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JRBM vol 7 Issue 1

Rapid flood risk assessment using GIS technology
By Yan Huang
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Limiting the time and effort needed for setting up and running an inundation model, as well as increasing the flexibility to changes in conditions arising from land use, the location studied and infrastructure, will increase the usefulness of Flood Risk Assessment (FRA) for decision makers. In this respect a traditional 2-dimensional (2D) hydrodynamic approach for inundation modelling is less desirable. Moreover, such complex models are less suited to uncertainty analyses based on a large number of simulations with multiple sources of uncertainty. This can be better accomplished using a Rapid Flood Risk Assessment (RFRA) approach which requires minimal data and modelling work. The approach is GIS-based, using only data on land use and elevation as input, and does not require hydrodynamic computations. A small section of the River Elbe in Germany served as case study to examine the applicability of the RFRA approach. For comparison, the inundation process was also modelled with the 2D-hydrodynamic modelling software SOBEK1D2D of WL | Delft Hydraulics. The results indicated that the rapid approach performs well in terms of estimating the damage caused by inundation depth, but poorly in terms of the dynamic flow velocity effects.
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Simulation of nutrient reduction scenarios with three different models. Does the selection of model affect the recommended set of measures?
By Tor Haakon Bakken, Mária Szomolányi, Attila Lázár, Torulv Tjomsland and Stig A. Borgvang
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This article compares and discusses the results of applying three different models in order to quantify the phosphorus loads in Kapos catchment, Hungary. The models range from the very simple TEOTIL operating on statistical data and export coefficients, via the semi-complex INCA-P to the highly complex and process-based SWAT. All models have been calibrated with use of basically the same input and calibration data. The models have, to the extent they are capable, been used further to simulate a set of theoretical pollution reduction scenarios. The calibration results showed that all the models are basically able to simulate historical loads of TotP on a catchment level, except maybe those years with particularly high or low loads (INCA-P in 1999 and TEOTIL in 2002). The scenario analysis showed that the models are to a varying degree capable of simulating the simplified scenarios, where TEOTIL seems to a limited extent suitable for such analysis. This study demonstrated that the selection of model can influence the output of the scenario analysis significantly, and the selection of tool to be applied should therefore be made with great care. The most obvious example is the comparison of the simulation of the reduced runoff from area sources (scenario E) with the simulation of reduced discharges from point sources (scenario F). Based on the simulation results, TEOTIL considers reduction in nutrient runoff from areas to be the most efficient measures, while INCA-P and SWAT results would suggest focusing on the reduction of point-source discharges.
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Openings towards integrated water resources management in Lao PDR
By Sari Jusi
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The specific objectives of the paper are to assess the existing institutional situation associated with water resources and the state of developing Integrated Water Resources Management (IWRM) process in Lao People’s Democratic Republic and based on that assessment, to shed light on problems and constraints in water sector and possibly suggest opportunities to meet the emerging challenges/the implementation of policies and institutional strengthening processes that will lead to improved management of water resources and governance. The key developmental challenge for enhancing good water resources governance in the country is the establishment of sustainable, effective and integrated approach to water resources management. To reach this, several objectives are to be fulfilled: integrated, intersectoral, and multi-objective decision making about water resources at the basin scale; broad participation and empowerment of stakeholders in water resources decision making; effective coordination among sectors and institutional scales; strong, effective, and culturally appropriate institutional, policy, and legal frameworks that reinforce integrated, accountable, participatory, and sustainable management and that minimize corruption; and informed and science-based decision making.
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Prediction of fisheries physical habitat values based on hydraulic geometry and frequency distributions of depth and velocity
By Ekaterina Saraeva and Thomas B. Hardy
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We propose a technique that allows the estimation of available physical fish habitat in small sized stream reaches (mean annual flow less than 3.5 m3/s) without the need to acquire and analyze extensive site-specific data commonly used in many instream flow studies. The technique utilizes a modified form of previously published equations that estimate velocity and depth frequency distributions based on reach average velocity and depth which in turn can be calculated using widely known at-a-station hydraulic geometry equations. Velocity and depth frequency distributions are then combined with fish preferences for velocity and depth to produce habitat versus discharge relationships for a desired range of flows. When the resulting physical habitat versus discharge relationships for target fish species and life stages are compared to weighted usable area relationships (habitat versus discharge relationships derived using hydraulic and habitat models) developed from site-specific studies, the prediction error was shown to be less than 15%.
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Sediment management in the Dutch Rhine Branches
By Jan Sieben
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A brief review of historic normalisation and sediment management in the Dutch Rhine branches is given. Aiming for maintaining navigability and safety against flooding, this river engineering has triggered large-scale bed level developments that affect for example the use and maintenance of the fairway. The observed trend of bed level changes is explained using simplified theoretical equilibrium approaches.With numerical simulations, future developments are predicted and potential measures are defined to prevent bottle necks in the fairway. Finally a strategy is recommended to develop a sediment management that aims for an economic and sustainable fairway in the Dutch Rhine branches.
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Comparison of spawning habitat predictions of PHABSIM and River2D models
By Mark Gard
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This study compared the predictions of two instream flow habitat models, the Physical Habitat Simulation System (PHABSIM) and River2D, with regards to spawning habitat for chinook salmon, Oncorhynchus tschawytscha, and steelhead trout, Oncorhynchus mykiss. Spawning habitat was simulated with both models for eight sites in the Sacramento River, five sites in the American River and one site in the Merced River, California, using habitat suitability criteria developed from data collected on redds in each of these rivers. For four out of five cases, both models correctly predicted that the combined suitability, calculated as the product of the depth, velocity and substrate suitabilities, of occupied locations was significantly greater than the combined suitability of unoccupied locations. There was little difference in the flow-habitat relationships for each site and set of habitat suitability criteria predicted by the two models. The use of River2D, rather than PHABSIM, is still warranted given its ability to model complex flow conditions which cannot be simulated with PHABSIM.
