bluuebunny/crossref_metadata_2025 huggingface dataset:
Potential impacts to freshwater ecosystems caused by flow regime alteration under changing climate conditions in Taiwan
Authors: Suen J.-P.
Published: April 2010

Abstract. Observed increases in the Earth's surface temperature bring with them associated changes in precipitation and atmospheric moisture that consequentially alter river flow regimes. This paper uses the Indicators of Hydrologic Alteration approach to examine climate-induced flow regime changes that can potentially affect freshwater ecosystems. Analyses of the annual extreme water conditions at 23 gauging stations throughout Taiwan reveal large alterations in recent years; extreme flood and drought events were more frequent in the period after 1991 than from 1961–1990, and the frequency and duration of the flood and drought events also show high fluctuation. Climate change forecasts suggest that such flow regime alterations are going to continue into the foreseeable future. Aquatic organisms not only feel the effects of anthropogenic damage to river systems, but they also face on-going threats of thermal and flow regime alterations associated with climate change. This paper calls attention to the issue, so that water resources managers can take precautionary measures that reduce the cumulative effects from anthropogenic influence and changing climate conditions.
Inverse modeling of soil characteristics from surface soil moisture observations: potential and limitations
Authors: Loew A. , Mauser W.
Published: April 2010

Abstract. Land surface models (LSM) are widely used as scientific and operational tools to simulate mass and energy fluxes within the soil vegetation atmosphere continuum for numerous applications in meteorology, hydrology or for geobiochemistry studies. A reliable parameterization of these models is important to improve the simulation skills. Soil moisture is a key variable, linking the water and energy fluxes at the land surface. An appropriate parameterisation of soil hydraulic properties is crucial to obtain reliable simulation of soil water content from a LSM scheme. Parameter inversion techniques have been developed for that purpose to infer model parameters from soil moisture measurements at the local scale. On the other hand, remote sensing methods provide a unique opportunity to estimate surface soil moisture content at different spatial scales and with different temporal frequencies and accuracies. The present paper investigates the potential to use surface soil moisture information to infer soil hydraulic characteristics using uncertain observations. Different approaches to retrieve soil characteristics from surface soil moisture observations is evaluated and the impact on the accuracy of the model predictions is quantified. The results indicate that there is in general potential to improve land surface model parameterisations by assimilating surface soil moisture observations. However, a high accuracy in surface soil moisture estimates is required to obtain reliable estimates of soil characteristics.
Surface soil moisture estimates from AMSR-E observations over an arid area, Northwest China
Authors: Wang L. , Wen J. , Zhang T. , Zhao Y. , Tian H. , Shi X. , Wang X. , Liu R. , Zhang J. , Lu S.
Published: April 2010

Abstract. In this paper, 7 years (during the growing season (April–October) of 2002–2008) of the Advanced Microwave Scanning Radiometer (AMSR-E) data taken at a frequency of 6.9 GHz for night observations at both polarizations are processed and used to conduct 7 years of surface soil moisture dataset for an arid area, in Northwestern China. This soil moisture dataset can contribute to better understanding the climate change and forecast modeling for this area. Based on the first-order radiative transfer model calculation, a unique method for estimating surface soil moisture over the study area is developed. Considering extremely complex topography over the study area, we have to present a parameterization of surface roughness at the 6.9 GHz and spatial resolution of the AMSR-E using the annual minimum MPDI (Microwave Polarization Difference Index). For validation purpose, the comparisons of soil moisture patterns with precipitation fields are made. The results indicate the evolutions of soil moisture estimated from the AMSR-E and antecedent ground daily precipitations are in a good agreement. Furthermore, a series of rainfall traces is captured over the Taklimakan Desert. Comparisons of the estimated values of soil moisture with the ground observations are also made for two reprehensive sites over 2002–2004. The results indicate there has a good agreement between them, with higher correlation coefficients (R=0.649, 0.604) and RMSE (3.5, 5.4%), and the soil moisture product derived from the AMSR-E is realistic and acceptable. This new long time series of estimated soil moisture will prove valuable for other studies of climate change and model evaluation.
Dryness/wetness variations in China during the first 50 years of the 21st century
Authors: Zhai J. Q. , Liu B. , Hartmann H. , Su B. D. , Jiang T. , Fraedrich K.
Published: April 2010

Abstract. This study investigates future changes of dryness/wetness in China during the first 50 years of the 21st century according to the Standardized Precipitation Index (SPI), which is calculated by monthly precipitation data of ECHAM5/MPI-OM. Three anthropogenic greenhouse gas emission scenarios SRES-A2, SRES-A1B and SRES-B1 have been considered. The frequency of dry/wet periods in ten river basins is counted and the trend is analyzed and detected by a linear regression model and the Mann-Kendall non-parametric test. The results reveal that there is a trend towards drier conditions from Northeast to Southwest China in scenario A2 and a similar spatial distribution pattern in scenario A1B and B1. Areas with a high frequency of drought are detected under three scenarios. In the next half century, the Haihe River basin is expected to show a significant trend towards drier conditions, which pass the 95% confidence level in scenario A2. In the Yellow River basin, the Huaihe River basin, the Yangtze River basin and the Pearl River basin an obvious trend towards wetter conditions has been detected in scenario A1B. The Songhuajiang River basin, the Haihe River basin, the Yellow River basin and the Huaihe River basin show a trend towards wetter conditions, which passed the 90% confidence level in scenario B1. In addition, a decadal variation of dryness/wetness is projected for all the river basins.
Characteristics of precipitation system accompanied with Changma front at Chujado, Korea, 5 to 6 July in 2007
Authors: You C.-H. , Lee D.-I. , Jang S.-M. , Jang M. , Uyeda H. , Shinoda T.
Published: April 2010

