Projects: FLOOD RISK ASSESSMENT USING HEC-HMS

PROJECT REPORT TITLED

“FLOOD RISK ASSESSMENT

USING

HEC-HMS”

SUBMITTED BY

NAME ( Roll N,.)

B.TECH(CIVIL ENGINEERING)

GUIDED BY

………………………

DEPARTMENT OF CIVIL AND ENVIROMENTAL ENGINEERING

College Name

(Autonomous institute Affiliated to University of Mumbai)

MUMBAI-400019

2010-2011

PROJECT REPORT TITLED

“FLOOD RISK ASSESSMENT

USING

HEC-HMS”

SUBMITTED BY

NAME ( Roll N,.)

B.TECH(CIVIL ENGINEERING)

GUIDED BY

………………………

DEPARTMENT OF CIVIL AND ENVIROMENTAL ENGINEERING

College Name

(Autonomous institute Affiliated to University of Mumbai)

MUMBAI-400019

2010-2011

STATEMENT BY THE CANDIDATE

I wish to state that the work embodied in this titled “FLOOD RISK ASSESSMENT USING HEC_HMS” forms my contribution to the work carried out under the guidance of prof…………………………… at the veermata Jijabai Technological institute . This work has not submitted for any other degree or diploma of any university/institute wherever references have been made to previous work of ,it has been clearly indicated

GAURAV DATTATRAYA GIRI Date:13-4-2011

(061010019)

CERTIFICATE

This to certify that Gaurav Dattatraya Giri a student of b.tech(civil engineering) has completed the project report titled “FLOOD RISK ASSESSMENT USING HEC_HMS” to our satisfaction

Professor :P.S.Chaudhari Dr.V.M Topkar

Project Guide Head(Civil and Enviromental Engineering Department)

CERTIFICATE

This to certify that Gaurav dattatraya Giri a student of b.tech(civil engineering)has completed the project report titled “FLOOD RISK ASSESSMENT USING HEC-HMS” to our satisfaction

Prof ……….Examiner

(Project Guide)

Date:13/4/2011 Place: Matunga

ACKNOWLEDGEMENT

I take this opportunity to express our sincere gratitude towards our guide prof. P.S.Chaudhari for his guidance and whole hearted support towards the completion of my project “FLOOD RISK ASSESSMENT USING HEC-HMS”

Every effort has been made to present our project in lucid in systematic manner . the completion of this task was not possible without the blending of dedication, hard work and foresightedness .

Thanks are also due to all those who directly or indirectly assisted me in the course of this project with their suggestion, constructive criticism and motivation.

I express our deepest gratitude towards our families, My H.O.D.( Dr V.M. Topkar ), my guide (P.S.Chaudhari),my lab assistant, friends for their unflinching support and understanding without it, the project could have been a task insurmountable

This project gave me wonderful opportunity to work me as a individual. And feel immensely satisfied that I emerged as intellectually stimulated and a co-0perative lot during this endeavor.

DATE

13/04/2011 ………….

(061010019)

PLACE

Matunga

ABSTRACT

Urban areas are subjected to many different types of hazards, which may be related to a variety of causes (geological, hydro-meteorological, biological, environmental, technological, etc). In order to assess the multi-hazard risk level of urban areas, and its spatial distribution, detailed information is required on the elements at risk, such as buildings, infrastructure, population, and economic activities. The use of detailed building information for the hazard risk assessment is essential. Very often this data is derived from existing building footprint maps, cadastral databases and population censuses. However, in many developing countries, such data sets are not available in digital format, or they are not compatible with other data or are restricted in their use. The lack of information about building footprints, linked to urban land use, is a major problem and its collection is further obstructed due to restrictions (financially and organisationally) on availability of high resolution data. This paper describes the process of preparing a database on elements at risk, for the Indian city of badlapur, which is subjected to multi-hazards, specifically earthquakes, urban flooding, urban fires, and technological hazards. Urban land use is taken as the principal factor in determining the various parameters that define the degree of vulnerability and capacity in relation to the different types of hazards. This study envisages the evaluation of public documents, and the use of publicly available high resolution imagery from Google Earth in combination with a field survey to compile an efficient database of urban mapping units, which are characterized by homogeneous land use and building types. An analysis of the existing Development Plan for 2010 is carried out in order to reach to an optimal classification of urban land use classes. Such a land use classification will allow to estimate the population distribution both spatially and temporally, based on a stratified sampling scheme and existing population census information per ward. The land use classes are characterized by a number of parameters like the age, building density, building height, occupancy, etc. The whole city is reclassified according to the new land use classes and then a sample survey of each of the land use class is carried out to look at the building profile. As an end result, the whole city is divided into urban mapping units with similar building profiles. The resulting polygons will be assessed for a case scenario of the 2001 earthquake and the assumptions and interpretations indicated.

Table of contents

CHAPTER 1

INTRODUCTION

1.1 Probldefination…………………………………………………………………….1

1.2 Risk assessment….……………………………………………………………………..1

1.3 Objective of the study…………………………………………………………………1

1.4 Organisation of the report…………………………………………………………..1

CHAPTER 2

LITERATURE REVIEW

2.1 Defination of flood hazard.....………………………………………………………………………………………2

2.2 Element of comprehensive flood risk analysis……………………….………………………………………………………………..2

2.3 Causes & impact of urban flood risk…………….…………………………………………………………………………………2

2.4Understanding urban flood hazard………………………………………………………………………………………… 4

2.5 local flood……………………………………………………………………………… 4

2.6Rivrine flood.……………………………………………………………………………5

2.7 Flash flood……………………………………………………………………………… 5

2.8 Coastal flood………………………………………………………………………… 6

2.9 Impact of urban flood………………………………………………………………6

2.10 Urban flood damge…………………………………………………………………7

2.11 Aim & approaches………………………………………………………………… 7

2.12 Rainfall variation……………………………………………………………………8

2.13 Causes of flood……………………………………………………………………….9

2.14 How to avoid flood………………………………………………………………….10

CHAPTER 3

METHODOLOGY

3.1Rational method………………………………………………………………………19

3.2 Risk assessment model……………………………………………………………20

3.3 Flood hazardous flow chart………………………………………………………21

CHAPTER 4

CASE STUDY

4.1 General…………………………………………………………………………………22

4.2 Various parameter of badlapur……………………………………… ……..22

4.3 History…………………………………………………………………………………23

4.4 Demography……………………………………………………………………………..24

4.5 Economy……………………………………………………………………………………24

4.6 Data used……………………………………………………………………………………24

CHAPTER5

5.1Summary………………………………………………………………………………36

5.2 Result…………………………………………………………………………………….36

5.3 Conclution………………………………………………………………………………42

5.4Future works………………………………………………………………………….42

Rrferences……………………………………………………………………………………43

Chapter 1 Introduction

1.1 problem definition

· Flooding :- The standard definition of a flood is “A general and temporary condition of partial or complete inundation of

normally dry land areas from (1) the overflow of inland or tidal waters, (2) the unusual and rapid accumulation

or runoff of surface waters from any source, or (3) mudflows or the sudden collapse of shoreline land”. A

simpler definition is too much water in the wrong place. Since water circulates from clouds to the soil to

streams to rivers to the oceans and returns to the clouds, a scientific definition of a flood is an imbalance in the “hydrological system” with more water flowing through the system than the system can draw off.