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Agricultural and water resources development in Thessaly, Greece in the framework of new European Union policies
By N. Mylopoulos, E. Kolokytha, A. Loukas and Y. Mylopoulos
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The main challenges that inter-relate sustainable development with water resources management are to secure water for all humanity and for food production as well, to protect the ecosystems, to manage risk, to create public awareness, to urge political will and to ensure cooperation and coordination of action in an integrated way for both national and international water issues. The response of Europe comes through the new Water Framework Directive (WFD) for the sustainable management of all European waters. Moreover EU provides the new Common Agricultural Policy (CAP) for the sustainable development of rural areas which all member states should comply with. This paper evaluates the perspectives of water resources management and economic development in the greater Thessaly area – an agricultural, rural area in Greece that faces a dramatic water resources problem, in the framework of the WFD 2000/60 and the new CAP.
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Extrapolation of site-specific weighted usable area curves and instream flow requirements to unmeasured streams within the Nooksack watershed in support of strategic watershed planning
By Ekaterina Saraeva and Thomas B. Hardy
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Given the large number of locations within the study watershed (Washington, USA) where instream flow information is required, a GIS based stratification procedure using multivariate data analysis techniques was developed to extrapolate either instream flow recommendations or habitat availability curves (weighted usable area curves) upon which instream flow recommendations could be developed from study sites to other sites where no site-specific information is available. One-hundred-seventy-two drainages were divided into 21 hydrologically and eomorphologically similar subgroups. Mean annual flow versus drainage area and 60% exceedence flow versus drainage area relationships were also developed for the study area. Monthly instream flow recommendations were then extrapolated to the unmeasured streams within the hydrologically and geomorphologically similar subgroups by scaling them by a percentage of the mean annual flow; weighted usable area curves were extrapolated to the unmeasured streams within the same subgroups by scaling the flows by a percentage of the 60% exceedence flow. Extrapolated monthly instream flow recommendations ranged between 0 and 76 percent but were generally within about 20 percent or less when compared to recommendations developed from site-specific analyses. Extrapolated weighted usable area relationships had an average root mean square error less than about 17% and reflected the basic functional relationships when compared to site specific analyses. This study demonstrates that either instream flow recommendations or weighted useable area relationships derived from site-specific data can be extrapolated to unmeasured sites for use within the context of strategic watershed planning based on the development and application of two extrapolation methodologies.
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JRBM vol 7 Issue 2

Managing salinity in the Indus Basin of Pakistan
By Asad S. Quereshi and Asaf Sarwar
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Waterlogging and salinity have plagued irrigated agriculture in the Indus Basin for the past 30–40 years. Approximately 6 million ha (35–40% of total irrigated area) experience these twin problems. As a result, the production potential of the Indus Basin has been reduced by 25%. Over the last 40 years, the Government of Pakistan has adopted engineering, reclamation, and biological measures to address these problems. Part of the engineering solution involved large-scale Salinity Control and Reclamation Projects (SCARPs) in all four provinces. The program covered 8 million ha and cost approximately US$2 billion. Two big disposal projects were also initiated to solve the drainage disposal problems. To address the saline soil problem, some of the measures tested include leaching of salts by excess irrigation, use of chemicals (such as gypsum and acids), and addition of organic matter and biological measures (such as salt-tolerant plants, grasses, and shrubs). The success of these initiatives has been limited: 35–40% of irrigated land still suffers from high water tables and moderate to severe salinity. Lack of coordination among federal and provincial governments, research institutes, and national and international organizations; conventional farming and irrigation methods used by farmers; limited attention to reclamation and saline agricultural approaches; and lack of resources are some of the reasons for the low success rate. A more concerted effort that includes a greater focus on saline agriculture, capacity building of farmers, and promotion of local interventions to improve self-reliance is necessary for the management of salinity in the Indus Basin. A sustainable solution would also require coordination among different provinces and strengthening of federal and provincial government agencies.
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Energy supply and the expansion of groundwater irrigation in the Indus-Ganges Basin
By Christopher A. Scott and Bharat Sharma
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Irrigation using groundwater has expanded rapidly in South Asia since the inception of the Green Revolution in the 1970s. Groundwater currently represents the largest source of irrigation in the Indus-Ganges Basin (IGB), which feeds over one billion people and provides direct livelihoods for hundreds of millions of farmers. Although abundant in absolute terms, groundwater is overexploited in the western IGB plains and is underutilized in the east. The spatial and temporal patterns of groundwater development are the result of multiple demand factors: (a) farmer investment, (b) subsidies and markets, and (c) population density; as well as supply factors: (d) sources of groundwater recharge, and (e) energy supply and pricing. This paper examines trends in electricity supply and groundwater development in the Indian portion of the IGB over the 1980 – 1999 period, with contextual reference to groundwater irrigation in Pakistan, Nepal, and Bangladesh. Principal findings include early-1980s’ growth in numbers of electric pumps across the Indian IGB followed by 1990s’ stagnation in the eastern part of the basin; this trend is linked to electricity supply and pricing policies, which have varied markedly from state to state. The eastern IGB presents an energy-groundwater paradox: a region rich in energy sources but with inadequate electricity supply that has led to increased reliance on diesel power, which in turn is limiting development of groundwater – one of this region’s most abundant and agriculturally productive resources.
