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2022 | Buch

River and Coastal Engineering

Hydraulics, Water Resources and Coastal Engineering

herausgegeben von: Dr. Ramakar Jha, Prof. Dr. Vijay P. Singh, Dr. Vivekanand Singh, Dr. L.B. Roy, Assist. Prof. Roshni Thendiyath

Verlag: Springer International Publishing

Buchreihe: Water Science and Technology Library


Über dieses Buch

This book deals with important topics of current interest, such as climate change, floods, drought, and hydrological extremes. The impact of climate change on water resources is drawing worldwide attention in these days; water resources in many countries are already stressed and climate change along with burgeoning population, rising standard of living, and increasing demand are adding to the stress. Further, river basins are becoming less resilient to climatic vagaries. Fundamental to addressing these issues is hydrological modelling which is covered in these books. Further, integrated water resources management is vital to ensure water and food security. Integral to the management is groundwater and solute transport. The books encompass tools that will be useful to mitigate the adverse consequences of natural disasters.

This book is useful for those working in river and coastal engineering. River Engineering is important for fluvial hydraulics, sediment transport, morphometry, desilting, trap efficiency, silting and desilting process. Coastal engineering includes storm surge forecast, optimization of harbour, wave modelling, and shoreline changes.


Establishing Sediment Rating Curves Using Optimization Technique

Water resource projects are affected by the amount and concentration of sediment transported by a river. In this regard, quantification of sediment volume is of paramount importance in river engineering practices. Spreadsheet embedded GRG (Generalized Reduced Gradient) technique has been used in the present paper to estimate Suspended Sediment Load (SSL). The sediment rating curves were also established using conventional method of linear regression. Sediment rating curves were developed for two sites i.e. Hermann site on Missouri river and Grafton site on Mississippi river. Comparative analysis of the GRG and linear regression method reveals that sediment loads estimated by GRG technique are more accurate than method of linear regression analysis in either case of calibration or validation. GRG technique is not only a simple optimization but has been found to converge to optimal solution quickly. Moreover, it provides explicit expression for development of sediment record.

Mohammad Zakwan, Zeenat Ara
A Study on Some Characteristics of an Alluvial Channel for Varying Flows

An attempt has been made here to study on some characteristics of an alluvial channel when its pattern undergoes a continuous change under two different flows in the context of fluvial and analytical data. The effect of inclusion of a training structure on these channels has also been studied. An experimental alluvial channel of 91.44 m in length with a trapezoidal cross section of 10 cm in depth, 10 cm bed width and side slope 2:1 was laid on a sand tray of 91.44 m in length and 9.144 m in width. At the entrance of the channel, an initial curvature was introduced to accelerate the meandering process. At first, a steady discharge of 0.003 cumecs was circulated through the experimental straight channel for 150 h when a regime channel was obtained. It was noticed that only three successive meanders of about same length had developed up to 36.576 m along the longitudinal direction of the channel. The rest portion of the channel remained straight. At this stage, a river training structure (barrage) was introduced at a section of 17.069 m from entrance of the channel. With same discharge, the flume was again allowed to run for 150 h until a regime channel was attained. The experiment was repeated with another discharge of 0.007 cumecs. From data analysis, it may be concluded that in the meandering reach, any change in cross-sectional flow area is associated with the increase of water surface width or total bed width which is again accompanied by increase in boundary resistance or power expenditure. As such, there may be a good correlation between scour and increase of water surface or total bed width and hence to power expenditure in the meandering reach. But it may not exist in the straight reach of the same channel.

Mayuraksha Bardhan
Model Study for Determination of Efficiency of a Typical Silt Ejector

After construction of a barrage in the main river Teesta in West Bengal, the off taking channel from one of its bank was designed to carry water and augment the discharge of a secondary river Mahananda. The discharge of the main river was heavily laden with silt. To control the quantity of silt, a Silt Ejector was proposed to be constructed in Teesta Mahananda Link Canal for getting silt-free water for irrigation. The design discharge of the canal upstream and downstream of the Silt Ejector was 438.91 cumecs and 382.28 cumecs respectively and the discharge through the Silt-Ejector was 56.63 cumecs. A geometric model of scale 1:36 was constructed in Indoor Hydraulics Laboratory on the basis of design drawings. The model incorporated about 500 m long stretch, about 400 m upstream and about 100 m downstream of the Silt Ejector. In the model, the Silt-Ejector structure was made of thin Perspex sheets. The model was run with the design discharge and with discharges 70, 50 and 30% of the design discharge. Four nos. of gauges were installed in the model at 360 m upstream, 75 m upstream, 22 m downstream and 100 m downstream of the Silt Ejector. Another gauge was installed in the escape channel. Velocity observations were taken at 324 m upstream, near the upstream face of the Silt Ejector and 80 m downstream point of the Silt Ejector. The observed model data were validated with respect to prototype data. Mustard seeds were used as silt-charge. The entire quantity of mustard seeds passed through the Silt Ejector into the Escape Channel for all discharges, except that of the 30% design discharge. This indicated that the efficiency of the Silt Ejector was good and satisfactory except for low discharge of the order of 30% of design discharge. No undesirable flow features were noticed at the entry of the Ejector.

Mayuraksha Bardhan
Comparative Review on Model Selection for Hydrological Studies

The objective of this review was to consolidate the latest hydrological models developed for application in hydrological studies. The paper briefly discusses various models available for simulation of specific processes in the hydrological cycle. The models presented in this paper are classified based on distributed, semi-distributed, stochastic and process based deterministic approach. These models are employed for research applications in sedimentation analysis, sub-surface modeling, hydraulic routing and hydrological prediction. The criteria used for the assessment of hydrological models are based on the simulation, governing equation and data availability of the model. The spatial and temporal scale of the models are selected for different components of the hydrological processes. These are the basic requirements that must be always addressed before selecting any model for future use.

