Hydrology Introduction, Weather & Hydrology, Precipitation

It treats of the waters of the Earth, their occurrence, circulation and distribution, their chemical and physical properties, and their reaction with the environment, including their relation to living things

Hydrology

It includes those segments of the field pertinent to planning, design, and operation of engineering projects for the control and use of water.

Engineering hydrology

8 IMPORTANCE OF HYDROLOGY:

 Water Resource Management

 Flood and Drought Prediction

 Environmental Conservation

 Infrastructure Design

 Climate Change Adaptation

 Irrigation and Agriculture

 Groundwater Management

 Urban Planning

Hydrology helps in assessing and managing water resources for drinking, agriculture, industry, and recreation.

Water Resource Management

Hydrological studies enable forecasting and mitigating the effects of floods and droughts by understanding water flow patterns and storage.

Flood and Drought Prediction

It aids in preserving ecosystems by monitoring water availability and quality for plants, animals, and humans.

Environmental Conservation

Civil engineers use hydrology to design structures like dams, reservoirs, bridges, and drainage systems that interact with water

Infrastructure Design

Understanding hydrological cycles helps in predicting and managing the impacts of climate change, such as altered rainfall patterns and sea level rise.

Climate Change Adaptation

Hydrology is essential for designing efficient irrigation systems, ensuring sustainable crop production

Irrigation and Agriculture

It supports sustainable extraction and protection of groundwater resources, which are vital for many communities.

Groundwater Management

Proper hydrological studies are key to stormwater management and reducing urban flooding

Urban Planning

3 TYPES OF HYDROLOGICAL PROBLEMS:

 Estimates of extremes rarely observed in a small data sample

 Hydrologic characteristics at locations where no data have been collected

 Estimates of the effects of human actions on the hydrologic characteristics of an area

Is what moves earth’s water around the planet where plants, animals, and humans can use it.

The Water Cycle

4 WATER CYCLE:

 Evaporation

 Condensation

 Transpiration

 Precipitation

is the heat source for the hydrothermal solutions, which contains both magmatic and meteoric matter.

Magma Chamber

The hydrologic characteristics of a region are determined largely by its _______ and _______, which _______ playing a dominant part.

geology and geography, climate

is the science that studies the Earth’s physical structure and substances, the history of rocks, the processes that act on them and the most economical way to use the world’s resources. _____ involves methods and knowledge from Biology, chemistry, physics and mathematics

Geology

the study of the diverse environments, places, and spaces of Earth’s surface and their interactions. It seeks to answer the questions of why things are as they are, where they are.

Geography

It refers to short term atmospheric conditions

Weather

It is the weather of a specific region averaged over a long period of time.

climate

It refers to long-term changes.

Climate change

Among climatic factors that establish the hydrologic features of a region are:

 The amount and distribution of precipitation

 The occurrence of snow and ice

 The effects of wind, temperature and humidity on evapotranspiration and snowmelt

2 CAUSES of The General Circulation of Wind:

 the uneven heating of earth’s surface through solar input

 the earth’s rotation

It determines weather and climate. And the earth’s chief source of energy.

Solar radiation

Both earth and sun radiate essentially as ________, i.e., they emit for every wavelength almost the theoretical maximum amount of radiation for their temperatures.

blackbodies

they emit for every wavelength almost the theoretical maximum amount of radiation for their temperatures.

blackbodies

• It is the deflection of the atmosphere sets up the complex global wind patterns which drive surface ocean currents.

• It is named after the French mathematician Gaspard Gustave de Coriolis (1792-1843), who studied the transfer of energy in rotating systems like waterwheels. (Ross, 1995)

Coriolis effect

Coriolis effect is named after the French mathematician _______________ (1792-1843), who studied the transfer of energy in rotating systems like waterwheels. (Ross, 1995)

Gaspard Gustave de Coriolis

it is defined by the coming together, or convergence, of the northern and southern hemisphere trade winds and a decrease in the pressure gradient

ITCZ or Intertropical Convergence Zone

It is more or less circular area of low atmospheric pressure in which the winds blow counterclockwise in the Northern Hemisphere

Cyclone

It is a weather pattern characterized by low air pressure, usually as a result of warming. Low-pressure systems are often associated with storms.

Low-pressure area

An area of relatively high pressure in which the winds tend to blow spirally outward in a clockwise direction in the Northern Hemisphere

Anticyclone

The semi-permanent and transitory features of the Migratory system are classified as: (2)

• Cyclone

• Anticyclone

It is a weather pattern characterized by high air pressure, usually as a result of cooling. High-pressure systems are usually associated with clear weather.

High-pressure area

Is a weather system that is the boundary separating two different types of air. One type of air is usually denser than the other, with different temperatures and different levels of humidity. This clashing of air types causes weather: rain, snow, cold days, hot days, and windy days.

