Paradigm shift concept in flood disaster vital ecosystems. The basis of IWRM is the environment.

Collaboration, coordination
management recognition that different uses of water among stakeholders, and stakeholder
resources are interdependent, and by integrating participation are central, and IWRM adapts to
Paradigm shift in flood control management management, multiple benefits can be achieved changing conditions.
means moving from reactive, infrastructure- from a single intervention In contrast, the sectoral approach is marked by
focused flood control to proactive risk disintegration and insufficient coordination,
management. It aims to prevent flood-related 1. Ridges (Divides): Ridges mark the with separate agencies responsible for different
problems before they occur, considers boundaries of a drainage basin. aspects of water use. This leads to inefficiencies
environmental sustainability, and integrates Precipitation falling on a ridge or and conflicts, as decision-making is often top-
various strategies for cost-effective flood risk peak will flow either toward or away down, with agencies making independent
reduction from the point of interest. choices. Weak governance exacerbates these
Connecting these ridges on a issues, potentially resulting in unsustainable
Application of structural measures in flood topographical map forms the water resource management.
management; boundary of the drainage basin.
With suitable sketches, describe the function
1. Dams and Reservoirs: Dams are 2. Tributaries: Tributaries are smaller of a flood bypass.
built across rivers to store excess channels or streams that collect serves the critical function of diverting excess
water during heavy rainfall. When rainwater and flow into larger channel water away from settled areas to
water levels rise due to heavy channels within the drainage basin. prevent flooding. This flood management
precipitation, the dam can release They combine and contribute to the technique involves channeling floodwater into a
water gradually, preventing overall flow of water within the low-lying depression or bypass area, which can
downstream flooding. basin. tolerate and safely accommodate the floodwater.
The operation of a flood bypass typically
2. Levees and Dikes: Levees and dikes 3. Channels: Channels are defined includes controlled weirs or spillways that
are embankments or barriers features on the ground that carry regulate the flow of water, directing it away
constructed along riverbanks or water through and out of a watershed from the main channel.
coastlines to contain floodwaters or drainage basin. These channels
within specific areas and protect can be rivers, creeks, streams, or Describe the Integrated flood management
adjacent lands from inundation. ditches. They can be permanent, (IFM) and the factors affecting it and the
flowing year-round, or dry most of Sustainable flood management (SFM).
3. Floodwalls: Floodwalls are vertical the year in certain regions.
barriers built to shield buildings and Integrated Flood Management (IFM) is a
critical infrastructure from rising comprehensive approach to flood management
4. Floodplain: When a channel
floodwaters in urban areas. They can that stresses collaboration among various
receives too much water, the excess
be made of concrete, steel, or other stakeholders, risk reduction, adaptability, and
water flows over its banks and into
materials. sustainability. It involves a combination of
the adjacent low-lying area, known
structural and non-structural measures,
as the floodplain. Flooding that
4. Channelization: This involves including flood defenses, land-use planning, and
occurs along a channel is referred to
modifying the natural path of rivers early warning systems. The success of IFM
as riverine flooding.
or streams through engineering relies on factors like resource availability,
works, such as straightening or community engagement, political will, and
deepening channels, to increase their scientific knowledge.
capacity to carry water and reduce Describe the followings approaches to flood Sustainable Flood Management (SFM), on the
flood risk. management: sustainable (holistic) approach other hand, is focused on minimizing
and unsustainable approach. environmental harm and promoting long-term
5. Flood Control Basins: These are resilience in flood management. SFM includes
large, flat areas designed to Sustainable (Holistic) Approach to Flood ecosystem-based approaches, nature-inspired
temporarily hold excess water during Management: This approach prioritizes long- solutions, community resilience building, and
heavy rains. They help to reduce term environmental well-being and balances the adaptive management. It aims to use natural
downstream flooding by providing diverse demands on water resources. It processes and nature-based solutions to reduce
temporary storage for floodwaters. emphasizes stakeholder involvement, integrates flood risk while fostering community resilience.
