Dépouillements

Three-dimensional turbulence structure of rectangular side-cavity zone in open-channel streams / Michio Sanjou in JRBM : International journal of river basin management, Vol. 10 N° 4 (Décembre 2012) 

Public ISBD [article]  in JRBM : International journal of river basin management > Vol. 10 N° 4 (Décembre 2012) . - pp. 293-305 Titre : Three-dimensional turbulence structure of rectangular side-cavity zone in open-channel streams Type de document : texte imprimé Auteurs : Michio Sanjou, Auteur ; Tetsuro Akimoto, Auteur ; Takaaki Okamoto, Auteur Année de publication : 2013 Article en page(s) : pp. 293-305 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Open-channel  flow  Side-cavity  zone  Numerical  simulation  and  mass/momentum  exchanges Résumé : Open-ended side-cavity zones are often observed in natural rivers. They appear in embayment and aligned spur-dike fields. Many pollutant clouds and suspended sediments are conveyed and trapped in the cavities, and it is thus very important in environmental hydraulics and river management to accurately predict mass and momentum exchanges through mainstream/side-cavity interface. It is well known that small-scale shedding vortices are generated due to shear instability induced by velocity differences between high-speed mainstream and low-speed embayment flows. A large momentum in the main-channel causes large-scale horizontal gyre in the cavity zone. The coherent turbulence structure in the mainstream/embayment boundary and the horizontal large-scale gyre structure play a key role in the mass/momentum exchanges. In particular, previous studies have pointed out that a rectangular-shaped cavity zone with an aspect ratio of 3.0 produces two kinds of gyres and shows a more effective exchange property in comparison with a square-shaped cavity. However, much uncertainty remains regarding the detailed hydrodynamics accompanied by three-dimensional turbulence motions. Using large eddy simulation, which is also compared with particle image velocimetry measurements, we predict three-dimensional current properties and turbulence structure. Based on these results, a significant relation between instantaneous vertical flows and the spanwise momentum transfer is shown. Furthermore, a phenomenological flow model is proposed for the side-cavity zone in the open-channel field. ISSN : 1571-5124 En ligne : http://www.tandfonline.com/doi/full/10.1080/15715124.2012.717943 [article] Three-dimensional turbulence structure of rectangular side-cavity zone in open-channel streams [texte imprimé] / Michio Sanjou, Auteur ; Tetsuro Akimoto, Auteur ; Takaaki Okamoto, Auteur . - 2013 . - pp. 293-305. Hydraulique Langues : Anglais (eng) in JRBM : International journal of river basin management > Vol. 10 N° 4 (Décembre 2012) . - pp. 293-305 Mots-clés : Open-channel  flow  Side-cavity  zone  Numerical  simulation  and  mass/momentum  exchanges Résumé : Open-ended side-cavity zones are often observed in natural rivers. They appear in embayment and aligned spur-dike fields. Many pollutant clouds and suspended sediments are conveyed and trapped in the cavities, and it is thus very important in environmental hydraulics and river management to accurately predict mass and momentum exchanges through mainstream/side-cavity interface. It is well known that small-scale shedding vortices are generated due to shear instability induced by velocity differences between high-speed mainstream and low-speed embayment flows. A large momentum in the main-channel causes large-scale horizontal gyre in the cavity zone. The coherent turbulence structure in the mainstream/embayment boundary and the horizontal large-scale gyre structure play a key role in the mass/momentum exchanges. In particular, previous studies have pointed out that a rectangular-shaped cavity zone with an aspect ratio of 3.0 produces two kinds of gyres and shows a more effective exchange property in comparison with a square-shaped cavity. However, much uncertainty remains regarding the detailed hydrodynamics accompanied by three-dimensional turbulence motions. Using large eddy simulation, which is also compared with particle image velocimetry measurements, we predict three-dimensional current properties and turbulence structure. Based on these results, a significant relation between instantaneous vertical flows and the spanwise momentum transfer is shown. Furthermore, a phenomenological flow model is proposed for the side-cavity zone in the open-channel field. ISSN : 1571-5124 En ligne : http://www.tandfonline.com/doi/full/10.1080/15715124.2012.717943