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Groundwater irrigation and livelihoods in the Ganga Basin: Analysis of minor irrigation policy in North Bengal, India
By Tushaar Shah
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In terms of water resources, North Bengal is one of the best-endowed regions in India. While the region has huge ground and surface water potential, it also concentrates a large number of rural poor who depend on smallholder farming and farm labor for their livelihoods. The issue central to water governance is how to best design instruments of public support to stimulate smallholder (minor) irrigation and harness the abundant groundwater resources to improve conditions for the region’s rural poor. Extreme poverty precludes private investments in minor irrigation on the scale necessary to make a significant and quick impact. As a result, subsidy support for minor irrigation investments has remained crucial in North Bengal as well as in much of the eastern Ganges basin. This paper assesses the North Bengal Terai Development Project (NBTDP) developed by the Government ofWest Bengal. During much of the 1990s, the North Bengal Terai Development Project shaped and implemented the Minor Irrigation Policy of the Government ofWest Bengal in this region. This paper deals with three distinct sets of questions regarding the subsidy policy: (1) What is the rationale for minor irrigation subsidies in North Bengal? (2) Does the North Bengal Terai Development Project’s subsidy policy achieve its minor irrigation objectives in an efficient, sustainable, and socially adequate manner? and (3) Is there scope for designing minor irrigation subsidy policies for better impact? The conclusion also explores what should be the objective of minor irrigation policy for North Bengal’s socioeconomic and aquatic conditions and how this might be achieved.
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Fishery resources trends and community-based management approaches adopted in the river Titas in Bangladesh
By M. G. Mustafa
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During 1997–2002, a Community Based Fisheries Management (CBFM) project was implemented to monitor fish catches in two sections of the River Titas (Goshipur to Gokornaghat section and Ka section), an important tributary of the Meghna River in Bangladesh and the lower Indo-Gangetic Plains. The study covered fishing activities, fisher’s participation in managing fishery resources, gear-diversification, changes in fishing patterns, and overall catch and effort. Fish catch monitoring results showed that production and species diversity increased over the duration of the project, due to the community management approach, which encourages participation of fishers, beneficiaries and communities in managing the renewable fishery resources. The study revealed that during 1997 to 2002 annual fish production increased by 233% and 15% in the two river sections, respectively. Overall species diversity increased by 30% in the river in 2002 compared to the baseline composition. However, overexploitation was observed in the Ka section of the river where professional fishers and catch through fish aggregating devices prevail.
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Exploring options of participatory water management for livelihood improvements in the Indo-Gangetic Basin
By Alok K. Sikka
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Water resource development has played an important role in livelihood improvement and poverty alleviation by improving food security, protecting against drought, providing access to water, and creating employment. Recent efforts of government, nongovernmental organizations (NGOs), and international agencies to promote participatory management of water resources in irrigated commands, rainfed areas, and uplands have paid rich dividends in the Indo-Gangetic Basin (IGB) and in IGB countries. There has been a paradigm shift from technology transfer toward decentralized, user-centered approaches, and more recently toward promotion of local institutions and governance. This paper reviews experience from various participatory water management approaches in canal-irrigated areas, groundwater-irrigated areas, rainfed areas, and uplands, and suggests practical ways forward for participatory water management.
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Projections of irrigation water demand in India: What do recent trends suggest?
By Alok K. Sikka
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Projected increases in irrigation water demand required to feed India’s population have been a significant component of the justification for the ambitious and highly contentious India’s National River Linking Project (NRLP), which, in its ultimate form, seeks to transfer water from relatively water-rich basins to those basins where demand has already outstripped supply. This paper re-examines some of the key assumptions underlying the irrigation demand estimations of the NRLP project, and concludes that a number of key assumptions are not consistent with recent trends. Major changes from earlier projections include rapidly changing consumption patterns and the dominance of groundwater as the source of irrigation water choice where available. The major challenge facing the agricultural water sector in India today and over the long term therefore is how to increase the groundwater stock (supply enhancement) to arrest declining groundwater tables, and how to sustain water use by minimizing uncontrolled groundwater pumping (demand management). While large-scale water developments, including inter-basin transfers, are likely still necessary, the characteristics of agricultural water demand and realities of available supplies need to be carefully reconsidered.
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Water supply and food security: Alternative scenarios for the Indian Indo-Gangetic River Basin
By Claudia Ringler, Sarah A. Cline and Mark W. Rosegrant
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India is one of the world’s largest countries in both size and population. The country is also very important in the world food market, accounting for 12% of global wheat production and 21% of global paddy production during 2000–03. Large-scale irrigation development been at the heart of rapid increases in food production achieved in India over the last five decades. Today, more than half of India’s cereal output is harvested on irrigated lands, and irrigated yields are more than double those of rainfed cereal yields. One of the most productive irrigation systems in India and the world is the Indo-Gangetic Basin (IGB) and plains, which account for a third of India’s cultivable area and about 60% of its irrigated area. While irrigation development and food production have expanded apace, increasing concerns have been raised about the sustainability of irrigated production systems in the IGB. This paper examines the likely future development for water and food in the IGB, based on an integrated water-food modeling framework, IMPACT-WATER. The impact of eliminating groundwater overdraft in the IGB and elsewhere on food supply and water usage is also examined.
