10 days) at an Al dose resulting in a gill Al concentration of up to 300 μg Alg−1 dw, a 3 day exposure resulting in a gill Al accumulation in the range of 25 to 60 μg Alg−1 dw reduces smolt to adult survival in a dose related manner by 20 to 50%. For smolt to adult survival, the biological significant response is delayed relative to the dose and occurs first after the fish enters the marine environment. In addition to exposure intensity and timing, exposure duration is important for the setting of critical limits.
A conceptual dynamic vegetation-soil model for arid and semiarid zones
Authors: Quevedo D. I. , Francés F.
Published: April 2010

Abstract. Plant ecosystems in arid and semiarid zones show high complexity from the point of view of water resources, since they depend on water availability to carry out their vital processes. In these climates, water stress is the main factor controlling vegetation development. The available water in the system results from a water balance where the soil, vegetation and the atmosphere are the key issues; but it is the vegetation which modulates (to a great extent) the total balance of water and the mechanisms of the feedback between soil and atmosphere, being the knowledge about soil moisture quite relevant for assessing available water and, as a consequence, for growth and plants maintenance and the final water balance in the system. A conceptual dynamic vegetation-soil model (CDVSM) for arid and semiarid zones was developed. This model based in a tank type conceptualization represents in a suitable way, for Mediterranean climate, the vegetation responses to soil moisture fluctuations. Two tanks interconnected were considered using the water balance equation and the appropriate dynamic equation for all considered fluxes. The first one corresponds to the interception process done by the vegetation. The second one models the upper soil moisture determination. In this tank parameters are based on soil and vegetation properties. The transpiration of the vegetation is a function of the soil moisture, the vegetation type and the biomass. Once all water state variables are evaluated at each time step, the modifications in the biomass are made as a function of transpiration rate and water stress. Simulations for monoculture of Quercus Coccifera L. were carried out. Results shows that CDVSM is able to represent the vegetation dynamic, reflecting how the monoculture is stabilized around 0.7 of relative biomass, with adaptation to the soil moisture fluctuations in the long term. The model shows the vegetation adaptation to the variability of the climatic conditions, demonstrating how either in the presence or shortage of water, the vegetation regulates its biomass as well as its rate of transpiration trying to minimize the total water stress.
Water management in the Senegal River Delta: a continuing uncertainty
Authors: Mietton M. , Dumas D. , Hamerlynck O. , Kane A. , Coly A. , Duvail S. , Pesneaud F. , Baba M. L. O.
Published: April 2010

Abstract. Water management is the driving force behind the productivity of the ecosystems of the Senegal River Estuary and floodplains. It is dependent on human decision-making, but has been separated from the River's flooding since the building of the Diama Dam. The current objectives of the Office de Mise en Valeur du fleuve Sénégal (OMVS: Senegal River Development Agency) are mainly turned towards the development of irrigated agriculture on the former floodplains and since 2002 the production of hydroelectric power at Manantali. In October 2003, a four-metre-wide runoff canal, which quickly widened into a breach several hundred metres across, was dug in the Barbary Spit area to protect the city of Saint-Louis from heavy flooding. The hydraulic quality of the area downstream from the dam has improved to the extent that there is no longer any flooding there, but as the management of the dams concerns only the section of the river between Manantali and Diama, a certain amount of flood risk probably still persists. The intrusion of seawater into the estuary is also threatening ecosystems and fresh water supplies, and abruptly altering agricultural practices such as fruit and vegetable growing in the Gandiolais district. When added to the tentative efforts to coordinate the management of the two dams, with no management objective downstream from Diama, such permanent modifications impose serious constraints on the managers and residents of the lower delta. This paper presents an overview of the constraints and uncertainties at different levels and scales. This wholly human-wrought environment can be considered as a learning experience, where a large number of variables need to be monitored closely and an ongoing process of participatory analysis should be backed up by multidisciplinary research.
A variable streamflow velocity method for global river routing model: model description and preliminary results
Authors: Ngo-Duc T. , Oki T. , Kanae S.
Published: April 2010

Abstract. This paper presents an attempt of simulating daily fluctuations of river discharge at global scale. Total Runoff Integrating Pathways (TRIP) is a global river routing model which can help to isolate the river basins, inter-basin transport of water through river channels, as well as collect and route runoff to the river mouths for all the major rivers. In the previous version of TRIP (TRIP 1.0), a simple approach of constant river flow velocity is used. In general, that approach is sufficient to model mean long-term discharges. However, to model short-term fluctuations, more sophisticated approach is required. In this study, we implement a variable streamflow velocity method to TRIP (TRIP 2.0) and validate the new approach over the world's 20 major rivers. Two numerical experiments, one with the TRIP 1.0 and another with TRIP 2.0 are performed. Input runoff is taken from the multi-model product provided by the second Global Soil Wetness Project. For the rivers which have clear daily fluctuations of river discharge, TRIP 2.0 shows advantages over TRIP 1.0, suggesting that TRIP 2.0 can be used to model flood events.
The architecture and prototype implementation of the Model Environment system
Authors: Donchyts G. , Treebushny D. , Primachenko A. , Shlyahtun N. , Zheleznyak M.
Published: April 2010

