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ERT 246 HYDROLOGY AND WATER RESOURCES

ENGINEERING

Ms Siti Kamariah Bt Md Sa’atSchool of Bioprocess Engineeringsitikamariah@unimap.edu.my

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Text Book

Bedient B. P; Huber W.C and Vieux B.E,. (2008) Hydrology & Floodplain Analysis, 4th Ed. Prentice-Hall, Inc, Upper Saddle River, NJ 07458

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Reference Books

Subramaya K.(2008),Engineering Hydrology, 3rd Ed. McGraw Hill,New York,N.Y

DID. (2000), Urban Stormwater Management Manual for Malaysia, DID, Malaysia

V.T. Chow, D.R. Maidment and L.W. Mays (1988,) Applied Hydrology, McGraw-Hill

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Course Objectives

At the end of the course, students are expected to be: 1. EXPLAIN and DISCUSS components of

hydrologic cycle. 2. Ability to DEMONSTRATE use of , ASSESS, and

PERFORM, techniques of hydrologic analyses. 3. ANALYZE and ASSESS hydrologic data for

engineering design and management

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INTRODUCTION

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What is hydrology

From Greek word “hudor” means water and “logy” means research.

The science dealing with all aspects of the waters of the Earth.

Water is essential for all living things. It also participates in the physical and geochemical evolution of most nonliving matter on Earth

Its adequate supply is a key factor for urban, agricultural, and industrial development

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What is hydrology

Deals with occurence,circulation, storange and distribution of surface and ground water on earth

Relates to water quality and quantity Hydrologic cycle and process Water resources management To solve human problem related to water

such as flood, water supply

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Hydrology and Water Resources Engineering

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Hydrology and Water Resources Engineering

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History of Hydrology - 1800s

Chezy Channel Formula in the 1780s Open channel flow experiments - 1800s US Army Corps of Eng established (1802) Darcy and Dupuit laws of ground water - 1850s USGS first measured Miss River flow in 1888 Manning’s Eqn - Open Channel Flow - 1889 U.S. Weather Bureau 1891 (NWS) Major Hurricane at Galveston - 1900 (8000 dead)

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History of Hydrology - 1900s

Early 1900s saw great expansion of water supply and flood control

dams in the western U.S. - in response to Dust Bowl and the Great

Depression of the 1920s & 30s

U.S. Dept of Agriculture began many hydrologic studies

Sherman UH and Horton infiltration theory - mid 1930s

U.S. Army Corps of Engineers (1930s) - large projects

Major Hurricane at Florida - over 2000 deaths

Penman (1948) - complete theory of evaporation

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Important of water

The most important resources after oxygen. Minimum requirement for human= 1.5L/d Plants also need water for photosynthesis

and nutrient transport Human civilization such as Nile River, Hwang

Ho River, Klang River Water related problem

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Problems in Hydrology

Extreme weather and rainfall variation Streamflow and major flood devastation River routing and hydraulic conditions Overall water supply - local and global scales Flow and hydraulics in pipes, streams and

channels Flood control and drought measures Watershed management for urban development

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Total water in the world = 1.36 x 1018 m3

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What percent of the Earth’s total volume of water is stored in the atmosphere?

0.001% Water vapor Clouds(water vapor condensed on

particulate)

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Major Hydrologic Cycle Processes

Precipitation Evaporation or ET (loss to atmosphere) Infiltration (loss to subsurface soils) Overland flow (sheet flow toward nearest stream) Streamflow Ground water flow and well

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The Hydrologic Cycle

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AtmosphereAtmosphere

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What two processes change liquid water into vapor that can ascend into the atmosphere?

•EvaporationEvaporation

•TranspirationTranspiration90%90%

10%10%What percent of the What percent of the water in the water in the atmosphere comes atmosphere comes from evaporation?from evaporation?

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Evaporation

•The process by which liquid water is transformed into a gaseous state

•Evaporation into a gas ceases when the gas reaches saturation

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Evaporation v. Precipitation

About equal on a global scale Evaporation more prevalent over the oceans than

precipitation Over land, precipitation exceeds evaporation Most water evaporated from the oceans falls back into

the ocean as precipitation 10% of water evaporated from the ocean is transported

over land and falls as precipitation Once evaporated, a water molecule spends ~ 10 days

airborne

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(Stomata are small openings found on the underside of leaves that are connected to vascular plant tissues.)

