Hydraulic Modeling

The relatively rapid recession of glaciers in the Himalayas and formation of moraine dammed glacial lakes (MDGLs) in the recent past have increased the risk of glacier lake outburst floods (GLOF) in the countries of Nepal and Bhutan and in the mountainous territory of Sikkim in India. As a product of climate change and global warming, such a risk has not only raised the level of threats to the habitation and infrastructure of the region, but has also contributed to the worsening of the balance of the unique ecosystem that exists in this domain that sustains several of the highest mountain peaks of the world. This study attempts to present an up to date mapping of the MDGLs in the central and eastern Himalayan regions using remote sensing data, with an objective to analyse their surface area variations with time from 1990 through 2015, disaggregated over six episodes. The study also includes the evaluation for susceptibility of MDGLs to GLOF with the least criteria decision analysis (LCDA). Forty two major MDGLs, each having a lake surface area greater than 0.2 km 2 , that were identified in the Himalayan ranges of Nepal, Bhutan, and Sikkim, have been categorized according to their surface area expansion rates in space and time. The lakes have been identified as located within the elevation range of 3800 m and 6800 m above mean sea level (a msl). With a total surface area of 37.9 km 2 , these MDGLs as a whole were observed to have expanded by an astonishing 43.6% in area over the 25 year period of this study. A factor is introduced to numerically sort the lakes in terms of their relative yearly expansion rates, based on their interpretation of their surface area extents from satellite imageries. Verification of predicted GLOF events in the past using this factor with the limited field data as reported in literature indicates that the present analysis may be considered a sufficiently reliable and rapid technique for assessing the potential bursting susceptibility of the MDGLs. The analysis also indicates that, as of now, there are eight MDGLs in the region which appear to be in highly vulnerable states and have high chances in causing potential GLOF events anytime in the recent future.

Alternate bars in rivers and streams develop as a result of differences in length scales involved in the adjustment of flow and sediment transport to irregularities of the bed. The amount of field evidence supporting theoretical insights is highly limited. Here, we present results from a large-scale field experiment in a 600 m long straight reach. Over a period of almost 3 years, the channel was allowed to evolve autogenously from initially flat bed conditions, subject to discharge variation. Alternate bars developed within 8 months from the start of the experiment. The initial stages of bar development included bar growth, both in wavelength and amplitude, and bar migration. The latter was too limited to classify the bars as being migrating bars; therefore, we classify the bars as nonmigrating bars. Toward the end of the experiment, the regular alternate bar pattern evolved into an irregular pattern and bar amplitude started to decrease. From the start of the experiment we observed a declining channel slope, from 1.8 m km−1 initially to 0.9 m km−1 halfway the experiment, after which it stabilized. We applied two bar theories to establish their predictive capacity. Both bar theories predicted the development of alternate bars under the constructed channel conditions. In response to the declining channel slope, both theories predicted a decreasing likelihood for the development of alternate bars. Our study shows that under field conditions, the applied bar theories may predict the initial stages of bed development.

Dams are major hydraulic structures regarding water control, therefore they have essential role in developing our civilization. Huge quantities of water are stored by dams in large reservoirs. Dam safety is threatened by increasing intensity and frequency of floods in the recent years. This issue requires development of improved spillway structures in order to avoid overtopping and failure of dams. As a consequence, dam engineering is progressing toward the concept of “labyrinth weir” due to its simplicity and very high hydraulic performance. Labyrinth structure is composed of vertical wall built on flat floor in a repetitive non-linear layout. Using this weir as spillway can satisfy large discharge requirements during flood events, and maintain large reservoir storage under normal flow conditions. From the economic point of view, the cost of labyrinth weirs is less than that of gated spillways in terms of both construction and maintenance. However, because of the large base area taken by the labyrinth layout which is not found on typical gravity dam sections, use of this weir is very limited in dams. Therefore, an improved version of labyrinth weir has been developed in the last decade as alternative to the traditional one. This solution was given the name Piano Key Weir as its repetitive layout is similar to the keys of piano. The base area of this weir has been reduced making it the favourable solution for dam rehabilitation and new dam projects. This book is the result of a comprehensive parametric study which was held as partial fulfillment of master’s degree in the University of Kufa (Iraq). The study is based on laboratory experiments which aim to determine the Piano Key Weir discharge coefficient for different geometrical configurations under free and submerged flow conditions. Eight geometrical parameters were tested using 26 models in an experimental flume. The book is divided into three parts, namely “Fundamentals”, “Physical Modeling”, and “Results and Discussion”. Part one “Fundamentals” contains two chapters and it is devoted to basic concepts, introductory ideas (Chapter 1) and literature review about the discharge capacity of Piano Key Weir (Chapter 2). Part two “Physical Modeling” describes the preparation and execution of experimental work. Functional relations of the parametric study have been developed in (Chapter 3) by dimensional analysis technique. (Chapter 4) presents the details of laboratory work including flume description, flow calibration, manufacturing of models and testing procedures. Finally, Part three “Results and Discussion” demonstrates the analysis and formulation of experimental results. (Chapter 5) discusses the visual observations during experiments and flow behavior in different conditions. Then, analysis of results for each physical model is presented in (Chapter 6) including free and submerged flow conditions. These results are then formulated in (Chapter 7) using statistical software to develop formulae that predict the values of discharge coefficient in different conditions. Correspondingly, additional resources are provided in the appendices of this book. Tables of data sets for the entire experimental work are given in (Appendix A). Comprehensive collection of illustrative photographs during various stages of testing is presented in (Appendix B), whereas (Appendix C) contains detailed drawings for all experimental models.