Abstract. An approach that simplifies software development of the model based decision support systems for environmental management has been introduced. The approach is based on definition and management of metadata and data related to computational model without losing data semantics and proposed methods of integration of the new modules into the information system and their management. An architecture of the integrated modelling system is presented. The proposed architecture has been implemented as a prototype of integrated modelling system using. NET/Gtk{#} and is currently being used to re-design European Decision Support System for Nuclear Emergency Management RODOS (http://www.rodos.fzk.de) using Java/Swing.
Spatially explicit seasonal forecasting using fuzzy spatiotemporal clustering of long-term daily rainfall and temperature data
Authors: Plain M. B. , Minasny B. , McBratney A. B. , Vervoort R. W.
Published: April 2010

Abstract. A major limitation of statistical forecasts for specific weather station sites is that they are not spatial in the true sense. And while spatial predictions have been studied, their results have indicated a lack of seasonality. Global Circulation Models (GCMs) are spatial, but their spatial resolution is rather coarse. Here we propose spatially explicit seasonal forecasting, based on the Fuzzy Classification of long-term (40 years) daily rainfall and temperature data to create climate memberships over time and location. Data were obtained from weather stations across south-east Australia, covering sub-tropical to arid climate zones. Class memberships were used to produce seasonal predictions using correlations with climate drivers and a regression rules approach. Therefore, this model includes both local climate feedback and the continental drivers. The developed seasonal forecasting model predicts rainfall and temperature reasonably accurately. The final 6-month forecast for average maximum temperature and rainfall produced relative errors of 0.89 and 0.56 and Pearson correlation coefficients of 0.83 and 0.82, respectively.
Incorporating infiltration modelling in urban flood management
Authors: Jumadar A. S. , Pathirana A. , Gersonius B. , Zevenbergen C.
Published: April 2010

Abstract. Increasing frequency and intensity of flood events in urban areas can be linked to increase in impervious area due to urbanization, exacerbated by climate change. The established approach of conveying storm water by conventional drainage systems has contributed to magnification of runoff volume and peak flows beyond those of undeveloped catchments. Furthermore, the continuous upgrading of such conventional systems is costly and unsustainable in the long term. Sustainable drainage systems aim at addressing the adverse effects associated with conventional systems, by mimicking the natural drainage processes, encouraging infiltration and storage of storm water. In this study we model one of the key components of SuDS, the infiltration basins, in order to assert the benefits of the approach. Infiltration modelling was incorporated in the detention storage unit within the one-dimensional urban storm water management model, EPA-SWMM 5.0. By introduction of infiltration modelling in the storage, the flow attenuation performance of the unit was considerably improved. The study also examines the catchment scale impact of both source and regional control storage/infiltration systems. Based on the findings of two case study areas modelled with the proposed options, it was observed that source control systems have a greater and much more natural impact at a catchment level, with respect to flow attenuation, compared to regional control systems of which capacity is equivalent to the sum of source control capacity at the catchment.
A new data assimilation approach for improving hydrologic prediction using remotely-sensed soil moisture retrievals
Authors: Crow W. T. , Ryu D.
Published: April 2010

Abstract. A number of recent studies have focused on enhancing hydrologic prediction via the assimilation of remotely-sensed surface soil moisture retrievals into a hydrologic model. The majority of these approaches have viewed the problem from purely a state or parameter estimation perspective in which remotely-sensed soil moisture estimates are assimilated to improve the characterization of pre-storm soil moisture conditions in a hydrologic model, and consequently, its simulation of runoff response to subsequent rainfall. However, recent work has demonstrated that soil moisture retrievals can also be used to filter errors present in satellite-based rainfall accumulation products. This result implies that soil moisture retrievals have potential benefit for characterizing both antecedent moisture conditions (required to estimate sub-surface flow intensities and subsequent surface runoff efficiencies) and storm-scale rainfall totals (required to estimate the total surface runoff volume). In response, this work presents a new sequential data assimilation system that exploits remotely-sensed surface soil moisture retrievals to simultaneously improve estimates of both pre-storm soil moisture conditions and storm-scale rainfall accumulations. Preliminary testing of the system, via a synthetic twin data assimilation experiment based on the Sacramento hydrologic model and data collected from the Model Parameterization Experiment, suggests that the new approach is more efficient at improving stream flow predictions than data assimilation techniques focusing exclusively on the constraint of antecedent soil moisture conditions.