PCS2: Flood Control and Drainage Engineering PDF

**PCS2: Flood Control and Drainage Engineering** **Ground Sill** What is a ground sill? - - **What is Riverbed Degradation?** --------------------------------- - Bed erosion, degradation or lowering, is a process by which the bed of the stream is eroded to a new lower level at a much fas...

**PCS2: Flood Control and Drainage Engineering** **Ground Sill** What is a ground sill? - - **What is Riverbed Degradation?** --------------------------------- - Bed erosion, degradation or lowering, is a process by which the bed of the stream is eroded to a new lower level at a much faster rate than occurs naturally. ------------------------------------------------------------------------------------------------------------------------------------------------------------- **What is a Dam?** ------------------ Dam Meaning- A dam is a structure constructed across a river or natural stream to collect water in a reservoir. The upstream side refers to the side of the barrier where water collects, and the downstream side refers to the opposite side. Dams are primarily constructed to generate electricity through the use of water. Hydroelectricity is the name given to this type of electricity. Dam-created reservoirs prevent flooding and offer water for purposes such as agriculture, human consumption, industrial use, aquaculture, and navigation. **Purposes of Dams** -------------------- Dams serve as multifunctional engineering structures designed to harness water resources for various purposes. They play a pivotal role in the following ways - - - - - - - - - **Multipurpose dams** combine two or more functions of traditional single-purpose dams into one hydro infrastructure project. A multipurpose dam may combine storing and supplying water for irrigation, industry, and human consumption with other uses such as flood control, power generation, navigation, run-off storage, and water discharge regulation. The construction of multipurpose dams is based on the same principles used for single-purpose dams (barriers across a body of water), but additional features may be included to accommodate their different purposes, such as irrigation channels or power generation facilities. Multipurpose dams are particularly appropriate in developing countries, as the multi-functionality of the operations can help meet several development goals simultaneously, such as those related to energy, water and food security, and economic development. ### **Classification Based on Materials of Construction** #### **Earth Fill Dams** An earth-fill dam is constructed of the earth (or soil) compacted in layers, with the most waterproof materials used to create the core and more porous materials used on the upstream and downstream sides. If the water level rises above the dam, a face made of crushed stone prevents wind or rain erosion, and a large spillway, typically made of concrete, guards against catastrophic washout. Because of the soil\'s shear strength, earth-fill dams can withstand forces applied to them. Although the weight of the earth-fill dam also aids in force resistance, its structural behavior differs greatly from that of a gravity dam. The majority of the time, wide valleys with flat flanks (abutments) are where earth-fill dams are constructed. They can be built at locations with weaker foundations because the foundation requirements are less stringent than those for gravity dams. They may be constructed on a variety of foundations. The height of earthfill dams depends upon the strength of the foundation.  **PANTABANGAN DAM** **Pantangan, Nueva Ecija** #### #### **Rock Fill Dams** Large boulders and rock fragments are used to construct a rock-fill dam. To lessen seepage through the dam, an impervious membrane is positioned on the rockfill on the upstream side. Typically, asphaltic concrete or cement concrete is used to create the membrane. Steel and timber membranes were also used in early rock-fill dams, but they are no longer in use. To distribute the water load and give the membrane support, a dry rubble cushion is positioned between the rock fill and the membrane. Sometimes, instead of an impervious upstream membrane, the rock-fill dams have an impervious earth core in the middle to stop seepage. The earth\'s core is placed up against a dumped rock fill. To prevent soil particles from being carried by water and piping, adequate filters must be placed between the earth core and the rock fill on both the upstream and downstream sides of the core. The side slopes of rock fill are typically maintained equal to the angle of repose of the rock which is generally taken as 1.4:1 or 1.3:1. Stronger foundations are needed for rock fill dams than those for earth fill dams. **ANGAT DAM** **Brgy. San Lorenzo, Norzagaray, Bulacan** #### #### #### **Concrete Dams** Concrete Dams are dams that are either constructed of plain concrete cement or reinforced concrete cement. Concrete dams can be gravity dams, buttress dams, arch dams, or any other form of dam constructed by the use of concrete. **AMBUKLAO DAM** **Bokod, Benguet** #### **Masonry Dams** #### Masonry dams are dams made primarily of stone and brick that are occasionally mortared together. They can be gravity or arch-gravity type. The Nagarjunasagar Dam in Andhra Pradesh and Telangana, India, is the largest masonry dam in the world. **MOLINO DAM OR PRINZA WATER DAM Las Pinas, Metro Manila** **Sabo dams** Built in the upstream areas of mountain streams accumulates sediment and suppress the production and flow of sediment. Those built at the exits of valleys work as a direct barrier to a debris flow that has occurred. A sabo dam with slits is particularly effective in capturing a debris flow because it has a larger capacity of sand pool under normal conditions. In case there is a fear of the flow-down of driftwood, a slit sabo dam is built as a preventive measure. **SABO DAM** **Ilocos Norte** **The function of slit-type sabo dam** 1. 