Engineering Homework

Homework assignment is at the end of Urban Stormwater lecture.Please follow the instructions carefully.
urban_environmental_impacts.pdf

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Overview
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Introduction
Urban Areas and existing issues
Sustainability – Green Infrastructure
Best Management Practices
3
• What were major cities,
Baltimore and
Washington D.C., like in
1500
• How are now now?
The darker areas show Baltimore and
Washington D.C. expanding overtime…
What does this expansion of urban and
suburban area mean in terms of
environmental impacts ???
Environmental impacts of human activities
Human activity
Environmental impacts
Urbanization
High population density
High demand of utility services
Air, water & land pollution
Increased demand for water, energy &
transport
Traffic congestion, noise pollution
Ground water depletion
Large volume of solid waste
Areas of evident poverty developed
Blockage of natural drainage / water runoff
increases due to impervious surfaces (road,
roofs, sidewalks, parking lots)
Morphological changes of river and stream
systems
Destruction of unique natural features & loss
of ecosystem services
Human activity
Environmental impacts
Deforestation
Loss of habitat/ biodiversity
Changes in local ecology
Changes in micro-climate
Loss of carbon sink
Soil erosion
Less water retention
Increased flooding
Industrialization
Air, soil & water pollution
Depletion of minerals and fossil fuel
High demand of energy & water
Waste generation
Thermal pollution
Land Use Change
• Urbanization, sprawl
• Increase demand on infrastructure,
energy, utilities, and service.
• Increase Impervious Surfaces
• Surface energy budget change
– Surface Temperature
– Urban Heat Island
• Changes in
– Surface water budget
– Surface carbon budget
‘Urban Sprawl’
• Impacts air, noise, water
• Traffic congestion
• Standard of living, quality of life, health,
safety
8
Environmental Impacts
• Air Emissions: CO, PM, VOCs, NOx, SO2, acid
deposition
• Air emissions
climate change
Impacts of the Built Environment
•
•
Material flow in (raw materials, water,
fuels) and out (products, waste,
pollution) of the built environment
Massive energy & material use for:
– Buildings
•
– Transportation (transport of
people & goods)
– Construction
Associated environmental impacts as
the built environment grows
– Air, water, and soil pollution
• Need for water…
Water requirements
• Drinking
• Cooking & Preparation of food
• Bathing, cleaning, washing & personal
hygiene
• Watering in gardens
• Water of livestock
• Sanitation
• Loss & wastage
Classification of water pollution
Pollution by putrescible materials (Oxygen demanding
waste)
Pollution by heated effluents (Thermal pollution)
Pollution by toxic materials (Pathogens)
Pollution by inert materials
Pollution by radio-active materials
Pollution by pesticides
Pollution by PCB
Pollution by oil spills
Pollution by heavy metals
Pollution by nutrients
Pollution by salts
Point Sources
Non-point source (NPS) Pollution
Chesapeake Bay Watershed
Watershed:
Two Definitions
1. A natural (or disturbed) unit of land on
which surface and subsurface waters
collect and from which they run off to a
common outlet.
[also an artificial or modified natural
watershed or “catchment” (British term)]
2. A ridge between two drainage basins.
[also a topographic (surface) or phreatic
(subsurface) divide]
Watershed and Watershed Divide
Elevation, area,
Aspect, slope, shape,
etc.
Watershed divide
High point
40%
10%
Land Use Decisions
Affect Runoff,
Recharge, and
Water Quality
Natural Cover
50%
75-100% Impervious
35%
35-50% Impervious
30%
55%
30%
35%
15%
Short-term impacts of land use change
• flooding
• property damage
• increased storm water drainage
•economic impacts
Long-term impacts of land use change
• Increase in surface water quantity
• Decrease in surface water quality
• Decreased groundwater recharge … eventually affecting
municipal supplies
• Increased downstream flooding
• Adverse affect on aquatic life
Runoff as a function of Imperviousness
Sprawl, impervious area, & impairment
Center for Watershed Protection 2003
Stream Enlargement due to Impervious Cover
Stream Quality Indicators
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Increased Runoff Volume
•
Increased Peak Discharge
•
Diminished Baseflow
•
Stream Channel Enlargement
Loss of Riparian Continuity
Decline in Stream Habitat Quality
Increased Stream Temperature
Increased Nutrient Load
Increased Sediment Load
Increased Metals & Hydrocarbons
Increased Pesticide Levels
Increased Chloride Levels
Increased Chloride Levels
Reduced Fish Spawning
Decline in Wetland Plant Diversity
Decline in Amphibian Community
Water Quality Impacts
Storm Drains Hasten Runoff and
Degrade Water Quality
Singapore
Hydrologically
Connected
Ecologically
Dysfunctional
ssible!
