A COMPARISON OF FLOODING IN MICHIGAN ANDONTARIO: 'SOFT' DATA TO SUPPORT 'SOFT'WATER

MANAGEMENT APPROACHESSubmitted July 1996; accepted December 1996

Written comments on this paper will be accepted until December 1997

Douglas W. Brownl, Syed M.A. Moin1, Michelle L. Nicolson2

AbstractThe months of August and September 1986 produced four unique and extreme

rainfall events. Average values of precipitation for each event ranged between 50

and 180 mm for 24-hour and 48-hour periods respectively. The heavy precipitation

caused extensive flooding and damage in Michigan ($500 million US for the two

months), while little flooding or damage occurred in Ontario (under $500, 000). The

paper examines the soils, watersheds and flood management practices in Michigan

and Ontario to determine if they are comparable. Next, the climatological events are

described for the months of August and September. Analysis of each event for indi-

vidual watersheds is pedormed using observed hydrograph characteristics such as

volumes of runoff, flood yields, flood hydrographs and stream discharges. Flood

damages are then tabulated and compared for each site, and a documentation of

each respective site's floodplain management policies is provided. lt was concluded

that although Michigan sustained extreme damages and suffered loss of life,

Ontario had higher flood yields for September. Even though Ontario's yields were

higher, the province recorded only a small fraction of Michigan's damages. The

study also identifies the need for establishing procedures for quantifying benefits

that are accrued from implementing sound floodplain management, and in reducing

otherwise intangible floodplain mapping benefits.

R6sum6Les mois d'ao0t et de septembre 1986 furent t6moins de quatre 6v6nementsuniques et extremes en fait de pr6cipitations. Les valeurs moyennes despr6cipitations pour chaque 6v6nement varient entre 50 mm et 180 mm pour des

o6riodes de 24 heures et de 48 heures respectivement. Les fortes pr6cipitations

causdrent des inondations et des dommages consid6rables au Michigan (500

millions de dollars US pour les deux mois), alors que peu d'inondations ou de

dommages se produisirent en Ontario (moins de 500 000 $). Le document examine

les sols, les bassins hydrographiques et les pratiques de gestion des inondations au

Michigan et en ontario pour d6terminer s'ils sont compatibles. Ensuite, les

6v6nements climatologiques sont d6crits pour les mois d'ao0t et de septembre. Une

analyse de chaque 6v6nement pour les bassins hydrographiques individuels est

men6e d l'aide de caract6ristiques hydrographiques observ6es comme les volumes

de ruissellement, les produits de l'inondation, les hydrogrammes de l'inondation et

les d6bits de cours d'eau. Les dommages caus6s par l'inondation sont ensuite mis

sous forme de tableaux et compar6s pour chaque site et une documentation est

1. Water lssues Division, Environmental Services Branch (Ontario Region), Environment Canada,

Burlington, ON2. Environmental Consultant, Mississauga, ON

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fournie d l'egard des politiques de gestion des zones inondables pour chaque siterespectif. ll fut conclu que mome si les inondations du Michigan avaient caus6 desd6gats extremes et fait des victimes, l'ontario avait connu des d6bits d'inondationplus 6lev6s pour septembre. Malgr6 cela, l'ontario n'a subi qu'une infime fractiondes degats que le Michigan a connus. L'6tude r6vdle 6galement le besoin d'6tablirune proc6dure pour quantifier les avantages qui d6coulent de la mise en oeuvre desaines pratiques de gestion des zones inondables et de la r6duction des avantagesautrement intangibles de la cadographie des zones inondables.

IntroductionOver the past twenty years two trendshave become evident in flood plain man-agement in Canada. First there has beena movement away from an almost exclu-sive reliance on structural measures(dykes, dams, and channelization) towardmore emphasis on non-structural 'soft' ap-proaches, such as land use and buildingrestrictions in hazard areas, financial disin-centives to developing hazard areas(Bruce, 1976). The other trend has been agreater interest on the part of governmentagencies in looking at the costs and bene-fits of water management projects (PublicAccounts Committee,'1979; TreasuryBoard Secretariat, 1 976).