· Problem of coastal area :-Dynamic coastal systems often show complex, non-linear morphological responses to change . Erosion,transport and deposition of sediment often involve significant time-lags (Brunsden, 2001), and the morphological evolution of sedimentary coasts is the outcome of counteracting transport processes of sediment supply versus removal. A shoreline may adopt an equilibrium, in profile or plan form, where these processes are in balance. However, external factors, such as storms, often induce morphodynamic change away from an equilibrium state. Climate change and sea-level rise affect sediment transport in complex ways and abrupt, non-linear changes may occur as thresholds are crossed

1.2 Risk assessment

· Loss of properties :- The incidence of flooding to residential property in the India has increased over recent years. In particular the floods of 2000 and 2002 were widespread and serious. The primary causes are climate change and development on floodplains. It is estimated by the Association of British Insurers that between 950,000 and 1,200,000 residential properties are at risk, representing about 4% of the total property stock of 26 million. The office of the Deputy Prime Minister puts the figure somewhat higher at 1,700,000 properties at risk. There is some evidence that the increase in flooding and flood risk to these residential properties is affecting their value and insureability. Effect of flood on living &non-living things:- deaths,injuries,building damages,rusting of steels.

1.3 Objective

1)To develope flood risk model

2)To develope flood submergence map

3)Verification or implementation of flood risk assessment model on sight.

4)Organization of report

(1) we studied what exactly flood is

(2) impacts of flood on living & non living things

(3) Objective 1

Chapter 2

Literature review

2.1 Definition of Flood hazard, Vulnerability and Risk

With regard to natural hazards, risk is defined as the probability that events of a given magnitude and a given loss will occur. Therefore, risk encompasses two aspects: hazard and vulnerability fig2.1 illustrates the definitions of flood hazard, vulnerability and risk. Flood hazard is defined as the exceedance probability of potentially damaging flood

Fig2.1 Hazard, vulnerability,risk

Source(www.cwc.com)

2.2 Element of comprehensive flood risk analysis- In a seminal paper Kaplan &Garrick suggested a quantative definition of risk which has found widespread use in many risk analysis field the basic answer is that a flood risk analysis answer a following questions

1)What can happen/what can do wrong

2) How likely is it that it will happen

3)If it does not will happen what are the consquences

Risk is quantified by the set of triple,R-(Si,Pi,Di)

Containing all relevent damage scnarious Si their associated probability Pi and the associated damage Di with regard to the definition given above the answers to question 1 and 2 yield an assessment of flood hazard question 3 deals with vulnerability

Add caption

Fig2.2 water level vs loss ratio of a building

Source(www.epa.com)

2.3 CAUSES AND IMPACTS OF URBAN FLOOD RISK

In order to fully understand urban flood risks it is crucial to be familiar with the different components that construct risks. Often risk is understood only superficially by equating it with the occurrence of an extreme event or hazard (flood, drought, earthquake, storm, landslide etc.) caused by natural forces or by a combination of natural forces and human influences. Although the occurrence of such a hazard is obviously the primary precondition, it is only one component in the creation of risk. The second component in the creation of risk is the fact that somebody or something has to be at risk; i.e. vulnerable to a hazard. This widespread definition makes the basic structure of risks very clear.

However with reference to the term vulnerability a further distinction is necessary in order to enhance the understanding of the creation of flood risks. The notion of vulnerability in this definition does not distinguish between the mere physical exposure to hazards on one hand and the susceptibility of persons or things to hazards on the other hand. At first glance this might be considered to be a distinction without difference but when it comes to the analysis of flood risk and to the question of which measures are most effective in reducing such risk this distinction does make a difference. Hence the following chapters are based on this extended Definition of risk:Risk is the probability of a loss, and this depends on three elements: hazard, vulnerability, and exposure.

2.4 UNDERSTANDING URBAN FLOOD HAZARDS

Floods result from a combination of meteorological and hydrological extremes as indicated in the table below. In most cases floods are additionally influenced by human factors. Although these

influences are very diverse, they generally tend to aggravate flood hazards by accentuating flood peaks. Thus flood hazards in built environments have to be seen as the consequence of natural and man-made factors

As a result of different combinations of causal factors, urban floods can basically be

divided into four categories:

· Local Floods

· Riverine Floods

· Coastal Floods

· Flash Floods

Floods in urban areas can be attributed to one or a combination of the above types. In order to manage urban floods it is essential to understand the causes and impacts of each one of them.

2.5 Local floods

Very high rainfall intensity and duration during the rainy season sometimes caused by seasonal storms and depressions and exacerbated by saturated or impervious soil. Built environments like cities generate higher surface run-off that is in excess of local drainage capacity, thereby causing local floods. Figure 2 illustrates exemplarily how urbanization leads to decreased rates of infiltration and increased surface runoff.

Local drainage capacity is primarily made up of a local stormwater drainage system composed of storm drainpipes, curb inlets, manholes, minor channels, roadside ditches and culverts. This system is intended to convey storm flows efficiently to the community’s primary drainage system, such as the main river chsannel or the nearest large body of water.

Unfortunately, many urban drainage facilities are not in good shape due to lack of cleaningand maintenance. Rubbish and debris tend to clog the bottlenecks of drainage facilities, thusreducing the drainage capacity and leading to increased surface runoff and back up effects,causing local floods. Localised flooding occurs many times a year in slum areas because there are few drains, most of the ground is highly compacted and pathways between dwellings become streams after heavy rain.