Mudesir Nesru, M. K. Nagaraj
An Automatic Integrated Tool for Deriving Morphometric Parameters

In the present scenario, geoinformatics is an important factor in study of morphometry for designing, and development of hydraulic structures. In the present study, an effort has been made to develop an automatic integrated tool using ArcGIS (Proprietary) software, which can be used to derive the morphometric parameters with minimum human errors and strain on the workstations used for analysis. The primary inputs to run this tool are Digital elevation Model (DEM), watershed outlet shape file and minimum number of streams for defining a stream which are user defined. All the important data required for morphometric analysis after the processing of the input data will be obtained from the developed tool as output. In total 13 parameters will be created as output from this model which are slope, aspect, hill shade, drainage density, Compound topographic Index, Shape factor, form factor, elongation ratio, circulatory ratio, wandering ratio, lemniscate, length area relationship and fitness ratio. This method generates a reliable database of morphometric parameters and is very useful in the field of hydrology, and watershed analysis.

Vinit Lambey, A. D. Prasad
Flood Frequency Analysis in Seonath and Hasdeo River Basins

Flood frequency analysis estimates reliable design flood, which is critical for the safety of any hydraulic, hydrologic construction and management. The overall objective of this study is to perform flood frequency analysis for Seonath and Hasdeo river basins of Chhattisgarh state, India. In this study, homogeneous regions are delineated by Ward cluster analysis. Cluster variables are L-moment ratios of annual maximum events and catchment characters. Index flood is performed for parametric quantile estimation of flood events. L-moments are employed in regionalization, frequency distribution selection, and distribution parameter estimation. Locally weighted polynomial model (Locfit) is performed for at-site frequency analysis. Flood quantiles are estimated for regions and at sites. In regional flood frequency analysis, regionalisation based on annual maximum flood series shows better flood quantiles than regionalisation based on site characteristics. It reveals that geophysical homogeneity does not mean hydrologic homogeneity. Regional formulae for annual mean discharge are formulated based on catchment character for estimation of flood quantiles for ungauged catchments.

Mani Kant Verma, Mukesh Kumar Verma
Assessment of Plan Form Development Due to Erosion and Deposition of Soil

Geologic erosion is a normal process of weathering that generally occurs at low rates in all soils as part of the natural soil-forming processes. Due to dynamic action of stream and rivers, many of the landforms such as an island in the stream suffer severe bank erosion. It changes the landform around and downstream of the island in the way that is very destructive. The erosive activities of stream have been very devastating and life threatening. There are many reasons behind this degradation such as difference in climate, changes in direction of water, man made changes of river path, land use pattern etc. A study has been carried out to describe and determine the changes in plan form development due to erosion and deposition of soil around an island in a natural stream. Determination of velocity profile in each section around the island and in the river section downstream of the island has been conducted by Acoustic Doppler Velocimeter (ADV) to quantify forces acting on and around the island. Changes in plan form development throughout the complete run for each set of experimental run involving an island of specific characteristics in a stream. Therefore, this study predicts detachment, transportation and deposition of cohesion less uniform and non-uniform sediments as well as run-off around an island of different shapes, sizes and materials. Measurements are carried out through different steps. Such as, Measurement of Discharge by Electronic Flow Meter, Discharge measurement using V Notch, Measurement for the Velocity Distribution with the help of ADV, the values of dry density were computed by using the observed value of bulk density and antecedent moisture content. Graphical presentation and comparative studies were done by Teraplot software.

Snigdhadip Ghosh, Vijay Kumar Dwivedi
Assessment and Application of the Morphometric Attributes of the Bharathapuzha River Basin, India Using Geographical Information System

Assessment of morphological attributes of a catchment area with inaccessible land parcels by geospatial technique is one of the major advantages of space technology. Due to the spatially varying and complex characteristics of catchments, the selection of data for morphometric analysis should be made very carefully. This study aims to assess the Bharathapuzha River basin’s morphometric nature, which has complex topographic features, using the Cartosat-1 Digital Elevation Model, a freely available National Digital Elevation Model (DEM) with 1-arc second resolution. Commonly in all morphometric studies, ignoring the topographical characteristics, DEM is chosen, and the drainage networks are extracted regardless of the threshold drainage area. In this study, DEM selection is done by considering the complex topography of the basin, and the drainage networks are extracted by defining a meaningful threshold. The primary catchment characteristics were directly mapped from the DEM, and by using them, the secondary characteristics were calculated. The drainage network obtained from this study closely matches with the natural pattern of the drainage network in the basin. Hence, this study demonstrates that the Indian National DEM from Cartosat-1 can be used confidently for morphometric studies of river basins with mountainous topography. The peak discharge and time of concentration of the basin were derived by using the estimated morphometric parametric values. Also, in this study, the groundwater potential zones of the basin were identified based on morphometric parameters.

Jisha John, N. R. Chithra, Santosh G. Thampi
Integrated Tool for Morphometric Analysis Using QGIS

Measurements of drainage basins and its parameters were evaluated earlier using conventional methods. At present, Geographic Information System (GIS) technique along with Remote Sensing data offers a better and precise way in performing morphometric analysis. Morphometric analysis of a watershed provides a quantitative description of a drainage system. It is an important aspect of the watershed characterization. As the analysis is having many parameters (drainage, slope, aspect, hillshade, watershed delineation, stream order, length of drainage channels, catchment area and perimeter, drainage density, form factor etc.) it requires different sequential operation to get all those results. When it come on handling numerous and big data set it tends to be tedious and time consuming and to overcome that some effort is to be made. In this study the main emphasis is given in developing an automatic integrated tool in GIS environment which helps in proper data handling results in reducing the time and workload of both user and the workstation. The Digital Elevation Model (DEM) of Asan river catchment is taken as the main input for the model and analysis is performed on it which exhibits suitable and accurate result and can be further utilize in watershed management.

