the urban drain problem: effects of new development and redevelopment on local hydrology

7/28/2019 The Urban Drain Problem: Effects of New Development and Redevelopment on Local Hydrology

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The Urban Drainage ProblemThe Effects of New Development/Redevelopment

on Local Hydrology

Aaron Shaffer

Dept. of Geography and Regional Planning

Indiana University of Pennsylvania


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Introduction

As regions become more developed, urbanization has a drasticimpact on local hydrology Consequences often go unnoticed for years before the severity of

development is made apparent

The growth of impervious surface has been identified as a primary

contributor to urban flooding in areas of recent or expandingconstruction and urban expansion

New urban development causes storm water to run off at a highervelocity, often causing a significant decrease in streams capacity tocarry floodwaters

The causes behind urban flooding involve several factors, bothdirect and indirect

Goal : Apply a conceptual model to compare data from urban and ruralstreams and the correlation to new development/re-developmentthrough a literature review


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Example of

Watershed Drainage

DischargeThe volume of water passing

through a specific section dependent on

the width of the stream

Velocity Distance vs. Time

Competence Maximum particle size a

stream can carry

Capacity Total amount of particles a

stream can carry

Topography Shape and features on the

surface of the earth

Watershed A region that collects waterwhich eventually ends up in a certain

drainage network

Drainage divide The separation of a

watershed by a ridge or high plateau


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Influences

Indirect

Dams and reservoirs cause aregional increase in rainfall

Increase in surface area

Seasonal snow melt Variations in weather patterns

i.e. Hurricanes

Changes in upstream environment

Budget cuts in environmental

funding to manage flood control

Direct

Vegetation Removal

Erosion

Soil Degradation

Sedimentation Flooding

Straightening of a stream channel

Inadequate storm water systems

Stream flow velocity data from the United States Geologic Surveys data loggers show an

increase in velocity for streams that had recently been modified or in areas where new

construction had taken place


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Urban VS Rural Stream Velocities

From 1960 to 2000, the maximum

annual discharge increased in Mercer

Creek as the area was developed into

an urban environment.

During the same period of time,

nearby rural stream Newaukum Creekremained relatively unchanged


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Flash Floods

Flash Flood Rapidly rising water level caused by heavy rainfall in a short period of

time

Can also be caused by the failure of a dam

Most commonly characterized by a wall of rushing water and debris

Strikes with little warning and can cause severe damage

Soil, forest, vegetation and wetlands replaced byconcrete, asphalt and other impermeable surfacesduring construction

Stream beds are often re-routed to accommodate newstructures, further limiting their ability to carryfloodwaters

Increased surface runoff from rain events get funneledinto a storm drain system, increasing velocity and

reflected in the outflow in which it is deposited


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Historical Cases

Most of the recent damage caused by flooding in westernPennsylvania is directly related to flash floods Flooding in western Pennsylvania - Pittsburgh Geologic Society

Johnstown Flood 31 May, 1889 Heavy rains over already saturated ground - 8 inches of rain/hour

~2200 killed $17 million in damage

Big Thompson Canyon, CO 31 July, 1976 Severe thunderstorm over the Rocky Mountains 8 inches of rain/hour

~145 killed Over 550 homes damaged or destroyed

$40 million in damage Mississippi and Missouri Rivers July 1993

Heavy period of rainfall lasting from early Spring to late July

~50 killed - 55,000 homes destroyed

$12 billion in damage


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Case Study - KCAC

Storm event Thursday, 26 July, 2012

Flash flooding caused by only 3.3 inches of rain

Chuck Kelly, Indiana Fire Association chief said"We had areas we pumped that we never pumped

beforeNearthe (Kovalchick Convention and Athletic

Complex), it was like a river. We had reports ofmanholes (covers) blowing off the sewersystem.


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KCAC Facts

The Kovalchick Complex

Opened in March of 2011

Encompasses 1,437,500 ft2 land area

Approx. 200,000 ft2 is comprised of

impervious surface

Increase in runs off from new

impervious surfaces and open area

Before

After


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KCAC Facts

Before After


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Results Point to Further Research QuestionsIncluding Data Collection

Primary Cause of Flash Flooding: Historical trend of overall increases in regional rainfall for a short

period of time

Combined with an increase in runoff from new urban developmentbreaching the capacity of the storm water drainage system

Suggestion of current research and literature: Since construction of the KCAC, potentially permanent increase in

flash flooding in the area?

Current stream flow data from the USGS provides a base ofscientific research proving that there is a general increase inthe size and frequency of flooding due to urbanization

Community at a higher risk for flood hazards and damage?


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Prospect of Future Research

Install data logger, record stream velocitymeasurements and compare to existing USGS

site at rural Two Lick Creek at Graceton, Pa


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Sources Chorley, Richard

Introduction to Geographical Hydrology

Gibson, Christine

Out 10 Greatest Natural Disasters

Konrad, Christopher

Effects of Urban Development on Floods Hossain, Faisal

Large Dams Can Affect Local Climates, says new study

Jurries, Dennis

Biofilters for Storm Water Discharge Pollution Removal

Williamson, Jamie Dams Can Trigger More Frequent Fierce Storms

Http://eros.usgs.gov/

http://www.kovalchickcomplex.com

http://nwis.waterdata.usgs.gov

ESRI ArcGIS - ArcMap

the urban drain problem: effects of new development and redevelopment on local hydrology

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