The use of Global Positioning System (GPS) in cadastral surveying has ignited much interest over the past decades. To take advantage of the rapid expansion of the GPS technology in both developed and developing countries, cadastral surveying firms and government agencies are increasingly turning their attention to the delivery of services through the GPS technology. GPS has made inroads in those applications requiring lower precision surveys and is fast becoming a primary technology for acquiring data for input into geographical and information system.

Unfortunately, cadastral surveyors in Malawi have a task of catching up to this technology since Malawi is poor and undeveloped. The adoption rate of GPS technology in cadastral surveying is not known. Therefore, to get on the same standard with our colleagues worldwide, there is a need to find out how fast we are updating our technology in cadastral surveying.

The research aimed at investigating the rate of adopting the use of Global Position System technology in Malawi’s cadastral surveying industry.

The research was carried out through structured questionnaires. The questionnaire forms were given to nine cadastral firms and were assessed using simple percentage calculations and displayed on both tables and pie charts.

After the study, a rate of adopting the GPS technology in the cadastral surveying industry was produced. The results showed a high rate of adopting the GPS technology at 71.43% which as compared to the rate of both developed (78.0%) and developing (70.1%) countries, is an indicator of progress in Malawi’s surveying industry.

Despite Malawi being poor, it can still facilitate access to the GPS technology which can contribute towards its Economic Recovery Plan and Malawi Growth and Development Strategy especially on poverty reduction and rural development.

North of Italy, it emerged that when the flow was next to the maximum project value, a relevant air entrainment was experienced at medium to low water levels in the head tank. The theoretical indepth of the matter has allowed to focus attention on the possible causes of the undesired phenomenon of the air entry, but it was necessary, in order to avoid heavy limitations in managing the plant in terms of maximum flow and/or minimum acceptable level in the head tank, to explore the possibility to apply small modifications to the intake geometry and in particular at penstock intake to avoid or at least limit the phenomenon. Tests were performed by means of a physical model (scale 1:10) of the head tank and penstock intake. With this model several different geometric configurations have been tested. Good results have been achieved simply by fixing, at the penstock intake, of a half-doughnut shape shield. Further tests on the modified plant operation have showed the real efficiency of the intervention.

Stream restoration efforts often aim at creating new unconstrained meandering channels without weirs and bank revetments. In reconstructed streams, the initial morphological response of the new streams is often rapid, until a dynamic equilibrium is reached. Here we report on a chute cutoff that occurred within 3 months after realization of a stream restoration project, caused by a plug bar that formed in response to a backwater effect. The temporal evolution of the morphology of both the new and the old channels was monitored over a period of nearly 8 months, including precutoff conditions. The observations can be separated into three stages. Stage 1 is the initial period leading to cutoff vulnerability, stage 2 is the actual cutoff, and stage 3 is the morphological adjustment in response to the cutoff. In stage 1, a plug bar was deposited in one of the channel bends. Hydrodynamic model results show the location of the plug bar coincides with a region where bed shear stress decreased in downstream direction due to backwater. Longitudinal channel bed profiles show that the channel slope decreased soon after channel reconstruction. Hence, sediment from upstream was available to form the plug bar. After the plug bar was deposited, an embayment formed in the floodplain at a location where the former channel was located (stage 2). The former channel was filled with sediment prior to channel construction. It is likely that the sediment at this location was less consolidated, and therefore, prone to erosion. The chute channel continued to incise and widen into the floodplain and, after 6 months, acted as the main channel, conveying the discharge during the majority of time (stage 3). The cutoff channel gradually continued to fill with sediment, from the moment the plug bar formed until the chute channel incised into the floodplain. Sedimentary successions of the deposited material show upward fining, which is in agreement with observations of chute cutoffs in rivers. Although the artificial setting limits the degree in which the observed processes can be projected on natural rivers, the observations prompt to investigate the role of backwater effects in natural chute cutoff initiation.

... One approach that can explicitly link hydrogeomorphic and ecological predictions in the design ... During infrequent overbank floods, lateral variations in channel and valley shape drive flow ... Numerical models that assess the presence of flow convergence routing are now being ...

Hydraulics is a topic in applied science and engineering dealing with the mechanical properties of liquids or fluids. At a very basic level, hydraulics is the liquid version of pneumatic. Fluid mechanics provides the theoretical foundation for hydraulics, which focuses on the engineering uses of fluid properties. In fluid power, hydraulics are used for the generation, control, and transmission of power by the use of pressurized liquids. Hydraulic topics range through some part of science and most of engineering modules, and cover concepts such as pipe flow, dam design, fluids and fluid control circuitry, pumps, turbines, hydro power, computational fluid dynamics, flow measurement, river channel behavior and erosion.Free surface hydraulics is the branch of hydraulics dealing with free surface flow, such as occurring in rivers, canals, lakes, estuaries and seas. Its sub-field open channel flow studies the flow in open channels.