South Asia's water conundrum / Ali Shafqat Akanda in JRBM : International journal of river basin management, Vol. 10 N° 4 (Décembre 2012) 

Public ISBD [article]  in JRBM : International journal of river basin management > Vol. 10 N° 4 (Décembre 2012) . - pp. 307-315 Titre : South Asia's water conundrum : Hydroclimatic and geopolitical asymmetry, and brewing conflicts in the eastern Himalayas Type de document : texte imprimé Auteurs : Ali Shafqat Akanda, Auteur Année de publication : 2013 Article en page(s) : pp. 307-315 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Ganges  Brahmaputra  Hydroclimate  Water  policy  Transboundary  issues  Water  conflict Résumé : Few regions in the world are nearing a large-scale water crisis as rapidly as South Asia, especially the basins in the Eastern Himalayas. Despite being known to be a water-rich part of the world, lack of integrated planning, and unfavourable natural and political settings have pushed this populous region towards basin-wide water scarcity, flood hazards, water quality and ecosystem degradation, and public health problems. Rapid growth of population and an unforgiving future climate complicate the situation and put millions more at risk. Meanwhile, the riparian nations continue unilateral efforts to develop their water resources without addressing the ecological integrity of the complex transboundary river system. This article provides an overview of the asymmetry in hydroclimatic conditions and unhelpful political realities that have pushed the region towards a looming large-scale water conflict. ISSN : 1571-5124 En ligne : http://www.tandfonline.com/doi/full/10.1080/15715124.2012.727824 [article] South Asia's water conundrum : Hydroclimatic and geopolitical asymmetry, and brewing conflicts in the eastern Himalayas [texte imprimé] / Ali Shafqat Akanda, Auteur . - 2013 . - pp. 307-315. Hydraulique Langues : Anglais (eng) in JRBM : International journal of river basin management > Vol. 10 N° 4 (Décembre 2012) . - pp. 307-315 Mots-clés : Ganges  Brahmaputra  Hydroclimate  Water  policy  Transboundary  issues  Water  conflict Résumé : Few regions in the world are nearing a large-scale water crisis as rapidly as South Asia, especially the basins in the Eastern Himalayas. Despite being known to be a water-rich part of the world, lack of integrated planning, and unfavourable natural and political settings have pushed this populous region towards basin-wide water scarcity, flood hazards, water quality and ecosystem degradation, and public health problems. Rapid growth of population and an unforgiving future climate complicate the situation and put millions more at risk. Meanwhile, the riparian nations continue unilateral efforts to develop their water resources without addressing the ecological integrity of the complex transboundary river system. This article provides an overview of the asymmetry in hydroclimatic conditions and unhelpful political realities that have pushed the region towards a looming large-scale water conflict. ISSN : 1571-5124 En ligne : http://www.tandfonline.com/doi/full/10.1080/15715124.2012.727824

Rehabilitating Israel's streams and rivers / Alon Tal in JRBM : International journal of river basin management, Vol. 10 N° 4 (Décembre 2012) 