with natural processes, and is cost-effective, The effectiveness of SFM depends on similar
6. Spillways: Spillways are structures adaptive, and dynamic. An example is the use of factors such as resource availability, community
designed to divert excess water away soft engineering solutions like wetland engagement, political will, and scientific
from dams, preventing the dam from restoration to reduce flooding impacts, promote knowledge. Both IFM and SFM are holistic
overtopping during heavy rainfall. biodiversity, and protect the environment. approaches to flood management, seeking to
Unsustainable Approach to Flood balance the needs of communities and the
7. Pumping Stations: In low-lying Management: This approach relies on over- environment in addressing flood risks.
areas or urban regions, pumping exploitation of resources, hard engineering Illustrate the hydrologic cycle and STATE the
stations are used to remove excess solutions, and environmental neglect. It often significance of FOUR of its main elements in
water and discharge it into nearby leads to high costs, short-term benefits, and flood management.
rivers or drainage systems. long-term consequences, including
environmental degradation and increased 1. Precipitation: Accurate knowledge
8. Weirs and Check Dams: Weirs and flooding risks. An example is the construction of precipitation patterns is crucial for
check dams are small structures built of concrete levees that can disrupt natural flood prediction and management.
across streams and rivers to slow floodplains, leading to ecological harm and Monitoring and forecasting
down the flow of water, reduce potentially worsening flooding downstream. precipitation help authorities prepare
erosion, and control flooding in for potential flood events, issue
smaller catchment areas. Describe water resources management in the warnings, and make informed
following contexts: IWRM approach and decisions about flood control
Explain the IWRM process and state its basis measures.
sectoral approach.
and illustrate a drainage basin and state its 2. Infiltration: Understanding how
In the IWRM approach, water resources
elements. much precipitation infiltrates the soil
management is framed as a comprehensive,
sustainable process, encompassing the and how quickly it does so is
The Integrated Water Resources Management
development, allocation, and monitoring of important for assessing the potential
(IWRM) process is a systematic approach to the
water resources while considering social, for soil saturation and groundwater
coordinated development and management of
economic, and environmental objectives. It aims recharge. Saturated soils can lead to
water resources, with the aim of maximizing
to meet the needs of both current and future increased runoff and higher flood
economic and social welfare while safeguarding
generations without compromising the risk. Managing land use to promote
 infiltration and minimize 2. Ring Placement: The rings are management systems, allowing for the effective
impermeable surfaces is an essential driven into the ground using a handling of excess water during heavy rainfall
aspect of flood mitigation. driving plate and hammer. Care is events.
3. Runoff: The volume and rate of taken to ensure they penetrate The advantages of detention/drainage in the
runoff are key factors in flood uniformly to a depth of 15 cm design for basin facilities.
management. If the rate of runoff without tilting or disturbing the soil
exceeds the capacity of natural or surface. Any disturbed soil around Detention basins in basin facility design offer
engineered drainage systems, it can the rings is tamped with a metal advantages like flood control, erosion
result in flooding. Managing and tamper to maintain consistency. prevention, and water quality improvement.
controlling runoff through proper 3. Water Filling: Both rings are They also help with peak flow reduction and
urban planning, flood control continuously filled with water, groundwater recharge, meeting regulatory
channels, and retention ponds can maintaining a constant water level. compliance. These structures are cost-effective
reduce flood risk. This water level is crucial for and versatile for various land uses.
4. Storage: Natural reservoirs and ensuring a steady-state condition for
groundwater storage play a critical infiltration. State SEVEN steps in design of a flood
role in regulating water flow and 4. Depth Adjustment: Water is poured control project.
reducing the severity of flooding. into the rings to reach the desired 1. Problem Identification and
Managing these storage systems can depth, typically between 2.5 to 15 Assessment: Begin by identifying the
help mitigate floods by controlling cm, with a minimum increment of 5 specific flooding issues and their
water release during heavy rainfall or mm. causes in the project area. Assess the
snowmelt periods. 5. Data Collection: Regular extent and severity of the problem.