2. **Sluiceway and Floodgate** Sluice gates consist of an aperture within an existing floodgate with a sliding plate cover that can be opened to varying degrees. This opening can be vertical, horizontal or rotational in design. It is also known as a sluice channel or simply a sluice, is a man-made water channel or course designed to control the flow of water. It is typically constructed to redirect or regulate the movement of water for various purposes, such as water management, irrigation, flood control, or mining operations. It can be constructed in different configurations, but they generally consist of a channel with gates or barriers that can be opened or closed to control the water flow. By adjusting the gates, the flow rate and direction of the water can be manipulated to meet specific needs. These are just a few examples of the diverse applications and functions of sluiceways. The design and implementation of a sluiceway depend on the specific requirements and objectives of the project or activity it is intended for. Overall, sluiceways play a crucial role in water management and resource extraction, providing a controlled pathway for water to flow in a desired manner. - - - - - - - **Floodgates** The operation profile of floodgates differs substantially from that of lock and weir gates. Floodgates are normally in stand-by condition. Their operational closing proceeds sporadically in the frequencies varying between a few times a year to once in a few years. It is the gate used to control the flow of water over a levee or in a reservoir. Some floodgates protect areas that are vulnerable to hurricanes or typhoons. There are many kinds of floodgates, all designed to hold water back sometimes and to let it flow at others. **Dikes** Dikes are typically designed to defend against a specified level of flooding. To remain effective, they need to be inspected, maintained and upgraded. Around the world, dikes have allowed people to settle on flood-prone lands. A dike (also called a dyke or levee) is an embankment constructed along a riverbank or coastal shoreline to prevent the flow of floodwaters onto land behind the dike. It is typically made of compacted earth and outfitted with flood boxes, gates and pumps to help regulate the water level on the landward side of the dike. **Culverts** Culverts are an essential part of stormwater drainage systems. They are particularly important for the effective management of surface runoff across roads and highways. A culvert is a short tunnel structure that primarily conveys water beneath an obstruction. In the context of stormwater management, culverts help to convey water from one side of an obstruction to the other. This serves important hydraulic functions, ensuring that surface runoff flows properly. A common function of a culvert is to convey surface runoff across the embankments that support raised roads. **Manggahan floodway, Pasig City San Roque Dam** **What is Drainage Channel?** **Drainage Channe**l is a type of linear drainage system that collects and channels water away from a surface, such as a driveway or patio. It is often used in areas with heavy rain or where water pools. **Three Types of Drainage Canal** o **Reinforced Concrete Pipe Culvert (RCPC)** Is a type of piping used for directing the flow of liquids or water underground. These pipes are typically used in a roadway and site development, as they are designed to convey a very large amount of liquid and built to withstand environmental stressors. This piping is ideal for infrastructure projects such as storm sewer conduits -- RCPC can handle large amounts of any runoff, flooding, or storm surges, safely diverting it from city or industry sector. **Where is RCPC used?** RCPC is a go-to for any utility project because it is one of the strongest and most durable building materials available. Because of its proven lifespan, often lasting more than 100 years, uses of concrete pipe include all types of major projects, such as:  **Brief History of Reinforced Concrete Pipe Culvert (RCPC)** **CAESAREA MARITIMA** Possuolana's use in building the seaport of Ceasarea Maritima is the earliest known example of underwater concrete technology. The first underground application of pipes and culverts to manage water and sewer flow is also attributed to the Romans. When ancient Rome became too overpopulated for a surface sewer ditch system, work began on a massive underground concrete culvert and pipe system that drained local marshes to remove the waste of Rome and carry it into the River Tiber. **CLOACAE MAXIMA** Rome's main sewer system The Cloacae Maxima was constructed around 300 BC as Rome's main sewer system. The eleven aqueducts that fed into the city were also harnessed to help flush out the system, and separate pipes were installed to channel this fresh water to various public fountains. Today, portions of such Roman concrete masterpieces are still standing and in use -- parts of