bluuebunny/crossref_metadata_2025 huggingface dataset:
A Bayesian spatial assimilation scheme for snow coverage observations in a gridded snow model
Authors: Kolberg S. , Rue H. , Gottschalk L.
Published: April 2010

Abstract. A method for assimilating remotely sensed snow covered area (SCA) into the snow subroutine of a grid distributed precipitation-runoff model (PRM) is presented. The PRM is assumed to simulate the snow state in each grid cell by a snow depletion curve (SDC), which relates that cell's SCA to its snow cover mass balance. The assimilation is based on Bayes' theorem, which requires a joint prior distribution of the SDC variables in all the grid cells. In this paper we propose a spatial model for this prior distribution, and include similarities and dependencies among the grid cells. Used to represent the PRM simulated snow cover state, our joint prior model regards two elevation gradients and a degree-day factor as global variables, rather than describing their effect separately for each cell. This transformation results in smooth normalised surfaces for the two related mass balance variables, supporting a strong inter-cell dependency in their joint prior model. The global features and spatial interdependency in the prior model cause each SCA observation to provide information for many grid cells. The spatial approach similarly facilitates the utilisation of observed discharge. Assimilation of SCA data using the proposed spatial model is evaluated in a 2400 km2 mountainous region in central Norway (61° N, 9° E), based on two Landsat 7 ETM+ images generalized to 1 km2 resolution. An image acquired on 11 May, a week before the peak flood, removes 78% of the variance in the remaining snow storage. Even an image from 4 May, less than a week after the melt onset, reduces this variance by 53%. These results are largely improved compared to a cell-by-cell independent assimilation routine previously reported. Including observed discharge in the updating information improves the 4 May results, but has weak effect on 11 May. Estimated elevation gradients are shown to be sensitive to informational deficits occurring at high altitude, where snowmelt has not started and the snow coverage is close to unity. Caution is therefore required when using early images.
Throughfall and temporal trends of rainfall redistribution in an open tropical rainforest, south-western Amazonia (Rondônia, Brazil)
Authors: Germer S. , Elsenbeer H. , Moraes J. M.
Published: April 2010

Abstract. Throughfall volumes and incident rainfall were measured between 23 August and 2 December 2004 as well as from 6 January to 15 April 2005 for individual rain events of differing intensities and magnitudes in an open tropical rainforest in Rondônia, Brazil. Temporal patterns of throughfall spatial variability were examined. Estimated interception was compared to modeled interception obtained by applying the revised Gash model in order to identify sources of throughfall variability in open tropical rainforests. Gross precipitation of 97 events amounted to 1309 mm, 89±5.6% (S.E.) of which reached the forest floor as throughfall. The redistribution of water within the canopy was highly variable in time, which we attribute to the high density of babassu palms (Orbignya phalerata), their seasonal leaf growth, and their conducive morphology. We identified a 10-min rainfall intensity threshold of 30 mmh-1 above which interception was highly variable. This variability is amplified by funneling and shading effects of palms. This interaction between a rainfall variable and vegetation characteristics is relevant for understanding the hydrology of all tropical rainforests with a high palm density.
Water saving through international trade of agricultural products
Authors: Chapagain A. K. , Hoekstra A. Y. , Savenije H. H. G.
Published: April 2010

Abstract. Many nations save domestic water resources by importing water-intensive products and exporting commodities that are less water intensive. National water saving through the import of a product can imply saving water at a global level if the flow is from sites with high to sites with low water productivity. The paper analyses the consequences of international virtual water flows on the global and national water budgets. The assessment shows that the total amount of water that would have been required in the importing countries if all imported agricultural products would have been produced domestically is 1605 Gm3/yr. These products are however being produced with only 1253 Gm3/yr in the exporting countries, saving global water resources by 352 Gm3/yr. This saving is 28 per cent of the international virtual water flows related to the trade of agricultural products and 6 per cent of the global water use in agriculture. National policy makers are however not interested in global water savings but in the status of national water resources. Egypt imports wheat and in doing so saves 3.6 Gm3/yr of its national water resources. Water use for producing export commodities can be beneficial, as for instance in Cote d'Ivoire, Ghana and Brazil, where the use of green water resources (mainly through rain-fed agriculture) for the production of stimulant crops for export has a positive economic impact on the national economy. However, export of 28 Gm3/yr of national water from Thailand related to rice export is at the cost of additional pressure on its blue water resources. Importing a product which has a relatively high ratio of green to blue virtual water content saves global blue water resources that generally have a higher opportunity cost than green water.
The protective and attractive covering of a vegetated embankment using coir geotextiles
Authors: Vishnudas S. , Savenije H. H. G. , Van der Zaag P. , Anil K. R. , Balan K.
Published: April 2010