Clear procedures have been developedfor determining the benefits and costs ofstructural flood control benefits (Paragon,1984; Book and Princic, 1975). These pro-cedures generally relate capital measuresfor reducing damages at specific sites, andthe determination of a frequency distributionfor flood levels for the areas being protect-ed; and the development of stage-damagecurves based either on past damages orthe use of existing damage functions for dif-ferent types and values of structures. Thesetwo functions are then combined to derivean average annual damage, and a presentvalue of damages is determined using sev-eral discount rates. The costs of structuralflood control measures are the estimatedcapital costs plus the present value of antic-ipated annual maintenance costs. The netbenefits of a capital project are the presentvalue of flood damages prevented, less thepresent value of the capital cost. Theamount of damage prevented is generallybased on existing flood plain development,

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as most federal and provincial agencies donot accept the inclusion of additional bene-fits that might accrue from additional devel-opment in the protected area (EnvironmentCanada,1979).

It has been much more difficult to de-termine the costs and benefits of non-struc-tural approaches. Several studies havebeen conducted at specific sites that weremapped under the FDR Programme(Millerd et al., 1991; Weiss, 1987) The gen-eral approach in these studies has been toestimate the amount of flood vulnerable de-velopment that had been prevented inareas mapped under the Flood DamageReduction Programme for a specific watercourse and then look at the damages thatwould be prevented. These estimates ofdamages prevented were then comparedto the costs of mapping and the administra-tive costs of implementing and managingflood plain development restrictions. Theestimate of damages prevented can bebased on some actual flood events, or anaverage annual damage determined fromf lood level f requency relationships.

The benefits derived in these studieshave been uncertain as they are based onknown short-term development plans, oron guesses or predictions of what devel-opment might have occurred in flood vul-nerable areas in the absence of flood riskmapping and flood plain controls.

The two studies noted above showedquantifiable, but somewhat modest, netbenefits from the application of mappingand flood plain development restrictions toseveral specific areas. The short-termbenefits found in these small site studiesmay not fairly represent the full potential ofthe non-structural approach, as land use

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planning and development restrictions havea slow but progressive impact on flood vul-nerability. A different picture may emerge if

we could evaluate the damages prevented

through the application of flood plain devel-opment restrictions over a longer period of

time and over a wider area.The intensive rainstorms that tracked

across Michigan and southern Ontario inAugust-September of 1986 provide a good

opportunity to compare damages in a

province and adjacent state with very dif-ferent approaches to flood plain manage-ment. Ontario has had an ongoingprogramme of flood plain managementsince the mid 1950s following the disas-trous flooding from Hurricane Hazel. Theprogramme has been province-wide andsupported by provincial legislation(Conservation Authorities Act, PlanningAct) and local implementation by conserva-tion authorities and municipalities. TheOntario programme was broadened in

1978 to include the padicipation of the fed-

eral government through the Canada-Ontario Flood Damage ReductionProgramme. Therefore the damages thatoccurred from the 1986 floods were affect-

ed by 30 years of legislative floodplain man-

agement by different levels of government.In Michigan, the aPProach to flood

plain management has been different, and

could be characterized as being more re-

active and less comprehensive in the ap-

olication of land use and developmentcontrols. A major part of this approach has

been reactive through participation in the

U.S. National Flood lnsurance Program(NFIP). State regulatory controls on floodplain developrnent have not been uniform-

ly applied. The focus of flood plain regula-

tion has been to flood proof or elevate new

development rather than keeping develop-ment out of the floodPlain.

Since the areas affected by the 1986

floods appeared to be comparable in cedain

$$ r,nf;-Ei!

L6gend

W Lake Humn Sralnage Easin

g Laks Mishige* Drainage Basin g666gp

n Leke Eiie DIaina$e &a3in

ffi Lake $up€ri0r 0r6inags B6sit1

n Leke Onlario Bralnage Bacin

U$lcamda Boadet

r eftles/Trynsl$llchigan lffakrshsds sg s-

Figure 1: Location Map Showing the Great Lakes in North American Context and

Michigan and Ontario Watersheds

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respects (population, urban development,physiography, rainfall and runoff volumesand frequencies), a comparison of actualflood damages in these two jurisdictionsappeared to be an excellent opportunity tocompare two long-term approaches toflood plain management. In essence,Michigan would serve as a control andOntario as the example of comprehensiveflood plain management applied over alonger-term and to a large area.

Objectives of StudyThe large disparity in damages betweenthe two jurisdictions warranted f urtheranalysis. This study compares the phsiog-raphy, land-use, floodplain developmentand floodplain policies, rainfall and runoffto indicate what factors were most imoor-tant in explaining the large differences inoamages.

Land Use, Climate andHydrologyTo properly compare the floodplain man-agement policies, it is necessary to deter-mine if the two study areas are similar.Four variables are chosen to determinewhether a comparison is justified: landuse, climate, soil and hydrology, as below.