Abstract. The rainy season from June to July in the East Asia is called as the Changma in Korea, the Meiyu in China, or the Baiu in Japan. The mesoscale convective systems which occur near a front frequently lead to severe weather phenomenon such as localized gust and heavy rainfall. An intensive field experiment was conducted at Chujado (33.95° N, 126.28° E) to characterize the precipitating system and the size distribution during a Changma period between 21 June 2007 and 11 July 2007. The precipitation system caused heavy rainfalls in Chujado for 20 h and three identified rainfall cases were analyzed using the Doppler radar data, disdrometer data, NCEP/NCAR reanalysis data, and sounding data Based on the radar reflectivity at Chujado, each rainfall system maintained for 7 h, 4 h, and 9 h, respectively. The analysis with the total vertical wind shear (TVWS) and the directional vertical wind shear (DVWS) shows that the temperature gradient was the strongest near the surface. Both warm and cold advections were occurred in all cases. The deep warm advection turns out to cause the longer rainfall lifetime and stronger rainrate but smaller raindrop size. The unstable atmospheric condition, which has cold advection at the surface and warm advection in higher level, causes the larger size diameter of raindrop.
Regional estimation of daily to annual evapotranspiration with MODIS data in the Yellow River Delta wetland
Authors: Jia L. , Xi G. , Liu S. , Huang C. , Yan Y. , Liu G.
Published: April 2010

Abstract. Evapotranspiration (ET) from the wetland of the Yellow River Delta is one of the important components in the water cycle, which represents the water consumption by the plants and evaporation from the water and the non-vegetated surfaces. Reliable estimates of the total evapotranspiration from the wetland is useful information both for understanding the hydrological process and for water management to protect this natural environment. Due to the heterogeneity of the vegetation types and canopy density and of soil water content over the wetland (specifically over the natural reserve areas), it is difficult to estimate the regional evapotranspiration extrapolating measurements or calculations usually done locally for a specific land cover type. Remote sensing can provide observations of land surface conditions with high spatial and temporal resolution and coverage. In this study, a model based on the Energy Balance method was used to calculate daily ET using instantaneous observations of land surface reflectance and temperature from MODIS when the data were available on clouds-free days. A time series analysis algorithm is then applied to generate a time series of daily ET over a year period by filling the gaps in the observation series due to clouds. A detailed vegetation classification map is used to help identifying areas of various wetland vegetation types in the YRD wetland. Such information is also used to improve the parameterizations in the energy balance model to improve the accuracy of ET estimates. This study shows that spatial variation of ET is significant over the same vegetation class at a given time and over different vegetation types in different seasons in the YRD wetland.
Groundwater ecohydrology: GIScience tools to forecast change and sustainability of global ecosystems, studies in Africa, Europe and North America
Authors: Steward D. R. , de Lange W. J. , Yang X. , Vasak S. L. , Olsthoorn T. N.
Published: April 2010

Abstract. This study examines the interface between groundwater hydrology and ecology, and addresses a scientific grand challenge to develop a comprehensive, systematic understanding of continental water dynamics by linking the hydrosphere and biosphere. There exists a current lack of data interoperability between groundwater modeling tools due to differences in numerical techniques – Analytic Element Method (AEM), Finite Difference Method (FDM), and Finite Element Method (FEM) – which lend themselves well to either vector or raster data, and legacy input/output file formats that are not well suited across models. Nonetheless, investigative computational tools are all founded in the same conceptualization of hydrologic properties associated with mass, flux, pathways and residence time. A consistent framework is developed using modern Geographic Information Science (GIScience) methods to organize and archive important information from international datasets and previous groundwater ecohydrology studies organized around aquifer and water point, line, polygon and raster features. Case studies illustrate the efficacy of this platform to address existing data interoperability issues for representative groundwater ecohydrology problems of global significance including the impact of human-induced forcings, change in species, and forcings by natural processes on groundwater ecohydrology. In North America, we study the relationships between groundwater pumping in the Ogallala Aquifer and changes in riparian habitat and phreatophyte species composition. In Europe, we study the impacts of changes in forest species composition on groundwater recharge and baseflow to biologically diverse fens and wetlands in the Veluwe sand hill region of The Netherlands. In Africa, we study the wetlands of the Okavango Delta in Botswana that forms an oasis in the midst of the Kalahari Desert and the role of groundwater in flushing salts from this freshwater ecosystem. In each study, we document the current state of knowledge, identify pertinent datasets and previous studies, develop new conceptual and computer models, and summarize findings. This computational platform provides a framework to study sustainability, to forecast the impacts of changes in forcings, and to provide a scientific underpinning that informs management and public policy debate.
Assessment of water penetration problem in unsaturated soils
Authors: Barari A. , Omidvar M. , Ghotbi A. R. , Ganji D. D.
Published: April 2010