Abstract. This paper presents the results of a field experiment conducted in Kerala, South India, to test the effectiveness of coir geotextiles for embankment protection. The results reveal that treatment with geotextile in combination with grass is an effective eco-hydrological measure to protect steep slopes from erosion. In the context of sustainable watershed management, coir is a cheap and locally available material that can be used to strengthen traditional earthen bunds or protect the banks of village ponds from erosion. Particularly in developing countries, where coir is abundantly available and textiles can be produced by small-scale industry, this is an attractive alternative for conventional methods. This paper analyses the performance of coir geotextile in different treatments with respect to soil moisture content, protection against erosion and biomass production.
Relationships between statistics of rainfall extremes and mean annual precipitation: an application for design-storm estimation in northern central Italy
Authors: Di Baldassarre G. , Castellarin A. , Brath A.
Published: April 2010

Abstract. Several hydrological analyses need to be founded on a reliable estimate of the design storm, which is the expected rainfall depth corresponding to a given duration and probability of occurrence, usually expressed in terms of return period. The annual series of precipitation maxima for storm duration ranging from 15 min to 1 day, observed at a dense network of raingauges sited in northern central Italy, are analyzed using an approach based on L-moments. The analysis investigates the statistical properties of rainfall extremes and detects significant relationships between these properties and the mean annual precipitation (MAP). On the basis of these relationships, we developed a regional model for estimating the rainfall depth for a given storm duration and recurrence interval in any location of the study region. The applicability of the regional model was assessed through Monte Carlo simulations. The uncertainty of the model for ungauged sites was quantified through an extensive cross-validation.
Searching for the Holy Grail of scientific hydrology: Qt=(S, R, Δt)A as closure
Authors: Beven K.
Published: April 2010

Abstract. Representative Elementary Watershed concepts provide a useful scale-independent framework for the representation of hydrological processes. The balance equations that underlie the concepts, however, require the definition of boundary flux closures that should be expected to be scale dependent. The relationship between internal state variables of an REW element and the boundary fluxes will be nonlinear, hysteretic and scale-dependent and may depend on the extremes of the heterogeneities within the REW. Because of the nonlinearities involved, simple averaging of local scale flux relationships are unlikely to produce an adequate decription of the closure problem at the REW scale. Hysteresis in the dynamic response is demonstrated for some small experimental catchments and it is suggested that at least some of this hysteresis can be represented by the use of simple transfer functions. The search for appropriate closure schemes is the second most important problem in hydrology of the 21st Century (the most important is providing the techniques to measure integrated fluxes and storages at useful scales). The closure problem is a scientific Holy Grail: worth searching for even if a general solution might ultimate prove impossible to find.
Regional climate model data used within the SWURVE project – 1: projected changes in seasonal patterns and estimation of PET
Authors: Ekström M. , Jones P. D. , Fowler H. J. , Lenderink G. , Buishand T. A. , Conway D.
Published: April 2010

Abstract. Climate data for studies within the SWURVE (Sustainable Water: Uncertainty, Risk and Vulnerability in Europe) project, assessing the risk posed by future climatic change to various hydrological and hydraulic systems were obtained from the regional climate model HadRM3H, developed at the Hadley Centre of the UK Met Office. This paper gives some background to HadRM3H; it also presents anomaly maps of the projected future changes in European temperature, rainfall and potential evapotranspiration (PET, estimated using a variant of the Penman formula). The future simulations of temperature and rainfall, following the SRES A2 emissions scenario, suggest that most of Europe will experience warming in all seasons, with heavier precipitation in winter in much of western Europe (except for central and northern parts of the Scandinavian mountains) and drier summers in most parts of western and central Europe (except for the north-west and the eastern part of the Baltic Sea). Particularly large temperature anomalies (>6°C) are projected for north-east Europe in winter and for southern Europe, Asia Minor and parts of Russia in summer. The projected PET displayed very large increases in summer for a region extending from southern France to Russia. The unrealistically large values could be the result of an enhanced hydrological cycle in HadRM3H, affecting several of the input parameters to the PET calculation. To avoid problems with hydrological modelling schemes, PET was re-calculated, using empirical relationships derived from observational values of temperature and PET.
Development of probability distributions for regional climate change from uncertain global mean warming and an uncertain scaling relationship
Authors: Hingray B. , Mezghani A. , Buishand T. A.
Published: April 2010