Land UseThe promise of agricultural land drewmany immigrants to the Great Lakes basinin the 19th century. By the mid-1800s,most of the region where farming was pos-sible was settled: 400,000 people inMichigan and 500,000 in what was knownas Upper Canada. As population grew,dairying and meat production for local con-sumption began to dominate agriculture,and speciality crops such as fruits, vegeta-bles, and tobacco became increasingly im-portant. The rapid large-scale clearing ofthe land changed the lower basin'secosystem. Greater surface runoff led toincreased seasonal fluctuation in waterlevels and the creation of more flood-prone lands along waterways. Nearly allthe settlements that grew into cities in the

128

region were established on the waterwaysthat transpoded people, raw materials andgoods, eg. Detroit in Michigan andHamilton in Ontario.

In the study area in Michigan, the mostprevalent land use today is intensive gen-eral farming, with some specialized fieldcrops such as fruits and tobacco. Thelargest urban centre is the region ofMetropolitan Detroit with a population ofapproximately seven million; there areseven cities with populations of 100,000 -200,000. The study area in Ontario ismore dependent upon specialized dairyingas well as specialized field crops, with in-tensive general farming in the more south-western regions. There are fewer urbancentres of 100,000 - 200,000 than inMichigan. The largest urban centre inOntario is the Toronto-Hamilton corridorwith approximately five million people.Overall, for the purposes of this paper,land use in the two studv areas is similar.

SoilThe physiography and surficial depositsof both the Ontario and Michigan water-sheds are the result of the last ohase ofthe Wisconsin glaciation. The soils con-sist mainly of Podzolics and Gleysolics(Foth and Schafer, 1980). The fine-tex-tured and well-drained Podzolic soilsoccur in the heartland of southwesternand southcentral Ontario, and in thenorthern portion of Michigan. AlthoughPodzolics are the dominant soils in somecounties in Ontario, Gleysolics can alsooccur. Podzolic soils have a lower naturalfertility than do the Gleysolics, are high inwater infiltration, but low in water reten-tion for the soil as a whole. In the moregently rolling areas, the soils are moresusceptible to erosion, but can support avariety of agricultural activities such aslivestock, cereal grains, hay and pasture,and cash crops.

Gleysolic soils occur extensively in thecentral and southeastern oortion ofMichigan and in some counties in Ontario.Gleysolic soils are poorly drained because

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normal development has been restricted bynaturally high water tables. They are highin organic matter, and consist of at least4Q"/" clay. Consequently, tile drains andopen ditches are used extensively to allevi-ate flooding and to improve soil fertility.

The soils of the study watersheds inOntario and Michigan have a mixture ofwell-drained Podzolics and poorly drainedGleysolics. The 14 watersheds are distrib-uted throughout southwestern Ontario(drainage areas between 303 km2 to 6770km') and portions of Michigan (drainageareas 1764 km2 and 12691 km2) and in-clude both types of soils. Each region hasdeveloped successful soil drainage net-works, so neither region has the advan-tage of greater soil permeability.

ClimateDuring the summer and early fall of 1986,there were four unioue rainfall events thatoccurred in both Ontario and Michigan,each lasting trom 24 hours to almost 72hours. The most intense precipitation oc-curred on August 15, August 26,September 10-1 1 , and September 29.

In 1986, rainfall was above averagethroughout the first half of the year inOntario. The month of August continuedthe trend of above-average precipitationfrom southern Lake Huron through LakeSimcoe, Toronto, and eastward to Ottawa.At Toronto, the rainfall for the month was2550/" above normal (DOE, 1986). For themajority of the gauges in Michigan, Augustrainfalls were generally close to average,

Figure 2: Land Use in Michigan and Ontario Watersheds. (Dark regions show heavyagriculture, lighter shade in Michigan is light agriculture, lighter shade onOntario is dairy farming. From The Great Lakes - An environmental Atlasand Resource Book, 1988.)

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indicating dryer conditions before and afterthe rainfall events.

Showers were almost a daily occur-rence in Ontario and Michigan f romAugust to early October. Rainstorms typi-cally formed in large clusters and often in-tensified late at night. The Augustprecipitation pattern was largely defined bythe heavy rainfalls of August 15 andAugust 26 - 27. Both events recordedmaxima of 60 - 90 mm of precipitationnorth of Toronto, and several monthly rain-fall records were set in and aroundToronto. On August 15, between 40 - 80mm of rain fell on densely-populated areasof southern Ontario in 90 minutes. InMichigan for this date, precipitation wasnot as heavy; only four stations recordedmore than 25 mm of rain with the majorityof stations receiving only 10 mm.