Abstract. Unsaturated flow of soils in unsaturated soils is an important problem in geotechnical and geo-environmental engineering. Richards' equation is often used to model this phenomenon in porous media. Obtaining proper solution to this equation therefore provides better means to studying the infiltration into unsaturated soils. Available methods for the solution of Richards' equation mostly fall in the category of numerical methods, often having restrictions for practical cases. In this research, two analytical methods known as Homotopy Perturbation Method (HPM) and Variational Iteration Method (VIM) have been successfully utilized for solving Richards' equation. Results obtained from the two methods mentioned show a remarkably high precision in the obtained solution, compared with the existing exact solutions available.
The European flood risk directive: challenges for research
Authors: Mostert E. , Junier S. J.
Published: April 2010

Abstract. In recent years, flood management has shifted from protection against floods to managing the risks of floods. In Europe, this shift is reflected in the Flood risk directive of October 2007 (2007/60/EC; FRD). The FRD requires EU Member States to undertake a preliminary assessment of flood risks and, for areas with a significant flood risk, to prepare flood hazard and flood risk maps and flood risk management plans. The purpose of this paper is to introduce the FRD and discuss the challenges that the FRD poses to research. These challenges include the issue how to define and measure ''flood risk'', the selection of alternatives to be assessed, coping with uncertainty, risk communication, nurturing trust and promoting collaboration. These research challenges cannot be addressed properly within any single discipline and without involving the flood risk managers and other stakeholders. The paper therefore concludes that there is a large need for interdisciplinary and participatory research. This constitutes in fact the biggest research challenge.
Consumptive water use associated with food waste: case study of fresh mango in Australia
Authors: Ridoutt B. G. , Juliano P. , Sanguansri P. , Sellahewa J.
Published: April 2010

Abstract. In many parts of the world, freshwater is already a scarce and overexploited natural resource, raising concerns about global food security and damage to freshwater ecosystems. This situation is expected to intensify with the FAO estimating that world food production must double by 2050. Food chains must therefore become much more efficient in terms of consumptive water use. For the small and geographically well-defined Australian mango industry, having an average annual production of 44 692 t of marketable fresh fruit, the average virtual water content (sum of green, blue and gray water) at orchard gate was 2298 l kg−1. However, due to wastage in the distribution and consumption stages of the product life cycle, the average virtual water content of one kg of Australian-grown fresh mango consumed by an Australian household was 5218 l. This latter figure compares to an Australian-equivalent water footprint of 217 l kg−1, which is the volume of direct water use by an Australian household having an equivalent potential to contribute to water scarcity. Nationally, distribution and consumption waste in the food chain of Australian-grown fresh mango to Australian households represented an annual waste of 26.7 Gl of green water and 16.6 Gl of blue water. These findings suggest that interventions to reduce food chain waste will likely have as great or even greater impact on freshwater resource availability as other water use efficiency measures in agriculture and food production.
Iterative approach to modeling subsurface stormflow based on nonlinear, hillslope-scale physics
Authors: Spaaks J. H. , Bouten W. , McDonnell J. J.
Published: April 2010

Abstract. Soil water transport in small, humid, upland catchments is often dominated by subsurface stormflow. Recent studies of this process suggest that at the plot scale, generation of transient saturation may be governed by threshold behavior, and that transient saturation is a prerequisite for lateral flow. The interaction between these plot scale processes yields complex behavior at the hillslope scale. We argue that this complexity should be incorporated into our models. We take an iterative approach to developing our model, starting with a very simple representation of hillslope rainfall-runoff. Next, we design new virtual experiments with which we test our model, while adding more structural complexity. In this study, we present results from three such development cycles, corresponding to three different hillslope-scale, lumped models. Model1 is a linear tank model, which assumes transient saturation to be homogeneously distributed over the hillslope. Model2 assumes transient saturation to be heterogeneously distributed over the hillslope, and that the spatial distribution of the saturated zone does not vary with time. Model3 assumes that transient saturation is heterogeneous both in space and in time. We found that the homogeneity assumption underlying Model1 resulted in hillslope discharge being too steep during the first part of the rising limb, but not steep enough on the second part. Also, peak height was underestimated. The additional complexity in Model2 improved the simulations in terms of the fit, but not in terms of the dynamics. The threshold-based Model3 captured most of the hydrograph dynamics (Nash-Sutcliffe efficiency of 0.98). After having assessed our models in a lumped setup, we then compared Model1 to Model3 in a spatially explicit setup, and evaluated what patterns of subsurface flow were possible with model elements of each type. We found that Model1 tended to generate relatively smooth, steady state-like spatial patterns. Model3 generated more complex patterns, in which lateral flow could be concurrently increasing and decreasing in different parts of the hillslope. We realize that the concepts proposed in this manuscript do not represent the only way in which nonlinear dynamics may be implemented in a model of subsurface stormflow. However, we believe that development of new model structures and the subsequent confrontation of model results with existing preconceptions will lead to a better understanding of subsurface stormflow and catchment runoff dynamics.
Variability of rainfall in Peninsular Malaysia
Authors: Wong C. L. , Venneker R. , Uhlenbrook S. , Jamil A. B. M. , Zhou Y.
Published: April 2010