Abstract. To produce probability distributions for regional climate change in surface temperature and precipitation, a probability distribution for global mean temperature increase has been combined with the probability distributions for the appropriate scaling variables, i.e. the changes in regional temperature/precipitation per degree global mean warming. Each scaling variable is assumed to be normally distributed. The uncertainty of the scaling relationship arises from systematic differences between the regional changes from global and regional climate model simulations and from natural variability. The contributions of these sources of uncertainty to the total variance of the scaling variable are estimated from simulated temperature and precipitation data in a suite of regional climate model experiments conducted within the framework of the EU-funded project PRUDENCE, using an Analysis Of Variance (ANOVA). For the area covered in the 2001–2004 EU-funded project SWURVE, five case study regions (CSRs) are considered: NW England, the Rhine basin, Iberia, Jura lakes (Switzerland) and Mauvoisin dam (Switzerland). The resulting regional climate changes for 2070–2099 vary quite significantly between CSRs, between seasons and between meteorological variables. For all CSRs, the expected warming in summer is higher than that expected for the other seasons. This summer warming is accompanied by a large decrease in precipitation. The uncertainty of the scaling ratios for temperature and precipitation is relatively large in summer because of the differences between regional climate models. Differences between the spatial climate-change patterns of global climate model simulations make significant contributions to the uncertainty of the scaling ratio for temperature. However, no meaningful contribution could be found for the scaling ratio for precipitation due to the small number of global climate models in the PRUDENCE project and natural variability, which is often the largest source of uncertainty. In contrast, for temperature, the contribution of natural variability to the total variance of the scaling ratio is small, in particular for the annual mean values. Simulation from the probability distributions of global mean warming and the scaling ratio results in a wider range of regional temperature change than that in the regional climate model experiments. For the regional change in precipitation, however, a large proportion of the simulations (about 90%) is within the range of the regional climate model simulations.
Modelling the impacts of projected future climate change on water resources in north-west England
Authors: Fowler H. J. , Kilsby C. G. , Stunell J.
Published: April 2010

Abstract. Over the last two decades, the frequency of water resource drought in the UK, coupled with the more recent pan-European drought of 2003, has increased concern over changes in climate. Using the UKCIP02 Medium-High (SRES A2) scenario for 2070–2100, this study investigates the impact of climate change on the operation of the Integrated Resource Zone (IRZ), a complex conjunctive-use water supply system in north-western England. The results indicate that the contribution of individual sources to yield may change substantially but that overall yield is reduced by only 18%. Notwithstanding this significant effect on water supply, the flexibility of the system enables it to meet modelled demand for much of the time under the future climate scenario, even without a change in system management, but at significant expense for pumping additional abstraction from lake and borehole sources. This research provides a basis for the future planning and management of the complex water resource system in the north-west of England.
Estimates of future discharges of the river Rhine using two scenario methodologies: direct versus delta approach
Authors: Lenderink G. , Buishand A. , van Deursen W.
Published: April 2010

Abstract. Simulations with a hydrological model for the river Rhine for the present (1960–1989) and a projected future (2070–2099) climate are discussed. The hydrological model (RhineFlow) is driven by meteorological data from a 90-years (ensemble of three 30-years) simulation with the HadRM3H regional climate model for both present-day and future climate (A2 emission scenario). Simulation of present-day discharges is realistic provided that (1) the HadRM3H temperature and precipitation are corrected for biases, and (2) the potential evapotranspiration is derived from temperature only. Different methods are used to simulate discharges for the future climate: one is based on the direct model output of the future climate run (direct approach), while the other is based on perturbation of the present-day HadRM3H time series (delta approach). Both methods predict a similar response in the mean annual discharge, an increase of 30% in winter and a decrease of 40% in summer. However, predictions of extreme flows differ significantly, with increases of 10% in flows with a return period of 100 years in the direct approach and approximately 30% in the delta approach. A bootstrap method is used to estimate the uncertainties related to the sample size (number of years simulated) in predicting changes in extreme flows.
Developing daily precipitation scenarios for climate change impact studies in the Guadiana and the Tejo basins
Authors:   Hong Xu, Corte-Real J. ,   Budong Qian
Published: April 2010

Abstract. Hydrological models to evaluate the impacts of climate change in the water resources sector require spatially correlated daily precipitation scenarios as model inputs. This paper presents a practical procedure for developing such precipitation scenarios using multisite stochastic weather models or generators conditional on large-scale daily circulation patterns, based on GCM-simulated future mean sea level pressure (MSLP) fields. The procedure is demonstrated on the basis of HadCM3 and HadAM3H simulations with an example for two river basins in the Iberian Peninsula. Changes in daily precipitation scenarios for the region generated by stochastic models are consistent with large-scale precipitation scenarios from direct GCM outputs; however, more localised characteristics have to be found from downscaled precipitation scenarios rather than from direct GCM outputs. This may imply that possible changes in downscaled precipitation reflect the underlying physics in GCMs, so that downscaled daily precipitation scenarios may be more suitable for impact models than the coarse GCM outputs.
A view from the watershed
Authors: Penman H. L. , Pereira H. C. , Nash J. E. , Nixon M.
Published: April 2010