the Cloacae Maxima are visible, as are the underwater concrete ramparts at Caesarea Maritima. Some two thousand years later, these concrete structures remain sturdy even with continuous exposure to water and liquid erosion. o **Reinforced Concrete Box Culverts (RCBC)** RCBC are ideal for situations where depth or height restrictions demand wide, shallow conduits to handle required flows, as well as: Installation where circular or elliptical concrete pipe cannot provide adequate flow capacity. BoX culverts are a superior substitute for cast-in-place box culverts, long span metal arches, short bridges, and multibarrel circular culverts or drains, providing unmatched strength, durability and versatility. **Advantages and Features of Box Culverts** **Durability**: concrete box culverts are highly durable and can withstand environmental conditions and heavy loads, ensuring long-term performance. **Strength**: they offer high strength, making them suitable for use in areas where heavy loads or traffic are expected. **Versatility**: concrete box culverts are available in various sizes and shapes to suit project requirements, providing versatility in design and application. **Easy Installation**: they are relatively easy to install compared to other types of culverts, which can help reduce construction time and costs. **Low Maintenance**: once installed, concrete box culverts require minimal maintenance, reducing long-term maintenance costs. **Hydraulic Efficiency**: concrete box culverts have a smooth interior surface which helps maintain hydraulic efficiency and ensures efficient water flow. o **Open Channels** Open channel systems treat stormwater runoff through a combination of filtration through a vegetative cover and infiltration. **Types of Open Channels** **Grass Channel** are modifications of traditional conveyance channels that provide some water quality treatment. Grass channels have a broad, mildly sloped channel, and a thick vegetative cover. **Dry Swale** are vegetated channels with moderate slopes. In dry swales, a prepared soil bed is designed to filter the runoff for water quality. These are designed to drain water quality volume in 24 hours. **Wet Swale** are similar to stormwater wetlands in their use of wetland vegetation to treat stormwater runoff. Wetland vegetation can be planted or allowed to naturally colonize these systems. These are designed to retain the water quality volume for 24 hours. Their use may be restricted due to concerns regarding odor and mosquitos. **Filter Strips** It provides a buffer, usually grass, between development and streams or stormwater conveyance systems. They provide some pollutant removal and infiltration and reduce the velocity of overland flow before it reaches the streams. These systems are often part of a riparian buffer system, including a forested buffer at the stream edge (Schueler, 1995). The use of filter strips is limited by the amount of space they consume. **Open Channel Flow Section Geometries** **Rectangular channels** have vertical or near vertical sides which are formed with reinforced concrete retaining walls, I-walls, or U-frame structures. The channel bottom may be paved or unpaved depending on the resistance of the in-situ material to erosion. **Trapezoidal channels** have sloped sides and are formed by excavating in situ materials. The sloped sides and channel bottom may require paving for protection, depending on the stability of the sides and the resistance of the in-situ materials to erosion. **Triangular Channel** is an open channel with a triangular cross section where both sides slope from vertical at the same angle. The flow routing through a Channel Connection is described in Analysis of Junctions and Connections. Several parameters that are typically used to specify the size and shape of a triangular cross-section. The proper cross section for a reach of the channel is one that provides adequate hydraulic capacity at the minimum cost. Economic considerations for selecting the channel section include the costs of design and construction, right-of-way, required relocations, and maintenance and operation. A trapezoidal channel is usually the most economical channel when right-of-way is available and is, therefore, the more commonly used channel section. A rectangular channel may be required for channels located in urban areas where the right-of-way is severely restricted or available only at a high cost. **NON-STRUCTURAL MEASURES** Non-structural measures are strategies that aim to mitigate disaster risks and impacts without the need for physical construction, relying instead on knowledge, practices, and agreements. These measures encompass the development and implementation of policies and laws to establish and enforce safety standards, conducting comprehensive research and risk assessments to analyze hazards and vulnerabilities, and providing training and education to enhance disaster preparedness and response capabilities. Additionally, building codes, although not involving physical structures, set essential standards for construction practices to ensure resilience against specific hazards. Public awareness programs also play a critical role in informing and engaging communities about disaster risks and effective response strategies. Collectively, non-structural measures serve to complement physical infrastructure by addressing the human and systemic factors that significantly contribute to overall disaster