Depending on the local hydro-geological situation, groundwater rising or subsurface flows can be other causes in the generation of local floods. Local floods are generally

confined to rather small geographical areas and are normally not of long duration. However in regions of extended rainy seasons (monsoon climates), local floods may last for weeks, resulting in widespread destruction.

2.6 Riverine floods

River floods are triggered by heavy rainfall or snow melt in upstream areas, or tidal influence from the downstream. Ground conditions such as soil, vegetation cover, and land use have a direct

bearing on the amount of runoff generated. River floods occur when the river run-off volume exceeds local flow capacities. The river levels rise slowly and the period of rise and fall is particularly long, lasting a few weeks or even months, particularly in areas with flat slopes and deltaic areas. Failure or bad operation of drainage or flood control works upstream can also sometimes lead to riverine flooding.

Urban areas situated on the low-lying areas in the middle or lower reaches of rivers are particularly exposed to extensive riverine floods. In most major river basins, flood plains are subjected to annual flooding. Often, urban growth expands over some of the floodplains, reducing the area into which floods can naturally overflow. Where parts of the city are below flood level and are protected by artificial levees, there is risk that they may be breached and cause devastating urban flooding.

When towns and cities get flooded by major rivers overtopping their banks flood protection has to be seen in the context of the entire river basin, which may fall in more than one administrative jurisdiction. Where a river basin lies within a single nation state, integrated river basin management principles should be applied by an agency cutting across ministries concerned with both rural and urban interests to ensure that activities in upstream areas do not worsen the flood situation for towns and cities downstream. For large, international rivers, river basin commissions are required to manage the water resources and floods in the entire basin for the benefit of all communities in the different nations sharing the basin.

2.7 Flash floods

Flash floods occur as a result of the rapid accumulation and release of runoff waters from upstream mountainous areas, which can be caused by very heavy rainfall, cloud bursts, landslides, the sudden break-up of an ice jam or failure of flood control works. They are characterized by a sharp rise followed by relatively rapid recession causing high flow velocities. Discharges quickly reach a maximum and diminish almost as rapidly.

Flash floods are particularly common in mountainous areas and desert regions but are a potential threat in any area where the terrain is steep, surface runoff rates are high, streams flow in narrow canyons and severe thunderstorms prevail. Especially in densely populated areas, they are more destructive than other types of flooding

2.8 Coastal floods

High tides and storm surges caused by tropical depressions and cyclones can cause coastal floods in urban areas located at estuaries, tidal flats and low-lying land near the sea in general. Coastline configurations, offshore water depth and estuary shape can influence the intensity of coastal floods. Moreover, high tides may impede the discharge of rivers and drainage systems, leading to local or riverine floods. Tidal effects in the estuarine reaches can keep the river levels high for long periods of time and sustain flooding. Thus the cities located in estuarine reaches have to bear the combined impacts of riverine as well as coastal floods due to storm surges and tidal effects. Coastal areas are exposed to sea erosion, which is particularly likely with the increase in the sea roughness due to climate change.

Tsunamis, mainly triggered by powerful offshore earthquakes, can also cause coastal floods though infrequently.

2.9 IMPACTS OF URBAN FLOODS

Urban floods have large impacts particularly in terms of economic losses both direct and indirect. Flood risks are a function of exposure of the people and the economic activities along with the vulnerability of social and economic fabric. As such the impact of such floods on the lives and livelihoods of people, a function of their vulnerability, needs to be understood. A number of urban

characteristics particularly in low and middle income countries that have relevance to the increased flood risks are:

· Concentrated population due to concentrated income earning opportunities;

· Large impermeable surfaces and construction of buildings;

· Concentration of solid and liquid waste without any formal disposal systems;

· Obstructed drainage systems;

· Intensive economic activities;

· High value of infrastructure and properties;

· Forcing out of poor from official land markets giving rise to informal flood.

· Housing without any health and hygiene standards; and

· Changes in regions around cities

2.10Losses due to floods- (1) Direct losses: Losses resulting from direct contact with flood water, to buildings and infrastructure

(2)Indirect losses: Losses resulting from the event but not from its direct impact, for example, transport disruption, business losses that can’t be made up, losses of family income etc.

In both loss categories, there are two clear sub-categories of loss:

(3)Tangible losses: Loss of things that have a monetary (replacement) value, for example, buildings, livestock, infrastructure etc.

(4)Intangible losses: Loss of things that cannot be bought and sold, for example, lives and injuries, heritage items, memorabilia etc.

2.11 URBAN FLOOD DAMAGES

The impacts of urban floods can be

1)Physical

2)Economic, and

3)Environmental

In addition to the exposure and vulnerability, discussed in previous sections, the magnitude of the damage depends on the flood type (especially in terms of depth, flow velocity, water quality, duration and sediment load). While in rural areas the damages due to floods are mostly direct in terms of loss of agricultural production, the damages in urban context are more complex. Damages due to floods can be categorized as indicated in Box-1. Figure 6 provides an overview of typical flood losses and distinguishes moreover between primary, secondary and tertiary loss categories. Although the impacts of urban floods are almost exclusively adverse, it should be kept in mind that riverine floods in rural areas often have positive ecological effects.

It is important to understand the construct of likely flood damages in a given situation in order to take preventive actions to mitigate these likely damages. Both direct and indirect primary potential losses can be prevented through better land use planning, which also impact the potential secondary losses. Better flood emergency response mechanisms help reduce potential secondary losses.

2.12 Aim and approches of urban flood-

The ultimate aim of integrated urban flood risk management is to minimize human loss and economic damages, while making use of the natural resources for the benefit and well being of the people.

However it is realized that absolute flood security is in most cases utopian. Flood risks cannot be entirely avoided, thus they have to be managed. Consequently, flood management does not strive to eliminate flood risks but to mitigate them. This may be achieved either by reducing flood risks to an acceptable level or by retaining, sharing or transferring flood risks through respective measures. These measures should form part of an integrated risk management process. The basic steps of an integrated management process a

1) Risk assessment,

2) Planning and implementation of measures,

3) Evaluation and risk reassessment.

2.13 Steps of the risk management process-

An urban flood risk management plan has to start with the assessment of present and future flood risks. As presented in chapter three the clear understanding and distinction between the three components that create risk - hazard, exposure and vulnerability - provides the necessary information for factoring in most flood related aspects in the overall management of risks and at the same time contribute substantially to the development and well being of the society.