Abstract. Papers by H. L. Penman, H. C. Pereira, J. E. Nash and M. Nixon presented at a one-day Symposium to mark the opening of the Institute of Hydrology's new building in 1973 and reprinted from Institute of Hydrology Report No. 20.
Uncertainty in geological and hydrogeological data
Authors: Nilsson B. , Højberg A. L. , Refsgaard J. C. , Troldborg L.
Published: April 2010

Abstract. Uncertainty in conceptual model structure and in environmental data is of essential interest when dealing with uncertainty in water resources management. To make quantification of uncertainty possible is it necessary to identify and characterise the uncertainty in geological and hydrogeological data. This paper discusses a range of available techniques to describe the uncertainty related to geological model structure and scale of support. Literature examples on uncertainty in hydrogeological variables such as saturated hydraulic conductivity, specific yield, specific storage, effective porosity and dispersivity are given. Field data usually have a spatial and temporal scale of support that is different from the one on which numerical models for water resources management operate. Uncertainty in hydrogeological data variables is characterised and assessed within the methodological framework of the HarmoniRiB classification.
Modelling microbiological water quality in the Seine river drainage network: past, present and future situations
Authors: Servais P. , Billen G. , Goncalves A. , Garcia-Armisen T.
Published: April 2010

Abstract. The Seine river watershed is characterized by a high population density and intense agricultural activities. Data show low microbiological water quality in the main rivers (Seine, Marne, Oise) of the watershed. Today, there is an increasing pressure from different social groups to restore microbiological water quality in order to both increase the safety of drinking water production and to restore the possible use of these rivers for bathing and rowing activities, as they were in the past. A model, appended to the hydro-ecological SENEQUE/Riverstrahler model describing the functioning of large river systems, was developed to describe the dynamics of faecal coliforms (FC), the most usual faecal contamination indicator. The model is able to calculate the distribution of FC concentrations in the whole drainage network resulting from land use and wastewater management in the watershed. The model was validated by comparing calculated FC concentrations with available field data for some well-documented situations in different river stretches of the Seine drainage network. Once validated, the model was used to test various predictive scenarios, as, for example, the impact of the modifications in wastewater treatment planned at the 2012 horizon in the Seine watershed in the scope of the implementation of the european water framework directive. The model was also used to investigate past situations. In particular, the variations of the microbiological water quality in the Parisian area due to population increase and modifications in wastewater management were estimated over the last century. It was shown that the present standards for bathing and other aquatic recreational activities are not met in the large tributaries upstream from Paris since the middle of the 1950's, and at least since the middle of the XIXth century in the main branch of the Seine river downstream from Paris. Efforts carried out for improving urban wastewater treatment in terms or organic matter and nutrient loading resulted in a sensible reduction of microbiological contamination, but were not specific enough toward bacteriological contamination for achieving the objective of restoring levels compatible with bathing activities in the Parisian area.
Assessing winter storm flow generation by means of permeability of the lithology and dominating runoff production 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 direct discharge and 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 dominating runoff generation 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; the independent variables were the permeability of the substratum, preliminary derived dominating runoff generation processes and a combination of both. It is demonstrated that the permeability and the preliminary derived processes carry different layers of information. Cross-validation and statistical tests 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 dominant runoff generation processes. From the statistical tests 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 runoff generation 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 dominating runoff generation processes served as independent parameters.
Marine modification of terrestrial influences on Gulf hypoxia: Part II
Authors: Krug E. C. , Merrifield K.
Published: April 2010

Abstract. This study examines potential marine modification of two classes of terrestrial influence on Gulf hypoxia: (1) the flow of nutrient-rich water from the Mississippi/Atchafalaya River Basin and (2) the massive physical, hydrological, chemical and biological change associated with the Atchafalaya’s partial capture of the Mississippi River. The latter involves repartitioning of a total flow of about 20 000 m3 sec−1, equal to that of 13 Nile Rivers, and a sediment load of 210 million metric tonnes yr−1,nearly 20 times that delivered by all of the rivers of the East Coast of the USA. Also involved is the loss of hundreds-to-thousands of years of stored nutrients and organic matter to the Gulf from enormous coastal wetland loss. This study found that the oceanography of the Gulf minimises the impact of both classes of terrestrial influence from the Mississippi River and its nearby estuaries on Gulf hypoxia. Oceanographic conditions give events associated with the Atchafalaya River a disproportionately large influence on Gulf hypoxia. A truly holistic environmental approach which includes the full effects of this highly dynamic coastal area is recommended to better understand and control Gulf hypoxia.
Development of catchment research, with particular attention to Plynlimon and its forerunner, the East African catchments
Authors: Blackie J. R. , Robinson M.
Published: April 2010

