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GIS: A Living Document for Risk Assessment

Monica Mosure

July 23, 2012

Many water infrastructure systems in the United States are near the end of their intended designed lives, and municipalities around the nation are faced with finding funds to repair or replace these systems. As this is a costly endeavor, municipalities are developing future system repair and replacement plans with help from geographical information systems (GIS) and engineers. GIS-based data, expert engineering analysis, information gathering, and maintenance efforts from municipalities are making sure communities can make system repairs or upgrades at the right time and in the right place by properly allocating available funds.


The first step to future system repair and replacement planning is gathering information about existing water and sewer infrastructure. Municipalities obtain CCTV data, survey structures, and create GIS databases, but putting this existing GIS data to use and looking at the entire water infrastructure is like building a puzzle; one must first have all puzzle pieces and then each piece must be placed in the proper spot to complete the puzzle.

What Is GIS and Why Is It a Good Tool?

 GIS is an information system that integrates various types of data. It can be edited, analyzed, and shared. As a result, a GIS system is a living document, accessible by an entire staff, and continually updated as field information becomes available.


Municipalities can use a GIS system to capture an enormous amount of usable data, with benefits such as:

  • Automated cost estimating for planning purposes;
  • Geo-referenced data, such as complaints and sewer deficiency ratings, that help identify system problem areas;
  • Links to multiple datasets. For example, clicking on a manhole and having access to upstream and downstream sewer video as well as the manhole inspection report; and
  • Geo-referenced storage of all infrastructure information in one spot. Record plans, complaints, tap records, CCTV data, etc. are all stored within GIS and not in various places throughout an office.


GIS links existing information to future decision making. With access to all records at your fingertips, it is easier to determine what information you have and what information you still need to make a decision.

Risk Assessment

GIS also aids in developing a risk assessment plan. Risk assessment plans may measure or examine:

  • How much risk a municipality can assume regarding possible infrastructure failure;
  • How critical individual sewers and waterlines are;
  • The likelihood of infrastructure failure and the consequences if it does fail;
  • The importance of determining infrastructure thresholds and comparing it to the amount of risk a municipality is willing to assume; and
  • The point at which a sewer in fair condition but with a high consequence of failure should be repaired and how it compares to a damaged sewer with a low consequence of failure.


To supply communities with adequate, cost-efficient water and sewer services, municipalities must look at all of the pieces of the water and wastewater infrastructure puzzle. GIS makes finding each puzzle piece much easier, and the judgment of seasoned engineers helps place puzzle pieces into their correct positions