Risk assessment has to be carried out in an integrated manner, i.e. identifying all the possible water related hazards, including how they are likely to develop in the future as a consequence of urbanisation or other development activities. To be useful in land-use planning the risk assessment shall be carried out within a multi-hazard concept. The hydrologic and hydraulic characteristics of these hazards has to modelled in the context of the river basin, and the economic, political, socio-cultural and ecological environment of the flood prone area. Such an assessment should give information about the probability of a hazard’s occurrence and the respective potential of loss. Hence the quantification of risks has to start with the analysis of hydro-meteorological data and the hydraulic simulation of floods. A number of different scenarios should be modelled in order to factor in the consequences of likely future changes on urban floods (future development of urbanization, climate variability and change, land use changes etc.). The results of such models provide information about the expected flood frequencies and magnitudes (extent, depth, duration and flow velocities), thereby marking those areas and subjects, which are exposed to floods.

2.14 Rainfall variation-The amount of precipitation of any type, primarily liquid. It is usually the amount that is measured by a rain gauge. Refer to rain for rates of intensity and the quantitative precipitation for forecasting. If it is vary according to the area then it is called rainfall variation

Factors affecting runoff-

1 )Man made- Urban development can greatly increase the amount of precipitation that is converted to runoff in a drainage basin. Most paved surfaces and rooftops allow no water to infiltrate, but instead divert water directly to storm channels and drains. Urbanization is of serious concern to water resources for several reasons. -
First, the increased amount of water flowing to streams during storms causes larger floods, and floods build to a peak faster because of the rapid flow of water over smooth surfaces.

Second, motor vehicles leave oils and exhaust residues on streets, and household and industrial chemicals also collect on pavement surfaces. These nonpoint-source pollutants are readily washed off during storms, contaminating streams into which urban runoff flows. Careless disposal of hazardous wastes on streets or in storm drains adds to the problem.

Third, most precipitation has no chance to percolate downward to groundwater, so the supply of groundwater to wells is reduced.

2 )Natural- Steep slopes in the headwaters of drainage basins tend to generate more runoff than do lowland areas. Mountain areas tend to receive more precipitation overall because they force air to be lifted and cooled.

gentle slopes, water may temporarily pond and later soak in. But on steep mountainsides, water tends to move downward more rapidly. Soils tend to be thinner on steep slopes, limiting storage of water, and where bedrock is exposed, little infiltration can occur. In some cases, however, accumulations of coarse sediment at the base of steep slopes soak up runoff from the cliffs above, turning it into subsurface flow.

3 )Increase in population-with the increase in population runoff increases to agreat extent it has four sources :

· farm land and manage green space

· industrial

· residentional

· commercial

2.15 Causes of flood-

Natural floods are the floods that are caused naturally by the overflow of the huge volume of water, from rivers, lakes, oceans, or by heavy rains or downpours, hurricanes, cyclones, or tsunamis, Heavy rainfalls are one of the major causes of floods. The level of water in rivers or lakes rises due to heavy rainfalls. When the level of water rises above the rive banks or dams, the water starts overflowing, which causes floods. The water overflows to the areas adjoining to the rivers, lakes or dams, causing floods or deluge. The flood water causes havoc and great destruction in the areas where it flows. Floods occur more in the regions that get heavy rainfalls.

Sometimes floods are caused due to poor dams that can not hold great volume of water and they give up causing floods in adjoining areas. Hence, there are always different causes of floods. However, human causes of floods can be avoided. Humans should let the nature go its own way.

Heavy rainfall that is unable to drain away and ponds
Rivers exceeding their capacity and overtopping their banks
High sea and tide levels inundating adjacent land
Waves over the sea, estuaries and large lakes overtopping beaches, banks and coastal defences
Groundwater rising up above ground level
Turloughs swelling and flooding surrounding land
Water from melting snow running off into swollen rivers

· Human activities can increase the occurrence of flooding.

For example-

1).By covering green areas with impermeable surfaces (e.g. car parks), the amount of water that seeps into the ground is reduced. This increases the speed and volume of water run-off.

2)Encroachment into, and blockage of, river channels reduce their capacity to carry water away, increasing water levels at times of high flow.

2.16How to avoid flood-

1)Storage-

Collapsible, flexible storage tanks provide the ideal solution for temporary or long term storage of water and most aqueous solutions.
Fast and easy to install with standard size capacities available from 100 to 150,000 gallons.

.by constructing a dam for storage of water we can reduce the flood to a great extent

2)Diversion-

many river diversion particularly temporary diversion are carried out on small river and strem a 300m section of the existing river channel upstream was dregated to increase hydraulic capacity a 325m diversion channel with capacity m3/s was constructed on landfill site to convey extra flow from the upgrated works

3)Retention- drain all storm water as quick as possible to avoid flood

4)Detentation-

A detention pond is a basin that lies in a low area near a river or stream and is designed to protect areas from flooding. Dry detention ponds are generally used to hold over-flow water temporarily until it drains into another location. Wet detention ponds manage storm water by maintaining a permanent pond of water in a basin that removes pollutants and only drains partial amounts storm water.

Dry detention basins are the most common type of detention pond. These dry ponds can help control flood waters, prevent downstream channel scouring and may help reduce pollutants. Dry detention ponds also tend to require less maintenance and cost less than other detention pond alternatives.

· flood controlling structure-Dams are generally constructed to store water for domestic and industrial use, for irrigation, to generate hydro electricity or prevent flooding.The type of Dam constructed is based on factors such

· as local geology, shape of the valley, climate, and availability of materials, manpower and plant.

2.17There are three main types of dam:

1) Gravity

2) Arch

3) Buttress

1)Gravity dams

Gravity dams are of relatively simple design. They are usually slightly curved in plan and rely on self weight to resist the hydrostatic forces that act upon it.

83 % of dams over 15m high are earth or rock embankments and 11% are concrete gravity dams. Typical heights of large gravity dams are between 50 – 150m.

2)Arch dams

· Arch dams are nearly always constructed from reinforced concrete but only use about 20% of the concrete that would be required for a gravity dam.

· The strength of the arch is used to pass on the hydrostatic force to the

foundation which must consist of very strong rock.

· Arch dams require narrow, steep sided valleys where the length of the dams crest is limited to about 10 times its height.

· Typical arch dams are 70 – 250m in height and make up only 4% of the worlds large dams.

Fig 2.2 Arch dam

Source (www.google.com)

2.17.3Buttress Dams

Buttress dams are a combination of arch and concrete gravity dams. Flat slab type dams have a continuous upstream slab face with downstream buttresses to provide strength and stability. Multiple arch type dams are used when the valley is too wide for a single arch dam.