State FOUR factors affecting infiltration. measurements of water levels are 2. Data Collection: Gather essential
1. Precipitation: The intensity, taken at predetermined time intervals data, including topographic maps,
duration, and vegetal cover of after the start of the experiment. hydrological data, rainfall records,
rainfall determine how much water Time intervals usually start at 5 and information about existing
can seep into the ground. Light and minutes and can extend to 10, 15, 20, infrastructure and land use.
prolonged rain promotes infiltration, 30, 40, 60, and 90 minutes, and so 3. Hydrological and Hydraulic
while intense rainfall may hinder it. on, for up to at least 6 hours. Analysis: Conduct detailed analysis
2. Soil Characteristics: The type of 6. Infiltration Rate Plot: The data to understand the flow of water,
soil, like clay or sandy soil, collected is used to plot the including rainfall-runoff modeling,
influences how quickly water is infiltration rate versus time. Initially, river discharge, and hydraulic
absorbed. Sandy soils allow faster the infiltration rate may vary, but calculations to estimate potential
infiltration, while clayey soils absorb after a certain period, it stabilizes. flood levels.
water more slowly. 7. Steady State Condition: Steady- 4. Design Criteria: Establish the design
3. Land Cover: Vegetation and land state conditions, where the criteria for the project, which may
use impact infiltration. Vegetation infiltration rate becomes relatively include setting the target flood
protects soil from compaction and constant, may require about 20-30 protection level and other project
enhances permeability, while minutes. The exact duration of the objectives.
impervious surfaces like roads experiment depends on factors such 5. Conceptual Design: Develop initial
encourage runoff. as soil type and initial moisture design concepts and alternatives for
4. Geology and Topography: Steep content. flood control measures, considering
terrain leads to quicker runoff and Describe: various options such as levees, dams,
reduced infiltration, while flat land (i) FOUR chief factors affecting stormwater management, and
provides more time for water to basin runoff. drainage systems.
infiltrate. Rainfall Intensity (i): The intensity of rainfall, 6. Detailed Engineering Design: Once a
Explain antecedent moisture content and which is the amount of rainfall per unit of time, preferred option is chosen, proceed
state its impact on flooding. influences runoff. Higher rainfall intensity leads with the detailed engineering design,
Antecedent Moisture Content (AMC) is the to increased runoff. including structural designs,
moisture level in the ground before a rainfall Rainfall Amount: The total amount of rainfall hydraulic structures, and
event. A high AMC indicates saturated soil, plays a significant role in runoff. Greater construction plans.
which leads to quicker saturation during rainfall, amounts of rainfall result in higher runoff. 7. Environmental Impact Assessment:
increasing surface runoff and flood risk. Soil Permeability: The permeability of the soil Assess the potential environmental
affects runoff. Soils with lower permeability impact of the flood control project
allow less water to infiltrate, resulting in higher and develop strategies to mitigate or
State the economic design for extreme events runoff. minimize any adverse effects. This
The economic design of extreme events in Soil Moisture: The moisture content of the soil may involve obtaining necessary
hydraulic design focuses on determining the also impacts runoff. Saturated soils absorb less permits and approvals.
most cost-effective storm sewer capacity. It water, so immediately after a drought when soils State the economic value of wetlands
involves a trade-off between the sewer's are dry, there is higher infiltration and less 1. Flood Control: Wetlands, such as
capacity (Q), initial and annual costs, and runoff. peatlands and wet grasslands, play a
overflow frequency. A greater sewer capacity The detention concept. crucial role in flood control. They act
leads to higher costs but less frequent overflows, Detention in stormwater management refers to as natural sponges, absorbing excess
which can cause property damage and the temporary storage of excess rainwater, rainfall and regulating its flow into
associated expenses. Investing more to reduce typically implemented through various streams and rivers. By preventing
overflow frequency is justifiable, especially for structures such as ponds, tanks, or underground rapid runoff, wetlands help reduce
severe overflows. storage systems. The primary purpose of the risk of flooding, minimizing
detention is to control the release of stormwater, damage to properties and
Describe infiltration measurement by double slowing down its movement and mitigating infrastructure, which translates into
ring infiltrometer. potential flooding, erosion, and water pollution. significant economic savings and
The infiltration measurement using a double- By storing the excess water temporarily, reduced disaster recovery costs.