Abstract. Dr J.S.G. McCulloch was deeply involved in the establishment of research catchments in East Africa and subsequently in the UK to investigate the hydrological consequences of changes in land use. Comparison of these studies provides an insight into how influential his inputs and direction have been in the progressive development of the philosophy, the instrumentation and the analytical techniques now employed in catchment research. There were great contrasts in the environments: tropical highland (high radiation, intense rainfall) vs. temperate maritime (low radiation and frontal storms), contrasting soils and vegetation types, as well as the differing social and economic pressures in developing and developed nations. Nevertheless, the underlying scientific philosophy was common to both, although techniques had to be modified according to local conditions. As specialised instrumentation and analytical techniques were developed for the UK catchments many were also integrated into the East African studies. Many lessons were learned in the course of these studies and from the experiences of other studies around the world. Overall, a rigorous scientific approach was developed with widespread applicability. Beyond the basics of catchment selection and the quantification of the main components of the catchment water balance, this involved initiating parallel process studies to provide information on specific aspects of catchment behaviour. This information could then form the basis for models capable of extrapolation from the observed time series to other periods/hydrological events and, ultimately, the capability of predicting the consequences of changes in catchment land management to other areas in a range of climates.
Rare earth element concentrations in dissolved and acid available particulate forms for eastern UK rivers
Authors: Neal C.
Published: April 2010

Abstract. Variations in concentration of yttrium (Y), lanthanum (La), cerium (Ce), neodymium (Nd), samarium (Sm) and gadolinium (Gd) among rivers of eastern England and the border with Scotland are described in relation to the dissolved (<0.45 µM) fraction and acid-available particulate (AAP) fractions. The rivers cover a range of rural, agricultural and urban/industrial environments. Yttrium and the lanthanides show significant levels of both dissolved and acid-available particulate forms (typically about 40% in the dissolved form). For the dissolved phase, Y and the lanthanides are linearly correlated with each other and with iron: most of this dissolved component may be in a micro-particulate/colloidal form. The Y and lanthanide relationships show marked scatter and there are anomalously high La concentrations at times for the rivers Great Ouse, Thames and Wear that are probably linked to pollutant sources. For the Ouse, and especially for one of its tributaries, the Swale, relatively high Sm concentrations are probably associated with mineralisation within the catchment and contamination of the associated flood plain. For the AAP components, there are strong linear relationships with Y and the lanthanides across all the rivers. There is also a strong link between these AAP associated REE and AAP iron, although the scatter is greater and the industrial rivers have a lower lanthanide to iron ratio, probably due to iron-rich contaminants.
Acid episodes in the Allt a'Mharcaidh, Scotland: an investigation based on sub-hourly monitoring data and climatic patterns
Authors: Bonjean M. C. , Hutchins M. G. , Neal C.
Published: April 2010

Abstract. Stream waters in the Allt a'Mharcaidh catchment (Cairngorms, Scotland) have been monitored for flow, conductivity and pH at sub-hourly resolution; and for a range of chemical, biological and physical parameters, less intensively, since the mid-1980s. The Allt a'Mharcaidh stream is subject to acidic events (pH<5.5) triggered by both hydrology and sea-salt inputs from the atmosphere. This paper investigates the drivers of these acidic events using variables derived from sub-hourly monitored data. It also examines the influence of the North Atlantic Oscillation (NAO) on episode severity. Sub-hourly datasets are used to derive multiple regression models expressing stream H+ concentration as a function of the sea-salt conductivity and the peak instantaneous flow rate amongst other explanatory variables. The relationship between sea-salt conductivity and the NAO is significant but hidden due to issues such as time lags and the influence of atmospheric patterns other than the NAO.
The Dart estuary, Devon, UK: a case study of chemical dynamics and pollutant mobility
Authors: Schuwerack P.-M. M. , Neal M. , Neal C.
Published: April 2010