On August 26, more widespread pre-cipitation occurred, with a large poftion ofcentral Michigan inundated with 30 - 50

mm. The area of heaviest concentrationwas Detroit with 73.4 mm of rain. InOntario, the highest recorded precipitationwas at Elmira with 92.2 mm. At most sites,the rainfall occurred within a span of five toseven hours during the evening of the26th. Both August events produced morerainfall in southwestern Ontario than in

Michigan, with some regions in Michiganreceiving below-normal amounts. OnAugust 15, Ontario received twice theamount of precipitation than Michigan, andon August 26, Ontario recorded approxi-mately three times that of Michigan.

The highest amount of precipitationduring the study period occurred onSeotember 10 - 1 1 . Two thirds of southernOntario received at least 50 mm of precipi-

tation from this two-day event, Two-day to-tals reached 177 mm at Exeter (DOE,1994). The storm area in Michigan mea-sured approximately 290 km in an east-west direction and 100 km north-south.

Figure 3: Precipitation in the Great Lakes Basin, August 15, 1986

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Within this area, rainfall varied from 200 -300 mm. Such precipitation rates were notseen in Ontario, although many precipita-tion records were set.

The final rainfall event for the study pe-riod occurred on September 29. The pre-cioitation was clustered in westernMichigan with values ranging from 20 - 40mm, with a small pocket of greater than 50mm. The heaviest precipitation fell in asmall area near London (89.1 mm) with aheavy band of 50 - 70 mm occurring fromToronto to Blyth. In comparison, areasnear Windsor received very little precipita-tion. Amounts were not as substantial asfor the three previous rainfall events, but alarge area east of Lake Huron receivedmore than 25 mm. The last rainfall eventbrought similar amounts of precipitation toboth regions, but the distribution patternwas erratic. There were isolated oocketsof heavy rain in both Ontario andMichigan. As a summary for the month,

rainfall totals exceeded 480 mm at severalMichigan recording stations, with a meanrainfall for the month exceeding 355 mmfor central Michigan.

HydrologyA total of fourteen watersheds were select-ed in Ontario and Michigan to examine thehydrologic and hydraulic impacts of the fourrainfall events. The forms of analysis usedwere flood yields and volumes of runoff.The drainage areas in Ontario were theMaitland, Grand, North Thames, Saugeen,Sydenham, Don and Humber rivers; inMichigan, the Pere Marquette, Muskegon,Grand, Tittabawassee, Shiawassee, Flint,and Cass rivers. These watersheds werechosen after the approximate extent of rain-fall in August and September was mapped.

Flood yields are volumetric measure-ments that permit streams of differingdrainage areas to be compared on thebasis of flows. The equation

Figure 6: Precipitation in the Great Lakes Basin, September 29, 1986

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Q"= Q/A (1)

was used, where:Q"= Flood Yield (m3/s/km2),Q = Maximum lnstantaneous

Discharge (m3/s), andA = Drainage Area (km').

The maximum instantaneous dis-charge (Q) in each of the 14 watershedareas (A) was plotted against the respec-tive drainage areas (A). The plotted resultsnormalizes the flows on a oer unit basisand allows for the comparison of flows towatersheds of varying sizes. When thelogarithm of the flood yield (Qs) is plottedagainst the logarithm of the drainage area,a linear relationship is obtained.

Using the calculated maximum instan-taneous discharge, the flood yields inAugust in Ontario are higher than inMichigan with calculated slopes of -0.37and -0.50 (Figure 7). These results show

typical watershed responses as both pre-

cipitation events produced higher amountsof precipitation in Ontario than in Michigan.

For September, the flood yields wereplotted against drainage areas, and slopeswere calculated at -0,23 and -0.29 forOntario and Michigan respectively (Figure8). Again, the slope of the regression line

is less steep in Ontario although inSeptember, more rain was recorded in

Michigan and more flow records were set.

ln summary, streams had a higher maxi-mum instantaneous discharge in Ontarioper drainage area.

