To some extent, development projects are a product of their environment. Be they New Urbanist or conventional, all development projects are located within particular communities, on particular parcels of land. These locations can influence the design of projects with respect to flood hazard mitigation, whether (for example) because communities have certain characteristics that inspire them to place a high (or low) priority on natural hazard mitigation or because project sites are of a certain size that enables (or disallows) development to be located away from floodplain portions of the site. This section provides a descriptive summary of community and site characteristics for projects under study that are expected to help determine flood hazard mitigation features in the projects.
Community characteristics relate to community population, population growth, wealth, and flood history.
The Population variable measures the community population in the year that the project was approved. To aid interpretation, Population is measured in thousands.
The Growth variable measures the percentage change in community population between the year that the project was approved and 10 years previous.
The Wealth variable measures community median home value in 1999. To aid interpretation, Wealth is measured in thousands.
The Aid variable measures the extent of a community’s recent flood damages. Respondents were asked to indicate whether the community had been declared eligible for federal disaster aid as a result of flooding during the years 1995-2005. Responses are coded such that “1” equals “Yes” and “0” equals “No.”
Table 4.24 shows descriptive statistics for community characteristics.
Table 4.24 Descriptive Statistics for Community Characteristics
Population Percent Growth Percent Wealth Percent Aid Percent
0-150,000 23.5 (2.4)-13.0 23.5 0-100,000 28.8 Yes 34.8 150,001-450,000 25.0 13.1-20 23.6 100,001-130,000 21.2 No 65.2 450,001-800,000 23.6 20.1-37.0 26.4 130,001-180,000 24.2
800,000+ 27.9 37.1+ 26.5 180,001+ 25.8
Mean 716,760 Mean 25.8 Mean $155,327 Mean -- Standard
Deviation 1,256,210 Standard Deviation 18.6 Standard Deviation $77,453 Standard Deviation -- Minimum 19,610 Minimum (2.4) Minimum $61,600 Minimum -- Maximum 9,937,739 Maximum 93.4 Maximum $422,700 Maximum --
n 68 n 68 n 66 n 66
NUDs in the study tend to be located in relatively large communities, with the average community population in the year of project approval being over 716,000 and over three-fourths of the projects being in communities with populations greater than 150,000. However, some NUDs are located in small communities as well, as the populations range down to a low of just under 20,000. The relatively large average size of the communities in which NUDs are located should bode well for the strength of local development management programs in communities under study, as larger communities tend to have stronger programs (Hutton & Mileti et al., 1979; Burby & French, 1981; Burby & French, 1985; Godschalk et al., 1989).
In addition to locating in relatively large communities, the NUDs under study also tend to be located in rapidly expanding communities. The average community grew by over 25 percent in the ten year-period prior to the year construction began. For the sake of comparison, the population of the United States increased by nearly nine percent from 1980 to 1990, and by nearly 13 percent from 1990 to 2000 (U.S. Census). Two communities experienced negative population growth; all other communities experienced positive growth. While the range of growth rates from –2.4 to 93.4 percent is quite large, most of the
communities (nearly 74%) grew at 37% percent or less. These relatively rapid growth rates should foster development management program strength, as communities tend to respond to population growth by adopting stronger programs (Hutton & Mileti et al.,1979; Burby & French, 1981; Burby et al., 1988).
Just as the communities are relatively large and fast-growing, they are also relatively wealthy. The median median home value for the communities under study in 1999 of $130,750 is over 9 percent higher than the median home value for the United States of $119,600 for the same time period. That being said, NUDs are also located in relatively poor communities as well, with more than one-fourth of the projects being in communities with median home values of $100,000 or less. As with population and population growth, community wealth for the projects under study may provide a significant boost to
development management program strength. Since the communities tend to be relatively wealthy, they may experience a boost in development management strength that is associated with wealthier communities (Hutton & Mileti et al., 1979; Burby & French, 1981; Burby & French, 1985; Burby et al., 1988; Godschalk et al., 1989; Burby & Dalton, 1994).
Nearly two-thirds of the NUDs are located in communities that had not been declared eligible for disaster aid as a result of flooding at any point during the years 1995 to 2005. This has implications for flood hazard mitigation features in development projects, in that individuals are unlikely to prioritize flood hazard mitigation unless “flooding is manifestly severe or frequent, a major flood has recently occurred, or (he/she) has past experience at some other location to make (him/her) wary of the problem” (James, Laurent, & Hill, 1971, p. 8). The lack of recent experience with major flood damage in the majority of communities under study likely suggests that most of the communities did not view flood hazards as a realistic threat worthy of attention, and may not have prioritized directing development away from the floodplain, incorporating structural protection techniques, and preserving
environmentally sensitive areas (without the initiative of planners). Again, this highlights the potential importance of planners in promoting flood hazard mitigation, in that they may need to be proactive in educating their communities regarding the need to address natural hazards in project design.