Typical heights of buttress dams are 30 – 90m for a flat slab and 40 – 220m for a multiple arch, with 2% of the worlds largest dams being buttress type.

2.18 Models or software-there are two software available for flood risk assessment

(1) HEC-HMS- The Hydrologic Modeling System (HEC-HMS) is designed to simulate the precipitation-runoff processes of dendritic watershed systems. It is designed to be applicable in a wide range of geographic areas for solving the widest possible range of problems. This includes large river basin water supply and flood hydrology, and small urban or natural watershed runoff. Hydrographs produced by the program are used directly or in conjunction with other software for studies of water availability, urban drainage, flow forecasting, future urbanization impact, reservoir spillway design, flood damage reduction, floodplain regulation, and systems operation.

(2) SWMM- The EPA Storm Water Management Model (SWMM) is a dynamic rainfall-runoff simulation model used for single event or long-term (continuous) simulation of runoff quantity and quality from primarily urban areas. The runoff component of SWMM operates on a collection of subcatchment areas that receive precipitation and generate runoff and pollutant loads. The routing portion of SWMM transports this runoff through a system of pipes, channels, storage/treatment devices, pumps, and regulators. SWMM tracks the quantity and quality of runoff generated within each subcatchment, and the flow rate, flow depth, and quality of water in each pipe and channel during a simulation period comprised of multiple time steps.

(3) GIS TOOLS-1)Arc Gis- ArcGIS is a suite consisting of a group of geographic information system (GIS) software products produced by Esri. At the desktop GIS level, ArcGIS can include:

ArcReader, which allows one to view and query maps created with the other Arc products;
ArcView, which allows one to view spatial data, create layered maps, and perform basic spatial analysis;
ArcEditor which, in addition to the functionality of ArcView, includes more advanced tools for manipulation of shapefiles and geodatabases; or
ArcInfo which includes capabilities for data manipulation, editing, and analysis.

(4) GRAMM++- GRAM++ is a geographic information system (GIS) software developed by the Centre of Studies in Resources Engineering (CSRE), Indian Institute of Technology (lIT), Bombay, India with support from United Nations Development Programme (UNDP) and Department of Science and Technology (DST), Government of India.

GRAM++ has rich functionality to support: Spatial database preparation by import of data from popular GIS formats, Mar editing and onscreen digitization of scanned document, Analysis using tools such as Vector analysis, TIN, Network analysis enabling map display, query, statistical chart generation, distance calculation, thematic map generation, terrain modeling and contour generation, shortest path and spatial allocation problem, GRAM++ has also equally rich raster functionality. Raster analysis allows map algebra, map overlay, buffering, regroup, watershed analysis; zonal/focal/local analysis terrain modeling allows bUilding DEM from contours or spot heights, visibility, profile plotting, slope/aspect/relief. Image processing supports a range of popular features such image enhancement and filtering, principal component transform, band arithmetic, neural network for analysing remotely sensed images that can lead to build up of GIS databases.

(5) Raster model- Raster data models incorporate the use of a grid-cell data structure where the geographic area is divided into cells identified by row and column. This data structure is commonly called raster.

2.18.6 vector model- Vector is a data structure, used to store spatial data. Vector data is comprised of lines or arcs, defined by beginning and end points, which meet at nodes. The locations of these nodes and the topological structure are usually stored explicitly. Features are defined by their boundaries only and curved lines are represented as a series of connecting arcs. Vector storage involves the storage of explicit topology, which raises overheads, however it only stores those points which define a feature and all space outside these features is 'non-existent'.

Fig2.3 Vector model

Source(www.strwm.com)

CHAPTER 3

Methodology

3.1General- Flood forecasting is an important component of flood warning, where the distinction between the two is that the outcome of flood forecasting is a set of forecast time-profiles of channel flows or river levels at various locations, while "flood warning" is the task of making use of these forecasts to make decisions about whether warnings of floods should be issued to the general public or whether previous warnings should be rescinded or retracted.

3.2Tools used:

.1)HEC-HMS

2)HEC-RAS

3)SWMM

3.2.1HEC-HMS- The Hydrologic Modeling System (HEC-HMS) is designed to simulate the precipitation-runoff processes of dendrite watershed systems. It is designed to be applicable in a wide range of geographic areas for solving the widest possible range of problems. This includes large river basin water supply and flood hydrology, and small urban or natural watershed runoff. Hydrographs produced by the program are used directly or in conjunction with other software for studies of water availability, urban drainage, flow forecasting, future urbanization impact, reservoir spillway design, flood damage reduction, floodplain regulation, and systems operation.

3.3HEC-HMS information-

Developing an HEC-HMS Project

To develop a hydrologic model, the user must complete the following stepe

Create a new project.

(1)Input time series, paired, and gridded data needed by the basin or meteorological model.

(2)Define the physical characteristics of the watershed by creating and editing a basin model.

(3)Select a method for calculating sub basin precipitation and enter required information. Evapo-transpiration and snow melt information are also entered at this step if required.

(4) Define the control specifications.

(5)Combine a basin model, meteorological model, and control specifications to create a simulation.

(6)View the results and modify the basin model, meteorological model, or control specifications as needed.

Fig3.1 Dem model

Source(www.docstock.com)

WATERSHED MODEL

HEC-HMS

RAINFALL

Fig3.2 Hydraulogical mode

Source(www.docstock.com)

Rainfall

Runoff

Fig3.3 Rainfall,Runoff model

Source (www.irrigation.com)

· Rainfall – losses = Runoff.

· Rainfall, rainoff hydrological model =

Fig 3.4 Hydrological model, source(www.irrigation.com)

3.3RATIONAL METHODS Q = CIA

Where Q = discharge

C = constant

I = intensity rainfall

A = area of flows

FOLLOWING METHODS ARE USED

1. Decken’s formula

2. Fanning formula

3. Inglis formula

4. Creager’s formula

5. Faller’s formula

GIS RASTER MAP

RISK IS ZERO

DECIDE RISK LEVEL

Flowchart: Decision: FLOOD MAGNITUDE VERIFICATION

NO YES

Fig3.4 Risk assessment model Source(www.waterstock.com)

If ,

1.water depth < flood magnitude = no flood

2.water depth > flood magnitude = flood

DEPTH	RISK FACTOR	COLOR CODE
30 cm	1	Green
60cm	2	Yellow
90 cm	3	Blue
120 cm	4	Brown

Table 3.1 Depth magnitude

DEATH

PHYSICAL DISABILITY

GIS raster model decision

Fig3.5 Flood hazardous model

CHAPTER4-

CASE STUDY

4.1Flood problem in badlapur-

The area near Ulhas River is an urban area, its densely populated and contain vital infrastructure. Continuing development in flood-prone areas increases the risk.