A comoarison of volumetric runoff in

the 14 watersheds was also made to per-

mit a comoarison of runoff from watershedto watershed, acknowledging that thedrainage basins differed in area. To calcu-late the volume of runoff, the trapezoidalrule was used. The first rainfall event in

August did not produce significant volumes

Flood YieldMlchigau - August / September 1986

1.000

N-\()O

oF

fT

o.100

o.o10

0.ool10000

+ SeptemberObserved + SeptemberRegression

-'-+<--Augustobserved +AuguslRegression

1000

Figure 7: Flood Yields for the Michigan Watersheds, AugusUSeptember 1986

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of runoff. The highest runoff of 21 .54 mmwas calculated in one of the Toronto tribu-tary watersheds and the lowest volume ofrunoff calculated was a tributary in theeastern region of Michigan. With the out-liers removed, the mean volume of runoff inOntario watersheds was only 3.09 mm andthe volume was comparable in Michiganwith 4.14 mm.

The rainfall on August 26 producedmore runoff in Michigan than the previousmonth, but in Ontario the mean was al-most 10 mm higher than the mean for theAugust 15 event at 12.60 mm. A tributaryin the Toronto region recorded the high-est runoff at 41 .O7 mm and the lowestrecorded was the tributary in Michiganmentioned above at 1.18 mm. The vol-ume of runoff was fairly uniform inMichigan and ranged from 1.18 mm to8.34 mm. In Ontario the volumes weremore diversified and ranged trom 2.4Qmm to 41 .07 mm.

For the September 10 - 11 event, ahigher total of precipitation was recorded

in Michigan than in Ontario. With the out-liers removed the mean volume of runoffin Ontario was 54.74 mm, almost 10 mmmore than the mean for Michigan (45.09mm). Most watersheds in the area affect-ed by heavy rainfall had at least 40 - 60mm of runoff . The highest calculatedrunoff volume in Ontario was 71 .10 mm.

The final event in September againproduced large volumes of runoff , al-though not as much precipitation wasrecorded. Presumably, this was becausethe soils were saturated from the previ-ous rains. With the outliers removed,Ontario had, for the third time, a highervolume of runoff at 53.87 mm, comparedto Michigan's 47.88 mm. The volumes inOntario ranged 'from 29 mm to 74.40 mm.

With the exceotion of the event ofAugust 15, the seven Ontario watershedsproduced larger mean volumes of runoff,but the mean values were never greaterthan 10 mm. Although Michigan sustainedlarger amounts of precipitation, Ontario'swatersheds oroduced more runoff.

Flood YieldOnlqrio - I

.q' 1.000E

bc)a+ 0.100-Ic)

- 0.010o

LL

+ S€pf€mb€rObsrued + SeptembsrFegr€ssion

---I- Augusl ObFrusd * August Regre$ion

Figure 8: Flood Yields for the Ontario Watersheds, AugusUSeptember 1986

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Regulations and FloodplainManagementFrom the previous section, it was evidentthat the climatological and watershed re-sponses of Michigan and Ontario basinswere similar. The flood damages in thetwo jurisdictions were, however, substan-tially different. Some of the anomalies inthe difference of flood damages can betraced to the age of settlement in the wa-tershed (and by extension, settlement inthe floodplain), density of settlement,floodplain management practice, etc. Inthis section, two different floodplain man-agement models are examined: theOntario floodplain regulations and thefloodplain management styles in Michigan.

OntarioIn Ontario, the development of floodplainregulations can be traced to the early1940s. In this period, floodplain regula-tions were closely tied to the conservationmovement for soil erosion from agriculturalwatersheds. For management purposes,Conservation Authorities like the GrandRiver Conservation Authority were estab-lished, based on watershed boundaries asthe administration unit and restricted to theurban areas in southern Ontario. Thefloodplain regulations followed the disasterof Hurricane Hazel in 1954. The mandatefor floodplain management was enhancedin the late 1950s.

The floodplain management approachtaken by Ontario Conservation Authoritieswas two pronged: damage preventionand flood protection. Flood damage pre-vention is attained by first identifyingflood risk areas, and then regulating andcontrolling the development in suchareas. Flood protection is achieved byconstruction of multipurpose reservoirs,dams, channelization, etc.

ln Ontario, floodplains are regulatedprimarily under two Provincial Acts. ThePlanning Act provides the broad guidelinesfor developing planning documents, land-use planning and sustainability of varioususes. The Conservation Authorities Act

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deals primarily with floodplain manage-ment asoects. This Act lies below thePlanning Act, but covers the majority ofurban and potential growth centres in theprovince. The Conservation Authorities Actspells out the mandate of an Authority in

areas of compliance with land use, whichis compatible with the floodplain.Generally, Conservation Authorities regu-late any fill or construction in a corridorthat envelops the floodplain. The delin-eation of such regulatory lines are usuallybased on slope stability criteria, and otherphysical separators like lot and concessionlines, road alignment, etc.