Mozambique is affected by severe floods, droughts, and cyclones. In combination with the social and economic consequences of decades of civil war, it is also a country highly vulnerable to natural disasters. In order to reduce flood risks in the lower part of the Búzi River Basin in central Mozambique, a people-centered Early Warning System was implemented by the Mozambican government in cooperation with the German Cooperation Agency GIZ. Part of this project consists of the implementation of a flood forecasting system. This thesis was developed under this framework with the objective to support this goal. Due to data inconsistencies and gaps, procedures were developed to validate time series analysis, discard inconsistent data, and interpolate results spatially. Precipitation-runoff and hydrological flow routing were developed using the HEC-HMS model. Model parameters obtained in one sub-basin were scaled to other parts of the Búzi River Basin with less or unreliable data. Calibration was performed manually. Diverse improvements were achieved compared to existing forecasting, for instance, regarding lead time and peak flow. Better hydrological data is necessary, specially discharge measurements at high water levels and more reliable hydro-meteorological data in order to provide more accurate flood predictions. Therefore, the model should be used with caution until this data is obtained. Key Words: Búzi River Basin - Early Warning System - Búzi River - Flood forecasting - Hydrological modeling - People-centered

This paper presents a new hydraulic model for efficiently simulating the spatially-distributed 9 dynamics of water surface elevation, wave speed and inundation extent over large data sparse 10 domains. The numerical scheme is based on an extension of the diffusion plus inertia hydraulic 11 model LISFLOOD-FP to include a new sub-grid scale representation of channelized flows. The 12 scheme is shown to be numerically stable and scalable, with the aid of some simple test cases, 13 before being applied to an 800 km reach of the river Niger in Mail. The Niger application focused on 14 the performance of four different model structures: a model without channels (2D model), a model 15 without a floodplain (1D model), a model of the main channels and floodplain (1D/2D model) and 16 the sub-grid approach developed in this paper. Inclusion of both the channel network and the 17 floodplain was shown to be essential, meaning that large scale models of this region, including 18 routing models for land surface schemes, will require a floodplain component. Including sub-grid 19 scale channels on the floodplain changed inundation dynamics over the delta significantly and 20 increased simulation accuracy in terms of water level, wave propagation speed and inundation 21 extent. Furthermore, only the sub-grid model showed a consistent parameterisation when calibrated 22 against either gauge or ICESat water level data, suggesting that connectivity provided by small 23 channels is a strong control on the hydraulics of the floodplain, or, at the very least, that low 24 resolution gridded hydraulic models require additional connectivity to represent the flow dynamics 25 at this test site. 26 *Corresponding author: Tel: +44 (0)117 92 88290; fax: +44 E-mail address: [email protected] 28

Field investigation and hydraulic modeling of the Jökulsá á Fjöllum outflow channel in the northern highlands of Iceland suggest a larger than previously modeled jökulhlaup catastrophic release of glacial floodwaters probably occurring just after early Holocene deglaciation. Although earlier investigations described a similar large paleoflood event, our hydraulic model parameter estimates and floodplain inundation maps correlate with new field evidence presented here. Due to its temporal and voluminous outflow we consider potential jökulhlaup sources and mechanisms and also its relevance as an Earth analog to Mars fluvial geomorphology and processes. In this study, we reconstruct this large jökulhlaup event using HEC-GeoRAS to extract three-dimensional channel geometry and the HEC-RAS hydraulic model. Depositional and erosional landforms across the 435-485 km 2 flood inundation area provide field evidence of high water lines (trimlines) required for hydraulic model constraints. Hydraulic modeling results related to this field evidence and the unambiguous inundation of Ferjufjall along the Mt. Herðubreið reach gives a conservative peak discharge rate of 2.2 × 10 7 m 3 s −1 and a mean flow velocity of 14.9 m s −1 . By comparison, this is larger than the 1.8 × 10 7 m 3 s −1 peak discharge of the Kuray paleoflood in the Altai Mountains of Siberia, which is the largest previously documented paleoflood on Earth. This study suggests that this paleoflood through the Jökulsá á Fjöllum channel is the largest known on Earth.

Crowdsourced data can effectively observe environmental and urban ecosystem processes. The use of data produced by untrained people into flood forecasting models may effectively allow Early Warning Systems (EWS) to better perform while support decision-making to reduce the fatalities and economic losses due to inundation hazard. In this work, we develop a Data Assimilation (DA) method integrating Volunteered Geographic Information (VGI) and a 2D hydraulic model and we test its performances. The proposed framework seeks to extend the capabilities and performances of standard DA works, based on the use of traditional in situ sensors, by assimilating VGI while managing and taking into account the uncertainties related to the quality, and the location and timing of the entire set of observational data. The November 2012 flood in the Italian Tiber River basin was selected as the case study. Results show improvements of the model in terms of uncertainty with a significant persistence of the model updating after the integration of the VGI, even in the case of use of few-selected observations gathered from social media. This will encourage further research in the use of VGI for EWS considering the exponential increase of quality and quantity of smartphone and social media user worldwide. ARTICLE HISTORY

Recession of high-mountain glaciers in response to climatic change frequently results in the development of moraine-dammed glacial lakes. Moraine dam failure is often accompanied by the release of large volumes of water and sediment, termed a Glacial Lake Outburst Flood (GLOF). Chukhung Glacier is a small (~3 km2) receding valley glacier in Mt. Everest (Sagarmatha) National Park, Nepal. Unlike many Himalayan glaciers, which possess a thick mantle of supraglacial debris, its surface is relatively clean. The glacier terminus has receded 1.3 km from its maximum Holocene position, and in doing so provided the space for an ice-contact moraine-dammed lake to develop. The lake had a maximum volume of 5.5 x 10-5 m3 and drained as a result of breaching of the terminal moraine. An estimated 1.3 x 105 m3 of material was removed from the terminal moraine during breach development. Numerical dam-breach modelling, implemented within a Generalised Likelihood Uncertainty Estimation (GLUE) framework, was used to investigate a range of moraine-dam failure scenarios. Reconstructed outflow peak discharges, including failure via overtopping and piping mechanisms, are in the range 146-2200 m3 s-1. Results from two-dimensional hydrodynamic GLOF modelling indicate that maximum local flow depths may have exceeded 9 m, with maximum flow velocities exceeding 20 m s-1 within 700 m of the breach.  The floodwaters mobilised a significant amount of material, sourced mostly from the expanding breach, forming a 300 m long and 100 m wide debris fan originating at the breach exit. moraine-dam. These results also suggest that inundation of the entire floodplain may have been achieved within ten minutes of initial breach development, suggesting that debris fan development was rapid. We discuss the key glaciological and geomorphological factors that have determined the evolution of a hazardous moraine-dammed lake complex and the subsequent generation of a GLOF and its geomorphological impact.