Factors that tend to increase the risk include:

4.1.1 Ageing drainage infrastructure. A lot of the sewerage and drainage network is old and its condition isunknown.

4.1.2 More buildings. As new developments cover previously permeable ground, the amount of rainwater running off the surface into drains and sewers increases dramatically.

4.1.3Increase in paving. The proportion of impermeable ground in existing developments is increasing as

people build patios and pave over front gardens.

4.1.4 Climate change. Wetter winters and heavier summer showers are expected to put more pressure on urban drainage. Climate models predict that winter rainfall will increase by 20-30% by the 2080s. Such an

increase could lead to a much larger (up to 200%) increase in flood risk.

4.2Various Parameters of badalapur-

Badlapur, also known as Kulgaon-Badlapur, is one of the fastest growing towns in MumbaiConurbation, India.Badlapur is 5 kilometers from the railway station. Due to the population growth in the nearbycities, many people working in Mumbai have moved to Badlapur for affordable real estateprices, pleasant weather, beautiful location and quiet neighborhoods along with a proximity toMumbai by the Central Railway, one of the two nationally owned operating companies that formthe Mumbai Suburban Railway and that developed the city near the Badlapur Railway Stationfaster than actual Badlapur village. Now Badlapur city encompasses the Old Badlapur Village,Kulgaon, Manjarli, Belavali, Katrap and many other small villages.

4.3History-

Badlapur city is located at 19°09′00″N 73°16′01″E / 19.15, 73.267.[1] It is in Thane district in Maharashtra State. It has an average elevation of 44 meters (144 feet). It is a railway station on the Mumbai-Pune route of the Central Railway and is located about 68 km (42.25 M) fromMumbai, 34 km (21 M) from Thane and 10 km (6.21 M) from Ulhasnagar. Badlapur is a terminalstation for many Mumbai Suburban local trains. The town is well connected to the Mumbai-Puneexpressway and to Vashi through theMIDC road.This region consists of mountains. Badlapur city is virtually divided in 2 areas,East and West,by railway station. The East-Badlapur is mostly built on the hills also some parts of Westbadlapur.Beautiful Ulhas River flows between Kulgaon and Badlapur Gaon. Badlapur gaon isconnected with 2 bridges on the river. The old bridge is out of use due to its smaller size andcapacity.There has to be more trains introducedto badlapur. This is because many white collarworkers in four seasonshotel face problems while commuting.

4.4Demography-

As of 2001 India census, there were 97,917 people residing in the city. Males constituted 53% (51,878) of the population and females 47% (46,039). Badlapur had an overall literacy rate of 76.12%, higher than the national average of 59.5%; with 81.01% of the males and 72.15% offemales literate. 12% (11,999) of the population is under 6 years of age. There were 1,971 SC(2.01%) and 4,841 (4.94%) population come under ST category. People living in the city arepredominantly Marathi. There are also Buddhist, Gujarati, Sindhi, south Indian community.

The city is largely recognised as a middle class suburb of Mumbai.The majority of the population is Hindu and a substantial Muslim community also lives inBadlapur. There are many temples, Mosques, Churches in town. The major festival celebrationis Ganesh Chaturthi which many organizations, local groups celebrate with zest and passion. Inthis festival people of many different faiths participate and enjoy. The city has had very fewreligious conflicts, except one which occurred on October 21, 2002, in which 8 people wereinjured in a conflict between two groups.

4.5Economy-

MIDC has developed an industrial area within the limits of Kulgaon Badlapur Municipal Council.This area is reserved primarily for Chemical industries. The area has been developed indifferent blocks and carved out while keeping in mind the needs of small scale and large scaleindustries. This has stimulated the economical growth of the city.The majority of the city population is a working middle class. Some people are also dependenton farming as a primary source of income. There are branches of many national banks includingState Bank of India, Bank of Maharashtra, Canara Bank, IDBI Bank (previously known as

United Western Bank). Two major banks, UTI Bank which is now renamed as Axis Bank & StateBank of India are operating ATM facilities, providing access to all major cardholders.

4.6Data used:

Aster data

Basin Map: The contours of the area decided is marked and traced using google earth data and then transferred.

Google Earth Data: Google Earth is a virtual globe, map and geographical information program that was originally called EarthViewer 3D, and was created

by Keyhole, Inc, a company acquired by Google in 2004. It maps the Earth by the superimposition of images obtained from satellite imagery, aerial photography and GIS 3D globe.

Satellite Data: NRSC acquires and processes data from all Indian remote sensing satellites like CARTOSAT-1, CARTOSAT-2, RESOURCESAT-1, IRS-1D, OCEANSAT-1 and TES as well as foreign satellites like Terra, NOAA and ERS.

IMD data (Rainfall Data): we have used rainfall data of 26^th July 2005, Badlapur region, thane, Maharashtra. The data was obtained from Meteorological department.

Basin Map: Using Google Earth Software the area decided is traced using a contour. The area is enclosed and basin map is prepared Steps in rainfall runoff modelExample: This chapter illustrates the steps necessary to create a precipitation-runoff model Step 1: Create a New ProjeccCreate a new project by selecting File New… from the menu bar (Figure). Enter a project “Name,” enter a project “Description,” select a “Location” for storing project files, and choose the “Default Unit System” in the Create a New Project screen (Figure). A new folder with the same name as the project name is created in the selected directory. This folder will store all files created for this project. External HEC-DSS files, ModClark files, and background map files do not have to be stored in the project folder. A new project can also be created by selecting the Create a New Project button on the tool bar. Options for managing a project are available from the File menu option. These options include Open…, Save, Save As…, Delete, and Rename. The tool bar contains buttons to open a project and save the current project.