Abstract. This study analyzed and quantified the spatial patterns and time-variability of rainfall in Peninsular Malaysia on monthly, yearly and monsoon temporal scales. We first obtained an overview of rainfall patterns through the analysis of 16 point data sources. The results led to choosing three distinct regions, i.e.~the east coast, inland and west coast regions. For detailed analysis, Shepard's interpolation scheme was applied to the station data to produce daily rainfall fields on a 0.05 degree resolution grids for the period 1971–2006. The rainfall characteristics in time and space derived from a frequency analysis were found to be distinctly different in these three regions. In the east coast region, monthly rainfall shows a significant periodicity dominated by an annual cycle, followed by a half-year cycle. The inland and west coast regions show that the dominant periodic fluctuations in the monthly rainfall are dominated by a half-year cycle, followed by an annual cycle. The long-term rainfall variability analysis shows that the dry and wet conditions in Peninsular Malaysia are not primarily governed by the ENSO events. The results from the individual regions suggest that although the relative variability is influenced by ENSO, local and regional conditions have an effect on the interannual rainfall variability, which is superimposed on the large-scale weather conditions. A significant increasing trends in annual rainfall (9.3 mm/year) and northeast monsoon rainfall (6.2 mm/monsoon) were only detected in the west coast region. No trend was found in the monthly rainfall, except for November in the west coast region. The spatial variation analysis shows that the east coast region, which received substantially higher amounts of rainfall during the northeast monsoon, has lower spatial rainfall variability and a more uniform rainfall distribution than other regions. A larger range for the monthly spatial variation was observed in the west coast region.
Buffering of the salinity intrusion in estuaries by channel convergence
Authors: Gay P. S. , O'Donnell J.
Published: April 2010

Abstract. A one-dimensional advective-diffusive model is used to investigate the influence of channel convergence on the runoff-dependence of the distance salt intrudes from the ocean into estuaries. We express the runoff dependence of the dispersion coefficient as K~ρβ, and that of the intrusion extent as xs~ρ
Spatial modelling of the variability of the soil moisture regime at the landscape scale in the southern Qilian Mountains, China
Authors: Zhao C.-Y. , Qi P.-C. , Feng Z.-D.
Published: April 2010

Abstract. The spatial and temporal variability of the soil moisture status gives an important base for the assessment of ecological (for restoration) and economic (for agriculture) conditions at micro- and meso-scales. It is also an essential input into many hydrological processes models. However, there has been a lack of effective methods for its estimation in the study area. The aim of this study was to determine the relationship between the soil moisture status and precipitation and topographic factors. First, this study compared a linear regression model with interpolating models for estimating monthly mean precipitation and selected the linear regression model to simulate the temporal-spatial variability of precipitation in the southern Qilian Mountainous areas of the Heihe River Basin. Combining topographic index with the distribution of precipitation, we calculated the soil moisture regime in the Pailugou catchment, one representative comprehensive research catchment. The modeled results were tested by the observed soil water content for different times. The correlation coefficient between the modeled soil moisture status and the observed soil water content is quite high (e.g. R2=0.76 in June), assuring our confidence in the spatially-modeled results of the soil moisture status. The method was applied to the southern Qilian Mountainous regions. The results showed that the modelled distribution of the soil moisture status reflected the interplay of the local and landscape climate processes. The driest sites occur on some ridges in northern part and western part of the study area, which are very small catchment areas and of low precipitation rates; the wettest are registered in the low river valley of the Heihe River and its major tributaries are in the eastern part due to large accumulating flow areas and higher precipitation rates. Temporally, the bigger variation of the soil moisture status in the study occurs in July and smaller difference appears in May.
Relating surface backscatter response from TRMM Precipitation Radar to soil moisture: results over a semi-arid region
Authors: Stephen H. , Ahmad S. , Piechota T. C. , Tang C.
Published: April 2010