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JRBM vol 7 Issue 3

Introduction – Recent progress in understanding and managing diffuse pollution at catchment scale
By Adrian L. Collins
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Introduction
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Emerging priorities in the management of diffuse pollution at catchment scale
By Adrian L. Collins, Daniel F. McGonigle, Robert Evans, Yusheng Zhang, Doris Duethmann and Richard Gooday
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Implementation of water policies, such as the EU Water Framework Directive (WFD), has resulted in a large body of work aimed at understanding and managing catchment diffuse pollution. On this basis, a number of potential priorities can be highlighted for further work.With respect to specific pollutants, priorities include the need to characterise the potential role of groundwater-surface water interactions and biogeochemical processing in attenuating nitrate issues, the significance of farmyard/track, road and septic tank losses and in-stream processing for phosphorus abatement strategies and both inorganic and organic sediment sources using a common integrated source apportionment framework. Improved understanding of pollutant pressure-ecological impact relationships will require wider consideration of the synergistic, additive or antagonistic interplay of multiple stressors. Given the focus on ‘good ecological status’ and environmental objectives, freshwater ecology and the protection of optimal habitat conditions should be central to any catchment diffuse pollution management plan. The need to collect high quality empirical data to help convince stakeholders of the benefits of mitigation strategies remains paramount.
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Maintaining good water and soil quality in catchments containing deer farms
By Richard W. McDowell
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A three year study was undertaken to determine the effect of farmed deer on soil and water quality in two catchments in southern New Zealand. The objective was to benchmark their effects and try to incorporate some of the best management practices tested during the 3 yrs of study designed to mitigate any deleterious effects. Most sampling sites seldom met national guidelines for good surface water quality in lowland streams (eutrophication for nitrite/nitrate-N=0.444 mg N L⁻¹, dissolved reactive phosphorus = 0.01 mg P L⁻¹ and total phosphorus = 0.03 mg P L⁻¹; fish toxicity for ammoniacal-N=0.9 mgNL⁻¹; and contact recreation for Escherichia coli=260 cfu 100mL⁻¹). However, a sedimentation pond in one catchment and a riparian area fenced-off and set aside in-perpetuity caused decreases in loads of contaminants exiting catchments. Data gathered during the study showed that the planting of trees and provision of shelter could help mitigate some containment transfer associated with fence-line pacing, while fencing-off and planting wallowing areas significantly decreased contaminant loads in streams. However, an alternative wallowing site should be provided to accommodate deer behaviour otherwise deer will make a new wallow a short distance away from the old one that will also likely be connected to a waterway. An environmental-economic analysis for P losses indicated that decreasing soil Olsen P concentrations to the minimal agronomically possible was cost beneficial, but only decreased P losses by 0.2 kg Pha⁻¹yr⁻¹. Larger decreases (~1 kgPha⁻¹ yr⁻¹) were estimated to occur if wallows were fenced-off, planted and alternative wallowing sites installed. As a result of these data, some of the best management practices (BMPs) have been undertaken within the catchments and will improve soil and water quality in the future. However, farmers should be presented with a range of BMPs tested on an environmental and economic basis in order to fully assess their suitability to a farm.
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A model-based assessment of non-compliance of phosphorus standards for lakes in England and Wales
By Doris Duethmann, Steven Anthony, Laurence Carvalho and Bryan Spears
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High phosphorus concentrations causing eutrophication will prevent many lakes in England andWales from reaching good ecological status by 2015 according to the ECWater Framework Directive (WFD). The aim of this study was to estimate the percentage of lakes in England andWales that are likely to fail recently agreed WFD phosphorus standards. As measured lake phosphorus concentrations are only available for a small number of lakes a model-based approach was adopted. This involved estimating phosphorus loads from a wide range of sources including agricultural loads, sewage effluents, septic tanks, diffuse urban sources, atmospheric deposition, groundwater and bank erosion. Lake phosphorus concentrations were predicted using the Vollenweider model, and the model framework was satisfactorily tested against available observed lake concentration data. Applying the model to all lakes in England and Wales greater than 1 ha, it was estimated that under current conditions, roughly two thirds of the lakes would fail good ecological status with respect to phosphorus. According to our estimates, agricultural phosphorus loads represent the dominant source for the majority of catchments, but diffuse urban runoff also is important in many lakes and sewage effluents are the most frequent dominant source for lake catchments greater than 100 km2. Required reductions of phosphorus loads to increase the number of lakes achieving good ecological status and potential delays because of internal loading and biological resistances are briefly discussed.
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Mitigating sediment delivery to watercourses during the salmonid spawning season: potential effects of delayed wheelings and cover crops in a chalk catchment, southern England
By Adrian L. Collins and Paul S. Davison
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Identification of diffuse sediment pollution ‘hotspots’ requiring improved management in catchments supporting salmonids can be achieved using computer models. Accordingly, the PSYCHIC (Phosphorus and Sediment Yield CHaracterization In Catchments) model, which has been evaluated against empirical data, was used to simulate sediment pollution and its potential mitigation during the salmonid spawning season in a priority catchment identified by the England Catchment Sensitive Farming Delivery Initiative, drained by the Rivers Test and Itchen, in southern England. PSYCHIC predicted that approximately 83% (3912t or 24 kg ha⁻¹) of the baseline annual total sediment transfer to watercourses (4694t or 29 kg ha⁻¹) coincided with salmonid spawning. Blanket adoption of delayed wheelings on all winter cereal fields (34,000 ha) was predicted to attenuate baseline sediment delivery during the spawning season by 21%. Cover cropping for all spring crops (24,000 ha) was predicted to reduce baseline sediment transfers by 8%. Targeted deployment of these two mitigation methods to 900 ha of winter cereals and 730 ha of spring crops, representing just 3% of the study catchment characterized by a baseline sediment transfer during the spawning season of > 200 kg ha⁻¹, was predicted to reduce corresponding sediment inputs to river channels by 6% and 3%, respectively.