Public ISBD [article]  in JRBM : International journal of river basin management > Vol. 10 N° 4 (Décembre 2012) . - pp. 317-330 Titre : Rehabilitating Israel's streams and rivers Type de document : texte imprimé Auteurs : Alon Tal, Auteur ; David Katz, Auteur Année de publication : 2013 Article en page(s) : pp. 317-330 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Streams  Rehabilitaition  Restoration  Israel  Rivers Résumé : By the 1960s, the intermittent streams in Israel, emptying either into the Mediterranean or into the Dead Sea in the east, became perennial sewage conduits, with the local aquatic habitat decimated or changed beyond recognition. The natural flow of water that had once offered a seasonal pulse to these ephemeral wadis was typically tapped for agricultural utilization of drinking water. During the past two decades, there appeared initial signs that this ecological misfortune was reversible. In 2003, Israel's water law was finally amended, adding ‘nature’ to the list of legitimate recipients of fresh water allocations (along with agriculture, industry and household uses). New standards were set for waste-water treatment. Recent advances in the construction of Israel's desalination infrastructure have added substantial quantities of fresh water to Israel's national grid and raise the prospects of a new deal for Israel's streams. Improved regulation by Israel's agencies and upgraded levels of sewage treatment also promised to improve conditions in the contaminated waterways. This article offers an historic retrospective of the progress of Israel's streams made thus far and future restoration challenges. ISSN : 1571-5124 En ligne : http://www.tandfonline.com/doi/full/10.1080/15715124.2012.727825 [article] Rehabilitating Israel's streams and rivers [texte imprimé] / Alon Tal, Auteur ; David Katz, Auteur . - 2013 . - pp. 317-330. Hydraulique Langues : Anglais (eng) in JRBM : International journal of river basin management > Vol. 10 N° 4 (Décembre 2012) . - pp. 317-330 Mots-clés : Streams  Rehabilitaition  Restoration  Israel  Rivers Résumé : By the 1960s, the intermittent streams in Israel, emptying either into the Mediterranean or into the Dead Sea in the east, became perennial sewage conduits, with the local aquatic habitat decimated or changed beyond recognition. The natural flow of water that had once offered a seasonal pulse to these ephemeral wadis was typically tapped for agricultural utilization of drinking water. During the past two decades, there appeared initial signs that this ecological misfortune was reversible. In 2003, Israel's water law was finally amended, adding ‘nature’ to the list of legitimate recipients of fresh water allocations (along with agriculture, industry and household uses). New standards were set for waste-water treatment. Recent advances in the construction of Israel's desalination infrastructure have added substantial quantities of fresh water to Israel's national grid and raise the prospects of a new deal for Israel's streams. Improved regulation by Israel's agencies and upgraded levels of sewage treatment also promised to improve conditions in the contaminated waterways. This article offers an historic retrospective of the progress of Israel's streams made thus far and future restoration challenges. ISSN : 1571-5124 En ligne : http://www.tandfonline.com/doi/full/10.1080/15715124.2012.727825

An ecological assessment of a dammed pool formed by a slit check dam / Ji Hyun Kang in JRBM : International journal of river basin management, Vol. 10 N° 4 (Décembre 2012) 