Figure 4.1 Create a New Project Source(hec-hms software screen shot)

Step 2: Input Data

Time series data, paired data, and gridded data are created using component managers. Component managers are opened from the Components menu by selecting the Time-Series Data Manager, Paired Data Manager, or Grid Data Manager menu options At the top of these managers is an option that allows the user to select the gage, paired data, or grid data type. Buttons on the right side of the manager provide options to create a New…, Copy…, Rename…, or Delete the data type. Figure shows the Paired Data Manager (the Storage-Discharge data type is selected). Once a new input data type has been created, required information can be entered in the Component Editor. Input data can be entered manually or referenced to an existing record in a HEC-DSS file

Fig 4.2 paired data manager

Figure 4.3 Input Data Managers

Figure shows the Component Editor for a storage-discharge function. Open the Component Editor by clicking on the paired data function in the Watershed Explorer. The table can be renamed in the Watershed Explorer or in the Paired Data Manager. The “Data Source” options are Manual Entry and Data Storage System (HEC-DSS). If Data Storage System (HEC-DSS) is selected, the user is required to select a HEC-DSS file and a pathname. If Manual Entry is selected, the user must click the “Table” tab and manually enter the storage-discharge curve.

A time window is required before time-series data can be entered or viewed. A default time window is provided when a time-series gage is added to the project. To add an additional time window, click the right mouse button when the mouse is on top of the gage’s name in the Watershed Explorer. Select the Create Time Window option in the popup menu (Figure).

Figure 4.4 Component discharge editor for a storage discharge function

Figure 4.5 Create a time window for a time series gage.

Step 3: Create a Basin Model

A new basin model can be added to a project by selecting the Components -Basin Model Manager menu option (Figure). Click the New… button in the Basin Model Manager window. Enter a “Name” and “Description” in the Create A New Basin Model window and click the Create button (Figure). An existing basin model can be added to the opened HEC-HMS project by selecting the File - Import - Basin Model… menu option.

Figure 4.6 Open the basin model manager.

Figure 4.7 Create a new basin model

Once a new basin model has been added, hydrologic elements can be added and connected in the basin model map to reflect the drainage of the real world watershed. To open the basin model map in the Desktop, select the basin model in the Watershed Explorer, “Components” tab. Hydrologic elements are added by selecting one of the element tools on the tool bar (Figure ) and clicking the left mouse button in the basin model map. To connect an upstream element to a downstream element, place the mouse on top of the upstream element icon and click the right mouse button. Select the Connect Downstream option from the popup menu. Then place the mouse on top of the desired downstream element icon and click the left mouse button.

Create Copy…, Rename…, or Delete the basin model by clicking the right mouse button when the mouse is located on top of the basin model name in the Watershed Explorer. These options are also available from the Basin Model Manager. Similar menu options are available for managing hydrologic elements when using the right mouse button inside the Watershed Explorer. The Copy Element and Delete Element options are also available in the basin model map. Move the mouse on top of one of the hydrologic element icons and click the right mouse button to open a popup menu containing these options.

Basin model and hydrologic element parameter data are entered in the Component Editor. Select a basin model name or hydrologic element name in the Watershed Explorer to open the Component Editor. The Component Editor for a hydrologic element can also be opened by selecting the element icon in the basin model map.

Figure shows a Component Editor for a sub basin element. Notice the five tabs labeled “Subbasin,” “Loss,” “Transform,” “Baseflow,” and “Options.”

Fig 4.7 Hydraulic element tool

Fig 4.8 component editor for subbasin element

Step 4: Create a Meteorological Model

A meteorological model is added to a project in the same manner as the basin model. Select the Components - Meteorological Model Manager menu option. Click the New… button in the Meteorological Model Manager window and enter a “Name” and “Description” in the Create A New Meteorologic Model window. To import an existing meteorologic model, select the File - Import - Meteorologic Model… menu option. The meteorologic model can be renamed in the Watershed Explorer or from the Meteorologic Model Manager. Figure 16 shows the Component Editor for a meteorologic model.

One step in developing a meteorologic model is to define which basin models require precipitation from the meteorological model. Open the Component Editor for the meteorologic model by selecting it in the Watershed Explorer, “Components” tab. Select the “Basins” tab and change the “Include Subbasins” option to “Yes” for all basin models requiring precipitation from the selected meteorologic model (Figure). All subbasin elements contained in the selected basin model(s) will be added to the meteorologic model. Once added, parameters for the precipitation, evapotranspiration, and snowmelt methods can be defined for each subbasin element using the Component Editor.

Figure 4.9 Component editor for a metrological model

Step 5: Define Control Specifications

A control specification is added to a project by selecting the Components - Control Specifications Manager menu option. Click the New… button in the Control Specifications Manager window and enter a “Name” and “Description” in the Create A New Control Specifications window. The Component Editor (Figure) for a control specifications requires a start date and time, an end date and time, and a time step. Start and end dates must be entered using the “ddMMMYYYY” format, where “d” represents the day, “M” represents the month, and “Y” represents the year. Time is entered using the 24 hour format. Start and end times must be entered using the “HH:mm” format, where “H” represents the hour and “m” represents the minute. The time step is selected from an available interval list containing time steps from 1 minute to 24 hours. Calculations for most methods are performed using the specified time step; output is always reported in the specified time step.

Figure 4.10 Control specification

Step 6: Create and Compute a Simulation Run

A simulation run is created by selecting the Compute - Run Manager menu option. Click the New… button in the Simulation Run Manager window. The simulation run manager also allows the user to Copy…, Rename…, and Delete an existing simulation run. After clicking the New… button, a wizard opens to step the user through the process of creating a simulation run. First, a name must be entered for the simulation run, then a basin model, a meteorological model, and a control specifications must be selected. The new simulation run is added to the “Compute” tab of the Watershed Explorer (Figure). Notice the “Compute” tab of the Watershed Explorer contains a separate folder for each simulation type: simulation runs, optimization trials, and analyses.

The Watershed Explorer expands to show all simulation runs in the project when the “Simulation Runs” folder is selected. A simulation run can also be created by selecting the Compute Create Simulation Run menu option. In the Component Editor for a

simulation run, the user can enter a “Description” and change the basin model, meteorological model, and control specifications from drop-down lists (Figure).

The simulation run can be renamed in the Watershed Explorer or from the Simulation Run Manager. Click the right mouse button when the mouse is located on top of the simulation run’s name in the Watershed Explorer and select the Rename… option. Other options available when clicking the right mouse button include Compute, Create Copy…, and Delete. The Compute menu can also be used to compute a simulation run. First, the simulation run must be selected from a list of current simulation runs. Select the Compute - Select Run menu option and choose the desired simulation run (Figure). To compute the selected simulation run, reselect the Compute menu and click the Compute Run option at the bottom of the menu (Figure). The selected run should be in brackets following the Compute Run option

Fig 4.12 Create simulation run

Fig 4.13 Computing the selected simulation run

Step 7: View Model Results

Graphical and tabular results are available after a simulation run, an optimization trial, and an analysis have been computed (refer to the appendix for a description of optimization trials and analyses). Results can be accessed from the Watershed Explorer or the basin model map. Results are available as long as no edits were made to model components (sub basin parameters, time-series data, etc.) after the simulation run, optimization trial, or analysis were computed. If edits were made, the simulation run, optimization trial, or analysis must be re-computed.