Abstract. Water, sediments and gill and digestive gland tissues of adult common shore crab (Carcinus maenas), collected at Noss Marina, Sandquay (Britannia Royal Naval College), the Dartmouth Pier, Warfleet Cove and Sugary Cove in the Dart estuary, Devon, UK, were analysed for major, minor and trace elements in spring 2004. Total acid-available measurements analysed included the truly dissolved component and acid-available sediments. Trace metal concentrations are associated largely with particulate and micro-particulate/colloidal phases, the latter being able to pass through standard filter papers. Wide ranges of chemical concentrations were found in the water, sediments and tissues at all the locations. In the water column, 48% of the variance is linked to the sea-salt component (Cl, Na, K, Ca, Mg, B, Li and Sr) and the sediment-associated acid-available fractions are linked to Fe-rich lithogenous materials (Ba, Co, Cu, Fe, Mn, V and Zn). In the sediments, trace elements of Cd, Co, Cr, Fe, Pb, Mn, Ni and V are correlated with the sea salts and associated with the fraction of fine sediments within the total sediment. In the gills and the digestive gland tissues of crabs, high concentrations of Al, Cu and Fe are found and there are correlations between acid-available trace metals of Cu, Cr, Fe, Mn, Ni, Sr and Zn. The relationships between trace metal contaminants, their site-specific concentrations, their temporal and spatial variability and the effects of human activities, such as moorland/agriculture with historic mining and recreational activities in the lower Dart estuary, are discussed.
Thresholds, switches and hysteresis in hydrology from the pedon to the catchment scale: a non-linear systems theory
Authors: O’Kane J. P. , Flynn D.
Published: April 2010

Abstract. Hysteresis is a rate-independent non-linearity that is expressed through thresholds, switches, and branches. Exceedance of a threshold, or the occurrence of a turning point in the input, switches the output onto a particular output branch. Rate-independent branching on a very large set of switches with non-local memory is the central concept in the new definition of hysteresis. Hysteretic loops are a special case. A self-consistent mathematical description of hydrological systems with hysteresis demands a new non-linear systems theory of adequate generality. The goal of this paper is to establish this and to show how this may be done. Two results are presented: a conceptual model for the hysteretic soil-moisture characteristic at the pedon scale and a hysteretic linear reservoir at the catchment scale. Both are based on the Preisach model. A result of particular significance is the demonstration that the independent domain model of the soil moisture characteristic due to Childs, Poulavassilis, Mualem and others, is equivalent to the Preisach hysteresis model of non-linear systems theory, a result reminiscent of the reduction of the theory of the unit hydrograph to linear systems theory in the 1950s. A significant reduction in the number of model parameters is also achieved. The new theory implies a change in modelling paradigm.
Towards integrated environmental models of everywhere: uncertainty, data and modelling as a learning process
Authors: Beven K.
Published: April 2010

Abstract. Developing integrated environmental models of everywhere such as are demanded by the requirements of, for example, implementing the Water Framework Directive in Europe, is constrained by the limitations of current understanding and data availability. The possibility of such models raises questions about system design requirements to allow modelling as a learning and data assimilation process in the representation of places, which might well be treated as active objects in such a system. Uncertainty in model predictions not only poses issues about the value of different types of data in characterising places and constraining predictive uncertainty but also about how best to present the pedigree of such uncertain predictions to users and decision-makers.
Hydrological catchment modelling: past, present and future
Authors: Todini E.
Published: April 2010

Abstract. This paper discusses basic issues in hydrological modelling and flood forecasting, ranging from the roles of physically-based and data-driven rainfall runoff models, to the concepts of predictive uncertainty and equifinality and their implications. The evolution of a wide range of hydrological catchment models employing the physically meaningful and data-driven approaches introduces the need for objective test beds or benchmarks to assess the merits of the different models in reconciling the alternative approaches. In addition, the paper analyses uncertainty in models and predictions by clarifying the meaning of uncertainty, by distinguishing between parameter and predictive uncertainty and by demonstrating how the concept of equifinality must be addressed by appropriate and robust inference approaches. Finally, the importance of predictive uncertainty in the decision making process is highlighted together with possible approaches aimed at overcoming the diffidence of end-users.
CLASSIC: a semi-distributed rainfall-runoff modelling system
Authors: Crooks S. M. , Naden P. S.
Published: April 2010

Abstract. This paper describes the development of a semi-distributed conceptual rainfall–runoff model, originally formulated to simulate impacts of climate and land-use change on flood frequency. The model has component modules for soil moisture balance, drainage response and channel routing and is grid-based to allow direct incorporation of GIS- and Digital Terrain Model (DTM)-derived data sets into the initialisation of parameter values. Catchment runoff is derived from the aggregation of components of flow from the drainage module within each grid square and from total routed flow from all grid squares. Calibration is performed sequentially for the three modules using different objective functions for each stage. A key principle of the modelling system is the concept of nested calibration, which ensures that all flows simulated for points within a large catchment are spatially consistent. The modelling system is robust and has been applied successfully at different spatial scales to three large catchments in the UK, including comparison of observed and modelled flood frequency and flow duration curves, simulation of flows for uncalibrated catchments and identification of components of flow within a modelled hydrograph. The role of such a model in integrated catchment studies is outlined.
Eutrophication control in river-systems: an application of INCA-P to the River Lugg
Authors: Wade A. J. , Butterfield D. , Griffiths T. , Whitehead P. G.
Published: April 2010