Public ISBD [article]  in JRBM : International journal of river basin management > Vol. 10 N° 4 (Décembre 2012) . - pp. 331-340 Titre : An ecological assessment of a dammed pool formed by a slit check dam Type de document : texte imprimé Auteurs : Ji Hyun Kang, Auteur ; So Kazama, Auteur Année de publication : 2013 Article en page(s) : pp. 331-340 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Slit  check  dam  Dammed  pool  Physical  properties  Water  quality  Invertebrate  community  Duration  of  dammed  pool Résumé : This study surveyed physical, chemical, and biological parameters in a dammed pool in comparison to those of the adjacent main stream. Because the dammed pool in this study was a unique zone formed by a slit check dam, the properties of the pool and the main stream could be considered representative of the conditions with and without a slit check dam, respectively. Data were collected in the dammed pool and in the reach of the main stream above the slit check dam in the Wasada Stream, Miyagi Prefecture, Japan. The dammed pool exhibited a lower velocity and finer substrate than those of the main stream. In addition, the water temperature in the dammed pool was slightly higher than in the main stream. Dissolved Oxygen and Chemical Oxygen Demand in the pool were lower than the allowable standards for water pollution. The pool exhibited worse biological indices of water quality than the main stream. Out of a total of 18 taxa found in the stream, only 5 taxa were found in the dammed pool. Most individuals in the dammed pool belonged to the genus Chironomus, which tends to colonize heavily polluted sites. According to these various indicators, the water quality of the dammed pool was lower than that of the main stream. The longest durations of the presence of the dammed pool mainly occurred during snowmelt and during the rainy season. The average duration of the presence of the dammed pool was calculated as 14 days. The dammed pool exhibited a short-duration cycle of formation and extinction according to seasonal variations in water discharge. This cycle reduces the negative effects of the pool on water quality. Therefore, the dammed pool has a minimal negative effect on restoration of the entire reach of the Wasada Stream. ISSN : 1571-5124 En ligne : http://www.tandfonline.com/doi/full/10.1080/15715124.2012.727826 [article] An ecological assessment of a dammed pool formed by a slit check dam [texte imprimé] / Ji Hyun Kang, Auteur ; So Kazama, Auteur . - 2013 . - pp. 331-340. Hydraulique Langues : Anglais (eng) in JRBM : International journal of river basin management > Vol. 10 N° 4 (Décembre 2012) . - pp. 331-340 Mots-clés : Slit  check  dam  Dammed  pool  Physical  properties  Water  quality  Invertebrate  community  Duration  of  dammed  pool Résumé : This study surveyed physical, chemical, and biological parameters in a dammed pool in comparison to those of the adjacent main stream. Because the dammed pool in this study was a unique zone formed by a slit check dam, the properties of the pool and the main stream could be considered representative of the conditions with and without a slit check dam, respectively. Data were collected in the dammed pool and in the reach of the main stream above the slit check dam in the Wasada Stream, Miyagi Prefecture, Japan. The dammed pool exhibited a lower velocity and finer substrate than those of the main stream. In addition, the water temperature in the dammed pool was slightly higher than in the main stream. Dissolved Oxygen and Chemical Oxygen Demand in the pool were lower than the allowable standards for water pollution. The pool exhibited worse biological indices of water quality than the main stream. Out of a total of 18 taxa found in the stream, only 5 taxa were found in the dammed pool. Most individuals in the dammed pool belonged to the genus Chironomus, which tends to colonize heavily polluted sites. According to these various indicators, the water quality of the dammed pool was lower than that of the main stream. The longest durations of the presence of the dammed pool mainly occurred during snowmelt and during the rainy season. The average duration of the presence of the dammed pool was calculated as 14 days. The dammed pool exhibited a short-duration cycle of formation and extinction according to seasonal variations in water discharge. This cycle reduces the negative effects of the pool on water quality. Therefore, the dammed pool has a minimal negative effect on restoration of the entire reach of the Wasada Stream. ISSN : 1571-5124 En ligne : http://www.tandfonline.com/doi/full/10.1080/15715124.2012.727826

Three-dimensional numerical modelling of reservoir flushing in a prototype scale / Stefan Haun in JRBM : International journal of river basin management, Vol. 10 N° 4 (Décembre 2012) 

Public ISBD [article]  in JRBM : International journal of river basin management > Vol. 10 N° 4 (Décembre 2012) . - pp. 341-349 Titre : Three-dimensional numerical modelling of reservoir flushing in a prototype scale Type de document : texte imprimé Auteurs : Stefan Haun, Auteur ; Nils Reidar B. Olsen, Auteur Année de publication : 2013 Article en page(s) : pp. 341-349 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Erosion  processes  Lakes  and  reservoirs  RANS  models  Three-dimensional  models  Water-sediment  interface  interactions Résumé : A fully three-dimensional numerical model for reservoir flushing has been tested against field measurements for the Angostura reservoir in Costa Rica. The numerical program solves the Reynolds-averaged Navier–Stokes (RANS) equations in three-dimensions and uses for discretization the finite-volume method together with a second-order upwind scheme. The used grid is unstructured and non-orthogonal, made of a mixture of hexahedral and tetrahedral cells. In addition to the bathymetry data of the prototype, the model uses grain size distributions of the bed, discharge rates and water levels during the flushing. Simulated bed level changes during the flushing are presented in this study as well as the computed amount of eroded sediments. Where the amount of flushed out sediments show reasonable agreement, differences in the developed flushing channel simulated by the model and compared to the prototype were observed. However, the presented study shows that due to the increasing development of three-dimensional RANS models, the simulation of a reservoir flushing in a prototype becomes feasible. ISSN : 1571-5124 En ligne : http://www.tandfonline.com/doi/full/10.1080/15715124.2012.736388 [article] Three-dimensional numerical modelling of reservoir flushing in a prototype scale [texte imprimé] / Stefan Haun, Auteur ; Nils Reidar B. Olsen, Auteur . - 2013 . - pp. 341-349. Hydraulique Langues : Anglais (eng) in JRBM : International journal of river basin management > Vol. 10 N° 4 (Décembre 2012) . - pp. 341-349 Mots-clés : Erosion  processes  Lakes  and  reservoirs  RANS  models  Three-dimensional  models  Water-sediment  interface  interactions Résumé : A fully three-dimensional numerical model for reservoir flushing has been tested against field measurements for the Angostura reservoir in Costa Rica. The numerical program solves the Reynolds-averaged Navier–Stokes (RANS) equations in three-dimensions and uses for discretization the finite-volume method together with a second-order upwind scheme. The used grid is unstructured and non-orthogonal, made of a mixture of hexahedral and tetrahedral cells. In addition to the bathymetry data of the prototype, the model uses grain size distributions of the bed, discharge rates and water levels during the flushing. Simulated bed level changes during the flushing are presented in this study as well as the computed amount of eroded sediments. Where the amount of flushed out sediments show reasonable agreement, differences in the developed flushing channel simulated by the model and compared to the prototype were observed. However, the presented study shows that due to the increasing development of three-dimensional RANS models, the simulation of a reservoir flushing in a prototype becomes feasible. ISSN : 1571-5124 En ligne : http://www.tandfonline.com/doi/full/10.1080/15715124.2012.736388