Abstract. The Tropical Rainfall Measuring Mission (TRMM) carries aboard the Precipitation Radar (TRMMPR) that measures the backscatter (σ°) of the surface. σ° is sensitive to surface soil moisture and vegetation conditions. Due to sparse vegetation in arid and semi-arid regions, TRMMPR σ° primarily depends on the soil water content. In this study we relate TRMMPR σ° measurements to soil water content (ms) in Lower Colorado River Basin (LCRB). σ° dependence on ms is studied for different vegetation greenness values determined through Normalized Difference Vegetation Index (NDVI). A new model of σ° that couples incidence angle, ms, and NDVI is used to derive parameters and retrieve soil water content. The calibration and validation of this model are performed using simulated and measured ms data. Simulated ms is estimated using Variable Infiltration Capacity (VIC) model whereas measured ms is acquired from ground measuring stations in Walnut Gulch Experimental Watershed (WGEW). σ° model is calibrated using VIC and WGEW ms data during 1998 and the calibrated model is used to derive ms during later years. The temporal trends of derived ms are consistent with VIC and WGEW ms data with correlation coefficient (R) of 0.89 and 0.74, respectively. Derived ms is also consistent with the measured precipitation data with R=0.76. The gridded VIC data is used to calibrate the model at each grid point in LCRB and spatial maps of the model parameters are prepared. The model parameters are spatially coherent with the general regional topography in LCRB. TRMMPR σ° derived soil moisture maps during May (dry) and August (wet) 1999 are spatially similar to VIC estimates with correlation 0.67 and 0.76, respectively. This research provides new insights into Ku-band σ° dependence on soil water content in the arid regions.
Statistical downscaling of precipitation: state-of-the-art and application of bayesian multi-model approach for uncertainty assessment
Authors: Hashmi M. Z. , Shamseldin A. Y. , Melville B. W.
Published: April 2010

Abstract. Global Circulation Models (GCMs) are a major tool used for future projections of climate change using different emission scenarios. However, for assessing the hydrological impacts of climate change at the watershed and the regional scale, the GCM outputs cannot be used directly due to the mismatch in the spatial resolution between the GCMs and hydrological models. In order to use the output of a GCM for conducting hydrological impact studies, downscaling is used. However, the downscaling results may contain considerable uncertainty which needs to be quantified before making the results available. Among the variables usually downscaled, precipitation downscaling is quite challenging and is more prone to uncertainty issues than other climatological variables. This paper addresses the uncertainty analysis associated with statistical downscaling of a watershed precipitation (Clutha River above Balclutha, New Zealand) using results from three well reputed downscaling methods and Bayesian weighted multi-model ensemble approach. The downscaling methods used for this study belong to the following downscaling categories; (1) Multiple linear regression; (2) Multiple non-linear regression; and (3) Stochastic weather generator. The results obtained in this study have shown that this ensemble strategy is very efficient in combining the results from multiple downscaling methods on the basis of their performance and quantifying the uncertainty contained in this ensemble output. This will encourage any future attempts on quantifying downscaling uncertainties using the multi-model ensemble framework.
Hydroclimate variability and its statistical links to the large-scale climate indices for the Upper Chao Phraya River Basin, Thailand
Authors: Singhrattna N. , Babel M. S. , Perret S. R.
Published: April 2010

Abstract. The local hydroclimates get impacts from the large-scale atmospheric variables via atmospheric circulation. The developing of their relationships could enhance the understanding of hydroclimate variability. This study focuses on the Upper Chao Phraya River Basin in Thailand in which rainfall is influenced by the Indian Ocean and tropical Pacific Ocean atmospheric circulation. The Southwest monsoon from the Indian Ocean to Thailand is strengthened by the temperature gradient between land and ocean. Thus, the anomalous sea surface temperature (SST) is systematically correlated with the monthly rainfall and identified as the best predictor based on the significant relationships revealed by cross-correlation analysis. It is found that rainfall, especially during the monsoon season in the different zones of study basin, corresponds to the different SST indices. This suggests that the region over the ocean which develops the temperature gradient plays a role in strengthening the monsoon. The enhanced gradient with the SST over the South China Sea is related to rainfall in High Rainfall Zone (HRZ); however, the anomalous SST over the Indian Ocean and the equatorial Pacific Ocean are associated with rainfall in Normal and Low Rainfall Zone (NRZ and LRZ) in the study area. Moreover, the identified predictors are related to the rainfall with lead periods of 1–4 months for the pre-monsoon rainfall and 6–12 months for the monsoon and dry season rainfall. The study results are very useful in developing rainfall forecasting models and consequently in the management of water resources and extreme events.
Assessment of vadose zone sampling methods for detection of preferential herbicide transport
Authors: Peranginangin N. P. , Richards B. K. , Steenhuis T. S.
Published: April 2010