The criteria used for identifying the lim-

its of flood risk area in Southern Ontarioare based on the maximum of HurricaneHazel-generated flood flow, the 1-in-100year flood flow or an observed historicalflood. No return period is ascribed toHurricane Hazel-generated flows, but forthe size of watersheds in the Grand Riverwatershed, for example, these may rangefrom 200 to 300-year return period flood.

The Grand River ConservationAuthority followed this approach in the late

1950s and 1960s. The first generationflood risk maps were produced to form thebasis of planning, guiding flood-prone de-velopment away from flood risk areas andpermitting floodplain compatible land use.

ln situations where development existedwithin an identified floodplain, flood protec-

tion measures were implemented whereeconomically feasible. Several flood con-trol structures were constructed using thisapproach. The 1970s saw a gradual shiftto damage prevention approach. When the1986 flood event occurred, flood plainmanagement had been in effect for over30 years.

On March 31, 1978, Canada andOntario signed the Flood DamageReduction Program Agreement. To lessenthe amount of flood damages, the program

discourages f lood-vulnerable developmentwithin identified floodplains. The two mainobjectives of the program were to; identifyflood risk areas, reduce flood damage and

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risk to life by regulating new developmentin these areas; and to find feasible ways toreduce future flood damage to existing de-velooment.

Maps are produced displaying the areaof flood risk for each watercourse identi-fied in the program. The flood risk area inOntario is the area which would be inun-dated by the Regulatory Flood, which isthe 1-in-100 year flood, or the regionalflood, whichever is greater. Within theflood risk area, certain government poli-cies are applied. Communities may haveflood risk areas that are considered to be aone-zone or two-zone flood risk area. (Atwo-zone area indicates the two separateareas of a floodway and a flood fringe, thearea where water tends to be shallowerand slower).

In a one-zone flood risk area, the fol-lowing policies are in effect:

. no future federal or provincial govern-ment buildings or structures that arevulnerable to flood damage will beplaced in the flood risk area,

. funds from government sources, suchas the Canada Mofigage and HousingCorporation will no longer be availablefor new buildings or structures placedin the flood risk area and subiect toflood damage,

. any buildings or structures vulnerableto flood damage placed in the flood riskarea after designation will not be eligi-ble for flood disaster assistance, and

o the two governments will encouragelocal municipalities to adopt OfficialPlan Policies and zoning restrictionson development in the flood risk area.

Where a two-zone approach is used,the above policies apply to the floodwayzone only. Development is allowed withinthe flood fringe providing it is adequatelyprotected from flood damage. However,any development that existed prior to thedesignation of the flood risk areas is eligiblefor government flood disaster assistance.

The designation of flood risk areas isnot intended to stop all use in the flood-plain, but land use such as greenbelts,parks and agriculture lowers the damagepotential and does not aggravate floodconditions. Flooding in the river valleyswas extensive in the Toronto area inAugust 1986, but propeny damages werenegligible since few buildings are permit-ted in the floodplain.

MichiganFloodplain regulations and flood insuranceare the two non-structural approaches foradjusting to flood hazard in Michigan. Toimplement these approaches, land useregulations, development policies, flood-proofing, disaster preparedness and re-sponse plans, f lood forecasting andwarning systems are used (FEMA,1986).

The Floodplain Regulatory Authority,which came into effect in 1968, falls underthe broad heading of land use regulations.The Authority defines floodplains based onthe Regulatory Flood which in Michigan isthe 1-in-100 year flood. Development ofany residential properties is prohibited inthe floodway but other development is al-lowed if it can be oroved that the newstructure would not increase flood eleva-tions or divefi flows. However, new build-ings can rarely meet these criteria.

The Subdivision Control Act guidesthe division of large parcels of land intosmaller lots for the purpose of sale orbuilding. The 1-in-100 year floodplainmust be mapped, basements are not al-lowed in fill areas, and no openings lowerthan the flood elevations are permitted.Two similar Acts, the Condominium Actand the Mobile Homes Commission Actalso restrict residential develooment infloodplains. The only stipulation to theCondominium Act is that the lowest floorof the structure must be built above the 1-in-100 year floodline. The Mobile HomesCommission Act allows for floodproofing,but no mobile homes can be located in afloodway. lf pads are used, they must beabove the Regulatory Flood level.