Inclusive spaces in integrated river basin management / K. G. Sreeja in JRBM : International journal of river basin management, Vol. 10 N° 4 (Décembre 2012) 

Public ISBD [article]  in JRBM : International journal of river basin management > Vol. 10 N° 4 (Décembre 2012) . - pp. 351-367 Titre : Inclusive spaces in integrated river basin management : Discerning multiple boundaries of resource relations Type de document : texte imprimé Auteurs : K. G. Sreeja, Auteur ; C. G. Madhusoodhanan, Auteur ; P. K. Shetty, Auteur Année de publication : 2013 Article en page(s) : pp. 351-367 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : River  basin  Boundaries  Inclusive  basin  Inter-basin  water  transfers  Management  scales  Western  Ghats Résumé : The existence of multilayered boundaries and networks in a river basin redefines the river basin geographies and concepts and poses extreme challenges to centralized notions of Integrated River Basin Management (IRBM). The paper traces various boundaries that exist due to the physical peculiarities, political situations, resource transfer scenarios and socio-economic networks in one of the most exploited river basins in the highly populated biodiversity hotspot of the Southern Western Ghats in India and analyses the implications for IRBM. The coexistence of multiple, dynamic and often overlapping boundaries existing within and beyond the hydrological boundary encompasses an inclusive region of resource engagement coined as ‘inclusive basin’ which embeds in it various communities of interests. The governance in such an ‘inclusive basin’, heavily mediated by the power gradients of the boundaries involved, can be envisaged as an issue-based polycentric approach which incorporates these interest group domains at multiple scales. The paper attempts a critical examination of the multilayered boundaries that connect the natural hydrographic basin to its physical, social and political settings and their influence on natural resources management, conservation and conflict resolution, especially in the light of the National River Linking Project. ISSN : 1571-5124 En ligne : http://www.tandfonline.com/doi/full/10.1080/15715124.2012.739172 [article] Inclusive spaces in integrated river basin management : Discerning multiple boundaries of resource relations [texte imprimé] / K. G. Sreeja, Auteur ; C. G. Madhusoodhanan, Auteur ; P. K. Shetty, Auteur . - 2013 . - pp. 351-367. Hydraulique Langues : Anglais (eng) in JRBM : International journal of river basin management > Vol. 10 N° 4 (Décembre 2012) . - pp. 351-367 Mots-clés : River  basin  Boundaries  Inclusive  basin  Inter-basin  water  transfers  Management  scales  Western  Ghats Résumé : The existence of multilayered boundaries and networks in a river basin redefines the river basin geographies and concepts and poses extreme challenges to centralized notions of Integrated River Basin Management (IRBM). The paper traces various boundaries that exist due to the physical peculiarities, political situations, resource transfer scenarios and socio-economic networks in one of the most exploited river basins in the highly populated biodiversity hotspot of the Southern Western Ghats in India and analyses the implications for IRBM. The coexistence of multiple, dynamic and often overlapping boundaries existing within and beyond the hydrological boundary encompasses an inclusive region of resource engagement coined as ‘inclusive basin’ which embeds in it various communities of interests. The governance in such an ‘inclusive basin’, heavily mediated by the power gradients of the boundaries involved, can be envisaged as an issue-based polycentric approach which incorporates these interest group domains at multiple scales. The paper attempts a critical examination of the multilayered boundaries that connect the natural hydrographic basin to its physical, social and political settings and their influence on natural resources management, conservation and conflict resolution, especially in the light of the National River Linking Project. ISSN : 1571-5124 En ligne : http://www.tandfonline.com/doi/full/10.1080/15715124.2012.739172