ring instrument involves the following steps: detention structures help in reducing the peak 2. Water Quality Improvement:
1. Equipment Setup: A double-ring flow surges in urban areas, protecting against Wetlands act as natural filtration
infiltrometer is used, consisting of flooding, and improving water quality. They systems, enhancing water quality in
two concentric metal rings with play a critical role in regulating the flow of various ways. They efficiently
diameters ranging from 22.5 to 90 stormwater, ensuring that it is released at a remove pollutants like nitrogen,
cm. The outer ring helps eliminate manageable rate into the surrounding phosphorous, heavy metals, toxins,
edge effects and controls the spread environment. Detention structures are an and nutrients from water. For
of water from the inner ring. essential component of sustainable stormwater example, wetlands transform harmful
 nitrogen in water into benign 3. Standardize Monetary Estimates: 5. Community Benefits: BMPs
nitrogen gas and trap pollutants in Make estimates comparable using enhance the amenity of urban areas,
their sediments. By purifying water compound interest calculations with making them aesthetically attractive.
and reducing the need for expensive an appropriate minimum attractive They also reduce damage to
water treatment processes, wetlands rate of return. communities caused by flooding and
contribute to cost savings for water 4. Selection of Alternative: Choose or foster a sense of resilience and
treatment facilities and ensure a recommend one alternative based on sustainability.
sustainable supply of clean water for monetary comparisons, considering
communities financial and non-financial factors. Techniques used by BMPs/SUDS/LID:
Briefly explain engineering economy 1. Source Control: Managing
Describe engineering economy under the The engineering economy study process stormwater at its source is a
following topics: involves collecting and analyzing data. fundamental technique. BMPs aim to
Principal resources and the products of these Analytical methods are used to express reduce the immediate impact of
resources alternatives in terms of money. Data gathering rainfall by addressing it close to
Engineering economy focuses on converting includes obtaining cost and pricing information where it falls.
resources from one form or location to another. from engineers. This data collection is an 2. Permeable Paving: This technique
In water resource planning, key resources ongoing effort, and systems need to be in place involves using materials like
involved are: to record relevant data as it becomes available. pervious concrete, which allow
1. Naturally Available Water: Accounting and technical departments should rainwater to infiltrate rather than run
Resources like HEPS and steam. collaborate to establish these recording systems off. It reduces surface runoff and
2. Land: Subject to drowning, for future engineering economy studies. flooding risks.
excavation, or development. Effect of wetlands on flood peak 3. Stormwater Detention: BMPs
3. Building Materials: Used in implement systems to detain
construction. stormwater temporarily, preventing it
4. Manpower: Skilled labor, engineers, from overwhelming drainage
and workers. systems and reducing flood hazards.
5. Equipment: Specialized machinery. 4. Stormwater Infiltration: Promoting
These resources lead to various products: the infiltration of stormwater into the
1. Irrigation Water ground helps prevent surface runoff
2. Water Supply and flooding. It mimics natural
3. Hydroelectric Power hydrological processes.
4. Waterways for Navigation 5. Evapotranspiration: Techniques
5. Low Water Regulation like green roofs enhance
6. Flood Control evapotranspiration, allowing
7. Recreation vegetation to absorb and evaporate
8. Water Quality Control E plain the importance of, and the techniques rainfall, reducing runoff.
Alternatives and the factors governing these used by, best management practices (BMPs/
alternatives SUDS or LID) in flood management. Distinguish between flood control and flood
An engineering economy study compares They focus on reducing and mitigating the management
technical alternatives, expressing their adverse effects of urban development on Flood Control is a flood risk management
differences in monetary terms. Water flooding. These practices employ various approach that primarily aims to prevent or
engineering resource planning involves techniques to manage stormwater and minimize reduce floodwaters from inundating vulnerable
selecting from physically feasible options, each its impact on local ecosystems and areas. It often relies on structural interventions
with multiple alternatives. Factors governing communities. such as dams, levees, and reservoirs to regulate
these choices include economic considerations, Importance of BMPs/SUDS/LID in Flood water flow and contain floods. The primary
financial feasibility, social approval, and Management: objective of flood control is to block or divert
environmental impacts. 1. Flood Reduction: BMPs help floodwaters to minimize immediate damage to
reduce the impact of surface water property and infrastructure. Flood
The 3 questions posed by General John Carty drainage systems, mitigating Management, on the other hand, is a more
regarding every engineering proposal are . flooding risks. They promote comprehensive and holistic approach to flood
Why do this at all'! Why do it now? Why do effective stormwater management, risk. It combines both structural and non-
it this way?explain the engineering answer to preventing the overflow of urban structural measures to address flooding.