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Nitrogen driving force and pressure relationships at contrasting scales: implications for catchment management
By Per StÅLnacke, Annelene Pengerud, Marianne Bechmann, Josette Garnier, Christoph Humborg and Vladimir Novotny
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The major objective of this study was to compile and examine empirical relationships between the driving forces and pressures that affect nitrogen cycling. Special attention was paid to riverine loads, fluxes, and concentrations of nitrogen in relation to agricultural factors (e.g., land use and fertilisers) at various spatial scales (plot, field, catchment, river basin, nation, region, continent, and world). Results of the present analyses and assessments reported in the literature indicate that at global, continental and inter-river basin scales, the level of riverine nitrogen loads (pressures) can be readily derived from simple empirical relationships with driving forces like population density and agricultural factors (e.g., proportion of arable land and fertiliser use). It seems that statistically derived relationships do not hold or are much weaker at the scales of single river basins and smaller catchments, whereas nitrogen losses appear to be correlated with fertiliser use at the smallest scales (plot and field). It is important to recognize this spatial nutrient paradox, particularly when such functional relationships are applied in the contexts of management and decision making. The implications for management are given further consideration in this paper.
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Assessing the impact of Nitrate Vulnerable Zones in England on nitrate loss from agricultural land
By Eunice I. Lord, Steve G. Anthony and Richard D. Gooday
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The impact of the 2002 NitrateVulnerable Zone Action Programme (NVZAP) in England was assessed using survey data linked to modelling. Baseline nitrate losses were estimated using the NEAP-N national model, and impacts of individual measures were estimated by linking survey data on land management change to models or impact estimates derived from controlled experiments. Results were scaled up using mapped agricultural census data. The reduction in nitrate leaching attributable to the 2002 NVZAP was estimated as 5%, the majority being due to better adjustment of fertiliser inputs to crop requirement and manure-derived N. Closed periods for manure application in autumn were locally effective, especially within arable systems, but the national impact was small because of the small land area affected. Overall impacts were greatest on sandy soils with large poultry or pig units, where losses were previously very high, and least on extensive grassland systems, where losses were previously low. Some mitigation measures had little impact because good practice is already widespread or because they targeted surface runoff pathways, which are more important for pollutants such as P, sediment, ammonium and pathogens. The potential evolution of measures is discussed along with some key limitations and uncertainties associated with the estimation process.
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Modelling diffuse nitrogen loadings of ungauged and unmonitored lakes in Denmark: application of an integrated modelling framework
By Hans Thodsen, Brian Kronvang, Hans Estrup Andersen, Søren E. Larsen, Jørgen Windolf, Torben B. Jørgensen and Lars Troldborg
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According to the EU Water Framework Directive all freshwater bodies must obtain good ecological status by 2015. In Denmark this means that all lakes with a surface area above 5 ha (~600 lakes) must be evaluated individually and mitigation measures must be enforced if the ecological status is below “good”. In consequence, the nutrient pressures from point and diffuse sources must be assessed based on a quantification of the nutrient loading of each lake. In this study we focus on the loading of nitrogen. Few of the 600 lakes are monitored for runoff and nitrogen loading. Therefore, a national 3D hydrological model covering all major parts of the country was used to estimate runoff from the lake catchments. The diffuse nitrogen input to each lake was simulated with an empirical nitrogen model. Where lakes are located upstream/downstream of each other, a calculation chain involving the nitrogen retention in lakes was created. A case study was selected using a large river basin including 23 lakes in Denmark. The cost-effectiveness of reducing nitrogen loadings from different sub-catchments in the case study river basin to the sea was calculated. The cost-effectiveness associated with reducing the N-loading from the most expensive sub-catchment is shown to be 20 times more expensive than from the cheapest sub-catchment.
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Modelling nitrate river water quality for policy support
By Steve G. Anthony, Martyn Silgram, Adrian L. Collins and Laura E. Fawcett
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In response to the need for nitrate policy support in the UK, ADAS UK Ltd. has developed the EveNFlow modelling tool. EveNFlow is conceptually based and allows for surface and subsurface pathways and multiple diffuse sources, associated with different soil-crop-livestock combinations. Sources of nitrate losses from agricultural and non-agricultural land, urban areas and point sources are all represented. The output provides information in the form of daily time-series at any point along the catchment river network, losses from the base of the soil profile and exported nitrate loads associated with key vectors, e.g. livestock and arable land. In order to model N losses, UK wide GIS datasets for agricultural activity, climate and soil type are used. EveNFlow builds on existing models, either through their coupling or in the form of metamodels. These component models include: SLIMMER; a simple functional N loss model; a crop water use/drainage model based on elements of the MORECS and IRRIGUIDE models, and a series of export coefficients for N potentially available for leaching at the beginning of the drainage season for a range of livestock and crop types from the NEAP-N model. The final model is capable of simulating a long daily time-series of flow and nitrate-N concentrations. As an example, EveNFlow is applied to the Yorkshire Ouse (3315 km²) catchment, UK, and two of its subcatchments, which have contrasting land use and climatic regimes. The results compare favourably with hydrological and chemical data collected over the period 1990–2000 at monitoring sites on these rivers.