resilience. - -it involves a comprehensive approach to reduce flood risks and mitigate impacts in areas prone to flooding. This strategy includes zoning and land-use regulations, implementing flood control infrastructure, promoting sustainable development practices, and enhancing community awareness and preparedness. Effective floodplain management aims to balance the need for development with the preservation of natural floodplain functions, ultimately reducing vulnerability and improving resilience to flood events. With our changing environment, floodplains and other flood--prone areas need to be examined in relation to how they might affect or be affected by development. ** Floodplain Risk analysis** Development planners need to: - - **Floodplain mapping**- the overall goal of flood maps is to provide information on the past and the likely or potential extent of floods and their impacts which help in making decisions on various aspects of integrated management of floods. -  **Floodproofing** It is defined as any combination of structural or nonstructural adjustments, changes, or actions that reduce or eliminate flood damage to a building, contents, and attendant utilities and equipment. Building Relocation / Structure relocation - Move a building out of flood hazard area.  Bayanihan in the Philippines  **Building Elevation** Elevate the entire building above the expected flood level. - - **Building Floodwalls** Building a wall around your structure to hold back floodwaters. **Dry Floodproofing** - DamEasy Flood Barriers in Philippines  **Wet Floodproofing** Making uninhabited portions of your structure resistant to flood damage by allowing water to enter during flooding. Successful Wet Floodproofing involves the following: - - - - - **Watershed management** Watershed management refers to the process of implementing land use and water practices that protect the quality of the water and natural resources within a watershed. The main aim of watershed management is to conserve the soil, plant, and water resources of a catchment while benefiting humanity. Watershed is an area of land that drains all the streams and rainfall to a common outlet such as the outflow of a reservoir, mouth of a bay, or any point along a stream channel.  **Types of Watershed** Watersheds are classified depending upon the size, drainage, shape and land use pattern. - - - - - Components of watershed management programme 1\. Soil and water conservation 2\. Water harvesting 3\. Crop management 4\. Alternate land use systems  A good forest cover which prevents erosion and siltation. **Disaster management** **Pre-Disaster** Pre-Disaster also referred to as Emergency management, means preparing for potential calamities and responding to them as quickly, strategically and effectively as possible. Forecasting, Monitoring and Warning System An integrated system of hazard monitoring, forecasting and prediction, disaster risk assessment, communication and preparedness activities systems and processes that enables individuals, communities, governments, businesses and others to take timely action to reduce disaster risks in advance of hazardous events Dissemination of Flood Information ❖ Information, Education & Communication Programs ❖ Stockpiling of emergency materials ❖ Communication Equipment and Network ❖ Evacuation Plan (location & access to evacuation center) Disaster Preparedness Preparedness is a set of actions that are taken as precautionary measures in the face of potential disasters. Being prepared helps in achieving goals and in avoiding and mitigating negative outcomes. ❖ Understand Risks ❖ Develop an Emergency Plan ❖ Prepare an Emergency Kit ❖ Prepare Your Home ❖ Stay Informed Training of Trainers Training of Trainers (ToT) for pre-disaster preparedness is essential for ensuring that those who will train others are well prepared and knowledgeable. A guide on how to conduct an effective ToT program for disaster preparedness: ❖ Establish Objectives ❖ Curriculum Development ❖ Select Trainers ❖ Training Methods ❖ Training Delivery ❖ Assessment & Evaluation ❖ Certification ❖ Monitoring & Improvement Community Dialogues Community dialogues are crucial for fostering collaboration, sharing information, and building resilience before a disaster strikes. A guide on how to organize and conduct effective community dialogues for pre-disaster preparedness: ❖Define Objectives ❖Plan the Dialogue ❖Promote the Event ❖Conduct the Dialogue ❖ Evaluate and Improve Tabletop Exercise A tabletop exercise is a discussion-based simulation used to test and improve disaster response plans and procedures. It involves participants working through a hypothetical disaster scenario to evaluate their responses and coordination. A guide on how to conduct a tabletop exercise for pre-disaster preparedness ❖ Define Objectives ❖Assemble Participants ❖Design the Scenario ❖ Conduct the Exercise ❖ Debrief and Evaluate ❖ Continuous Improvement Evacuation Drill An evacuation drill is a practical exercise designed to prepare individuals and organizations for safely and efficiently evacuating a building or area during an emergency. Conducting regular evacuation drills helps ensure that everyone knows their roles, the evacuation routes, and how to respond calmly under pressure. Communication/Warning System Church bell or "bandillo" is being used to alarm the town folks and nearby barangays. This will give an alert that people should evacuate. Small and hand