Recession of high-mountain glaciers in response to climatic change frequently results in the development of morainedammed glacial lakes. Moraine dam failure is often accompanied by the release of large volumes of water and sediment, termed a Glacial Lake Outburst Flood (GLOF). Chukhung Glacier is a small (~3 km 2 ) receding valley glacier in Mt. Everest (Sagarmatha) National Park, Nepal. Unlike many Himalayan glaciers, which possess a thick mantle of supraglacial debris, its surface is relatively clean. The glacier terminus has receded 1.3 km from its maximum Holocene position, and in doing so provided the space for an icecontact moraine-dammed lake to develop. The lake had a maximum volume of 5.5 × 10 5 m 3 and drained as a result of breaching of the terminal moraine. An estimated 1.3 × 10 5 m 3 of material was removed from the terminal moraine during breach development. Numerical dam-breach modelling, implemented within a Generalised Likelihood Uncertainty Estimation (GLUE) framework, was used to investigate a range of moraine-dam failure scenarios. Reconstructed outflow peak discharges, including failure via overtopping and piping mechanisms, are in the range 146-2200 m 3 s -1 . Results from two-dimensional hydrodynamic GLOF modelling indicate that maximum local flow depths may have exceeded 9 m, with maximum flow velocities exceeding 20 m s -1 within 700 m of the breach. The floodwaters mobilised a significant amount of material, sourced mostly from the expanding breach, forming a 300 m long and 100 m wide debris fan originating at the breach exit. moraine-dam. These results also suggest that inundation of the entire floodplain may have been achieved within ten minutes of initial breach development, suggesting that debris fan development was rapid. We discuss the key glaciological and geomorphological factors that have determined the evolution of a hazardous moraine-dammed lake complex and the subsequent generation of a GLOF and its geomorphological impact.

Meyer, William J., "Effect of spatial and temporal variability of antecedent moisture content on model-generated runoff from an arid watershed" (2010). UNLV Theses, Dissertations, Professional Papers, and Capstones. Paper 761. flood control facility design or other water resource related decisions are based on synthetic hydrographs. In the Mojave Desert region of Southern Nevada, the duration of storm used to develop these synthetic hydrographs is the 6 hour storm. The 6 hour storm is used to simulate high intensity summer storms. Additionally, soils information used in the calculations for these synthetic hydrographs is taken from maps that are generally developed for a broad range of issues and do not consider spatial or temporal variability in the hydraulic properties. Both the antecedent moisture content (AMC) as well as the hydraulic conductivity can vary due to a number of physical conditions that change within a specific soil type, and this variation can have a significant impact on the watershed runoff response. The objective of the research is to determine if calculated runoff volumes are due to the spatial variation of soil hydraulic properties, and which of these is more important. The thesis also addresses the importance of storm frequency as it relates to rainfall/runoff process and the spatial variation of soil hydraulic properties. A iv pedo-transfer function has been used for this study to develop the variation of the AMC parameter for the final hydraulic/hydrologic models. The effective hydraulic conductivity was evaluated at one half the calculated saturated hydraulic conductivity value. The AMC was varied for three different scenarios on 7 individual soil surfaces on a 228 km 2 arid watershed in the Mojave Desert using a multi-model platform. The modeling software packages used for the thesis are Rosetta, HYDRUS-1D, ArcGIS, FLO-2D and HEC-1. All data were geospatially rectified on the watershed to account for the spatial variation of the soil parameters. Temporal variation of the water content on each soil surface was evaluated using atmospheric demand and the soil properties over a 30-day period. The results show that the spatial variability of hydraulic conductivity has a considerable effect on the calculated flowrates in a two-dimensional model (FLO-2D).

The integration of three hydraulic GIS (Geographic Information System) applications is presented which represent the water infrastructures of cities and urban areas and US streams and rivers. The water infrastructures include drinking water distribution systems, wastewater collection systems and source water. The National Research Council [1] states that problems dealing with the collective behavior of networks such as river systems, water distribution systems and waste water collection systems are complex because they include feedback loops, produce counter-intuitive behaviors and exhibit behaviors that cannot be predicted from the attributes of individual components. A complex system includes all of the above individual components, yet also exhibits emergent collective behavior caused by the interactions among its features. The integration of these applications have been developed for use in planning, response, training and development of monitoring strategies to address potential deliberate or accidental toxic contamination events.