The Problem: Conventional Site
Design
Collect
Concentrate
Convey
Centralized
Control
Definition
The planned manipulation of
one or more factors of a
natural or disturbed drainage
so as to effect a desired
change in or maintain a
desired condition or function
of the water resource.
Objectives
• Protection
– Precluding the need for rehabilitation
– Maintenance of sustainability
• Rehabilitation
– Restoration of abused lands
– Re-establishment of pre-disturbance conditions
• Enhancement
– Improvement of water quality, quantity, or
regimen (rate of delivery) to meet human or
environmental needs
Protection
Often, riparian
areas alone
constitute the
most significant
hydrologically
sensitive areas on
a watershed.
Susquehanna River, Maryland
Rehabilitation
Restoration of vegetative cover to meet needs for forest and agricultural land
resources can be accomplished through the creation of an attractive working
landscape . . .
Eastern Belgium
Water Quality Control
• Control over nonpoint sources of pollution (NPS) is
a major objective of watershed management.
• NPS are diffused (as opposed to point sources of
pollution) and are the product of many different
types of land use and, especially, land abuse,
where no care is taken to properly manage the
land.
• NPS are best controlled by Best Management
Practices (BMPs), and are often financed at least
in part with public funds on the grounds that
pollution knows no artificial boundaries.
Point Source Pollution Control
Waste water
treatment for
industries and
municipalities
greatly reduce
water pollution by
high-tech facilities
that release
effluent under a
permit to meet
United States
government
standards…
Blue Plains Waste Water Treatment Plant, Washington, DC
Some Best Management Practices
Nebraska
Iowa
New York
Clockwise from left:
New York
? culvert discharges onto
energy-absorbing rip rap;
? hay bales control sediment on
a highway construction project;
? farmland with strip cropping,
contour plowing, grassed
waterways, and buffer strips;
? six-months’ dairy cow manure
storage on a dairy farm; and
? a temporary silt-fence sediment
control dam.
South Carolina
Implications
• Best Management Practices derive from
ideas about how water quality is
degraded by several land uses.
• BMPs are established to anticipate and
preclude water quality degradation.
• Since runoff occurs naturally across
civilization’s artificial boundaries, funds
from and for the public are used to help
pay for the water quality protection.
Green Infrastructure
Green infrastructure is defined as an interconnected network of green
space that conserves natural ecosystem values and functions and
provides associated benefits to human populations. Green infrastructure
is the ecological framework needed for environmental, social and
economic sustainability
-Benedict and McMahon (2006)
-Low Impact Development Practices
-Urban Tree Canopy / Conservation and Planting
Helps to improve / reduce:
-Stormwater impacts
-Heat island effect
-Energy and water use
-Air quality / Carbon capture (sequester)
Ecosystem Services From Vegetation
•
•
•
Trees and other plants provide important
natural services that humans can derive
benefits from.
The tree leaves and branches covering
the ground is the tree canopy. The extent
of the area covered by tree canopy
determines the benefits provided for the
surrounding environment.
As canopy cover increases, so do the
benefits: such as:
climate control and energy savings
improvement of air, soil, and water quality
increased infiltration and interception of
stormwater runoff;
reduction of the greenhouse gas carbon
dioxide;
provision of wildlife habitat
Low Impact Development (LID)
•
An approach to land development to mimic the pre-development
site hydrology to reduce runoff and NPS.
Conservation
Forest/Woods
Infiltrable Soils
Storage, Detention &
Filtration
Rain gardens
Drainage swales
Minimization
– Reduce imperviousness
Green roofs
Porous Pavement
– Soil Compaction
http://cobweb.ecn.purdue.edu/runoff/lthianew/lidIntro.htm
What Do LID BMPs Look Like?