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Particulate organic carbon sources and delivery to river channels in the Somerset Levels ECSFDI priority catchment, southwest UK
By Adrian L. Collins, Desmond E. Walling, Louise Webb and Paul King
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Soil erosion and sediment delivery represent an important transport pathway for particulate organic carbon (POC) in fluvial systems. Catchment management strategies designed to protect soil resources therefore require reliable information on the significance of key sediment sources for POC transfers. Within this context, a composite fingerprinting procedure, incorporating uncertainty and prior understanding of catchment processes, was used to investigate the significance of eroding pasture or cultivated topsoils, damaged road verges, channel banks/subsurface sources and point source discharges as POC sources and the associated net delivery to river channels across the Somerset Levels, southwest UK. Overall mean relative contributions of POC from the five individual sediment sources were estimated at 41 ± 2% (pasture topsoils), 18 ± 1% (STWs), 15 ± 2% (cultivated topsoils), 14 ± 1% (damaged road verges) and 12 ± 2% (channel banks/subsurface sources). Respective estimates of net sediment-associated POC delivery to watercourses, provided by integrating sediment source ascription 50^thpercentiles bounded by 95% confidence limits, organic carbon content, sediment yield ranges and sub-catchment or land use areas, ranged between 2.4-48.5 kg ha⁻¹ yr⁻¹, 0-16.5 kg ha⁻¹ yr⁻¹, 1.7-119.2 kg ha⁻¹ yr⁻¹, 0-13.8 kg ha⁻¹ yr⁻¹ and 0-7.4 kg ha⁻¹ yr⁻¹.
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JRBM vol 7 Issue 4

Combining a conceptual framework and a spatial analysis tool, HABITAT, to support the implementation of river basin management plans
By M. Haasnoot and K. E. van de Wolfshaar
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Since the Ramsar meeting in 1971 many plans and agreements are developed to conserve and improve the quality of wetlands throughout the world. Within the European Union for example legislation has been developed in four Directives which require thatwater managers test activities on ecological effects. Moreover, in most areas measures have to be taken and included in river basin management plans in order to achieve ecological objectives in terms of occurrence of species and habitats set by EU Directives. To improve quality and conserve areas it is needed to assess the effects of current land use and autonomous developments and to identify the effectiveness of measures. Different studies have already addressed the need for models to quantify these effects.We developed a conceptual framework to analyse the cause-effect chain from management to new environmental conditions and to the potential occurrence and quality of species and habitats using response curves. To our knowledge, this is the first framework presented that has the ecological assessments embedded within the structure, which allows for ecological assessments within the development of management plans rather than at the end of the development. For this purpose a spatial analysis tool is used (HABITAT), which is developed for a broad spectrum of users, from ecologists to managers, and purposes, from ecological assessments to flood risk assessments. The framework is applicable on an (inter) national scale and can promote the dialog between politicians, managers and ecologists. In this paper we demonstrate that the conceptual HABITAT framework for ecological impact assessment is able to support the development and implementation of ecologically sound management plans and illustrate this with a case study for the lake Markermeer in The Netherlands.
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Fish passage over hydraulic structures in Midwestern Rivers of the USA
By Dimitrios C. Dermisis and Athanasios N. Papanicolaou
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The main objective of this study was to examine the hydraulic performance of knickpoint-control structures (i.e., riprap weirs, grouted-riprap weirs, baffled and non-baffled fish ladders) to facilitate unimpeded fish passage. The hydraulic performance of these structures, located in Midwestern streams, was evaluated by determining the mean and turbulent flow characteristics in the vicinity of the structures via detailed field tests. Non-intrusive mean flow measurements were performed using a 3-dimensional sidelooking Flowtracker handheld Acoustic Doppler Velocimeter (ADV) and by utilizing the newly developed Large Scale Particle ImageVelocimetry (LSPIV) technique. Non-intrusive turbulent flow measurements were performed using a field ADV with a high sampling frequency. Results from the mean flow measurements illustrated that the mean flow depth (Y) and velocity (V) atop the structures were critical for evaluating the performance of the structures. In addition, the present study suggested that the (Y, V) should be viewed in conjunction with the drainage area (DA), slope (S) of the structure, and structure type. The DA size affected (Y, V) in the streams, S affected the power of the water action, and the structure type could cause flow acceleration/deceleration. Results from the turbulent flow measurements illustrated that the flow approaching the structures became 3-dimensonal, while the size of eddies in the baffled fish ladder were found to disorient fish in the transverse direction due to sudden constriction. In short, the results presented herein illustrated that a complete assessment of the hydraulic performance of structures should include not only the conventional permissible criteria for (Y, V) but also the turbulent flow characteristics at the locations atop the structures.
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Seasonal variability of groundwater—surface exchange and its implications for riparian groundwater nitrate retention at the Havel River
By Stefan Krause, Axel Bronstert and Erwin Zehe
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The IWAN (Integrated Water Balance and Nutrient Dynamic) model was used to quantify the spatially and temporally variable impact of groundwater—surface water interactions on the groundwater nitrate dynamics in a riparian floodplain of the Havel River, Germany. The model coupled simulation of the floodplain water balance and groundwater nitrate dynamics to quantify the exchange fluxes and the nitrate transport between the river and the riparian groundwater. Investigations of the riparian water balance indicated extensive heterogeneity of process interactions between the groundwater and surface water, which have a temporally and spatially variable impact on the floodplain water balance, groundwater dynamics and river discharge. The simulated transport of nitrate across the groundwater—surface water interface was transient, varying both in intensity and direction. The floodplain acted as a nitrate sink or source with a seasonal periodicity. Riparian groundwater contributed with seasonally variable nitrate loads of the Havel River. The simulated annual groundwater nitrate contributions of the research area represented on average 1% of the observed nitrate loads of the Havel River. However, in summer the groundwater nitrate contributions were significantly higher, representing more than 20% of the river loads. The simulation results indicated that 93% of the nitrate input into the riparian zone was attenuated within the groundwater, highlighting the role of the riparian floodplain as an important retention filter for diffuse nutrient pollution.