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The National Flood Insurance Program(NFIP) promotes a variety of non-structuralmeans for flood and erosion damage re-duction. While not a protective measure,flood insurance does require adoption ofcertain floodplain management measuresand serves to mitigate the effects of flood-ing on individual policyholders. FEMA,which administers the NFIP, conductsFlood lnsurance Studies (FlS) to developflood risk data for communities which havechosen to participate in the program(Kehoe, 1989). In Michigan, approximately600 of the 1776 communities participate inthe NFIP. Using the results of an FlS,FEMA prepares a Flood Insurance RateMap (FIRM) deplcting Special FtoodHazard Areas within the community. TheFIRMs however, do not contain any floodelevation information that would be helofulto a community for floodplain manage-ment. Special Flood Hazard Areas areareas whlch would be subject to floodingin the occurrence of a 10O-year flood.Struclures existing prior to the publicationof a flood insurance rate map are eligiblefor insurance at a lower cost than thosestructures constructed subsequent to thepublication of a FIRM Within the NFlp,floodproofing is also available to thosestructures that are non-residential.

In Michigan, communities have the op-tion of adopting their own floodplain man-agement policy. About 80% ofcommunities follow the State ConstructionCode, which is an amendment to theBuilding Officials and Code Administrators(BOCA) National Building Code. TheAmendment does not regulate the locationor the type of development within thefloodplain, but states that no basementscan be built within a floodplain, and sub-grades must be above the flood elevation.Only non-residential units can be flood-oroofed.

In total, 95% of Michigan's communi-ties follow one form of non-structural flood-plain management. The commonregulation in the policies states that build-ings must have at least their lowest floor

Canadian Water Resources JournalVol.22, No.2, 1997

above the Regulatory Flood. However,many of the local policies that may beadopted do not deter the development ofresidential units within floodplain but onlyrestrict the height of the lowest floor.

In Michigan, the Depafiment of NaturalResources (MDNR) regulates floodway oc-cupancy. This occurs only when a buildingpermit is involved. As building permits arerequired for new construction or substan-tial improvements, the adequacy of theState or County building code enforcementprogram becomes the definitive element ofthe regulatory process (FEMA, 1986). ltwas found by FEMA's Inter-agency ActionTeam that proper knowledge of Statebuilding codes, zoning, the NFIP, andoverall the wise use of floodolain was lack-ing. lt was also discovered that the en-forcement of existing codes andregulations was lax. Since many of theregulations and codes were not adheredto, the residents of Michigan had a greaterexposure to flood hazards.

Although in many communities theflood elevations exceeded the 1OO-yearflood level, more appropriate use of thefloodplain would have alleviated manyphysical and psychological damages.Instead of allowing communities to adopttheir own floodplain management policies,more cohesion of floodplain regulationswithin the State is needed. Enforcement ofexisting policies would probably have mini-mized damages, but Michigan still paysmillions of dollars in flood relief and reha-bilitation annually.

DiscussionFrom the presentation of the two floodplainmanagement models, it is obvious that theobjectives of the two programs, reductionof future flood damages, are the same, butthe methods of achieving these objectivesand the success in implementing the flood-plain management models are quite differ-ent. These are briefly discussed.

In Ontario, a Conservation Authority isformed by agreement of all participatingmunicipalities and these are represented

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in the administration of the ConservationAuthorities Act. Further, the ConservationAuthorities and municipalities work handin hand in approving development pro-posals or alterations to properties withinor close to floodplain. Also, in implement-ing the Conservation Authorities Actthrough the fill regulations, the CAs tendto retain a buffer of safety between theactual floodline and regulatory fill lines.While this may give an illusion of over-regulation, the difference in flood dam-ages, as presented in Table 1, confirmsthe socio-economical benefits of such anapproacn.

In contrast, in Michigan, the FloodInsurance Program is not mandated tokeep the development away from the flood-plain. lt requires different premiums for thevarious flood zones; inner zones carry high-er premiums and vice-versa. Also, the par-ticipation in the program is voluntary with asignificant number of municipalities not par-

ticipating. The approach taken in Ontario,when interpreted from the insurance pro-gram perspective is that the premiums fordeveloping within an identified floodplain

are so high that people cannot afford themand hence there is incentive to move devel-opment away from the floodPlain.