The process of water loss from plants through stomata.

•passive process that depends on:~humidity of the atmosphere ~the moisture content of the soil

•only 1 % of the water transpired used for growth•transports nutrients from the soil into the roots and carries them to the various cells of the plant •keeps tissues from becoming overheated

Transpiration

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Precipitation

The vapor that accumulates or freezes on condensation nuclei is acted on by gravity and falls to Earth’s surface.

rain, freezing rain, sleet, snow, or hail

primary connection in the water cycle that provides for the delivery of atmospheric water to the Earth

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Meteorological factors affecting surface Runoff

Type of precipitation Rainfall intensity Rainfall amount Rainfall duration Distribution of rainfall over the drainage basin Direction of storm movement Precipitation that occurred earlier and resulting soil

moisture Meteorological conditions that affect

evapotranspiration

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Physical characteristics affecting surface runoff

Land use Vegetation Soil type Drainage area Basin shape Elevation Topography, especially the slope of the land Drainage network patterns Ponds, lakes, reservoirs, sinks, etc. in the basin,

which prevent or delay runoff from continuing downstream

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Human factors affecting surface runoff

Urbanization -- more impervious surfaces reduce infiltration and accelerate water motion

Removal of vegetation and soil -- surface grading, artificial drainage networks increases volume of runoff and shortens runoff time to streams from rainfall and snowmelt

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Most runoff…

Drains to a creek– To a stream

To a river– To an ocean

– Rarely runoff drains to a closed lake– May be diverted for human uses

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Groundwater begins as INFILTRATION

Precipitation falls and infiltrates into the subsurface soil and rock

•Can remain in shallow soil layerCan remain in shallow soil layer•Might seep into a stream bankMight seep into a stream bank•May infiltrate deeper, recharging May infiltrate deeper, recharging an aquiferan aquifer•May travel long distancesMay travel long distances•May stay in storage as ground May stay in storage as ground waterwater

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How much ground water?

Ground water occurs only close to the surface (a few miles down)– Density of soil/rock

increases with depth– The weight of the rocks

above condense the rocks below and squeeze out the open pore spaces deeper in the Earth

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Watershed

A basin, drainage or catchment area that is the land area that contributes runoff to an outlet point

Outlet pointWatershed boundary

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Watersheds

We all live in a watershed! Area of land from which all water drains,

running downhill, to a shared destination - a river, pond, stream, lake, or estuary

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Watersheds

Area of land that drains to a single outlet and is separated from other watersheds by a drainage divide.

Rainfall that falls in a watershed will generate runoff to that watershed outlet.

Topographic elevation is used to define a Watershed boundary (land survey or LIDAR)

Scale is a big issue for analysis

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Functions

Captures precipitation – its characteristics influence how much is captured

Stores water once it infiltrates into soil (important to plants)

Slowly releases water into streams, rivers, oceans

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Why are watersheds important?

Activities within a watershed impact runoff and water quality of water leaving the watershed

Must manage at a watershed level rather than other boundaries to attain goals related to runoff and water quality

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Watershed Characteristics

Size

Slope

Shape

Soil type

Storage capacity

Reservoir

Divide

Natural stream

Urban

Concrete channel

1 mile

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• Important hydrologic characteristic

• Elongated Shape

• Concentrated Shape

• Affects Timing and Peak Flow

• Determined by geo - morphology of stream

Watershed Shapes

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Measurement and Unit

3 types of measurement– Depth

mm,cm,m, inch, ft Total rainfall, river depth, evaporation

– Volume cm3,m3,liter, ft3,meter hectare, km3

Rainfall volume in tank, water requirement, ocean volume

– Flowrate L/s, L/min, m3/s Stream flowrate, flow in pipe

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Units

Rainfall volume is normally measured in inches or cm Rainfall rate or intensity in inches/hr or cm/hr Infiltration is measured in inches/hr or cm/hr Evaporation is measured in inches or in/hr (cm/hr) Streamflow is measured in cfs or m3/s Ground water flows are measured as ft3/day or m3/day

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Hydrological Data

Meteorological Data– Temperature, relative humidity, moisture, wind speed, sun – Data can be obtained fom JMM

Rainfall data– DID

Streamflow record– DID

Water quality record– JAS, ASMA

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Water Balance/Budget

dS/dt = I – O

Where

dS/dt = change in storage per time

I = inflow

O = outflow

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Water Balance/Budget

Input-Output = Change in storage P-R-G-E-T = ∆S

Where

P = precipitation

R = surface runoff

G = ground water flow

E = evaporation

T = transpiration

∆S = change in storage

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Example 1

A catchment received inflow and outflow in 10 and 15 m3/s for 24 hours. How much volume changes?

