EXAMINING URBAN IMPERVIOUS SURFACE DISTRIBUTION & ITS DYNAMIC CHANGE IN HANGZHOU

Longwei Li, Dengsheng Lu, & Wenhui Kuang

Presentation By: Josiah Parry

SOME NEW TERMS

➤ Impervious Surface Area (ISA)

➤ Man-made surfaces that water cannot penetrate

➤ Albedo

➤ proportion of light reflected from a surface

➤ Modified Normalized Difference Water Index (MNDWI)

➤ NDVI for water

➤ QuickBird

➤ Sub-meter accuracy imaging.

WHAT IS A DECISION TREE?

HANGZHOU

➤ 5.8 million people 1990

➤ 8.8 million people 2013

➤ GDP increased 315 Billion in 23 years

➤ Mountainous in the West

➤ STUDY GOAL:

➤ Track expansion of city center.

➤ Focus on directions and densification

METHODS

➤ Create fractional images (breaking down pixels into smaller segments) why???

➤ Calculate MNDWI

➤ Use decision tree classification to produce High Albedo (bright) & Low Albedo images

➤ Produces bright, dark, & confused ISA

➤ Cluster confused ISA and manually determine if ISA

➤ Compare ISA from different time stamps

➤ Preform accuracy assessment

METHODS CONT.

➤ Calculate density (D = ISA / A) for each fraction

➤ Calculate difference in ISA

➤ Diff = ISA(t2) - ISA(t1) / t2 - t1

➤ Two types of increased ISA

➤ Densification and Expansion

➤ Calculate ISA amounts for each Elevation and Slope

➤ Why would they do this?

RESULTS

SEE ANY PATTERNS?

QUICK EXAMPLE OF BAD VISUALIZATION

SLOPE ISA INTERACTION

SEE ANY PATTERNS?

SLOPE ISA INTERACTION