Room for the river / Jeroen Rijke in JRBM : International journal of river basin management, Vol. 10 N° 4 (Décembre 2012) 

Public ISBD [article]  in JRBM : International journal of river basin management > Vol. 10 N° 4 (Décembre 2012) . - pp. 369-382 Titre : Room for the river : Delivering integrated river basin management in the Netherlands Type de document : texte imprimé Auteurs : Jeroen Rijke, Auteur ; Sebastiaan Van Herk, Auteur ; Chris Zevenbergen, Auteur Année de publication : 2013 Article en page(s) : pp. 369-382 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Delta  Programme  Flooding  Integrated  river  basin  management  The  Netherlands  Room  for  the  River  Transition  Water Résumé : This article describes how the governance arrangements of the 2.2 billion Euro water safety programme Room for the River are enabling a transition towards integrated river basin management in the Netherlands. We observe that in terms of integrating multiple objectives and spatial scales, the programme design and multi-level governance processes in the programme have enabled the establishment of integrated plans and designs. We conclude that Room for the River plays an important role in a transition to integrated river basin management in the Netherlands through practical implementation of the strategic policy vision for integrated water management. Also, through application of a mixed centralized–decentralized governance approach, the programme has tackled governance pitfalls related to centralized planning approaches that previously impeded integrated water management. Although several of the governance lessons of the programme are being adopted by, for example, the Delta Programme, we have identified a risk that continuity of the newly introduced governance approach may be lost when the Room for the River programme is completed in 2015. ISSN : 1571-5124 En ligne : http://www.tandfonline.com/doi/full/10.1080/15715124.2012.739173 [article] Room for the river : Delivering integrated river basin management in the Netherlands [texte imprimé] / Jeroen Rijke, Auteur ; Sebastiaan Van Herk, Auteur ; Chris Zevenbergen, Auteur . - 2013 . - pp. 369-382. Hydraulique Langues : Anglais (eng) in JRBM : International journal of river basin management > Vol. 10 N° 4 (Décembre 2012) . - pp. 369-382 Mots-clés : Delta  Programme  Flooding  Integrated  river  basin  management  The  Netherlands  Room  for  the  River  Transition  Water Résumé : This article describes how the governance arrangements of the 2.2 billion Euro water safety programme Room for the River are enabling a transition towards integrated river basin management in the Netherlands. We observe that in terms of integrating multiple objectives and spatial scales, the programme design and multi-level governance processes in the programme have enabled the establishment of integrated plans and designs. We conclude that Room for the River plays an important role in a transition to integrated river basin management in the Netherlands through practical implementation of the strategic policy vision for integrated water management. Also, through application of a mixed centralized–decentralized governance approach, the programme has tackled governance pitfalls related to centralized planning approaches that previously impeded integrated water management. Although several of the governance lessons of the programme are being adopted by, for example, the Delta Programme, we have identified a risk that continuity of the newly introduced governance approach may be lost when the Room for the River programme is completed in 2015. ISSN : 1571-5124 En ligne : http://www.tandfonline.com/doi/full/10.1080/15715124.2012.739173

Estimation of the uncertainty in water level forecasts at ungauged river locations using quantile regression / Kathryn L. Roscoe in JRBM : International journal of river basin management, Vol. 10 N° 4 (Décembre 2012) 