Bu çalışmanın amacı Pamukkale Üniversitesi Kınıklı
Yerleşkesi’nin taşkın afetine maruz kalma potansiyelinin ve
bu afete karşı alınacak önlemlerin belirlenmesi amacıyla
detaylı bir modelleme çalışması yapmaktır. Bu modelleme
kapsamında yerleşkenin akış yukarısında yer alan
Hamamdere Havzası’ndan gelmesi muhtemel olan taşkın
sularının yerleşkede bulunan mevcut derivasyon kanalı ile
herhangi bir taşkın afetine neden olmadan uzaklaştırılıp
uzaklaştırılamayacağı belirlenmiştir. Bu işlemlerin yerine
getirilebilmesi amacıyla coğrafi bilgi sistemleri (CBS)
kullanılarak yerleşke içindeki yapıları ve derivasyon
kanalını içerecek şekilde bir sayısal yükseklik modeli
oluşturulmuş ve bu model kullanılarak yerleşke alanına ait
HEC-RAS tabanlı bir hidrolik model kurulmuştur.
Geliştirilen HEC-RAS tabanlı hidrolik model farklı taşkın
senaryoları
Taşkınlar, ülkemizde depremlerden sonra gözlenen en
önemli doğal afetlerin başında gelmektedir. Son yıllarda
özellikle küresel iklim değişikliğinin etkisiyle taşkınlar doğal
olarak oluşabildiği gibi, plansız kentleşme, dere
yataklarının imara açılması, doğal bitki örtüsünün tahrip
edilmesi gibi nedenlerden dolayı
insan kaynaklı
nedenlerden dolayı da oluşabilmektedir. Bu nedenle,
taşkın afetine maruz kalacak alanların ve bu afete karşı
alınacak yapısal ve yapısal olmayan önlemlerin önceden
belirlenmesi güncelliğini koruyan önemli bir mühendislik
problemidir. Bu problemin çözümünde coğrafi bilgi
sistemleri (CBS) ve hidrolik modelleme teknikleri yaygın
olarak kullanılmaktadır. 
için çalıştırılmış ve yerleşke alanının
Hamamdere Havzası’ndan gelecek bir taşkın afetine
maruz kalma potansiyeli detaylı olarak değerlendirilmiştir.

Crowdsourced data can effectively observe environmental and urban ecosystem processes. The use of data produced by untrained people into flood forecasting models may effectively allow Early Warning Systems (EWS) to better perform while support decision-making to reduce the fatalities and economic losses due to inundation hazard. In this work, we develop a Data Assimilation (DA) method integrating Volunteered Geographic Information (VGI) and a 2D hydraulic model and we test its performances. The proposed framework seeks to extend the capabilities and performances of standard DA works, based on the use of traditional in situ sensors, by assimilating VGI while managing and taking into account the uncertainties related to the quality, and the location and timing of the entire set of observational data. The November 2012 flood in the Italian Tiber River basin was selected as the case study. Results show improvements of the model in terms of uncertainty with a significant persistence of t...

Ballast rail has a vital fuction to support the train's load and its dynamic forces. This load is then distributed to the subgrade layer through pile of gravel under the ballast. Most of the design about the gravel layer (ballast) doesn't take into account the effect of flood overflow on the rail, which is very likely to occur during rainy season. The Flood flows above the rail will reduce the ballast stability and then eroded. Part or most of the gravel were flushed out, thus resulting the ballast to be weak and may collapse, which is vey dangerous to the train traffic. Its therefore requires to investigate stability of the ballast under flood flow above the rail condition and any measure or improvement required by Hydraulic Modeling.

It is obvious to all people the importance of water as an essential element for life, hence, water loss is a lifethreatening and alarming predictor of the future. Leakage problem is one of the most important causes of water loss in water systems; therefore, it was and is still a matter of attention of many researchers, who are in search of the most effective methods to solve this problem using many techniques. These techniques vary with one another in terms of accuracy, cost and speed of obtaining results. This research paper presents a part of an extensive research work, which aims to develop a geospatial approach for solving the leakage detection problem in water systems using an integrated geospatial system. This paper will show a sample of the results that has been obtained through a lab experiment, which explains the changes in hydraulic behavior of the network due to the change in leakage size and leakage location as a step for validating the mentioned approach.

Floods have recently become a major hazard in West Africa (WA) in terms of both their magnitude and frequency. They affect livelihoods, infrastructure and production systems, hence impacting on Sustainable Development (SD). Early Warning Systems (EWS) for floods that properly address all four EWS components, while also being community and impact-based, do not yet exist in WA. Existing systems address only the main rivers, are conceived in a top-down manner and are hazard-centered. This study on the Sirba river in Niger aims to demonstrate that an operational community and impact-based EWS for floods can be set up by leveraging the existing tools, local stakeholders and knowledge. The main finding of the study is that bridging the gap between top-down and bottom-up approaches is possible by directly connecting the available technical capabilities with the local level through a participatory approach. This allows the beneficiaries to define the rules that will develop the whole system...

The failure of a lava dam 165,000 yr ago produced the largest known flood on the Colorado River in Grand Canyon. The Hyaloclastite Dam was up to 366 m high, and geochemical evidence linked this structure to outburst-flood deposits that occurred for 32 km downstream. Using the Hyaloclastite outburst-flood deposits as paleostage indicators, we used dam-failure and unsteady flow modeling to estimate a peak discharge and flow hydrograph. Failure of the Hyaloclastite Dam released a maximum 11 × 10 9 m 3 of water in 31 h. Peak discharges, estimated from uncertainty in channel geometry, dam height, and hydraulic characteristics, ranged from 2.3 to 5.3 × 10 5 m 3 s −1 for the Hyaloclastite outburst flood. This discharge is an order of magnitude greater than the largest known discharge on the Colorado River (1.4 × 10 4 m 3 s −1 ) and the largest peak discharge resulting from failure of a constructed dam in the USA (6.5 × 10 4 m 3 s −1 ). Moreover, the Hyaloclastite outburst flood is the oldest documented Quaternary flood and one of the largest to have occurred in the continental USA. The peak discharge for this flood ranks in the top 30 floods (N10 5 m 3 s −1 ) known worldwide and in the top ten largest floods in North America.