Various characteristics of project sites can foster (or foil) flood hazard mitigation goals. This study focuses on five site characteristics: acreage, number of dwelling units, location, age, and floodplain exposure.
The Acres variable measures the size of the development project in acres. To aid interpretation, Acres is measured in hundreds.
The Units variable measures the size of the development project in dwelling units. To aid interpretation, Units is measured in hundreds.
The Location variable measures the location of the development project within the local community. Responses are coded such that “1” equals “greenfield” and “0” equals “infill or redevelopment.”
The Age variable measures the age of the project, calculated by subtracting the year in which project construction began from 2006.
The Exposure variable measures the percentage of the development site that is located inside the 100-year floodplain.
Table 4.25 shows descriptive statistics for site characteristics.
Table 4.25 Descriptive Statistics for Site Characteristics
Acres Percent Units Percent Location Percent Age Percent Exposure Percent
0-60.0 25.0 0-200 25.0 Greenfield 66.2 0-4 27.9 0-5.0 29.4 60.1-170.0 25.0 201-600 27.9 Infill/Redev. 33.8 5-6 28.0 5.1-13.0 22.1 170.1-500.0 25.0 601-1,300 22.1 7-9 23.5 13.1-32.0 22.8
500.1+ 25.0 1,301+ 25.0 10+ 20.6 32.1+ 25.7
Mean 538 Mean 1,340 Mean -- Mean 7 Mean 25.7
Standard Deviation 856 Standard Deviation 2,047 Standard Deviation -- Standard Deviation 4 Standard Deviation 30.0 Minimum 10.5 Minimum 10 Minimum -- Minimum 1 Minimum 0.20 Maximum 4,500.0 Maximum 12,000 Maximum -- Maximum 21 Maximum 100.0
n 68 n 68 n 68 n 68 n 68
As expected, NUDs tend to be relatively large, with the average project in the study containing 538 acres and 1,340 dwelling units. The NUDs range in size from 10.5 acres to 4,500 acres, with 10 to 12,000 dwelling units. The large number of acres in the average project should be conducive to flood hazard mitigation, in that projects should have enough room to work with in directing development away from the floodplain and preserving the most sensitive portions of the site. At the same time, the large number of dwelling units in the projects should have the opposite effect, in that accommodating more units may mean using more of the project footprint and encroaching upon more sensitive areas.
While it is true that the average project is relatively large, there is nevertheless a subset of smaller projects in the sample that do not fit the large-scale profile of the “typical”
New Urbanist project (Berke et al., 2003a, p. 8). There are 17 projects in the sample that are fairly small (i.e. 60 acres or less). While these projects may not appear to be New Urbanist because of their small size, 11 (or 65 percent) of the 17 “small” projects are either infill or redevelopment projects, compared to just 34 percent of the entire sample (with the remaining 66 percent of the entire sample being located in greenfield locations). Since it is reasonable to expect infill/redevelopment projects to be smaller on average than greenfield projects, this helps explain why some of the projects in the sample are smaller than what might be
expected for New Urbanist developments. That two-thirds of the projects are located in greenfield locations should mean both that these projects will have more flexibility in avoiding hazardous areas and in protecting environmentally sensitive areas, and (because they are undeveloped) that these projects will have more environmentally sensitive areas to protect in the first place (in comparison with infill/redevelopment projects).
As the name “New Urbanist” implies, the projects in the study are fairly new, with an average age of seven years (as of 2006). Nearly 80% of the projects are less than 10 years old. Two of the projects were built in the 1980s, when New Urbanist development was first starting to take off. Because the projects are new, they should be able to take advantage of the increasing awareness that has grown in recent decades regarding the importance of flood hazard mitigation in general, and of preserving environmentally sensitive areas in particular.
The influence of floodplain exposure on flood hazard mitigation should be two- pronged. On one hand, greater exposure to the floodplain should increase perceptions of risk on the part of developers, citizens, elected officials, and planners, and thus increase the priority that is placed on mitigation. On the other hand, greater exposure to the floodplain makes it more difficult to locate development outside the floodplain and to protect
environmentally sensitive areas within and around the floodplain. Since the average
exposure is relatively low at nearly 26 percent, it would seem that many projects should have enough flexibility to avoid floodplain portions of the site, if they place sufficient priority on flood hazard mitigation to do so.