Public ISBD [article]  in JRBM : International journal of river basin management > Vol. 10 N° 4 (Décembre 2012) . - pp. 383-394 Titre : Estimation of the uncertainty in water level forecasts at ungauged river locations using quantile regression Type de document : texte imprimé Auteurs : Kathryn L. Roscoe, Auteur ; Albrecht H. Weerts, Auteur ; Marinus Schroevers, Auteur Année de publication : 2013 Article en page(s) : pp. 383-394 Note générale : Hydraulique Langues : Anglais (eng) Mots-clés : Quantile  regression  Uncertainty  Operational  water  management  Flood  forecasting  Ungauged  forecast  locations  Interpolation Résumé : River water level forecasts play an essential role in operational river management, and uncertainty estimates in the forecasts can support and influence decision-making. Currently, uncertainty estimates in the water level forecasts are commonly available at forecast locations where water level measurements are available, but are lacking at the remaining ungauged forecast locations. In the research presented in this paper, we investigate the combined use of (i) spatial interpolation of the errors (or residuals) in water level forecasts to ungauged locations, and (ii) quantile regression, which is a widely used technique to estimate the quantiles of a distribution, in this case, the error distribution around water level forecasts. The methodology was applied to the IJssel River in the Netherlands, using seven measurement locations and 5 years of hindcasted water levels. We applied a simple inverse-distance interpolation of the residuals in the water level forecasts, and carried out quantile regression on the interpolated residuals. Validation of the methodology showed that the estimated quantiles represented the observations to about 5% accuracy for forecast lead times of 24 h and greater. For shorter lead times, the accuracy varied per station, but was generally poorer due to the relatively greater spread of the interpolated residuals around the true residuals for shorter lead times. For delta rivers such as the IJssel River, the presented methodology is an easy-to-implement and (for lead times of 24 h or greater) accurate technique to augment river level forecasts at ungauged locations with uncertainty estimates. Improvement of the method would be supported by further research into interpolation techniques that take into account additional factors such as proximity of a tributary, influence of wind, or the proximity of a model boundary. ISSN : 1571-5124 En ligne : http://www.tandfonline.com/doi/full/10.1080/15715124.2012.740483 [article] Estimation of the uncertainty in water level forecasts at ungauged river locations using quantile regression [texte imprimé] / Kathryn L. Roscoe, Auteur ; Albrecht H. Weerts, Auteur ; Marinus Schroevers, Auteur . - 2013 . - pp. 383-394. Hydraulique Langues : Anglais (eng) in JRBM : International journal of river basin management > Vol. 10 N° 4 (Décembre 2012) . - pp. 383-394 Mots-clés : Quantile  regression  Uncertainty  Operational  water  management  Flood  forecasting  Ungauged  forecast  locations  Interpolation Résumé : River water level forecasts play an essential role in operational river management, and uncertainty estimates in the forecasts can support and influence decision-making. Currently, uncertainty estimates in the water level forecasts are commonly available at forecast locations where water level measurements are available, but are lacking at the remaining ungauged forecast locations. In the research presented in this paper, we investigate the combined use of (i) spatial interpolation of the errors (or residuals) in water level forecasts to ungauged locations, and (ii) quantile regression, which is a widely used technique to estimate the quantiles of a distribution, in this case, the error distribution around water level forecasts. The methodology was applied to the IJssel River in the Netherlands, using seven measurement locations and 5 years of hindcasted water levels. We applied a simple inverse-distance interpolation of the residuals in the water level forecasts, and carried out quantile regression on the interpolated residuals. Validation of the methodology showed that the estimated quantiles represented the observations to about 5% accuracy for forecast lead times of 24 h and greater. For shorter lead times, the accuracy varied per station, but was generally poorer due to the relatively greater spread of the interpolated residuals around the true residuals for shorter lead times. For delta rivers such as the IJssel River, the presented methodology is an easy-to-implement and (for lead times of 24 h or greater) accurate technique to augment river level forecasts at ungauged locations with uncertainty estimates. Improvement of the method would be supported by further research into interpolation techniques that take into account additional factors such as proximity of a tributary, influence of wind, or the proximity of a model boundary. ISSN : 1571-5124 En ligne : http://www.tandfonline.com/doi/full/10.1080/15715124.2012.740483

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