In this article two modeling approaches were developed based on the use of US Geological Survey digital elevation model (DEM) data. These models were utilized to delineate the extent of flooding induced by precipitation from Hurricane Floyd in a portion of Pitt County, North Carolina. The patterns of flood extent derived from the two models were compared to the extent of flooding indicated on a digital aerial photograph taken two days after peak flood levels had been reached. In addition, floodplain boundaries based on Federal Emergency Management Agency Q3 maps were compared to the extent of flooding on the aerial photo. Actual emergency response operations undertaken through the Pitt County Emergency Operations Center during the flood event are described, and are used to provide a context for evaluating the potential utility of these models. The flood extents produced by the modeling methods performed well at representing the actual extent of the flooding.r 2001 Elsevier Science L...

Floods have recently become a major hazard in West Africa (WA) in terms of both their magnitude and frequency. They affect livelihoods, infrastructure and production systems, hence impacting on Sustainable Development (SD). Early Warning Systems (EWS) for floods that properly address all four EWS components, while also being community and impact-based, do not yet exist in WA. Existing systems address only the main rivers, are conceived in a top-down manner and are hazard-centered. This study on the Sirba river in Niger aims to demonstrate that an operational community and impact-based EWS for floods can be set up by leveraging the existing tools, local stakeholders and knowledge. The main finding of the study is that bridging the gap between top-down and bottom-up approaches is possible by directly connecting the available technical capabilities with the local level through a participatory approach. This allows the beneficiaries to define the rules that will develop the whole system...

Despite many deaths annually worldwide due to floods, no strategy exists to mechanistically map hydraulic hazards people face when entrained in a river. Previous work determined water depth-velocity product thresholds for human instability from standing or walking positions. Because whitewater rivers attract diverse recreation that risks entraining people into hazardous flow, this study takes the next step by predicting the hazard pattern facing people swept away. The study site was the 12.2-km bedrockalluvial upper South Yuba River in the Sierra Nevada Mountains. A novel algorithm was developed and applied to two-dimensional hydrodynamic model outputs to delineate three hydraulic hazard categories associated with conditions for which people may be unable to save themselves: emergent unsavable and steep emergent surfaces, submerged unsavable surfaces, and hydraulic jumps. Model results were used to quantify exposure of both an upright and supine entrained person to collision and body entrapment hazards. Hazard exposure was expressed with two metrics: passage proximity (how closely a body approached a hazard) and reaction time (time available to respond to and avoid a hazard). Hazard exposure maps were produced for multiple discharges, and the areal distributions of exposure were synthesized for the river segment. Analyses revealed that the maximum hazard exposure occurred at an intermediate discharge. Additionally, longitudinal profiles of the results indicated both discharge-dependent and discharge-independent hazards. Relative to the upright body, the supine body was overall exposed to less dangerous channel regions in passage down the river, but experienced more abrupt encounters with the danger that did occur.

This article introduces a novel method to locate leaks in trunk pipelines with a unique branch. The method is based on three state observers; each one with a specific assigned task. The aim of the first state observer (the orientation observer) is to indicate whether the leak is to the left (upstream) or to the right (downstream) of the branch. Depending on the indication of the orientation observer, one of the other two state observers (the locating observers) can be used to estimate the position of the leak. The three observers are based on second-order models that were built from the so-called rigid water column model of a pipeline and hydraulic gradient relations.

The relatively rapid recession of glaciers in the Himalayas and formation of moraine dammed glacial lakes (MDGLs) in the recent past have increased the risk of glacier lake outburst floods (GLOF) in the countries of Nepal and Bhutan and in the mountainous territory of Sikkim in India. As a product of climate change and global warming, such a risk has not only raised the level of threats to the habitation and infrastructure of the region, but has also contributed to the worsening of the balance of the unique ecosystem that exists in this domain that sustains several of the highest mountain peaks of the world. This study attempts to present an up to date mapping of the MDGLs in the central and eastern Himalayan regions using remote sensing data, with an objective to analyse their surface area variations with time from 1990 through 2015, disaggregated over six episodes. The study also includes the evaluation for susceptibility of MDGLs to GLOF with the least criteria decision analysis (LCDA). Forty two major MDGLs, each having a lake surface area greater than 0.2 km 2 , that were identified in the Himalayan ranges of Nepal, Bhutan, and Sikkim, have been categorized according to their surface area expansion rates in space and time. The lakes have been identified as located within the elevation range of 3800 m and 6800 m above mean sea level (a msl). With a total surface area of 37.9 km 2 , these MDGLs as a whole were observed to have expanded by an astonishing 43.6% in area over the 25 year period of this study. A factor is introduced to numerically sort the lakes in terms of their relative yearly expansion rates, based on their interpretation of their surface area extents from satellite imageries. Verification of predicted GLOF events in the past using this factor with the limited field data as reported in literature indicates that the present analysis may be considered a sufficiently reliable and rapid technique for assessing the potential bursting susceptibility of the MDGLs. The analysis also indicates that, as of now, there are eight MDGLs in the region which appear to be in highly vulnerable states and have high chances in causing potential GLOF events anytime in the recent future.