LID Hydrologic Analysis – CN
Prince George’s County, Department of Environmental Resources Low–Impact Development Hydrologic Analysis, July 1999
All sketches adapted from Prince George’s County, MD, LID IMP Guidance Document, 2002. www.lid-stormwater.net
Rain Gardens: Kansas City, MO
Raingardens are
bioretention areas
that increase
infiltration, recharge
groundwater, and
improve overall
water quality
McCarthy Garden in Kansas City
BIO-RETENTION AREAS
(Pretreatment and Water Quality)
Front 1,975 cu.ft. area that
receives overflow from the pervious
pavers and a rear 2,348 cu.ft. area
that receives overflow from both
the green roof system and the
internal cisterns.
Green Roof: Chicago, IL
A green roof is a roof that is planted with
vegetation. It can reduce the heat imprint of a
building and reduce off-site runoff
GREEN ROOF
6,350 sq.ft. green roof area
that drains to bio-retention
area below.
Porous Pavers
Washington, DC
PERVIOUS PAVERS
5,355 sq.ft. pervious paver
area that drains to a under
layer of stone and flows into
the adjacent bio-retentions
area.
Constructed Wetlands
• Removal Efficiency:
– 65-80% average
– 70% design
• Key Features:
– Large area
– Peak flow control
– Biological treatment
• Maintenance: low to moderate
• Cost: marginally higher than wet ponds
http://www.txnpsbook.org, 2002
Center for Energy Efficiency
Source: MADEP/MACZM Massachusetts Stormwater Management, Volume 2: Stormwater Technical Handbook, March 1997
and Renewable Energy,
UMass, Copyright, 2002
Constructed Wetland Treatment System
62
Rain is Resource
Capture & Use
Toilet Flushing
Car washing
Irrigation
Mixing
Washing
Gardening
Recharge
Benefits
Reduce Demand
Self-sufficiency
Save Money
Rain Water
Capture and
Use
WHY IS LID SO ATTRACTIVE?
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Universally Applicable (Unique Water Balance)
Economically Sustainable
Ecologically Sustainable
Lower Costs (Construction, Maintenance & Operation)
Multiple Benefits (air / water / energy / property values)
Provides benefits water volume reduction, water quality /
treatment
Ideal for Urban Retrofit
Common Sense Approach
Public Acceptance
Usually low maintenance
Low to no energy requirements
Can provide for scenic landscape
Tools to Assess Environmental
Impacts
What is DSS?
Decision support systems (DSS) consist of
Databases
Simulation models
Decision models
User interfaces
Information Technology
+
Decision Support System
that decision makers use to evaluate
the economic and environmental
impacts of competing alternatives.
To achieve sustainable economic,
social, and ecological systems…
Photo by NASA
Global Scale: UN, World Bank, World Court
Continental Scale: OAS, EEU, ADC, AU
Landscape Scale: Ecoregions, Watersheds
Photo by NASA
Photo by NASA
Regional: States, Counties
Local Scale: Cities, Communities, Districts
Sites Scale: Neighborhoods, Individual Sites
…preconditions of sustainable land and
resource use, economic viability, and
human well-being need to be defined at
all levels. Otherwise, achieving healthy
ecosystem services (and economic and
social systems) is dependent upon
individual ethics or values.
L-THIA
Long-Term Hydrologic Impact Assessment
Data requirements and components for analysis in L-THIA
Land use
Curve Number values
Soils
Location
Runoff depths
Daily precipitation
NPS pollutants
User supplied
information
Runoff volumes
Performed by L-THIA
https://engineering.purdue.edu/~lthia/
Use Basic
Spreadsheet
L-THIA
(Example)
Assignment
Use L-THIA (Basic Spreadsheet) to analyze idealize
representation of Baltimore City
• We will assume a site in the city is about 200 acres, (C soils)
• Scenario #1: Assume the land use of that site is all
Forest/Woods before it is developed.
• Scenario #2: The site is now developed, based on the current
land use, let’s assume of the total area is made up of:
• High Density Residential @ 65 %
• Commercial @ 35%
• Summarize in a table the outcomes of both scenarios and
determine the percent increase seen with the following:
Stormwater Volume, N, P, TSS, and Bacteria (remember units)
• Do some research on Stormwater BMPs and Low Impact
Development (LID). Provide a short write up (one page) on the
types of practices that could be used to reduce urban
stormwater impacts.
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