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Example 2

A catchment received annual rainfall 2500mm with 1400mm/year evapotranspiration. With losses to groundwater is 250mm per year and area of the catchment 70 km2, calculate volume of water flowing out from the catchment. Assume there is no changes in storage.

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Measurement and Unit

3 types of measurement– Depth

mm,cm,m, inch, ft Total rainfall, river depth, evaporation

– Volume cm3,m3,liter, ft3,meter hectare, km3

Rainfall volume in tank, water requirement, ocean volume

– Flowrate L/s, L/min, m3/s Stream flowrate, flow in pipe

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Units

Rainfall volume is normally measured in inches or cm Rainfall rate or intensity in inches/hr or cm/hr Infiltration is measured in inches/hr or cm/hr Evaporation is measured in inches or in/hr (cm/hr) Streamflow is measured in cfs or m3/s Ground water flows are measured as ft3/day or m3/day

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Units of Flow

After measures of volume, measures of flow are most important in hydrology.

CFS:– The important measures of flow are Cubic foot

per second (CFS) (which is used for streams and rivers).

– A small stream might be 1-10 CFS a large river 100,000 or more CFS.

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Units of Flow

GPM– Gallons per minute (GPM) is the typical unit for

production from wells. A typical well will product 20-100 GPM while very large wells will produce 2000 or more GPM.

MGD:– Millions of gallons per day (MGD) is a typical unit for

water treatment plants and sewage treatment plants. A small plant might be 1-10 MGD while a large plant might be 100-200 MGD.

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Units of Flow

CMS:– Cubic meters per second is not as common in

the U.S. but is common everywhere else.

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How thirsty are you?

The average person needs something like 1-2 quarts of water  a day,  although consumption could be much higher in hot arid areas.

Or during fraternity parties (of beer anyway)…

Gallons are therefore good units for individual water consumption.

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How thirsty is your toilet?

The typical consumption of water in residential settings is closer to 100 gallons per day per person.

Thus gallons is not a very convenient unit for measuring municipal water use.

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How thirsty is your cotton crop?

Agriculture consumes far more water than municipal uses, so gallons are rarely used for measuring agricultural water use.

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Acre Feet

 Rather the acre foot is the common measure for large quantities of water and is approximately 325,851 gallons.

This is the volume of water that will cover one acre of land to the depth of one foot. It is equal to 43,560 cubic feet of water.

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Other units

Units of water velocity are feet/sec or meters/sec and

Units of stage height are feet or meters. There are also units of concentration,

typically parts per million PPM or parts per billion PPB.

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CONVERSION FACTORS

Distance: 1 meter = 3.281 feet. 1 mile = 5280 feet 1 kilometer = 1,000 meters = 1,000,000 mm.Volume 1 cubic meter = 264.2 gallons. 1 cubic foot = 7.48 gallons, 28.32 liters. 1 liter = .2642 gallons. 1 acre foot = 325,851 gallons.

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CONVERSION FACTORS

Weight: 1 kg = 2.205  pounds. 1 cubic decimeter = 1 kg. 1 gallon = 8.33 pounds 1 cubic foot = 62.31 poundsVelocity: 1 meter/sec = 2.237 mi/hr. 1 foot/sec = 1.097 km/hr.Other factors. 1 inch of run-off per hour from one acre = 1 cubic

foot per second of flow.

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CONVERSION FACTORS

Flow 1 cubic meter per second = 35.32 cubic feet per

second 1 cubic foot per second for 1 day  = 1.98 acre feet. Conversion factors metric to U.S. Customary\ 1 hectare = 2.471 acres, 10,000 square meters. 1 acre = 43,560 square feet.

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Hydrological Data

Meteorological Data– Temperature, relative humidity, moisture, wind

speed, sun – Data can be obtained fom JMM

Rainfall data– DID

Streamflow record– DID

Water quality record– JAS, ASMA

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Thank You