Recession of high-mountain glaciers in response to climatic change frequently results in the development of morainedammed glacial lakes. Moraine dam failure is often accompanied by the release of large volumes of water and sediment, termed a Glacial Lake Outburst Flood (GLOF). Chukhung Glacier is a small (~3 km 2) receding valley glacier in Mt. Everest (Sagarmatha) National Park, Nepal. Unlike many Himalayan glaciers, which possess a thick mantle of supraglacial debris, its surface is relatively clean. The glacier terminus has receded 1.3 km from its maximum Holocene position, and in doing so provided the space for an icecontact moraine-dammed lake to develop. The lake had a maximum volume of 5.5 × 10 5 m 3 and drained as a result of breaching of the terminal moraine. An estimated 1.3 × 10 5 m 3 of material was removed from the terminal moraine during breach development. Numerical dam-breach modelling, implemented within a Generalised Likelihood Uncertainty Estimation (GLUE) framework, was used to investigate a range of moraine-dam failure scenarios. Reconstructed outflow peak discharges, including failure via overtopping and piping mechanisms, are in the range 146-2200 m 3 s-1. Results from two-dimensional hydrodynamic GLOF modelling indicate that maximum local flow depths may have exceeded 9 m, with maximum flow velocities exceeding 20 m s-1 within 700 m of the breach. The floodwaters mobilised a significant amount of material, sourced mostly from the expanding breach, forming a 300 m long and 100 m wide debris fan originating at the breach exit. moraine-dam. These results also suggest that inundation of the entire floodplain may have been achieved within ten minutes of initial breach development, suggesting that debris fan development was rapid. We discuss the key glaciological and geomorphological factors that have determined the evolution of a hazardous moraine-dammed lake complex and the subsequent generation of a GLOF and its geomorphological impact.

It is obvious to all people the importance of water as an essential element for life, hence, water loss is a life-threatening and alarming predictor of the future. Leakage problem is one of the most important causes of water loss in water systems; therefore, it was and is still a matter of attention of many researchers, who are in search of the most effective methods to solve this problem using many techniques. These techniques vary with one another in terms of accuracy, cost and speed of obtaining results. This research paper presents a part of an extensive research work, which aims to develop a geospatial approach for solving the leakage detection problem in water systems using an integrated geospatial system. This paper will show a sample of the results that has been obtained through a lab experiment, which explains the changes in hydraulic behavior of the network due to the change in leakage size and leakage location as a step for validating the mentioned approach. Keywords: Lea...

The integration of three hydraulic GIS (Geographic Information System) applications is presented which represent the water infrastructures of cities and urban areas and US streams and rivers. The water infrastructures include drinking water distribution systems, wastewater collection systems and source water. The National Research Council states that problems dealing with the collective behavior of networks such as river systems, water distribution systems and waste water collection systems are complex because they include feedback loops, produce counter-intuitive behaviors and exhibit behaviors that cannot be predicted from the attributes of individual components. A complex system includes all of the above individual components, yet also exhibits emergent collective behavior caused by the interactions among its features. The integration of these applications have been developed for use in planning, response, training and development of monitoring strategies to address potential deliberate or accidental toxic contamination events.

Floods have recently become a major hazard in West Africa (WA) in terms of both their magnitude and frequency. They affect livelihoods, infrastructure and production systems, hence impacting on Sustainable Development (SD). Early Warning Systems (EWS) for floods that properly address all four EWS components, while also being community and impact-based, do not yet exist in WA. Existing systems address only the main rivers, are conceived in a top-down manner and are hazard-centered. This study on the Sirba river in Niger aims to demonstrate that an operational community and impact-based EWS for floods can be set up by leveraging the existing tools, local stakeholders and knowledge. The main finding of the study is that bridging the gap between top-down and bottom-up approaches is possible by directly connecting the available technical capabilities with the local level through a participatory approach. This allows the beneficiaries to define the rules that will develop the whole system...

Vegetation resistance influences water flow in floodplains. Characterization of vegetation for hydraulic modeling includes the description of the spatial variability of vegetation type, height and density. In this research, we explored the use of dual polarized Radarsat-2 wide swath mode backscatter coefficients (σ°) and Landsat 5 TM to derive spatial hydraulic roughness. The spatial roughness parameterization included four steps: (i) land use classification from Landsat 5 TM; (ii) establishing a relationship between σ° statistics and vegetation parameters; (iii) relative surface roughness (Ks) determination from Synthetic Aperture Radar (SAR) backscatter temporal variability; (iv) derivation of the spatial distribution of the spatial hydraulic roughness both from Manning's roughness coefficient look up table (LUT) and relative surface roughness. Hydraulic simulations were performed using the FLO-2D hydrodynamic model to evaluate model performance under three different hydraulic modeling simulations results with different Manning's coefficient parameterizations, which includes SWL1, SWL2 and SWL3. SWL1 is simulated water

Vegetation resistance influences water flow in floodplains. Characterization of vegetation for hydraulic modeling includes the description of the spatial variability of vegetation type, height and density. In this research, we explored the use of dual polarized Radarsat-2 wide swath mode backscatter coefficients (σ°) and Landsat 5 TM to derive spatial hydraulic roughness. The spatial roughness parameterization included four steps: (i) land use classification from Landsat 5 TM; (ii) establishing a relationship between σ° statistics and vegetation parameters; (iii) relative surface roughness (Ks) determination from Synthetic Aperture Radar (SAR) backscatter temporal variability; (iv) derivation of the spatial distribution of the spatial hydraulic roughness both from Manning's roughness coefficient look up table (LUT) and relative surface roughness. Hydraulic simulations were performed using the FLO-2D hydrodynamic model to evaluate model performance under three different hydraulic modeling simulations results with different Manning's coefficient parameterizations, which includes SWL1, SWL2 and SWL3. SWL1 is simulated water