A front

2 major types of fronts:

cold fronts and warm fronts

_____ fronts often come with thunderstorms or other types of extreme weather. They usually move from west to east.

Cold fronts

_____ fronts usually show up on the tail end of precipitation and fog. As they overtake cold air masses, _____ fronts move slowly, usually from north to south

Warm fronts

It move faster than warm fronts because cold air is denser, meaning there are more molecules of material in cold air than in warm air.

Cold fronts

Because_______ aren't as dense or powerful as cold fronts, they bring more moderate and long-lasting weather patterns. _______ are often associated with high pressure systems, where warm air is pressed close to the ground. High-pressure systems usually indicate calm, clear weather.

Warm fronts

To the hydrologist, _____ is the general term for all forms of moisture emanating from the clouds and falling to the ground.

precipitation

From the time of its formation in the atmosphere until it reaches the ground, precipitation is of more interest to the ______.

meteorologist

Once precipitation reaches the ground, it becomes a basic element of hydrology.

Hydrologist

4 FORMATION OF PRECIPITATION:

1. The atmosphere must have moisture,

2. There must be sufficient nuclei present to aid condensation,

3. Weather conditions must be good for condensation of water vapor to take place, and

4. The products of condensation must reach the earth.

Where aerosol particles suspended in the air on which water can condense.

Cloud condensation nuclei (CCNs)

5 Examples of CCNs:

 Sodium chloride

 Clay mineral kaolinite

 Ammonium sulfate

 Smoke particles from fires or volcanoes

 Ocean spray or tiny specks of wind-blown soil

3 Properties of CCNs:

 Hydrophilic

 Hygroscopic

 Size: (1/100)th the size of a cloud droplet

4 CLOUD SEEDING

 A growing convective cloud with supercooled droplets is required.

 Silver iodide is used to assist the natural process of rain formation

 Provides “nuclei” on which ice crystals can form

 If they become large enough, they fall and melt on the way down, becoming rain.

3 TYPES OF PRECIPITATION:

• CONVECTIVE

• CYCLONIC

• OROGRAPHIC

due to intense heating of air at the ground, which leads to expansion and vertical rise of air.

CONVECTIVE

associated with the movement of large air-mass systems, as in the case of warm or cold fronts.

CYCLONIC

due to mechanical lifting of moist air masses over the windward side of mountain ranges.

OROGRAPHIC

2 MEASUREMENTS OF PRECIPITATION:

• NON-RECORDING RAIN GAGE

• RECORDING RAIN GAGES

1 NON-RECORDING RAIN GAGE

 Symon’s gage

9 RECORDING RAIN GAGES

 Tipping bucket

 Weighing type

 Floating type (natural syphon)

 Telemetering rain gage

 Radar

 Satellite

 Weighing type rain gauge (Recording gauge)

 Float-type rain gauge (Recording gauge)

 Automated rain gauges (Recording gauge)

WEATHER RADAR: (4)

How Weather Radar Measures Precipitation?

• Radar Emits Radio Waves

• Waves Hit Precipitation

• Reflected Signal Returns

• Radar Analyzes the Data

The radar dish sends out pulses of microwave energy.

Radar Emits Radio Waves

They scatter if the waves encounter raindrops, snow, or hail.

Waves Hit Precipitation

Some scattered waves return to the radar.

Reflected Signal Returns

Based on the intensity and movement of the reflected signal, the radar determines:

 Precipitation Type (rain, snow, hail).

 Intensity (light, moderate, or heavy rainfall).

 Movement & Speed (direction and speed of storms).

Radar Analyzes the Data

Radar Analyzes the Data – Based on the intensity and movement of the reflected signal, the radar determines:

 Precipitation Type (rain, snow, hail).

 Intensity (light, moderate, or heavy rainfall).

 Movement & Speed (direction and speed of storms).

Satellites use 2 main techniques to detect and measure precipitation:

 Passive Microwave Sensors

 Radar-Based (Active) Sensors

(4) APPLICATION OF PRECIPITATION DATA INTERPRETATION:

• Weather Forecasting

• Climate Monitoring

• Water Resource Management

• Disaster Preparedness

Helps predict rain, snow, storms, and floods.

Weather Forecasting

Tracks long-term precipitation trends and drought patterns.

Climate Monitoring

Determines water availability for agriculture and reservoirs

Water Resource Management

Early warnings for floods, hurricanes, and droughts.

Disaster Preparedness

A _______ is a plot of rainfall intensity vs. time. It is often used as input to hydrologic computer models for predicting watershed response to input rainfall.

Hyetographs

A ________ is a plot of the accumulated precipitation against time, plotted in chronological order. It is very useful in extracting the information on the duration and magnitude of a storm. Also, intensities at various time intervals in a storm can be obtained by the slope of the curve.

cumulative mass curve