There were enormous differences in

the damages that occurred in Ontario andMichigan from the August-September1986 floods. The comparison betweennon-agricultural damages is particularlystriking: less than $500,000 in Ontario,more than $200 million in Michigan, asseen in Table 1 (Nicolson, 1991). The non-agricultural sector is targeted by floodplainrestrictions, as agricultural uses are gener-

ally permitted in flood-prone areas. Also,there is a high degree of uncertainty aboutthe extent of agricultural losses that oc-curred in Ontario.

The large differences in non-agricul-tural flood damages cannot be accountedfor by differences in the intensity or vol-ume of rainfall; the volume or frequency of

the runoff; differences in phsiography; or

differences in population densities andamount of urban development. A majorreason for the large differences in dam-ages is in the large differences in theamount of flood plain development in the

Table 1: Estimated Flood Damages in Michigan and Ontario for August-September1986 Floods

. Figure includes both public and private losses.

.- A potential agricultural loss of $10,000,000 was oiriginally speculated by the Ontario Ministry of

Natural Resources, (Toronto Star, 1986) but no measurable loss was actually realized. Some

loss may have been incurred by the need to forego planting of winter wheat (which was replaced

by alternative crops in the spring), but this can not be confirmed.

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Sector Ontario Michigan

Public

Private

480,300- 66,848,900

136,417,990

Agricultural 0.. 106.366,310

Total non-agricultural 480,300 203,266,890

Total 480,300** 309,633,200

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two jurisdictions as a result of two differ-ent long-term approaches to flood plainmanagement.

SummarySince the mid-1950s Ontario has had anambitious and comprehensive flood-reduc-tion program. This has not been the casein much of the affected area in Michiganwhere flood plain restrictions have beenlimited. The 1986 floods show that forlarge flood events, the benefits of long-term non-structural flood plain manage-ment strategies can be enormous,possibly in the hundreds of millions of dol-lars saved in one year.

The benefits of non-structural floodplain management measures are cumula-tive and increase over time. The full bene-fits of these approaches cannot be fullyrepresented by studies based on shorterperiods of flood plain development control.As a result, the full benefits of non-struc-tural flood plain management approachesmay be under-estimated by planners andresource managers.

ReferencesBook, A.N. and R. Princic. 1975. EstimatingFlood Damages in the Fraser River Basin.Internal Report, Environment Canada,Ottawa.

Bruce, J. 1976. "National Flood DamageReduction Program" Canadian WaterResources Journal, 1 (1 ) :5-1 4.

Environment Canada, Inland WatersDirectorate 1979. Guidelines for theBenefit-Cost Analysis of Flood DamageReduction Projects.

Environment Canada, Inland WatersDirectorate. 1994. "Review of 1986Michigan-Ontario Flooding Report," InternalRepod by Glenn Rivers.

Foth, H.D. and J.W. Schafer. 1980. SorTGeography and Land Use, New York, JohnWiley and Sons.

Millerd, F., C. Dufournaud, and K. Schaefer.1991. A Benefit Cost Analvsis of Selected

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Projects Under the Canada-Ontario FloodDamage Reduction Program. A Report tothe Canada-Ontario Flood DamaoeReduction Program.

Nicolson, M.L. 1991. A Comparison ofFlood Damages on Climatologically andHydrologically Similar Areas, SeniorHonours Thesis, Depadment of Geography,University of Waterloo.

Nicolson, M.L. and S.M.A. Moin. 1990, 4Comparison of Flooding in Michigan andOntario - August - October, 1986, A Reportto Canada - Ontario Flood DamageReduction Program.

Paragon Engineering Limited. 1984. FloodDamages for Estimation Report to OntarioMinistry of Natural Resources.

Public Accounts Committee, Government ofCanada. 1979. Comments of members ofcommittee and Deputy Minister ofEnvironment Canada regarding the evalua-tion of flood control projects. Ottawa.

Toronto Star. Various lssues, October1 986.

Treasury Board Secretariat, Government ofCanada. 1976. Benefit-Cost AnalvsisGuide.

United States Federal EmergencyManagement Agency (FEMA). 1986.lnteragency Hazard Mitigation Report forMichigan. Chicago, lllinois.

United States Federal EmergencyManagement Agency (FEMA). 1986.Regional Disaster Summary, MichiganMajor Disaster Request. Chicago, lllinois.

United States Federal EmergencyManagement Agency (FEMA). 1986. "AUnified National Program for FloodplainManagement," Washington, D.C.

Weiss, G. 1987. "Benefits of Flood HazardMapping: The case of Pilot Butte Creek inRegina, Saskatchewan" Internal Report forInland Waters Directorate, EnvironmentCanada.

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