Abstract. The Integrated Catchments model of Phosphorus dynamics (INCA-P) was applied to the River Lugg to determine the key factors controlling delivery of phosphorus to the main channel and to quantify the relative contribution of diffuse and point sources to the in-stream phosphorus (P) load under varying hydrological conditions. The model is able to simulate the seasonal variations and inter-annual variations in the in-stream total-phosphorus concentrations. However, difficulties in simulating diffuse inputs arise due to equifinality in the model structure and parameters. The River Lugg is split into upper and lower reaches. The upper reaches are dominated by grassland and woodland, so the patterns in the stream-water total-phosphorus concentrations are typical of diffuse source inputs; application of the model leads to estimates of the relative contribution to the in-stream P load from diffuse and point sources as 9:1. In the lower reaches, which are more intensively cultivated and urbanised, the stream-water total-phosphorus concentration dynamics are influenced more by point-sources; the simulated relative diffuse/point contribution to the in-stream P load is 1:1. The model set-up and simulations are used to identify the key source-areas of P in the catchment, the P contribution of the Lugg to the River Wye during years with contrasting precipitation inputs, and the uptake and release of P from within-reach sediment. In addition, model scenarios are run to identify the impacts of likely P reductions at sewage treatment works on the in-stream soluble-reactive P concentrations and the suitability of this as a management option is assessed for reducing eutrophication.
Implications of changing from grazed or semi-natural vegetation to forestry for carbon stores and fluxes in upland organo-mineral soils in the UK
Authors: Reynolds B.
Published: April 2010

Abstract. In the UK, as organo-mineral soils are a significant store of soil organic carbon (SOC), they may become increasingly favoured for the expansion of upland forestry. It is important, therefore, to assess the likely impacts on SOC of this potentially major land use change. Currently, these assessments rely on modelling approaches which assume that afforestation of organo-mineral soils is "carbon neutral". This review evaluates this assumption in two ways. Firstly, UK information from the direct measurement of SOC change following afforestation is examined in the context of international studies. Secondly, UK data on the magnitude and direction of the major fluxes in the carbon cycle of semi-natural upland ecosystems are assessed to identify the likely responses of the fluxes to afforestation of organo-mineral soils. There are few directly relevant measurements of SOC change following afforestation of organo-mineral soils in the UK uplands but there are related studies on peat lands and agricultural soils. Overall, information on the magnitude and direction of change in SOC with afforestation is inconclusive. Data on the accumulation of litter beneath conifer stands have been identified but the extent to which the carbon held in this pool is incorporated into the stable soil carbon reservoir is uncertain. The effect of afforestation on most carbon fluxes is small because the fluxes are either relatively minor or of the same magnitude and direction irrespective of land use. Compared with undisturbed moorland, particulate organic carbon losses increase throughout the forest cycle but the data are exclusively from plantation conifer forests and in many cases pre-date current industry best practice guidelines which aim to reduce such losses. The biggest uncertainty in flux estimates is the relative magnitude of the sink for atmospheric carbon as trees grow and mature compared with that lost during site preparation and harvesting. Given the size of this flux relative to many of the others, this should be a focus for future carbon research on these systems.
A model selection protocol to support the use of models for water management
Authors: Boorman D. B. , Williams R. J. , Hutchins M. G. , Penning E. , Groot S. , Icke J.
Published: April 2010

Abstract. Models are widely used to assist water managers in their duties, yet there is little advice to help water managers select a model appropriate to their particular application. The advice that is available is specific to either the application type or models considered, focused on one aspect of model application, e.g. goodness-of-fit comparisons between observations and simulations and unrealistic, e.g. in separating model selection from wider aspects of the intended application. This paper proposes a model selection protocol that recognises the particular requirements of the application, the roles of individuals associated with modelling studies, and the importance of establishing an informed dialogue between them. Establishing this common understanding at the outset of any modelling study is highly important in securing a successful outcome to the modelling process.
Hydrological change: reaping prosperity and pain in Australia
Authors: Dunin F. X. , Smith C. J. , Denmead O. T.
Published: April 2010