Abstract. Accurate soil water sampling is needed for monitoring of pesticide leaching through the vadose zone, especially in soils with significant preferential flowpaths. We assessed the effectiveness of wick and gravity pan lysimeters as well as ceramic cups (installed 45–60 cm deep) in strongly-structured silty clay loam (Hudson series) and weakly-structured fine sandy loam (Arkport series) soils. Simulated rainfall (10–14 cm in 4 d, approximately equal to a 10-yr, 24 h storm) was applied following concurrent application of agronomic rates (0.2 g m−2) of atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine) and 2,4-D (2,4-dichloro-phenoxy-acetic acid) immediately following application of a chloride tracer (22–44 g m−2). Preferential flow mechanisms were observed in both soils, with herbicide and tracer mobility greater than would be predicted by uniform flow. Preferential flow was more dominant in the Hudson soil, with earlier breakthroughs observed. Mean wick and gravity pan sampler percolate concentrations at 60 cm depth ranged from 96 to 223 μg L−1 for atrazine and 54 to 78 μg L−1 for 2,4-D at the Hudson site, and from 7 to 22 μg L−1 for atrazine and 0.5 to 2.8 μg L−1 for 2,4-D at the Arkport site. Gravity and wick pan lysimeters had comparably good collection efficiencies at elevated soil moisture levels, whereas wick pan samplers performed better at lower moisture contents. Cup samplers performed poorly with wide variations in collections and solute concentrations.
The impact of climate change on hydrological patterns in Czech headwater catchments
Authors: Benčoková A. , Krám P. , Hruška J.
Published: April 2010

Abstract. The aim of this study was to estimate the impacts of anticipated global climate change on runoff and evapotranspiration in small-forested catchments. The investigated Lysina and Pluhův Bor catchments are situated in the Slavkov Forest in the western part of the Czech Republic. To forecast hydrological patterns for the period 2071–2100, outputs from two general circulation models, HadAM3H and ECHAM4/OPYC3, were downscaled by an RCAO (regional climate model) which ran the SRES emission scenarios A2 and B2 for each model. Bias-corrected RCAO daily outputs were used in combination with the hydrological model Brook90. Annual runoff is predicted to decline by 6–45%, and impacts on the distribution of monthly flow are predicted to be significant, with summer-autumn decreases of 29–96%, and winter increases of up to ~48% compared to mean flow from 1967–1990. Mean daily flows are estimated to decrease by 63–94% from August to November. These changes would have serious ecological consequences, since streams could regularly dry-up for short periods of time.
Identification and mapping of soil erosion areas in the Blue Nile-Eastern Sudan using multispectral ASTER and MODIS satellite data and the SRTM elevation model
Authors: El Haj Tahir M. , Kääb A. , Xu C.-Y.
Published: April 2010

Abstract. This paper is part of a set of studies to evaluate the spatial and temporal variability of soil water in terms of natural as well as land-use changes as fundamental factors for vegetation regeneration in arid ecosystems in the Blue Nile-Sudan. The specific aim is to indicate the spatial distribution of soil erosion caused by the rains of 2006. The current study is conducted to determine whether automatic classification of multispectral Advanced Space borne Thermal Emission and Reflection Radiometer (ASTER) imagery could accurately discriminate erosion gullies. Shuttle Radar Topography Mission (SRTM) is used to orthoproject ASTER data. A maximum likelihood classifier is trained with four classes, Gullies, Flat_Land, Mountains and Water and applied to images from March and December 2006. Validation is done with field data from December and January 2006/2007, and using drainage network analysis of SRTM digital elevation model. The results allow the identification of erosion gullies and subsequent estimation of eroded area. Consequently the results were up-scaled using Moderate Resolution Imaging Spectroradiometer (MODIS) images of the same dates. Because the selected study site is representative of the wider Blue Nile province, it is expected that the approach presented could be applied to larger areas.
The application of GIS based decision-tree models for generating the spatial distribution of hydromorphic organic landscapes in relation to digital terrain data
Authors: Bou Kheir R. , Bøcher P. K. , Greve M. B. , Greve M. H.
Published: April 2010

Abstract. Accurate information about soil organic carbon (SOC), presented in a spatially form, is prerequisite for many land resources management applications (including climate change mitigation). This paper aims to investigate the potential of using geomorphometrical analysis and decision tree modeling to predict the geographic distribution of hydromorphic organic landscapes at unsampled area in Denmark. Nine primary (elevation, slope angle, slope aspect, plan curvature, profile curvature, tangent curvature, flow direction, flow accumulation, and specific catchment area) and one secondary (steady-state topographic wetness index) topographic parameters were generated from Digital Elevation Models (DEMs) acquired using airborne LIDAR (Light Detection and Ranging) systems. They were used along with existing digital data collected from other sources (soil type, geological substrate and landscape type) to statistically explain SOC field measurements in hydromorphic landscapes of the chosen Danish area. A large number of tree-based classification models (186) were developed using (1) all of the parameters, (2) the primary DEM-derived topographic (morphological/hydrological) parameters only, (3) selected pairs of parameters and (4) excluding each parameter one at a time from the potential pool of predictor parameters. The best classification tree model (with the lowest misclassification error and the smallest number of terminal nodes and predictor parameters) combined the steady-state topographic wetness index and soil type, and explained 68% of the variability in field SOC measurements. The overall accuracy of the produced predictive SOC map (at 1:50 000 cartographic scale) using the best tree was estimated to be ca. 75%. The proposed classification-tree model is relatively simple, quick, realistic and practical, and it can be applied to other areas, thereby providing a tool to help with the implementation of pedological/hydrological plans for conservation and sustainable management. It is particularly useful when information about soil properties from conventional field surveys is limited.
Modeling hydrological processes influenced by soil, rock and vegetation in a small karst basin of southwest China
Authors: Zhang Z.-C. , Chen X. , Ghadouani A. , Shi P. , Xue X.-W.
Published: April 2010