held sirens are used by the barangay's heads. Flood Fighting Works Evacuation **SOLID WASTE** Solid waste refers to any discarded or unwanted materials. It includes various items such as paper, plastics, glass and food waste. The Resource Conservation and Recovery Act also states that solid waste can include sludge from industrial plants or other discarded materials that result from industrial, commercial, mining and agricultural operations While solid waste is often considered a solid state, the RCRA states that this type of waste does not have to be physically solid. In fact, many solid wastes are liquid, semi-solid or contain gaseous material. **Types of Solid Waste** Municipal Solid Waste (MSW) Municipal Solid Waste (MSW): This type includes everyday items discarded by households, such as paper, plastics, food scraps, textiles, packaging materials, yard waste and household hazardous waste like batteries or cleaning products Commercial Solid Waste Originating from commercial establishments such as offices, restaurants, shops and institutions, this waste type includes paper, packaging materials, food waste and other discarded items. Industrial Solid Waste Generated by industrial processes and manufacturing activities, industrial waste comprises materials like scrap metal, chemicals, solvents, sludge and other by-products from factories and production facilities. Construction and Demolition Debris Generated from construction, renovation and demolition activities, C&D waste includes concrete, wood, bricks, asphalt, metals, drywall and other materials used in building structures. Hazardous Waste Materials that pose a risk to human health or the environment due to their toxic, flammable, corrosive or reactive nature are considered hazardous. This category includes items like batteries, fluorescent bulbs, pesticides, certain chemicals and medical waste Electronic Waste Discarded electronic devices and equipment, such as computers, televisions, smartphones and appliances, can contain hazardous materials like lead, mercury and other components that require specialized handling and disposal. Agricultural Waste Generated from farming activities, agricultural waste includes crop residues, animal manure, pesticides and other waste produced in agricultural processes. **HOW SOLID WASTE IS MANAGED:** The diverse types of solid waste outlined above each require different management approaches, including recycling, composting, incineration, landfill disposal or other specialized treatments to minimize their environmental impact and promote sustainable waste management practices Recycling Recycling converts waste materials like paper, plastics, glass, metals, and electronics into new products, conserving resources, reducing waste, and reducing energy consumption. Composting Composting is the biological process of decomposing organic waste into nutrient-rich soil amendments, enhancing soil fertility, reducing landfill methane emissions, and reducing chemical fertilizer use. Incineration Incineration, a waste-to-energy process, reduces waste volume but raises concerns about air pollution, greenhouse gas emissions, and toxic substance release if not managed properly. Landfills Landfills, designed to minimize environmental contamination, can be managed effectively by collecting leachate and methane gas, but improper management can lead to soil and water pollution. Specialized Treatments Some types of waste, such as hazardous waste or certain industrial by-products, require specialized treatment methods to neutralize or detoxify hazardous components before disposal. These treatments may include chemical, physical or biological processes to render the waste less harmful to the environment. **WHEN DOES SOLID WASTE BECOME HAZARDOUS?** **Corrosivity:** waste with a pH below 2 or above 12.5, can corrode metals and cause tissue damage, including battery acid, cleaning agents, and rust removers. Examples include battery acid (sulfuric acid), certain cleaning agents, and rust removers. **Reactivity:** unstable and prone to violent reactions when exposed to heat, pressure, or water, can generate toxic gases, explode, or cause hazardous conditions. Examples include explosives, cyanide-containing waste, materials prone to violent reactions (such as unstable chemicals), and some pharmaceuticals. **Toxicity:** Waste is classified as toxic if it contains substances harmful to human health or the environment at concentrations above specified regulatory levels. Toxicity is typically determined through specific laboratory tests measuring the concentration of these substances. Examples include heavy metals (such as lead, mercury and cadmium), pesticides, certain organic compounds and other hazardous constituents. **REPUBLIC ACT NO. 9003** The Republic Act (RA) 9003, otherwise known as the Ecological Solid Waste Management Act of 2000, provides the necessary policy framework, institutional mechanisms and mandate to the local government units (LGUs) to achieve 25% waste reduction through establishing an integrated solid waste management plans based on 3Rs (reduce, reuse and recycling). **DPWH SOLID WASTE MANAGEMENT** According to the GUIDELINES AND PROCEDURES FOR THE IMPLEMENTATION OF D.O. 57, SERIES OF 2009 \"DPWH SOLID WASTE MANAGEMENT POLICY The Department of Public Works and Highways is committed to safeguard the environment through proper waste segregation to reduce the solid waste generated in all its Offices. REFERENCES: