EGCE-571: Hydraulics and Hydrology for Environmental Engineers Lecture 1

Hydraulic and Hydrologic Components:
- Key aspects include managing both the supply and excess of water resources.
Water Supply Management:
- Sources:
- Groundwater
- Surface water
- Reuse of water
- Transmission:
- Transportation of water from sources to treatment facilities.
- Water Treatment & Distribution Systems:
- Methods used to clean and distribute water for use.
- Wastewater Collection & Treatment:
- Techniques for gathering, treating, and disposing of used water.
Water Excess Management:
- Collection/Drainage System:
- Infrastructure for collecting excess water, especially during storms.
- Storage & Treatment:
- Techniques for managing excess water safely.
- Flood Control Components:
- Implementation of dams, diversions, channels, etc.

Chemical Composition:
- Water is made of two hydrogen atoms (H) and one oxygen atom (O), represented as H2O.
Polarity:
- Water molecules are polar, allowing them to dissolve many substances, which is critical in biological and chemical processes.
Phases:
- Water can exist in three states: solid, liquid, and gas, defining its unique nature as a substance.
Surface Tension:
- This property allows water to form droplets and is essential for plant uptake of water.
Solid Phase (Ice):
- Ice expands upon freezing, increasing its volume by 9%, which is contrary to most liquids.
- Ice is less dense than liquid water, causing it to float, a phenomenon beneficial for aquatic life.

Origin of Earth's Water:
- Space origin theories suggest water arrived on Earth via outgassing from the planet's core and meteorite collisions.
Distribution of Water on Earth:
- The Solar System is approximately 4.6 billion years old.
- Earth is often called the "blue planet", as 70% of its surface is covered with water.
- Water content in biological systems is significant:
- 80% of fruits and vegetables are water.
- Human body composition: 50-70% water and 82% of blood is water.
Sustainability Note:
- Humans can survive without food for several days but not without water, highlighting its critical importance.

Water's presence on Earth is theorized to be due to:
- Outgassing from the Earth's core.
- Collisions with meteorites bringing in water.

The total quantity of water on the Earth is estimated at about 1386 million cubic kilometers (M km³).
- Saline Water in Oceans:
- 96.5% of the Earth's water is found in oceans as saline, making it crucial for understanding freshwater scarcity.

Systems of Units:
- Two systems primarily in use:
- BG System (British Gravitational System): Also known as FPS or US customary units.
- SI System (International System): The metric system used globally.
Basic SI Units:
- There are 7 fundamental SI units:
- Length [L]
- Mass [M]
- Time [T]
- Electric Current [I]
- Temperature [Φ]
- Luminous Intensity [J]
- Amount of Substance [N]
- The units we will use in this course include:
- Length: meter (m)
- Mass: kilogram (kg)
- Time: seconds (s)
Derived Units:
- Created by combining basic units:
- Force: 1 N (Newton) = 1 kg·m/s² [MLT⁻²]
- Pressure: 1 Pa (Pascal) = 1 kg/(m·s²) [ML⁻¹T⁻²]
Dimensional Analysis:
- Important principle stating that dimensions on both sides of an equation must be the same.
- Example Formula: s = v × t
Unit Conversion Examples:
- 1 m = 3.28 ft
- 1 liter = 0.001 m³
- 1 bar = 10⁵ Pa

Calculate the units of coefficients c, k, and f(t) in the equation:
m rac{d^{2}y}{dt^{2}} + c rac{dy}{dt} + ky = f(t)
Where:
m is in kilograms,
y is in meters,
t is in seconds.

Focuses on the behavior of physical bodies under the influence of forces.
Two main branches:
- Statically equilibrium: Objects at rest.
- Dynamic behavior: Objects in motion.
Classical Mechanics:
- Newtonian Mechanics: Applies from projectiles to galaxies.
- Relativistic Mechanics: Deals with velocities close to the speed of light (v ≈ c).
Quantum Mechanics:
- Considers phenomena at the microscopic level.

Determine the net force in Newtons (N) required to accelerate a 10 kg mass at a rate of 40 m/s² (ignoring friction):
- (a) Horizontally
- (b) Vertically upward

Three Main States of Matter:
- Solid:
- Retains its shape and volume, does not flow easily.
- Liquid:
- Assumes the shape of its container but has a fixed volume, flows easily.
- Gas:
- Takes the shape and volume of its container, flows easily.
Classification of Liquid and Gas:
- Both classified as fluids, not maintaining a fixed shape nor resisting shear forces.

Similarities:
- Both are made up of molecules and classified as fluids.
- Molecules in both states are free to move compared to solids.
- Molecules in each phase are in continuous random motion.
Differences:
- Inter-molecular Forces:
- Liquids exhibit strong attractive and repulsive forces, while gases demonstrate minimal forces, only strong during close interactions (collisions).
- Viscosity:
- Liquids have significantly higher viscosity than gases.
- Volume:
- Liquids maintain a definite volume, whereas gases expand to fill their container.
- Molecular Exchange:
- Gases exchange molecules with ambient air while liquids do not.
- Surface:
- Liquids form a free surface, unlike gases, which do not have a defined upper boundary.
- Evaporation:
- Specific to liquids, gases do not exhibit this phenomenon.

Density:
- Defined as \rho = \frac{m}{V}, with units kg/m³.
Specific Weight:
- Given by \gamma = \frac{W}{V}, or \gamma = \rho g, in units of N/m³, representing weight per unit volume.
Temperature Dependency:
- Density of water can be approximated by the formula:
  \rho_{water} = 1000 - \frac{(T - 4)^{2}}{180}
Specific Volume:
- Defined as V_s = \frac{1}{\rho}
Specific Gravity:
- Definition: s{liq} = \frac{\rho{liq}}{\rho_{water}} at 4°C
- Reference for water: \rho_{water} = 1.0 g/cm³ = 1000 kg/m³ at 4°C
- Example for mercury: s_{Hg} = 13.6 - 0.0024T

Given 6 m³ of oil weighing 47 kN, compute:
- Specific weight, density, and specific gravity.

Consider a cylindrical tank with:
- Diameter = 8 m
- Depth = 5 m
Water at 15°C heated to 60°C results in spillage.
Given:
- \gamma_{15°C} = 9.798 kN/m³
- \gamma_{60°C} = 9.642 kN/m³
Problem-solving requires analysis under constant tank volume and temperature effect.

Analyze spillage in a previously discussed tank, under conditions where the tank itself has a thermal expansion coefficient of 4.6 \times 10^{-6}\frac{mm}{mm} /°C.