Indrajeet Sahu, A. D. Prasad, Ishtiyaq Ahmad
Short Term and Seasonal Observation on Shoreline Changes from Kanagachettikulam to Veerampattinam of the Puducherry Coastal Region Using GPS Technique

The Shoreline oscillations are the response of natural endeavours such as wind, wave and storm which are termed as short term or temporary modification. Shore line changes are the phenomenon of permanent modification to a coast induced by natural calamities such as Tsunami, sea level rise and by human intervention such as the improper implication of structures like the groin, detached breakwaters, seawalls and coastal related activities such as dredging and beach nourishment. In this study, an attempt has been made for the assessment of shoreline position, rate of sediment movement, short term shoreline oscillation and volumetric changes using a most reliable and accepted system of data acquisition and manipulation. Land based survey method was found to be more effective and reliable system for an real time monitoring the response of a beach to seasonal changes and enhances the prediction of an accurate short term shoreline changes which could be confidently used in the development of beach response models of any desired stretch of coastline. Using conventional land based surveying system poses a challenge to the coastal engineer since its tediousness and cumbersome in acquiring, storing and representing the valuable data. The recent developments in land based data acquisition system such as GPS survey can overcome the problems posed by the conventional system which is found to be more swift and reliable. For the above study, a stretch of about 16 km from Kanagachetticulam to Veerampattinam of the Puducherry coastal region situated along the East coast of South India was selected. The selected coastal stretch has been accustomed to abnormal shoreline change from the past few decades and has lost valuable coast and its upland. The assessment study pertaining to the above study area was conducted using GPS surveying technique for an effective real time observation on the periodical shoreline position for both parallel and normal oscillation of the coast. From the observation, it was found that, the coast has experienced tremendous erosion on the Northerly side, maybe due to the construction of the harbour, seawall, and reef structure at the southern side. A mathematical model study was developed for short term shoreline movement using real time data which was very much comparable with real time shoreline observation. In justification to the above, the periodical data’s collected from the study area revealed that, the steepness of the coast has transformed from steep to gentle slope during the Northeast monsoon with only a modest development of beach. During the South west monsoon it was observed that the beach has recessed and the steepness has increased than usual which showed a sign of erosion. A slow recession of beach was observed during the non monsoon period. From the real time observation and model study it was concluded that the coast has witnessed severe erosion along the Northern side of the study area.

V. Anandabaskaran, G. Vijayakumar
A Review of Computational Studies on Indian Coast Considering Climate Change Effects

Studies on global climate changes and extreme weather events have fascinated researches all over the world. The ever increasing carbon dioxide levels as a result of anthropogenic events had resulted in 2016 being the warmest recorded year, based on increasing levels of global temperature. Furthermore, the trends observed in Antarctica ice sheet depletion and Artic sea ice minimum, validates the effects of global warming. The above two factors have resulted in sea level rise, with the former contributing in terms of expansion of sea waters and latter increasing water as a result of melting of ice. Indian coast measures about 7517 km along the nine coastal states which hosts marine and coastal biodiversity. With 13 major ports and associated activities playing a prominent role in coastal population of 14.2% in coastal districts when compared with the rest of the country. The constant increase in coastal population also increases the greenhouse gases emissions which adds to the severity of climate change effects. The low lying areas along Indian coast are most venerable to coastal flooding and land subsidence aggravating the problem poses serious threat to the coastal population. The coastal protection works have been designed generally without considering the climate change effects. Hence, there is a need to study the wave parameters along the coast considering climate change effects and its effect on the coastal structures. Computational studies help in giving quick and realistic values considering different climate change scenarios. Hence, this paper provides an insight on research work carried by authors regarding the computational studies incorporating climate change effects on India.

Upadhyaya K. Sandesh, Subba Rao, Manu
Determination of Effective Discharge Responsible for Sediment Transport in Cauvery River Basin

The mechanism of sediment transport is mainly governed by surface water flow within the river basins. Excessive sediment transport plays an important role in reducing the carrying capacity of channel networks, storage capacity of reservoirs/dams. An important task for most of the hydrologists is to determine the reliable stream flow estimate which causes majority of the sediment transport within river basins/stream channels. The transport effectiveness of a stream flow event of particular magnitude in carrying a sediment load is defined as the product of the effect of that event (i.e. sediment transport rate corresponding to the stream flow event) and the frequency with which the event occurs. This approach is famously known as magnitude frequency analysis (MFA). MFA has been widely used to compute “effective discharge” which is considered as the stream flow that is responsible for transportation of majority of the sediments from a river basin or catchment over a long period of time. In MFA, the stream flow at a location is assumed to follow a continuous probability distribution (e.g., Normal, Lognormal, Exponential, Gamma, Generalized Pareto and Poisson) whereas the sediment transport is described by a power law function between stream flow and sediment rate. Subsequently, a transport effectiveness function is constructed by taking product of stream flow distribution with power law function. Finally, the effective discharge can be obtained by maximizing the transport effectiveness function with respect to stream flow. In this paper, effective discharge estimates were determined for 12 stream gauges in Cauvery river basin by fitting appropriate continuous probability distributions (Normal, Lognormal, Exponential, Gamma, Generalized Pareto and Poisson) and assuming power law relationship for sediment transport. Kolmogorov–Smirnov test (KS test) at 1% significance level was tested for fitting probability distributions to daily stream flow data at each of the gauges. Results indicated that all of the above distributions failed to fit stream flow data at all the gauges. However, following the previous literature, the daily stream flow data at every gauge was assumed to follow Log-normal distribution and corresponding effective discharge was determined. Further, recurrence interval was calculated for the effective discharge estimate at the each of the gauge. The results from this study can find use in effective planning and functioning of dams/reservoirs.