Select the “Results” tab of the Watershed Explorer to view a list of simulation runs, optimization trials, and analyses (Figure). Click the box next to the name of the simulation run, optimization trial, or analysis to expand the Watershed Explorer. Click the box next to a hydrologic element’s name to expand the Watershed Explorer even more to show available results for the hydrologic element. When a times series result is selected in the Watershed Explorer, a preview graph opens in the Component Editor. Figure shows a times series graph for a subbasin element (Subbasin-1). Multiple time series records can be added to the same graph by holding the Control key and clicking other time series results. Time series results from different basin model elements and from different simulation runs and optimization trials can be added to the same graph for comparison (Figure).

A copy of the preview graph will open by clicking the graph button on the toolbar (Figure).Results can also be accessed from the basin model map. After a simulation run computes, move the mouse on top of a basin model element and click the right mouse button. In the popup menu, select the View Results option and choose Graph, Summary Table, or Time-Series Table (Figure). Results can also be accessed from the toolbar. Select a basin model element in the basin model map or Watershed Explorer to make it active. Then choose the graph, summary table, or times-series table button on the toolbar.

Fig 4.14 Result view

Figure 4.15 Comparing result from different simulation run.

Fig 4.15 Junctions and basin

Source(hec-hms software)

Fig4.17 Tracing of badlapur and Gid line

Source(study area)

CHAPTER 5

5.1 SUMMARY

Rainfall runoff simulation is essential for dealing with flood problem .there are many simulation model available. In this study watershed modeling using HEC-HMS is discussed. Features of the HEC-HMS model are discussed . a case is studied about simulation of rainfall runoff for a watershed near Ireynor , Iowa. Two hydaulogical simulation model were used on being HEC-HMS and SWMM.it was found that HEC-HMS can generate better simulation with less caliberrated data

5.2 Result-

Fig no 5.1

Source (hec-hms result) Result for 25mm/h

Fig no 5.2 Result for 50mm/hr

Fig no 5.3 Result for 75mm/hr

Fig no 5.4 Result for100mm/hr

Fig5.5 Result for 150mm/hr

Fig 5.6 Result for 175 mm/hr

Fig 5.7 Result for 2oomm/hr

Fig 5.8 Result for 225mm/hr

Table5.1 Rainfall,peak outflow

Rainfall	Peak outflow
25mm/hr	1496.5m3/s
50mm/hr	1668.56m3/s
75mm/hr	2o65m3/s
100mm/hr	2567m3/s
125mm/hr	2738m3/s
150mm/hr	3345m3/s
175mm/hr	3789.45m3/s
200mm/hr	4494.45m3/s
225mm/hr	4745.5m3/s

5.3 CONCLUSION

Following conclusion can be drawn from this study :

· HEC-HMS model can give excellent simulation of runoff hydrograph when model parameter are fitted to the individual events .

· HEC-HMS can be used with very limited caliberation as compared to SWMM for predicting runoff from ungaged cathement and for evaluating future land use master plans.

· HEC-HMS model can be successfully used to evaluate the flood problem and can successfully predicting the runoff .

· Urban multi-hazard risk assessment is a procedure that requires a large amount of data. Part of this data can be used from existing sources. However, both in terms of the spatially optimal units for the risk assessment, as well as for the collecting of relevant attributes for building and population loss estimation, specific data needs to be collected. However, in order to make this process economically feasible, the collection of new data should be kept to a minimum. New developments in the availability of high resolution images, such as those made available in Google Earth might be an important new tool in this data collection, although it still has some main disadvantages, related to the direct comparison of data sets. A further integration these freely available data with GPS and Mobile GIS is expected to happen in the near future and will offer further opportunities in improving urban vulnerability assessment.

5.3 FUTURE WORKS

In this study we got an insight about HEC-HMS model now for further study a watershed area would be chosen and based on the rainfall data , topographical data etc. HEC-HMSmodel can be used to predict flood prone parts of the area.

REFERENCES

Ø Philip B.bedient, wayne C. huber 1988 hydraulogy and floodplain analysis

Ø J.obiukwu Duru , allen T. Hjelmfelt 1994. Investigating prediction capability of HEC-HMS and SWMM run off model, journal of hydraulogy 157 (1994)

Ø A.Szollosi nagy , C.Zevenbergain,2004. Flood management ISBN 0415359988, 9780415359986.

Ø Dawdy,D.R.,1991. Comparision of USGS and HEC-HMS kinematic run off model . in: S.Bowels and P.E. O’cionell (editors)

Ø Hydrologic Engineering Center (2000).

Ø Hydrologic Modeling System HEC-HMS Technical

Ø Reference Manual, U. S. Army Corps of Engineers.

Ø Hydrologic Engineering Center (2006). Hydrologic Modeling System HEC-HMS User’s

Ø Manual, Version 3.1.0, U. S. Army Corps of Engineers.

Ø Rasmussen, P. P. and C. A. Perry (2000). “Estimation of Peak Streamflows for Unregulated

Ø Rural Streams in Kansas,” Water-Resources Investigations Report 00-4079, U. S. Geological

Ø Survey.

Ø Rawls, W. J., D. L. Brakensiek and K. E. Saxton (1982). "Estimation of Soil Water Properties,"

Ø Transactions of the American Society of Agricultural Engineers, pp. 1316-1320.

Ø RoreatL. A. (2005) Storm Water Management Model User’s Manual, Version 5.0,

Ø EPA/600/R-05-040, U. S. Environmental Protection Agency.

Ø Shuttleworth, W. J. (1993).

Ø “Chapter 4 - Evaporation,” in Handbook of Hydrology, edited by D.R. Maidment, McGraw-Hill, Inc.

Ø www.google.com

Ø www.cwc.com

Ø www.scribd.com

Ø Hec-Hms 3.4 manual

Ø www.docstock.com

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VIBRATION ANALYSIS OF CYLINDRICAL THIN SHELL

Sunday 1 May 2011

FLOOD RISK ASSESSMENT USING HEC-HMS