Abstract. Hydrological processes in the karst basin are controlled by the permeable multi-media consisting of soil pores, epikarst fractures and underground conduits. Distributed modeling of hydrological dynamics in such heterogeneously hydrogeological conditions is a challenging task. Based on the multi-layer structure of the distributed hydrology-soil-vegetation model (DHSVM), a distributed hydrological model for a karst basin was developed by integrating mathematical routings of porous Darcy flow, fissure flow and underground channel flow. Specifically, infiltration and saturated flow movement within epikarst fractures are expressed by the "cubic law" equation which is associated with fractural width, direction and spacing. A typical karst basin located in Guizhou province of southwest China was selected for this hydrological simulation. The basin has detailed meteorological, soil moisture content and underground flow discharges. In addition, in situ measurements of soil properties and hydraulic conductivities were also available. Distribution of epikarst fractures was statistically generated based on fractural features data collected during field investigations. Hydraulic conductivities of epikarst fractures are estimated based on observed flow discharges as initial values. These parameters together with others are further calibrated through marching the observed and simulated soil moisture contents and underground flow discharges from the basin outlet. The results show that the new model was able to capture the sharp increase and decrease of underground streamflow hydrograph, and as such can be used to investigate hydrological effects in such rock features.
Detailed analysis of tsunami waveforms generated by the 1946 Aleutian tsunami earthquake
Authors: Tanioka Y. , Seno T.
Published: April 2010

Abstract. The 1946 Aleutian earthquake was a typical tsunami earthquake which generated abnormally larger tsunami than expected from its seismic waves. Previously, Johnson and Satake (1997) estimated the fault model of this earthquake using the tsunami waveforms observed at tide gauges. However, they did not model the second pulse of the tsunami at Honolulu although that was much larger than the first pulse. In this paper, we numerically computed the tsunami waveforms using the linear Boussinesq equation to determine the fault model which explains the observed tsunami waveforms including the large second pulse observed at Honolulu. The estimated fault width is 40–60 km which is much narrower than the fault widths of the typical great underthrust earthquakes, the 1957 Aleutian and the 1964 Alasuka earthquakes. A previous study of the 1896 Sanriku earthquake, another typical tsunami earthquake, suggested that the additional uplift of the sediments near the Japan Trench had a large effect on the tsunami generation. In this study, we also show that the additional uplift of the sediments near the trench, due to a large coseismic horizon-tal movement of the backstop, had a significant effect on the tsunami generation of the 1946 Aleutian earthquake. The estimated seismic moment of the 1946 Aleutian earthquake is 17–19 × 1020 20 Nm (Mw 8.1).
Study of tsunami propagation in the Ligurian Sea
Authors: Pelinovsky E. , Kharif C. , Riabov I. , Francius M.
Published: April 2010

Abstract. Tsunami propagation is analyzed for the Ligurian Sea with particular attention on the French coasts of the Mediterranean. Historical data of tsunami manifestation on the French coast are analyzed for the period 2000 B.C.–1991 A.D. Numerical simulations of potential and historical tsunamis in the Ligurian Sea are done in the context of the nonlinear shallow water theory. Tsunami wave heights as well as their distribution function is calculated for historical tsunamis and it is shown that the log-normal distribution describes reasonably the simulated data. This demonstrates the particular role of bottom irregularities for the wave height distribution function near the coastlines. Also, spectral analysis of numerical tide-gauge records is done for potential tsunamis, revealing the complex resonant interactions between the tsunami waves and the bottom oscillations. It is shown that for an earthquake magnitude of 6.8 (averaged value for the Mediterranean Sea) the tsunami phenomenon has a very local character but with long duration. For sources located near the steep continental slope in the vicinity of the French-Italian Rivera, the tsunami tide-gauge records in the vicinity of Cannes – Imperia present irregular oscillations with a characteristic period of 20–30 min and a total duration of 10–20 h. For the western French coasts the amplitudes are significantly less with characteristic low-frequency oscillations (period of 40 min–1 h).
ULF magnetic emissions connected with under sea bottom earthquakes
Authors: Ismaguilov V. S. , Kopytenko Yu. A. , Hattori K. , Voronov P. M. , Molchanov O. A. , Hayakawa M.
Published: April 2010

Abstract. Measurements of ULF electromagnetic disturbances were carried out in Japan before and during a seismic active period (1 February 2000 to 26 July 2000). A network consists of two groups of magnetic stations spaced apart at a distance of ≈140 km. Every group consists of three, 3-component high sensitive magnetic stations arranged in a triangle and spaced apart at a distance of 4–7 km. The results of the ULF magnetic field variation analysis in a frequency range of F = 0.002–0.5 Hz in connection with nearby earth-quakes are presented. Traditional Z/G ratios (Z is the vertical component, G is the total horizontal component), magnetic gradient vectors and phase velocities of ULF waves propagating along the Earth’s surface were constructed in several frequency bands. It was shown that variations of the R(F) = Z/G parameter have a different character in three frequency ranges: F1 = 0.1 ± 0.005, F2 = 0.01 ± 0.005 and F3 = 0.005 ± 0.003 Hz. Ratio R(F3)/R(F1) sharply increases 1–3 days before strong seismic shocks. Defined in a frequency range of F2 = 0.01 ± 0.005 Hz during nighttime intervals (00:00–06:00 LT), the amplitudes of Z and G component variations and the Z/G ratio started to increase ≈ 1.5 months before the period of the seismic activity. The ULF emissions of higher frequency ranges sharply increased just after the seismic activity start. The magnetic gradient vectors (∇ B ≈ 1 – 5 pT/km), determined using horizontal component data (G ≈ 0.03 – 0.06 nT) of the magnetic stations of every group in the frequency range F = 0.05 ± 0.005 Hz, started to point to the future center of the seismic activity just before the seismoactive period; furthermore they continued following space displacements of the seismic activity center. The phase velocity vectors (V ≈ 20 km/s for F = 0.0067 Hz), determined using horizontal component data, were directed from the seismic activity center. Gradient vectors of the vertical component pointed to the closest seashore (known as the "sea shore" effect). The location of the seismic activity centers by two gradient vectors, constructed at every group of magnetic stations, gives an ≈ 10 km error in this experiment.
Tsunami risk assessment in the Marquesas Islands (French Polynesia) through numerical modeling of generic far-field events
Authors: Hébert H. , Schindelé F. , Heinrich P.
Published: April 2010

Abstract. Earthquakes occurring at the Pacific Rim can trigger tsunamis that propagate across the ocean and can produce significant damages far away from the source. In French Polynesia, the Marquesas Islands are the most exposed to the far-field tsunami hazards, since they are not protected by any outer coral reef and since submarine slopes are less steep than in other islands. Between 1994 and 1996, four tsunamis have reached the bays of the archipelago, among them, the tsunami initiated by the Chilean Mw 8.1 earthquake, produced up to 3 m high waves in Tahauku Bay. Numerical modeling of these recent events has already allowed us to validate our method of resolution of hydrodynamics laws through a finite-difference scheme that simulates the propagation of the tsunamis across the ocean and computes the inundation heights (run-up) in remote bays. We present in this paper the simulations carried out to study potentially threatening areas located at the Pacific Rim, on the seismogenic Aleutian and Tonga subduction zones. We use a constant seismic moment source (that of the Mw 8.1 Chile 1995 earthquake, M0 = 1.2 1021 N.m) located at several potential epicenters, with the fault strike adapted from the regional seismotectonics pattern. Our results show that the sources chosen in the Aleutian trench do not produce large inundations in the Marquesas bays, except for the easternmost source (longitude 194° E). Sources located in the Tonga trench do not produce high amplifications either, except for the northernmost one (latitude 16° S). We also discuss the behaviour of the tsunami waves within the archipelago, and evidence contrasting responses depending on the arrival azimuths. These results show that, for a given initial seismic energy, the tsunami amplification in remote bays is highly dependent on the source location and fault strike.
Nonlinear tsunami generation mechanism
Authors: Nosov M. A. , Skachko S. N.
Published: April 2010

Abstract. The nonlinear mechanism of long gravitational surface water wave generation by high-frequency bottom oscillations in a water layer of constant depth is investigated analytically. The connection between the surface wave amplitude and the parameters of bottom oscillations and source length is investigated.
Geophysical Observatory in Kamchatka region for monitoring of phenomena connected with seismic activity
Authors: Uyeda S. , Nagao T. , Hattori K. , Hayakawa M. , Miyaki K. , Molchanov O. , Gladychev V. , Baransky L. , Chtchekotov A. , Fedorov E. , Pokhotelov O. , Andreevsky S. , Rozhnoi A. , Khabazin Y. , Gorbatikov A. , Gordeev E. , Chebrov V. , Sinitzin V. , Lutikov A. , Yunga S. , Kosarev G. , Surkov V. , Belyaev G.
Published: April 2010

Abstract. Regular monitoring of some geophysical parameters in association with seismicity has been carried out since last year at the Japan-Russian Complex Geophysical Observatory in the Kamchatka region. This observatory was organized in connection with the ISTC project in Russia and was motivated by the results of the FRONTIER/RIKEN and FRONTIER/NASDA research projects in Japan. The main purpose of the observations is to investigate the electromagnetic and acoustic phenomena induced by the lithosphere processes (especially by seismic activity). The seismicity of the Kamchatka area is analyzed and a description of the observatory equipment is presented. At present, the activity of the observatory includes the seismic (frequency range ∆F = 0.5 – 40 Hz) and meteorological recordings, together with seismo-acoustic (∆F = 30 – 1000 Hz) and electromagnetic observations: three-component magnetic ULF variations ( ∆F = 0.003 – 30 Hz), three-component electric potential variations ( ∆F < 1.0 Hz), and VLF transmitter’s signal perturbations ( ∆F ~ 10 – 40 kHz).