Hazard-Overlay

Documentation

The purpose of this project is to build an application that allows users to search for an address, and receive feedback on whether that address is impacted by certain geological hazards.

Define the Problem Statement

Is your housing susceptible to a natural hazards catastrophe?

The goal is to determine if an address in the 9-county Bay Area region is positively impacted by a geological hazard.

Project Management

• Task on Asana
• Data on Box

Data Sources

Zonal Geography:

1. Parcels 2010

Hazards include:

1. Alquist-Priolo Fault Zone
2. USGS Liquefaction Study Zone
3. Liquefaction Susceptibility Zones
4. Earthquake Induced Landslide Study Zones
5. Landslide Susceptibility Zones

Analysis Parameters

Dataset needs to be developed based on parcel features, with attributes indicating whether each parcel is in/out of a specific hazard.

Methodology applied to solve problem

GIS & Tabular Analysis
GIS Analysis:

1. Download Parcels 2010 & Hazard Layers
   Parcels 2010
   Alquist-Priolo Fault Zone
   USGS Liquefaction Study Zone
   Liquefaction Susceptibility Zones
   Earthquake Induced Landslide Study Zones
   Landslide Susceptibility Zones
2. Project all layers to consistent coordinate system
3. Query all five hazard layers for only relevant geographies
4. Export queried hazard layers features to project geodatabase
5. Union new hazard layers to create single data layer feature class
   a. cgs_liquefaction_study_areas (where zn_type=lq)
   b. cgs_landslide_study_areas (where zn_type=ls)
   c. usgs_liquefaction_susceptibility (where liq in (VH,H,M))
   d. alquist_priolo_zones (in/out) e. cgs_landslide susceptibilty (where GRIDCODE>=7)
6. Run identity operation on Parcels 2010 features and single layer hazard feature class; output to project geodatabase
7. Field Calculate new binary attribute denoting whether a parcel is either in/out of a specific hazard layer
8. Run dissolve function on Parcel_Id and sum the shape area for each associated hazard (5 fields in attribute table) for each record in order to determine shape area in/out of specific hazards in individual parcels

Tabular Analysis:
9. Resulting dissolve table used for Summary Statistics procedure based on in/out hazards for SUM of total area calculations
10. 3 Tables were then created for Fault zones, liquefaction (susceptibility and study areas), and landslide (susceptibility and study areas).
11. 3 Feature classes determined based on True denotations (dissolved on ‘True’) then associate with the 3 tables.
12. Projected feature classes were then unprojected to WGS84 for display processes for the Parcel Hazard application.

Expected Outcomes

Mapping application which determines the inclusion/exclusion of 5 particular natural hazard areas in the 9-county Bay Area region based on the location of a user's defined area of interest. A Parcel Hazard census of the 9-county Bay Area region as formatted like a 'look-up table'

Results

Hazard Mapping Application
Authoritative Parcel Hazard Look-up Table