Introduction
North Natomas residential
and commercial building currently accounts for nearly half of the development
activity in the city of Sacramento. In the wake of Hurricane Katrina, hydrologists
began reevaluating the Sacramento region's flood control system. It was surmized
that should Sacramento experience a catastrophic flood scenario, that the largest
loss of life and property could occur in some of the newest residential developments
in the surrounding region. These developments in areas such as North Natomas
were built directly within known catchment basins. Areas used for irrigation
of agriculture and diversion of runoff during the rainy season as part of the
valley flood control system. Given this basic geographic reality, how is it
then that a century's worth of experience and planning was so blatantly ignored,
zoning ordinances, modified and approved, that could put such a large crossection
of the city's population at risk?
The attempt
here is to determine the point in time between the annexation of these land
areas, and construction of these developments, when the zoning ordinances may
have been modified to allow for residential habitation. Since legal documentation
containing the exact details of the land negotiations and land use/zoning discussions
pertaining to those parcels involved tend to be difficult to uncover due to
their sensitive legal nature, I've determined the best approach would be accomplished
through map overlays, and inspection of historical aerial photography to determine
visually the time period during which the changes in zoning occurred. After
targeting an actual date range, news articles can be consulted and other research
to get a general idea on what factors were involved in such a gross oversight
of public safety in the face of known geographic realities.
In order to simplify the data search, and making the general assumption that zoning changes occured in multiple regions of this type simultaneously, I've chosen a sample zipcode 95835, North Natomas that is fairly representative of the trend. I've also acquired FEMA Q3 flood data that illustrates the current FIRM status of the region. Also I've acquired map information regarding the future status of the fema designations of the region referring to Deaccreditation of the flood protection in the area surrounding the.
Background
In the mid 20th Century, the city of Sacramento made it's largest jump in land
size. Much of this acquired land fell within FEMA 80-100 year floodzones, even
within allowances made for the aging valley levee system. The central valley
levee system established during the mid 19th century was designed specifically
to take advantage of the areas geology in order to divert water from the more
vulnerable already populated city centers.
When the city of Sacramento annexed parcels from the Natomas land company in 1961, there were no immediate efforts made to zone the parcels for use other than agricultural. The land these parcels occupied what was already identified as a catchment basin and was part of the network of basins that form the Yolo bypass project. However, sometime between the mid 1980's and early 1990's speculative developers began seeking ways to expand the regions land use to include residential communities and related commercial development in these areas. Somehow the zoning was allowed to change to allow construction despite it's FEMA status.
Methods
Historical aerial photography was acquired via USGS earthexplorer from 1988. USGS DOQQs, from August 1998 were acquired from the USGS seamless server. A simplified city annexation map was acquired from SAMCC to illustrate the origins of the land annexation in the region of north natomas and it's general acquisition dated. USGS topographic quadrangle for Taylor Monument displaying geographic features.
Results
FEMA Data shows that the areas in question fall clearly into Zones A and Zone AR (as of December 2008). Areas determined to be within the 100 year flood zone and areas within the 100 to 200 year flood zones where actual Base flood elevations have been determined.
A 1988 aerial survey shows that the area appears to be agricultural and undisturbed. Row crops and irrigation ditches predominate which was the norm for the region for decades.
1998 USGS aerial DOQQs reveal what appears to be the start of residential construction. Grading paths and clearing of vegetation are noticable. I began by visiting the SAMCC (Sacramento Archives) in order to located zoning maps from the period. The archive search turned up negative and there were no clear publically available maps.
Analysis
Difficulties
Aerial photography, for the most part was easy to acquire, directly via online sources from the USGS. DOQQs from 1998 on especially. Historical aerial photographic mosaics, were available at much lower resolution at a regional level online and acquisition dates were more limited. High resolution photoplates were available through the Sacramento Archives (SAMCC) from 1991, but had to be manually tiled in order to provide an overview of the entire zipcode study area and scanning was not allowed.
Based upon the overlays of the aerials, one could conclude that the change in zoning designations must have occurred somewhere between 1989 and 1997. In order to narrow this time frame furrther, the time needed to enact and pass changes in zoning and legal processes need to be accounted for. However, this required much more extensive and painstaking research than time allowed which would require pouring over city council meeting notes and minutes and news articles. So my search was ljmited to news headlines and mainstream analysis, paired with available geographic data. The biggest diffculty encountered actually turned out to be the most revealing. The unexplained rift of public land use and zoning data for the area during the early and mid 1990's pointed to interference and chaos at the local government level and prompted me to turn to non-spatial data such as marketing proposals and other documents that revealed the plans in more detail, with assumption of a positive reception..
Conclusion
After an exhaustive search for maps and documents containing land use and zoning designations for the City of Sacramento prior to 1988 it became apparent that the loopholes in federal versus state laws regarding development in FEMA designated flood zones were clearly big enough to drive a truck through. The sheer absence of what are normally routinely released mapping documents on local planning during the time period leading up to the development of North Natomas points to the possibility that there was a lot of behind the scenes wheeling and dealing by some pretty powerful individuals. However, the suppression of local processes that could have prevented such development is clearly more the result of the regulatory chaos and the interplay of local, state, and federal bureaucracy, and outright ignorance in some cases, that opened the door for opportunity for those who would profit from such development..