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A river basin as a common-pool resource: a case study for the Jaguaribe basin in the semi-arid Northeast of Brazil
By Pieter R. van Oel, Maarten S. Krol and Arjen Y. Hoekstra
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This paper applies ‘common-pool resource’ concepts to analyse to which extent the physical characteristics of a river basin facilitate or impede good management of water in different parts of a river basin. In addition, we compare the apparent manageability of water in the different parts of the basin with the actual agricultural performance in each area. As a case study we have analysed the Jaguaribe basin in the semi-arid Northeast of Brazil. To characterize a certain location within a river basin, the term ‘downstreamness’ is introduced and quantitatively defined. Depending on its ‘downstreamness’ each municipal district in the basin is categorized in one of three topographical zones: upstream, midstream or downstream. Per topographical zone, we evaluate to which extent five specific ‘conditions for good manageability’ are met. These five conditions have been taken from the literature on common pool resources. It appears that three conditions are increasingly met if we go from upstream to downstream, while the other two conditions are better met if we go in upstream direction. Factors that make water better manageable downstream are the better possibilities for water storage, better predictability of water flows and the lower level of mobility of water resources. Factors that make it easier to manage upstream water resources are the small spatial extent of the allocation problem and the clearly defined boundaries of the system. In the case of the Jaguaribe basin, the net result appears to be most favourable in the midstream zone, where the advantages and disadvantages for good water management are in the best balance. As a result, the agricultural performance, measured in terms of productivity and stability of production, is best in the midstream zone of the basin.
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Modelling the effect of dike shifting and land use practice on floodplain vegetation
By Jean-Luc de Kok and Harriëtte Holzhauer
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Model selection is a critical aspect of designing a tool for integrated river basin management.Without scientific guidelines models may be selected in an ad-hoc manner based on practical considerations such as data availability and computational load.A more systematic approach for model selection can be achieved by examining the interaction of coupled models in terms of sensitivity and uncertainty propagation at an early stage of the design. Such a design approach is also referred to by the term ‘appropriate modeling’. The recently completed decision-support system (dss) for the River Elbe in Germany includes a large-scale floodplain vegetation model and a 1D river schematization to describe the hydraulic conditions at a regional (500 km) scale. The key factors that influence the vegetation patterns are the flooding frequency in the floodplains and the land-use practice in the floodplain area. The choice between a 1D hydrostatic and 2D hydrodynamic schematization to describe the effect of dike shifting on the floodplain vegetation is used as case example to demonstrate the principle of appropriate modeling. Whether a 1D approach will be sufficient depends on the purpose and sensitivity of the models that are coupled. The differences between the vegetation patterns obtained with the 1D and 2D hydraulic approach are compared with the effects of climate change, land use, and data uncertainty to illustrate this.
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Hydrologic alteration assessment in Mediterranean Rivers: perspective from a South Italy case study
By Giancarlo Principato and Giuseppe Viggiani
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Water diversions from rivers are a main cause of ecosystem damage. The watercourses characterized by scarcity of flow and irregular flow regime, like Mediterranean rivers, are more prone to hydrologic alteration. The EU Water Framework Directive (WFD) prescribes conservation or recovery for rivers, but protection is often based on simple and empirical flow rules used to define release flow downstream of diversions. In this paper, according to the prescription of the WFD, a hydrologic alteration analysis has been conducted for the Crati River (Calabria, South Italy), which is characterized by irregular flow regime and pronounced summer droughts. The IHA-RVA method was chosen as an analysis method and four scenarios, resulting from constant and variable flow release regulation of the Calabria Basin Authority, have been examined. Different kinds of impact have been defined, namely deficit of flow, absence of flow event and excess of flow, which is specifically felt in rivers characterized by pronounced droughts. The inadequacy of a few common practices – such as increasing constant flow release or total release volume regardless of natural flow regime – is highlighted. Finally, the overall hydrologic alteration has been associated with the WFD classification of river quality, while difficulties related to the management of Mediterranean rivers are discussed.
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Evaluation of water demand Scenarios for the Olifants River catchment, South Africa
By Matthew McCartney and Roberto Arranz
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Water resource development has played a key role in the expansion of agriculture, mining and industry in the Olifants River catchment, but the colonial and apartheid regimes have left a legacy of inequity. Currently water deficit is one of the major constraints hampering further development and demand for water continues to grow. Against this background, the Water Evaluation And Planning model was used to provide a preliminary assessment of both the current situation and three plausible future scenarios. For each scenario the model was used to simulate water-use in five sectors (i.e., rural, urban, mining, irrigation and commercial forestry) over a 70-year period of varying rainfall and flow. Levels of assured supply were estimated and the economic cost of failing to supply water was predicted. Current shortfalls are estimated to be costing between US$ 6 and 50 million per year, depending on rainfall and, hence, river flows. If increases in demand are not checked this will increase significantly. Under a high demand scenario, the economic benefits increase greatly but, even with infrastructure development and improvements in demand management, the economic cost of insufficient water supply rises to US$ 10.5 million in most years and, in exceptionally dry years, up to US$ 312 million.
