Klotz at TFMA Fall 2008

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Using GIS to Evaluate Benefits of Flood Reduction in Sewered Areas

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Using GIS to Evaluate Benefits of Flood Reduction in Sewered Areas : 

Using GIS to Evaluate Benefits of Flood Reduction in Sewered Areas November 5, 2008

Introductions : 

Introductions Fergus Graham, PE Storm Water Division, Klotz Associates, Inc., Houston, TX Background Originally from Glasgow, Scotland 10 years of experience in Water, Wastewater & Stormwater Post Graduate Degree in Information Technology Passionate about the application of GIS and technology in engineering

Glossary of Terms : 

Glossary of Terms Amur I am Amurny I am not Burn Stream Dreich Misty Weather Haud yer weesht Be quiet! Thon That One Youse Y’all

Project Description : 

Project Description Client City of Houston Project Name Phase I Design Services for: Shepherd Westmoreland Glen Oak Purpose Identify Problems & Develop Design Alternatives Estimate Costs & Recommend Preferred Alternative Prepare Preliminary Engineering Report

Project Location : 

Project Location

Design Goals : 

Design Goals Design Criteria City of Houston Design Manual (Chapter 9) City of Houston Technical Paper 100 City of Houston Technical Paper 101 Basic Design Steps Analyze Existing System for 2 Year event Define Existing Problems Design Proposed System for 2 Year Event Analyze Proposed System for 100 Year Event Design Overland Flow Control for 100 Year Event

Locating Problem Areas : 

Locating Problem Areas Flood Complaint Data Source: 311 Call Centre Data: Flood Complaint Location Flooding Type: Street Flooding Passable Impassable House Flooding No. of Instances

Complaint Map : 

Complaint Map

Basic Complaint Density Map : 

Basic Complaint Density Map

Weighting/Scoring Complaints : 

Weighting/Scoring Complaints Simple Additive Score All Points Score 1 for being a complaint +1 if includes Street Flooding +1 if impassable +1 if includes House Flooding Weighted Score All Points Score 1 x w1 for being a complaint +1 x w2 if includes Street Flooding +1 x w3 if includes impassable +1 x w4 if includes House Flooding w1 + w2 + w3 + w4 = 1

Weighted Complaint Density Map : 

Weighted Complaint Density Map

Basic Complaint Density Map : 

Basic Complaint Density Map

Weighted Complaint Density Map : 

Weighted Complaint Density Map

Overland Flow Analysis : 

Overland Flow Analysis City of Houston Methodology 4 Methods: Method 1 – Hydraulic Grade Line Analysis Method 2 – Conduit & Overland Flow Analysis Method 3 – Conduit & Overland Flow with Storage Method 4 – Dynamic Flow Routing Analysis

Method 1 : 

Method 1 Proposed Design Analyzed at the 100-Year Event HGL must be below Maximum Ponding Elevation MPE is the elevation of natural ground at the road ROW Also need to consider maximum allowable street ponding: 6” at high points 18” at low points 100-Year HGL negates overland storage. Results in over-sized conduits.

Method 2 : 

Method 2

Method 3 : 

Method 3

Method 4 : 

Method 4 Time consuming dynamic model 1D model not always adequate for overland flow Assumes that overland flow travels in the same general direction as sub-surface flow

GIS Overland Flow Analysis : 

GIS Overland Flow Analysis

GIS Overland Flow Analysis : 

GIS Overland Flow Analysis

GIS Overland Flow Analysis : 

GIS Overland Flow Analysis

GIS Overland Flow Analysis : 

GIS Overland Flow Analysis

GIS Overland Flow Analysis : 

GIS Overland Flow Analysis

GIS Overland Flow Analysis : 

GIS Overland Flow Analysis

GIS Overland Flow Analysis : 

GIS Overland Flow Analysis

GIS Overland Flow Analysis : 

GIS Overland Flow Analysis

GIS Overland Flow Analysis : 

GIS Overland Flow Analysis

GIS Overland Flow Analysis : 

GIS Overland Flow Analysis

GIS Overland Flow Analysis : 

GIS Overland Flow Analysis

Benefit Analysis : 

Benefit Analysis Benefits often difficult to assess Huge advantage in selecting a solution GIS allows us to: Visually identify and quantify benefits of various proposed solutions

Benefit Analysis : 

Benefit Analysis

Benefit Analysis : 

Benefit Analysis

Benefit Analysis : 

Benefit Analysis

Benefit Analysis : 

Benefit Analysis

Benefit Analysis : 

Benefit Analysis

Benefit Analysis : 

Benefit Analysis

Benefit Analysis : 

Benefit Analysis

Benefit Analysis : 

Benefit Analysis

Benefit Analysis : 

Benefit Analysis

Benefit Analysis : 

Benefit Analysis

Benefit Analysis : 

Benefit Analysis

Benefit Analysis : 

Benefit Analysis

Benefit Analysis : 

Benefit Analysis

Benefit Analysis : 

Benefit Analysis

Benefit Analysis : 

Benefit Analysis 2-yr Return Period Losses: Existing Condition = $458,157 Proposed Condition = $169,005 These losses can be accumulated over the lifetime of the proposed system and compared to other proposed conditions. Perhaps not an absolute benefit….but certainly relative

Thanks for your attention!Questions? : 

Thanks for your attention!Questions?

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