Hydrodynamic modeling is used to analyse the inundation behavior of St. George village during extreme flood events, in particular for a flood happened in spring 2006. The study reach, 4 km in length, is situated in the Danube Delta, at the mouth of St. George distributary and includes St. George village. Land and bathymetric surveys were used to create a digital terrain model (DTM) of the river channel and the village. By coupling the geometry with hydrologic data, a 2D hydrodynamic model was built up with the help of the CCHE2D code (University of Mississippi). The model is based on integrating Saint-Venant shallow waters (depth averaged) equations through finite-difference implicit numerical scheme. It was calibrated in terms of roughness coefficients on measured values of water surface elevation registered in the St. George port. Flood maps obtained from computations were compared to satellite images from the same days of the spring 2006 extreme event. Inundation behaviour of the St. George village was analysed for different scenarios of river hydrological and sea level (variable because of wind waves) conditions. Findings were compared with high water marks and inhabitants testimonials. The model proved that sea level has a higher influence upon the inundability of the area than the river flood events.

Many urban and suburban communities in the Midwest are seeking to establish sustainable, morphologically and hydraulically varied, yet dynamically stable fluvial systems that are capable of supporting healthy, biologically diverse aquatic ecosystems-a process known as stream naturalization. This paper describes an integrated research program that seeks to develop a scientific and technological framework to support two stream naturalization projects near Chicago, Illinois. The research program integrates theory and methods in fluvial geomorphology, aquatic ecology, hydraulic engineering and social theory. Both the conceptual and the practical challenges of that integration are discussed. Scientific and technical support emphasize the development of predictive tools to evaluate the performance of possible naturalization designs at scales most appropriate to community based projects. Social analysis focuses on place based evaluations of how communities formulate an environmental vision and then, through decision making, translate this vision into specific stream naturalization strategies. Integration of scientific and technical with social components occurs in the context of community based decision making as the predictive tools are employed by project scientists to help local communities translate their environmental visions into concrete environmental designs. Social analysis of this decision making process reveals how the interplay between the community's vision of what they want the watershed to become, and the scientific perspective on what the watershed can become to achieve the community's environmental goals, leads to the implementation of specific stream naturalization practices.

It is obvious to all people the importance of water as an essential element for life, hence, water loss is a lifethreatening and alarming predictor of the future. Leakage problem is one of the most important causes of water loss in water systems; therefore, it was and is still a matter of attention of many researchers, who are in search of the most effective methods to solve this problem using many techniques. These techniques vary with one another in terms of accuracy, cost and speed of obtaining results. This research paper presents a part of an extensive research work, which aims to develop a geospatial approach for solving the leakage detection problem in water systems using an integrated geospatial system. This paper will show a sample of the results that has been obtained through a lab experiment, which explains the changes in hydraulic behavior of the network due to the change in leakage size and leakage location as a step for validating the mentioned approach.

Los diques fusibles son terraplenes compuestos por diferentes capas de arena y/o enrocamiento, diseñados como una cortina común, estable para toda condición de operación, excepto en el desbordamiento. Su diseño les permite erosionarse de manera relativamente predecible y controlada al momento en que el nivel de agua rebasa su cresta. Este tipo de estructuras es ampliamente usado para el control de avenidas en márgenes de cauces y como vertedores auxiliares para presas. Existen ejemplos de su aplicación en la presa Otter Creek en Utah, New Waddell, Bartlett y Horseshoe en Arizona y Guri en Venezuela.

ABSTRACT The various human activities are one of the main affecting factors on natural disasters. Human effects not suitable for land use potential can cause both physical and moral damages. Yeniciftlik stream basin, located within the boundaries of Beykoz, a suburb of Istanbul in Turkey, has been selected as the study area. It covers an area of 3.66 km2 of the Yeniciftlik River within the boundaries of the Beykoz district. Nowadays, there are many methods for flood researches. Not only new satellite technologies but also improvements of GIS provide important advantages in the researches of natural disasters. In this study, the effects of land use features on flood occurrence have been determined by using GIS and remote sensing. Pixel-based classification method has been used for analyzing land use features. IKONOS pan-sharpened satellite imagery has been used for current land use. Processes of flood analyze were performed by means of HEC-GeoRAS (ArcGIS 9.3) and HEC-RAS 4.0 (Hydrologic Engineering Centers River Analysis System) hydraulic software. In this study, geometric data composes the basis of the model. These data are rivers, river coasts, stream ways, cross sections and land use. The geometric data of the study area are produced with HEC-GeoRAS and all other data were gathered here before they were transferred to the HEC-RAS. After the input of the geometric data stream, data related to the basin where the modeling will be done were input. Hydraulic and hydrologic modeling for the flood risk studies, flood flow rates of 10, 50 and 100 years were calculated using maximum flood flow rates of 30 years, and flood risk maps were obtained making hydraulic modeling according to the data obtained.

Detention basins are one of the structural measures for floodwater control in urban environments. They are effective tools in flood mitigation, but some studies have shown that they may aggravate the condition if not properly sited. This study presents an innovative approach which directly incorporates hydrologic-hydraulic modeling results to site selection procedure of detention basins for flood control. Darakeh Catchment which is located in Tehran is selected as the case study. Hydrologic, physiographic and economic parameters are considered as siting criteria. SWMM model is employed for simulating hydrologic-hydraulic processes and evaluating the current drainage network against low-frequent storms. Modeling results, including flooded junctions and the flow hydrographs are used as input parameters to spatial decision making framework. The framework employs Analytical Hierarchy Process (AHP) as decision making structure and geographic information system (GIS) as spatial analyst tool. The output is a raster map which shows each cell potential for detention basin placement. The presented approach aims to improve siting procedure of these measures and other BMPs in an urban environment.