CaveBasinCV Scenario Comparison CaveBasinCV Scenario Comparison



Report Contents
Analysis Description
Scenarios in this Report
Report Summary
Scenario Maps
Photos and Other Graphics 		Charts
Assumptions
Indicator Values
Alerts


click icon to open or close this sectionAnalysis Description

This analysis estimates the impervious surface for an area southeast of Milton, Delaware.  The project is in the Broadkill watershed in Sussex County.  Impervious surface duplicates portions of the modeling in the following report.   

Southern New Castle County Priority Watershed Strategy

A Watershed-Based Approach to Protect Natural Resources in the MOT Planning District of Southern New Castle County, Delaware

Final Report July 4, 2006 

http://www.wr.udel.edu/publications/index.html 

Quoting this report on page 10:

"Research completed over the last 20 years shows an increasingly significant correlation between percent impervious surface coverage in a watershed and stream water quality. Streams with increasing imperviousness exhibit many of the following conditions: increased flood peaks, lower stream flow during dry weather periods, degradation in stream habitat structure, increased stream bank and channel erosion, fragmentation of riparian forest corridor, and a decline in fish habitat quality (Pelley, 1997)." 

The land use based impervious surface analysis uses the State's LU92 and LU02 layers.  The feature analysis uses building footprints and roads.  (Note that the structures based analysis for 1992 would decrease if the date of construction were known, allowing elimination of building constructed after 1992.)    The 2010 scenarios include building a PLUS project (2006-10-03) into Milton on Cave Neck for 370 units on 71 acres.  The build-out for 2002 uses current zoning; for 2010 the agricultural areas use 10 acre lots (not .5 acres); and the 1992 assumes no new construction.  The build-out dates have no meaning, they just were convenient place holders for each scenario.  

 

Impervious surfaces are artificial structures, such as pavements and building roofs, which seal the soil surface, eliminating rainwater infiltration and natural groundwater recharge.

 
click icon to open or close this sectionScenarios in this Report

Report Left-Side
Scenario:

Report Right-Side
Scenario:
click icon to open or close this sectionReport Summary
Report Date/Time:  Sunday, February 25, 2007 11:08 AM

Impervious surface modeling by Donley Associates Inc.  

click icon to open or close this sectionScenario Maps

Left-Side Map:

Right-Side Map:
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click icon to open or close this sectionGraphics
Photos and Other Graphics
Sussex County Zoning. Google Earth aerial. 
Sussex County Zoning. Google Earth aerial.
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click icon to open or close this sectionIndicator Charts
1992 2002 2010 All Scenarios 1992 2002 2010
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click icon to open or close this sectionAssumptions
click icon to open or close this sectionAssumptions
Assumption Default 1992 2002 2010 1992 2002 2010 Units
Driveway Width 12 12 12 12 12 12 12 feet
Footprint Ancillary Impervious 1.5 1.50 1.50 1.50 1.50 1.50 1.50
Footprint Impervious 1.5 1.50 1.50 1.50 1.50 1.50 1.50
Max Driveway Paved 100 100 100 100 100 100 100 linear feet
click icon to open or close this sectionAssumption Descriptions
Assumption Description
Driveway Width <none>
Footprint Ancillary Impervious <none>
Footprint Impervious <none>
Max Driveway Paved <none>


click icon to open or close this sectionIndicators
click icon to open or close this sectionIndicators
Indicator 1992 2002 2010 1992 2002 2010 Units
Build-Out Numeric Dwelling Units 0.00 3,375.00 1,104.00 0.00 3,375.00 1,104.00 DU
BuildoutImp 5 54 17 5 54 17 feet
Feature Impervious 5.22 5.22 9.58 5.22 5.22 9.58 feet
LandUseImp 5.63 6.21 9.04 5.63 6.21 9.04 acres
click icon to open or close this sectionIndicator Descriptions
Indicator Description
Build-Out Numeric Dwelling Units Total number of dwelling units resulting from numeric build-out.
BuildoutImp Impervious surface calculation based on existing features and build-out. The 2002 figure uses the current zoning densities in Sussex County. The 2010 figure reduces the Agricultural density from a minimum lot size of a half acre to 10 acre. The 1992 impervious surface assumes no new development approvals.
Feature Impervious Impervious surface analysis based on digitized structures and roads.
LandUseImp Estimated impervious surface based on the land use layers (LU02 and LU 92).


click icon to open or close this sectionAlerts
Alerts 1992 2002 2010 1992 2002 2010
Attribute Alerts
Not All Buildings Placed
Not all of the potential buildings could be placed by spatial build-out.		0 records6 of 15 records0 records0 records6 of 15 records0 records
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