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Mass movements triggered by theWenchuan earthquake and management strategies of quake lakes
By Zhaoyin Wang, Peng Cui and Ruiyu Wang
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TheWenchuan earthquake on May 12, 2008 triggered numerous avalanches and landslides and created many quake lakes. This paper studies the stability of mass movement deposits and quake lakes and the relation of the mass movements and quake lakes with riverbed incision by field investigations, satellite images and data analysis. The mass movements induced by theWenchuan earthquake released different degrees of potential energy. Landslides which occurred within quaternary deposits released most of their energy and had the highest stability and safety post-event. The avalanche deposits along the Minjiang River had the lowest stability and are dangerous because the slopes are still steep. The essential cause of the mass movement was riverbed incision. From the viewpoint of river training and management, some landslides might be prevented if riverbed incision were controlled. Two strategies are applied to manage the quake lakes: (1) to preserve the quake lakes; and (2) to remove the quake lakes. The Tangjiashan quake lake water was drained out by scouring a spillway on the landslide dam from 740m elevation down to about 714m because there was a high risk of dam-break flooding, which endangered a million people in the downstream reaches, when 200 millionm3 of water had stored in the lake. For quake lakes with low risk of dam failure, the preservation strategy was applied. The continuous rising of the Qinghai–Tibet plateau has resulted in continuous river-bed incision in most streams in the earthquake-hit area. In general, the morphological process of incised rivers goes through four stages: (1) rapid degradation; (2) degradation and widening; (3) widening and resiltation; and (4) equilibrium. Most of the rivers in the earthquake-hit area find themselves in Stage 2. The landslide dams and the quake lakes may form knickpoints on the stream bed profile; the slope below it is steep but the slope upstream is remarkably gentler, which prohibits rivers from incising over the length of the landslide mass and the reach upstream of the quake lakes. Preservation of the quake lakes may create high resistance to flow and change the stream from being in stage 2 into stage 3, thus reducing the mass movement potential in a future earthquake event.
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A comparative study in long-term river flow forecasting models
By M. Reza Ghanbarpour, Karim C. Abbaspour and Keith W. Hipel
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River flow forecasting experiments are carried out for rivers located in the Karun Basin and its sub-basins situated in the Southwestern Iran, because of the potential importance of these rivers for supplying relatively large amounts of water. More specifically, multiple linear regressions (MLR), autoregressive integrated moving average (ARIMA), deseasonalized autoregressive-moving average (DARMA), and Thomas-Fiering (TF) models were fitted to monthly, bimonthly, and seasonal river flow series. One-step-ahead forecasts for the test portion of the time series were generated using the selected set of candidate models. Forecasting performance of the models was compared based on the mean absolute error, root mean square error, normalized mean bias error and correlation coefficient between observed and forecasted values. The results indicate that the ARIMA model is a more reliable model for monthly river flow forecasting applications in the basins under study. For bimonthly and seasonal river flow forecasting, MLR models perform better
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Evaluation of the intrusion generated by a submerged contact chamber of hypolimnetic oxygenator in a reservoir
By Hiroshi Yajima, Jörg Imberger and Christopher Dallimore
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Physical characteristics of a hypolimnetic oxygenator known as aWater Environmental Preservation System (WEP), were investigated through field tests carried out in Sanbe Reservoir, Japan. Field data showed that the oxygen-rich intrusion traveled at nearly the same height as the outflow opening of the device. The thickness of the intrusion, travel time and other important values were derived from the field data. The results showed the flow to be similar to that of an intrusion emanating from a bubble plume after the plunging point and was controlled by an inertia-buoyancy force balance. The intrusion from the oxygenator was successfully simulated with a three-dimensional hydrodynamic and water quality simulation model (ELCOM-CAEYDM) including a simple integral model for the oxygenator.
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River management, landuse change, and future flood risk in China’s Poyang Lake Region
By David Shankman, Lisa Davis and Jan De Leeuw
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Poyang Lake is the largest freshwater lake in China covering 3800 km2 during the summer wet season. It drains into the Changjiang (Yangtze River) at its northern end through a narrow outlet. During the last half of the twentieth century (1949–1999) average annual maximum stage and number of severe flood events in China’s Poyang Lake region increased significantly. There are two primary causes for this trend. One was increasing Changjiang stage, which is the most important determinant of Poyang Lake stage. The second cause for increasing lake stage was levee construction at the margins of Poyang Lake that greatly limited lake size, and therefore, reduced floodwater storage. More recent changes affecting future flood risk include completion of the Three-Gorges Dam, which was intended for flood-control. The Three-Gorges Dam can be used to hold back floodwater for common annual floods, but the reservoir’s storage capacity is too small to reduce downstream discharge during the most severe floods. Also, flood control policies were modified during the past decade, and now focus on permanent removal of some levees and the opening of others during severe floods to increase floodwater storage. These policies have not been fully implemented, and the threat of severe floods affecting densely populated areas in the Poyang Lake region has not been eliminated.
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Managing reservoir sediment release in dam removal projects: an approach informed by physical and numerical modelling of non-cohesive sediment
By Peter W. Downs, Yantao Cui, John K. Wooster, Scott R. Dusterhoff, Derek B. Booth, William E. Dietrich and Leonard S. Sklar
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Sediment management is frequently the most challenging concern in dam removal but there is as yet little guidance available to resource managers. For those rivers with beds composed primarily of non-cohesive sediments, we document recent numerical and physical modelling of two processes critical to evaluating the effects of dam removal: the morphologic response to a sediment pulse, and the infiltration of fine sediment into coarser bed material. We demonstrate that (1) one-dimensional numerical modelling of sediment pulses can simulate reach-averaged transport and deposition over tens of kilometres, with sufficient certainty for managers to make informed decisions; (2) physical modelling of a coarse sediment pulse moving through an armoured pool-bar complex shows deposition in pool tails and along bar margins while maintaining channel complexity and pool depth similar to pre-pulse conditions; (3) physical modelling and theoretical analysis show that fine sediment will infiltrate into an immobile coarse channel bed to only a few median bed material particle diameters. We develop a generic approach to sediment management during dam removal using our experimental understanding to guide baseline data requirements, likely environmental constraints, and alternative removal strategies. In uncontaminated, noncohesive reservoir sediments we conclude that the management impacts of rapid sediment release may be of limited magnitude in many situations, and so the choice of dam removal strategy merits site-specific evaluation of the environmental impacts associated with a full range of alternatives.
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