Shobhit Maheshwari, Sagar Rohidas Chavan
Pervious Concrete as an Effective Urban Flood Management Tool

Pervious Concrete is a special type of concrete in which same size aggregates are used to increase the porosity. It is also called as no-fines concrete. It is a source Sustainable Urban Drainage System (SUDS) which minimizes the generation of urban runoff by allowing water to pass through the concrete system and thereby recharging the groundwater reserve. Since the runoff accumulates fine particles along its path, the concrete gets clogged which reduces the permeability of the concrete. It is necessary to evaluate the degradation of permeability as it is exposed to polluted runoff. In this paper, pervious concrete is prepared using aggregates of size 2.36–4.75 mm. To increase the strength, microGGBS (Ground Granulated Blast Furnace Slag) is used as an admixture. The compressive strength is calculated as IS 516-2004.The permeability is calculated using constant head principle. Since there is no standard instrument for calculating permeability of pervious concrete, a fabricated unit made of transparent acrylic is used. The concrete samples are 15 cm in diameter and 15 cm in length. The unit is designed in such a way that a constant head of 5 cm is maintained. The samples are exposed to water containing known concentration of soil for three cycles. The concentration are taken to mimic the extreme rainfall conditions for the study area. In between cycles, the samples are kept in oven at a temperature of 40° to simulate the temperature conditions after rainfall event. The degradation of permeability varies depending on the size of the clogging particle. In some cases, it reaches the half-life of the concrete. The results are useful for calculation of maintenance cycles for pervious concrete.

Preeti Jacob, G. S. Dwarakish, G. O. Sharath, G. N. Ramesh
Numerical Simulation of Wave Conditions for Mangrol Fishing Harbour

Fisheries sector is a powerful income and employment generator as it stimulates growth of a number of subsidiary industries and is a source of cheap and nutritious food and foreign exchange earner as well. The permissible limit for the fishing vessels is very stringent i.e. 0.3 m for operations at the berths. Suitable measures are also required to be taken to avoid broadside and breaking waves for safe maneuvering of the vessels near the entrance. Mathematical models are being comprehensively used to simulate wave conditions in harbours and ports. This paper describes the assessment of wave tranquility in the Mangrol harbour basin through numerical modeling. Initial layout plan suggested by Fisheries Department Gujarat, consisted of two breakwaters i.e. Eastern Breakwater of length 737 m and Western breakwater of length 532 m with south westerly harbour entrance opening of 135 m. Simulation were carried out for predominant incident wave directions with maximum significant wave height of 3.0 m. The numerical model studies indicated that the wave heights were generally within the permissible tranquility limit of 0.3 m almost for the entire year. However, major landing area in front of the south westerly harbour opening was exposed to direct attack of waves and the wave heights in these areas were greater than the permissible wave height of 0.3 m for about 75 days in a year. To reduce wave disturbance in the harbour basin and also to provide safe navigation and maneuvering near the entrance, the harbour layout was modified by extending the eastern breakwater length to 1110 m and by shortening the Western breakwater length to 250 m with increased north westerly harbour entrance of 240 m. This modified layout will provide tranquility conditions throughout the year near the berths and for parking of vessels inside the harbour. Due consideration was given to the direction and net quantity of prevailing littoral drift while orienting the harbour entrance.

Santosh Kori, Prabhat Chandra
Erodibility of Cohesive Sediments Using Jet Erosion Tests

In present work, an experimental study of jet erosion test was conducted and analysis of data was carried out along with the data of other investigators available in literature using Blaisdell approach. It was observed that the coefficient of erodibility as well as critical shear stress are significantly influenced by the geotechnical properties of the cohesive sediments. Temporal variation of coefficient of erodibility has also been found to be strongly dependent upon the duration of the jet erosion testing.

Sarfaraz Ali Ansari
Numerical Simulation of Desilting Chamber Using Flow 3D

Many run-of-river hydro power schemes are coming up on Himalayan Rivers. These perennial rivers have minimum design discharge for power generation right through the year and high heads are available for power generation. However, due to steep slopes and fragile geology of the region these rivers carry huge amount of sediment with them. The part of suspended sediment finds its way into the power intake and ultimately to the power house thus causing heavy damage to the turbines and other under water parts. Desilting chambers are provided to remove or minimize this sediment from the water conductor system. Central Water and Power Research Station, Pune (CWPRS) has vast experience in conducting physical model studies for desilting chambers. The theoretical assumptions of design are to be verified on a physical model for the adequacy / feasibility of the desilting chamber for 90% removal of suspended sediment coarser than 0.2 mm and efficacy of flushing tunnel below desilting chamber in transporting the settled sediment. However, in comparison with computational fluid dynamic (CFD) program, making additions and alterations in physical models is time consuming and costly, to improve their design. Therefore, the need of numerical simulation of desilting chamber arises. Recently, CWPRS has procured CFD based program named Flow3D to study some of the components of hydropower projects. The numerical simulation of desilting chamber using Flow3D, related aspects and various constraints are described in this paper.

M. Z. Qamar, M. K. Verma, A. P. Meshram, Neena Isaac
Flood Management—An Overview

Study of the History of development of flood control measures informs that from time immemorial, flood control structures have been constructed for protection of alluvial plains, low lands and human civilization from flood damage. Inspite of technological advances in meteorology and Engineering for planning and execution of flood control measures, floods still continue to plague many parts of the world causing unprecedented losses and destruction. At present, flood management includes structural and non structural methods. The management is to be improved and modified based on the experiences gained. In this paper, experiences of some the previous floods have been discussed in brief for the benefit of those actively involved in flood management. As such, flood management involves a constant search for ways to incorporate mitigative concepts into development decisions to reduce our vulnerability to natural hazards like floods for today and tomorrow.

Mayuraksha Bardhan
Grid Sensitivity Study of Modular Ocean Model in Capturing Regional-Scale Dynamics of Bay of Bengal Under Seasonal Wind Patterns

A suite of meso-scale and submeso-scale processes effect the ocean properties, such as the mixed layer depth, sea surface temperature (SST), sea surface salinity (SSS), which shape the weather and climate conditions by balancing the exchange of mass, momentum, energy, and heat between the atmosphere and the ocean. For the present study, a regional domain in the Bay of Bengal (BoB) is selected whose dynamics is important for understanding the Indian summer and winter monsoon seasons and the associated weather patterns. The BoB faces seasonal wind and current reversals, change in precipitation patterns and vertical stratification over the year, which introduces a host of mixing processes, namely baroclinic waves, eddies, filaments, gyres, and vortices. Further, these seasonal winds have varying intensities, which is a proxy for the wind shear. During June to August, the summer-monsoon wind flows eastward, while the winter-monsoon wind flows westward during December to February. The increased intensity of wind forcing during the summer monsoon period leads to a higher mixing layer depth (MLD) formation. The aim of this study is to model the effect of the ocean processes on the evolution of MLD, SSS, and SST over time and to understand the effect of grid resolution on MLD formation as well as on other ocean properties. Numerical experiments with multiple horizontal (1/4° and 1/8°) and vertical grid-sizes (0.5 m, 1 m, 3 m, 5 m, and 10 m at near surface region) were performed using Modular Ocean Model (MOM). It is seen that cases with at least 1 m vertical resolution near the surface region are able to capture the MLD variation over time. Experiments with coarser vertical resolutions fail to show the trends properly. However, the finer horizontal resolution (1/8°) shows MLD patterns similar to the experiments with the coarser horizontal resolution (1/4°) with little underestimations during summer-monsoon and winter-monsoon periods. For both the cases with coarser and finer horizontal grids, SSS is ~0.2–0.3 psu higher in the case with finer horizontal resolution whereas, the SST values do not differ much.

Mousumi Sarkar, Shweta Sharma, Siddhesh Tirodkar, Rajesh Chauhan, Sridhar Balasubramanian, Manasa Ranjan Behera
Bathymetry Retrieval Using Remote Sensing Techniques for Inter-tidal Regions of Tapi Estuary

Carrying out conventional bathymetry survey for inter-tidal zones is a tedious and time-consuming process. This demands to use of the remote sensing for such regions. However, remote sensing of intertidal zones has the issues of water clarity and turbidity, which contributes error in mapping the bottom topography. In this paper, the depth values of the inter-tidal zones have been extracted using two methods such as band ratio and tide co-ordinated shoreline method. In tide co-ordinated shoreline method, Near Infra Red (NIR) and Short Wave Infra Red (SWIR) bands have been used to delineate the land water boundary. The derived land water boundary will be tagged with corresponding tide levels of the time and pass of the satellite images. In band ratio method, often a highly reflective (blue) and a highly absorptive (NIR/SWIR) band is considered to derive the bathymetry from satellite images. However, each method works well in different conditions. Thus this work attempts to combine both the method to derive the bathymetry. The percentage error of derived depth from tide co-ordinated shoreline (TC) is 15.79%, from band ratio method (BR) is of 12.42% and the hybrid method (TCBR) is 1.3% (1005 sample location). The regression co-efficient (R2 value) achieved by the hybrid method is 0.765 including the regions of mudflats and deep channels. The regression co-efficient have been analysed for varying depth ranges. The result indicates the robustness of satellite images that can be used for deriving bathymetry even for turbid waters.

S. Shanmuga Priyaa, A. Aruna Kumar, Basanta Kumar Jena
Numerical Model Studies to Assess Wave Transmission Through Array of Wave Energy Converters, with Different Configurations

The energy demand in the world is increasing and the traditional energy resources like fossil are depleting. The generation of electricity using fossil fuel is polluting the environment. Hence the development of renewable and green energy resources is essential. Wave energy is such renewable and pollution free energy resource. The waves are generated by the wind blowing on a large area for long duration of time. The energy is concentrated in the wave form. The waves are more predictable. Hence wave energy is a promising energy resource. The Wave Energy Converter, WEC, is a unit which interacts with the waves in the near shore region and captures part of the wave energy. Thus the study of performance of wave energy converter, WEC, is an important area of ongoing research. The transmission through WEC was assessed primarily using wave flume tests. In last ten years the numerical studies of wave absorption and transmission through a WEC by considering the WEC as a permeable breakwater have been undertaken. To make wave energy extraction viable, wave energy farms consisting of many WECs will be necessary. Wave farms will maximize the production of electricity with affordable investment. Various configurations of the wave energy farm are being studied numerically using third generation wave transformation and propagation models. The Boussinesq Wave (BW) model can simulate wave penetration through permeable structures and also considers diffraction effects. In the present study, the wave transmission through array of WEC's for the three configurations consisting of a) single row of WEC's, b) Two rows of WEC's and c) Staggered array of WECs is investigated using MIKE 21 BW model. The effect of horizontal and vertical spacing for various wave heights and wave frequencies is estimated in a numerical flume. The optimal spacing depends on the wave length. The detailed results are presented in this paper.

K. H. Barve, K. S. Vighe, L. R. Ranganath
Physical and Numerical Modeling of Flow Pattern Near Upstream Guide Wall of Jigaon Dam Spillway, Maharashtra

Spillway is a hydraulic structure that is usually provided in dams to release surplus flood water that cannot be safely stored in the reservoir in order to prevent damage to the dam. In earthen dam if geological site for the spillway is not suitable in river gorge, then a spillway is provided at a suitable site which may be away from the river gorge. In such situation, a separate appurtenant structures are required to connect the spillway and the earthen dam. Guide walls are provided to connect the spillway with earthen dam. Suitable design of the guide wall is a key factor so as to guide the flow smoothly from river gorge for acceptable approach flow conditions in front of spillway. Jigaon Project is one of the major irrigation project under construction on River Purna of Maharashtra comprising of of 8.24 km long and 35.245 m high earthen dam. Hydraulic model studies for the original design of this project were conducted on 1:100 scale 3-D comprehensive model at CWPRS for evolving the optimum design of spillway with guide walls and to assess the performance of spillway. CWPRS conducted various alternatives to optimize the design of guide walls so that the approach flow conditions for the end spans could be improved. This paper is focused on original design as well as various alternatives for alignment of guide walls suggested by CWPRS to optimise the design of guide walls. CFD software, Flow 3D incorporating RNG turbulence model is used for numerical simulation. The results obtained from the physical model studies have been used for numerical validation.

Vaishali P. Gadhe, S. R. Patnaik, M. R. Bhajantri, V. V. Bhosekar
Assessing the Impact of Ports on Tiruvallur Coast of Tamilnadu

Coastal erosion is one of the significant issues throughout the globe. Coastal areas are more prone and vulnerable against the natural and anthropogenic changes that take place along the coast. A lot of developmental activities along the coast are being ubiquitous nowadays, which has a direct or indirect impact on the coastal areas. So that the effect of developmental activities on the coast should be studied and proper measures need to be suggested to reduce the impact. Coastal stretches from Ennore creek to Pulicat of Tiruvallur district are being focused on the study; this particular study area is selected because a lot of developmental activities have taken place for the last two decades such as the construction of ports and thermal power plants. The selected stretch has unique significance due to the neighboring estuarine ecosystem. Shoreline change would be migrating severely due to port and other structures, so causes of erosion should be properly identified, if not then erroneous decisions may be taken. So, analysis has been done using DSAS to identify the causes and hotspots of erosion. The future scenario of the coast is identified using the GENESIS response model.

S. Subburaj, R. S. Kankara, M. Umamaheswari, S. Chenthamil Selvan
Observed Spatio Temporal Trends of Precipitation and Temperature Over Afghanistan

Afghanistan is a semi-arid country and most vulnerable to climate extremes related hazards, including droughts and floods that has caused huge impact on the socio-economic development of the country. The present study analysed the observed precipitation and temperature trends for seven agro-climatic zones of Afghanistan over the period 1951 to 2007 with Asian Precipitation-Highly-Resolved Observational Data Integration towards Evaluation of Water Resources (APHRODITE). Change in the magnitude of precipitation and temperatures in recent years with reference to distant past was assessed by dividing the historical data into two parts as 1951–1990 and 1991–2006. Further, the trend analysis was performed on daily data to test the increasing or decreasing rainfall and temperature trends using Mann–Kendall trend test for each zone of Afghanistan. The maximum precipitation occurrence months were observed as January, February, March, April and May for all zones of Afghanistan. Whereas, June, July, August, September, October, November and December and generally considered as dry months. The maximum temperature was observed in the months of May, June, July and August, with hottest month as July for all seven zones of Afghanistan. The annual total precipitation has shown an increasing trend for the zones of South, South-West, East and Central, whereas, a decreasing trend has been observed for the zones of North, North-East and West zones. The trend analysis of the precipitation with gridded data sets reveals for most part of the Afghanistan region the rainfall has been observed as decreasing. Whereas, for all seven agro-climatic zones of Afghanistan an increasing trend of temperature in recent years of 2004 to 2016 were observed. Overall, the North, North-East and West zones of Afghanistan are more vulnerable with decreasing precipitation and increasing temperatures indicating more dry and warm periods indicating increasing drought conditions. Whereas, the South, South-West, East, and Central zones are more vulnerable with increasing trends of both precipitation and temperatures indicating increase of more wet and warm climates.

S. Rehana, P. Krishna Reddy, N. Sai Bhaskar Reddy, Abdul Raheem Daud, Shoaib Saboory, Shoaib Khaksari, S. K. Tomer, U. Sowjanya
Micro Hydro Power Generation in India-A Review

Hydropower technology has been around for more than a century. Hydropower comes from converting the energy in flowing water—using a water wheel or a turbine—into useful mechanical power. This power is then converted into electricity by an electric generator. Micro-hydropower systems are small hydropower plants that have an installed power generation capacity of less than 100 kilowatts (kW). Many micro-hydropower systems operate “run of river,” which means that no large dams or water storage reservoirs are built and no land is flooded. Depletion of fossil fuel and the inability to meet the rising demand of electricity are some drawbacks for the economic development of India. This paper presents the study to investigate the possibility of the micro hydro power generation and its advantages in India.

Aparna M. Deulkar, Vivek S. Chavhan, Pankaj R. Modak
An Analysis of Operational Life Cycle of SHP Plant Components: A Study in Himalayan Region

This paper presents the analysis of operational life of small hydropower plant components in the Himalayan region by using the actual maintenance detail. The maintenance data was collected from the existing small hydropower plants and were analysed according to the replacement of the different components in each plant. In order to validate the operational life cycle of SHP components as obtained by analysis, were compared with the expected useful life obtained from the literature. The results of the study conclude that the operational life of most of the components is near to the theoretical useful life. For some components, i.e. governor and DC battery system, the variation in analysed useful life is found large as compared to their theoretical life. This large variation is due to fast technology changes, which are more efficient, safer and user friendly.

Ravi Kumar, S. K. Singal
Spatio-temporal Variation and Trend Analysis of Groundwater Level in Bina and Khurai Blocks of Sagar District, Madhya Pradesh

Groundwater is the primary source of fresh water in the world, including areas with high rainfall and large amount of surface water. Groundwater is the primary source of water supply and an important component of the water cycle as it maintains the flow of rivers during periods of low rainfall. Groundwater levels have fallen sharply due to the increased reliance on groundwater in recent years. Therefore, in order to understand the level of groundwater use and analyse the groundwater scenario such as recharge, discharge etc. in the study area, analysis of groundwater trends is essential. In this study the Mann–Kendall t-test was used to analyze the data collected from the eight hydrological stations located in Bina and Khurai blocks in Sagar district. The monthly GWL data of fifteen observation wells in which twelve wells are dug well and three wells are Piezometric wells of Bina and Khurai blocks for the period 2000–2016 have been used for the study. The minimum and maximum GWL was found to be 0.10 m (bgl) which is 420.6 m above mean sea level (msl) and 27.60 m bgl (429.50 m amsl) respectively. Contour map shows that average GWL vary between 4.07 m and 18.75 m bgl (i.e., 401.18 m to 438.35 m (amsl)) during pre-monsoon and 0.51 m to 16.18 m bgl (i.e., 404.71 m to 440.92 m above msl) during post-monsoon. This analysis investigated the pattern and trends of the daily groundwater level data using Mann–Kendall t-test as means of non-parametric test and parametric Sen’s Slope test on seasonal basis. Pre-monsoon and Post monsoon variations in groundwater trend of Bina and Khurai blocks of Sagar district for 16 years (2000–2016) were analysed using statistical non-parametric tests-the Mann–Kendall (MK) test and Sen’s slope estimator. The Mann–Kendall test indicated falling trends at most wells and rising trends at some wells and at few wells there were no significant trends. Mann–Kendall test showed falling trend was observed in most wells during pre-monsoon and post-monsoon in both blocks signifying overexploitation of groundwater whereas no trend was observed in few wells. Sen’s Slope test was used to identify the significance of the slope and it was seen that declining trend was observed at 95% confidence interval. An average temporal variation of groundwater shows declining trend in Bina and Khurai blocks.

Shashi Poonam Indwar, Ankit Kumar, T. Thomas
Challenges in Launching Unusual Structure at Off Shore

Many launching works had been carried out by ship building industry using common method which is available in industries like Gravitational type, Floating type, Airbag type etc., using different methodology suitable for their design and site conditions. In recent times, launching has been carried mainly through airbag type as this type is proven to be very comfortable and economical upto 40% when compared to other methods. Also safety wise the airbag found be more appropriate normal ship structure because of its ease of operation. This paper highlights the design and working methodology based on the unusual structure launching in abnormal site condition with filled sea sand in unconsolidated condition. The paper focused a detailed study of challenges for launching unusual structures in coastal areas.

R. Suresh, K. Mullai Vendhan, K. Anbhazhagan, M. V. Ramanamurthy, G. Vijaya Kumar
Comparison of Numerical Models for Wave Structure Interaction Studies

In India, 45% of its 7500 km coastline is disintegrated. Infrastructural development like harbours, hinders the ideal sand sediment stream, additionally embankments and groins deter the long shore drift. Such constructions, which are beneficial for infrastructural growth, create problems to nature and part of society lying within those regions. Construction of a seawall seems a beneficial option for addressing the excessive unwanted erosion. For the design and construction of a seawall with increased sustainability, preliminary investigation on structures response to the attacked wave is essential. Such studies can be conducted experimentally, analytically and using numerical tools. Out of the various numerical tools with varying solvers available for such analysis, the most commonly adopted commercial packages for wave-structure interaction (WSI) studies are compared. Solvers based on Navier–Stokes equation, Volume of Fluid (VOF), Non-linear shallow water equations and Finite Element Method (FEM) are compared using literature. Comments on computational cost, results of overtopping and impact on structure, accuracy of results, scope of the numerical tools for WSI studies along with its pros and cons are presented. An attempt to simulate wave flume experiment by coupling of numerical tools incorporating VOF approach with FEM is performed for obtaining effective structural response. Further investigation is needed for structural response accuracy using the selected tools.

S. R. Shinde, V. V. Dabir, K. C. Khare, S. N. Londhe
Recent Developments of Tidal Energy as Renewable Energy: An Overview

As the ocean covers 70% of earth surface, it has a very significant role in providing the clean energy in the form of tidal energy, tidal currents, wave energy, temperature gradient and salinity gradient which are sufficient enough to meet the global energy demand. This paper presents an overview in respect of current state of research and development in the field of tidal energy as this form of renewable energy is considered as most advanced one. The article focuses on available technology to harness it, its estimated potential and its current exploitation level both globally as well as in India. Further, barriers and obstacles in its deployment and commercial exploitations have also been discussed.

Md. Masood Ahmad, Amit Kumar, Raushan Ranjan
River Cross Section Extraction from Elevation Models for Lower Ganga Basin

River cross-sections are the prime input to any river hydraulic model for simulation of water level and discharge. Field measurements of river cross-sections are labor intensive and expensive activities. Availability of measured river cross-sections is scanty in Lower Ganga basin. A method for generating river cross-sections using Digital Elevation Models is explained. Because of the poor resolution and insufficient vertical precision of such global data, distinguishing characteristics of hydraulic value is challenging, demanding pre-processing of the DEMs before usage. A vertical bias correction performed by comparing elevation points with recorded values results significant enhancement for DEM generated cross-sections. The model was calibrated for the period of 2005–2015 and validated for the years 2016 to 2018. The model findings are positive, indicating that the proposed technique has a high potential for use in places where topographic data is scarce.

Ratnesh Kumar, Ramakar Jha
Performance Study of Grid Connected Doubly Fed Induction Generator Designed for Small Hydropower Plant

The intention of current research exertion is to show the simulation and modeling of the hydro power turbine that is ambitious by the induction generator which is doubly-fed as well as the produced alternating current power prearranged to the grid. Intended for conveyance the alternating current power to the grid, we are applying two PWM voltage source converters which are allied back to back amid the utility grid and rotor terminals with the assist of mutual direct current link. The converter of machine side is used for fitting the excitation. The alternating current power flow in the midst of Alternating Current side and Direct Current bus is proscribed by grid side converter (GSC) as well as it permits the system to be operated in sub-synchronous speed and super- synchronous speed manner of operation. MATLAB/SIMULINK is used for Time domain simulations. The system is stable under different load conditions and that is investigated with the facilitate of model and simulations outcomes. To retain the system stability at whatever time the alternating current power stipulate is abruptly increasing in the utility grid side, induction generator which is doubly-fed (DFIG) system and Proportional integral (PI) controller is used.

Sundram Mishra, Sanjeev Kumar Gagrai, Madhu Singh
Study on Wave Transformation and Tranquillity Studies for the Development of Fish Landing Facility at Ajanur, Kasargod, Kerala

The role of fishing port may be considered as the interface between the netting of fish and its consumption. Many fishing harbours are also the source of major impacts on the physical and biological coastal environment. In today’s world of increased environmental awareness, a fishing port must be planned, designed and managed in harmony with both the physical and biological coastal environments. At each stage of process, whether it is planning, design or management, both technical and non-technical person become involved in the process. So in this paper, the work on development of fishery port at Ajnur, Kerala has been done. Mike C-Map data has been used for preparation of bathymetry and IMD wave data of 30 years for offshore in deep waters were analysed and tabulated in the percentage of occurrence of wave heights and direction. Wave transformation and tranquillity studies has been done using MIKE 21 SW and BW respectively on the proposed three layouts and it has been concluded that layout 3 is perfect for developing a fishery port both physically and economically as the wave heights inside the harbour is always less than wave tranquillity limit 0.3 m.

Amrita Jha, Biswakalyani Panda, J. D. Agrawal
Comparison of Numerical and Data Driven Approaches for Rainfall-Runoff Modeling

Modeling of rainfall-runoff process is still a challenging problem in the field of Hydrology in spite of availability of many tools and techniques. Though various physics based models, empirical and conceptual have been developed for modeling the rainfall-runoff process, the complexities involved make it a plausible case for more and more research. There are basically two methods for hydrological modeling: conceptual and physically-based approach called the theory-driven and empirical and black-box approach called the data-driven often connected by practitioners with statistical modeling. In first part of the present work a lumped conceptual numerical model is used for rainfall-runoff modeling in Coalburn catchment in the North of England (UK). It’s a well-known fact that numerical models have exogenous data requirements is a major impediment in application of such models particularly in catchments where all the data required for the numerical model is not measured or computed. This makes the problem suitable for use of data driven techniques which depend on the data rather than the underlying physics for modeling rainfall runoff process. In the present work, data driven techniques of MT, ANN and GP are employed to model the rainfall runoff process at Coalburn catchment situated in UK and the results are compared with MIKE 11 outputs. Artificial Neural Network is a universal approximator which mimics the human brain in that it requires to train the data before it is prior to apply for solving a real time problem. The Darwinian principal of survival of the fittest is working principle for Genetic Programming. It works on the genetic operations namely reproductions, mutation and crossover for creating generations of parents and children (computer programs) which yield outputs. Model Tree on the other hand works on the divide and conquer policy in which data is divided into number of bins and for each bin a liner regression model is developed. It was found that results of numerical model were better than data driven techniques when models were developed using rainfall, evapotranspiration and runoff. However in absence of evapotranspiration when numerical model could not be used all the three data driven techniques perform equally well in terms of model accuracy.

Digvijay Saruk, Shreenivas Londhe, Pradnya Dixit, Preeti Kulkarni
Numerical Modelling of Tidal Hydrodynamics Along River Tapi, Gujarat

Tapi, India’s second-largest westward draining river, originates at 752 m in the Multai Reserve Forest in Betul District, Madhya Pradesh. It flows west for 724 km until emptying into the Arabian Sea via the Gulf of Khambhat. The basin is located between the latitudes of 20° 5′ and 22° 3′ North, and the longitudes of 72° 38′ and 78° 17′ East. The study aims to understand the hydrodynamics of the tidally influenced River Tapi and estimate river discharge due to rainfall at the ONGC Bridge in Surat, roughly 14 km from the Arabian Sea. To accomplish the objectives, a two-dimensional hydrodynamic model was developed using the Delft3D modelling scheme. The offshore ocean boundary of the numerical model is forced using tidal components, while the upstream river boundary is forced with discharge estimated using HEC-HMS (hydrological modelling software). The model's estimated tide-induced currents are evaluated using observed field datasets, and the correlation is good. The results of the model showed tidally fluctuating hydrodynamic behavior during the year's pre and post-monsoon seasons.

R. Balaji, J. Satheeshkumar, R. Cornelius, R. Naveen, G. Prasantha, T. Prince
River and Coastal Engineering
herausgegeben von
Dr. Ramakar Jha
Prof. Dr. Vijay P. Singh
Dr. Vivekanand Singh
Dr. L.B. Roy
Assist. Prof. Roshni Thendiyath
Electronic ISBN
Print ISBN