Abstract. The adage: “There is no such thing as a free lunch”, is relevant to land-use hydrology in Australia. Changes in land use to achieve greater productivity of food and fibre may have an adverse effect on the water balance and hence on the natural resource capital of a catchment. An altered regime of catchment outflow accompanies those land-use changes which, together with land degradation, impairs available water resources in quantity and quality and threatens enterprise sustainability, notwithstanding the initial improvement in productivity. Central to any hydrological change is an altered pattern of seasonal and annual water use by vegetation that has become modified in function with an amended transpiration fraction of daily evapotranspiration. In Australia, since measurement of evapotranspiration became feasible, the hydrological consequences of changes in land use have been determined, allowing the benefits in terms of plant productivity achieved through enhanced water use efficiency to be weighed against changed catchment outflows, diminished in either quantity or quality. Four case studies are presented as examples of ecological and hydrological changes: two deal with the upland forest environment and two with arable lowlands. In an upland eucalypt forest, following wildfire with subsequent regeneration from natural seedling establishment, substantial reduction in water yield occurred throughout a 50-year period of succession in the even-aged stand. In comparison, the effect of converting eucalypt forest to pine plantations was less detrimental to the yield of water from the catchments, with substantial growth increases over 30 years. In the lowlands, agricultural productivity, both as annual pasture and as crop, far exceeds that of natural perennial grassland and woodland. This increase in productivity comes not so much from any change to the yield of total water outflow but at the expense of water quality, compromised with increased material transport in suspension and solution resulting from accelerated erosion in association with outbreaks of soil salinity and acidity. The present study is aimed at optimising management to give plant production outcomes that ensure environmental protection through resource conservation. In the uplands, harvesting of water is the dominant consideration so that conservative management with limited plant productivity is sought. In the lowlands, the objective is to devise novel ecosystems with profitable plant production that exercises due control on outflow in maintaining the chemical and physical integrity of the edaphic environment.
Role of climate change in recovery of acidified surface waters
Authors: Wright R. F. , Dillon P. J.
Published: April 2010

Abstract. Surface waters in Europe and North America have begun to recover in response to decreases in emissions of acidifying pollutants to the atmosphere. Variations in climate influence chemical and biological recovery. Part of the EU project Eurolimpacs (Integrated project to evaluate the impacts of global change on European freshwater ecosystems) focuses on the interactive effects of acid deposition and climate on freshwater ecosystems. This special issue of Hydrology and Earth System Sciences is devoted to this topic, and consists of studies conducted in 8 countries on aspects regarding episodes, nitrate, dissolved organic carbon, recovery and biological effects.
The application of an instrument for non-destructive measurements of soil temperature and resistance profiles at a high Arctic field site
Authors: Lloyd C. R.
Published: April 2010

Abstract. An easily constructed and installed instrument for measuring colocated soil temperature and resistance profiles is described. Minimum disturbance to the soil structure is achieved. The system indicates the melting front of permafrost at a high Arctic field site and shows the effect and extent of summer rainfall events upon the soil water profile. The system is capable of long-term recording of soil moisture profiles at a frequency commensurate with eddy correlation measurements of the surface fluxes of water vapour and carbon dioxide; it thus provides the information necessary for understanding the processes involved in the soil-atmosphere exchange of water and carbon dioxide.
RESEARCH NOTEA comparison between reference transpiration and measurements of evaporation for a riparian grassland site
Authors: Finch J. W. , Harding R. J.
Published: April 2010

Abstract. This paper compares direct measurements of evaporation with the values predicted for reference transpiration. The measurements of actual evaporation were made using an eddy correlation device on a grass field adjacent to the river Thames. Measurements of soil moisture and the driving meteorological variables were also made. The results showed that, during a period with minimal rainfall but no water stress, the cumulative values of reference transpiration compared very well with the cumulative measured evaporation and changes in soil moisture content. However, the values on specific days did not compare well. Following significant rainfall, the measured evaporation increased for a few days, probably due to evaporation of free water from the canopy or soil. Reference transpiration fell consistently below the measured evaporation once the soil moisture deficits exceeded 140 to 150 mm.
Modelling rainfall interception in unlogged and logged forest areas of Central Kalimantan, Indonesia
Authors: Asdak C. , Jarvis P. G. , Gardingen P. V.
Published: April 2010

Abstract. Rainfall interception losses were monitored for twelve months and related to vegetation and rainfall characteristics at the Wanariset Sangai on the upper reaches of the Mentaya river, Central Kalimantan. The rainfall interception losses were quantified for one hectare each of unlogged and logged humid tropical rainforests. The results show that interception loss is higher in the unlogged forest (11% of total gross rainfall) than in the logged forest (6%). Interception loss was also simulated by the modified Rutter model and Gash's original and revised models. Both the Rutter and revised Gash models predicted total interception loss over a long period adequately, and resulted in estimates of the interception loss that deviated by 6 to 14% of the measured values, for both the unlogged and logged plots.