Table 4.26 summarizes the community and project characteristic variables used in this study. The first column in the table lists the name of the variable; the second column provides a definition of the variable; the third column indicates the level of measurement of the variable; the fourth column identifies the source from which the variable was gathered.
Table 4.26 Community and Project Characteristic Variables
Variable Definition Measurement Source
Population Community population in year project was approved, in thousands Interval 2000 U.S. Census Growth Growth rate in community population between year project was approved and 10 years previous Interval 2000 U.S. Census Wealth Median home value in 1999, in thousands Interval 2000 U.S. Census Aid Whether the community had been declared eligible for federal disaster aid as a result of flooding from 1995-2005 Dichotomous (1=Yes, 0=No) Survey Acres Size of development site in acres, in hundreds Interval Survey
Units Number of dwelling units approved in development project, in hundreds Interval Survey
Location Location of development site within local community: greenfield, infill, or redevelopment
Dichotomous (1=greenfield, 0=infill or redevelopment
Survey
Age Age of project (2006 minus Year project construction began) Interval Survey Exposure The percentage of development site located inside the floodplain Interval Survey
4.5.5 Conclusions
Other things being equal, public safety goals are furthered when development is located outside the floodplain and environmentally sensitive areas in and around floodplains are protected. Together, these two strategies can significantly reduce both the incidence and severity of flooding and flood damages. Flood hazard mitigation is particularly important for NUDs, which locate more people on a given acreage than do conventional development projects. This chapter provided an overview of how well NUDs are avoiding the floodplain
and protecting environmentally sensitive areas, and looked at the current state of practice regarding various factors that are expected to be associated with flood hazard mitigation in the NUDs under study.
Overall, NUDs appear to be doing a decent job of keeping people out of the
floodplain, by locating residential and commercial land uses outside of the floodplain in the majority of projects. This may suggest that planners were successful in directing land uses away from the floodplain. However, there is still a sizeable number of projects with these land uses located inside the floodplain, and infrastructure is located inside the floodplain more often than not. There also may be room for improvement among NUDs with respect to structural protection and protecting environmentally sensitive areas.
Variation among NUDs with respect to observed flood hazard mitigation features raises questions regarding the factors that explain this variation. Chief among these factors in terms of importance to this study are planner characteristics. Planners display mostly strong commitment to hazard mitigation and environmental preservation, which means that associations between their commitments and flood hazard mitigation features in the projects can be expected to be positive. One potential limiting factor on planners’ ability to influence project design is the apparently low planning staff capacity available for site plan review. The average project had a small number of planners available, which might have limited their collective ability to identify and address natural hazard issues. On the other hand, given the average strength of planners’ commitment, it is possible that a small number of planners with strong commitment could make up for deficiencies in staff capacity. Along these same lines, planning agencies relied more heavily on the facilitative enforcement style than on the
systematic. This too may have helped counter deficient capacity by fostering successful negotiations with developers regarding the incorporation of flood hazard mitigation features.
In an effort to isolate the association of planner characteristics with flood hazard mitigation features from other factors that might also be associated with mitigation features, this study controls for the local government site plan review process and characteristics of communities and project sites. These factors are controlled for in the regression analyses conducted in Chapter 5. In general, the two components of site plan review (i.e.
development management programs and public participation) are found in this chapter to be somewhat lacking, as development management programs are somewhat weak and public participation levels are low. These findings are potentially worrisome from the standpoint of flood hazard mitigation, in that these two components of site plan review are each expected to have a positive influence.
The communities in which the NUDs are located tend to have large, rapidly growing, and wealthy populations, all of which should inspire mitigation efforts. For the most part, site characteristics in the projects also appear to be conducive to mitigation efforts. Projects generally appear to have sufficient portions of their footprint outside of the floodplain and sufficient acreage to allow for avoiding floodplain portions of the site, and projects are located in greenfield locations more often than not, where there is more flexibility to incorporate flood hazard mitigation features. The projects also tend to be relatively new, which should increase the likelihood that flood hazard mitigation features were incorporated. Lastly, the large number of dwelling units in the average project may have made it more difficult for project designers to avoid placing development in the floodplain and avoid damaging environmentally sensitive areas.