each of these questions. drainage systems and minimizing Structural measures may include levees and
1. Why do this at all? This query sudden flood events. floodplain zoning, while non-structural
pertains to profitability. In business, 2. Water Quality: BMPs improve measures encompass land-use planning, early
actions are taken when they yield a water quality by allowing natural warning systems, community preparedness, and
profit. filtration, reducing pollutants, and sustainable development practices. The main
2. Why do it now? This question preventing contamination of other objective of flood management is not only to
addresses whether the proposer has water sources. They help protect mitigate immediate flood risks but also to
considered the timing of the ecosystems and contribute to the reduce overall flood risk and its social,
investment or expenditure. Could provision of clean drinking water. economic, and environmental impacts.
delaying it result in greater profit? 3. Environmental Preservation: OR Flood Control aims to prevent or reduce
3. Why do it this way? This question SUDS and LID replicate natural floodwaters using structural measures like dams
ensures that the individual making systems, restoring wetlands and and levees, focusing on immediate risk
the proposal has explored all floodplains. This ecological mitigation. In contrast, Flood Management is a
available alternatives and verifies approach minimizes the need for comprehensive approach that combines
that the chosen solution is the most concrete flood defences and benefits structural and non-structural measures,
profitable one. the environment by maintaining and emphasizing long-term resilience, community
describe the FOUR steps in an engineering enhancing natural habitats. preparedness, and sustainable development. It
economy study. 4. Cost-Effective: These practices are addresses broader risks, including socio-
1. Identify Promising Alternatives: cost-effective in the long term. economic and environmental impacts. Flood
Begin by recognizing viable options Unlike concrete flood defence management works with nature, involving
and understanding their unique systems, they require minimal community engagement and education, while
features. maintenance costs as natural flood control is more narrowly focused on
2. Monetary Estimations: Convert elements like wetlands and native blocking floodwaters during events. Modern
physical assessments into monetary woodlands grow and mature over flood risk management leans toward flood
values, including timelines, asset time. management due to its sustainability and
lives, and study period duration. community-centric nature.
Causes of flooding
1. Atmospheric Hazards: Large
amounts of rainfall resulting from
atmospheric hazards, particularly
excessive rainfall, are a primary
source of flood hazards. The
intensity of precipitation beyond a
flood-producing threshold can lead
to flooding. Smaller drainage basins
may experience rapid flood flow due
to higher unit-depth of flood runoff.
2. Pluvial or Overland Floods: These
floods occur when rainfall or
snowmelt isn't absorbed into the land
and instead flows over surfaces,
including urban areas, before
reaching drainage systems. They are
often caused by localized summer
storms and can affect a large area for
a prolonged time. Urban areas with
impermeable surfaces experience
pluvial flooding more frequently.
3. Land Use Change: Urbanization,
involving highly impermeable
surfaces like roofs and roads, reduces
infiltration, increasing runoff. Urban
areas often have surface drains and
sewers that deliver water rapidly to
channels, reducing the lag period
between storm rainfall and peak
flow. Constrictions in natural river
channels, such as bridge supports,
reduce their carrying capacity.
4. Deforestation: Deforestation
contributes to increased flood runoff
and sediment deposition in channels.
Small basins have observed
significant increases in flood peak
flows and suspended sediment
concentrations due to deforestation.
Forest clearance, often for fuelwood,
is a notable factor.
5. Human Causes: Intensive land use
in floodplains occurs due to
population pressures and land
shortages. Floodplain encroachment
is driven by economic growth and
population redistribution, leading to
the demand for flood protection.
Structural engineering works, like
flood embankments, can
inadvertently encourage further
floodplain development due to the
perception that these structures
render areas safe.