measuring drought impacts: the illinois case

WATER RESOURCES BULLETINVOL. 25, NO.1 AMERICAN WATER RESOURCES ASSOCIATION FEBRUARY 1989

MEASURING DROUGHT IMPACTS: THE ILLINOIS CASE'

Stanley A. Changnon, Jr. and William E. Easterllng2

ABSTRACT Drought is an interaction between physical processesand human activities. This study quantified the impacts of precipi-tation deficiencies on streamfiow, reservoirs, and shallow groundwater supplies. An in-depth analysis of newspaper accounts ofdroughts between paired cities, one in drought and one not indrought, were used to measure the differences in the types ofdrought impacts, and in the time of onset of impacts as related todeveloping precipitation deficiencies. Precipitation deficienciesrelated to the onset and the magnitude of surface water supplyadjustments, and to shallow ground water problems, were estab-lished. Thus, monitoring and prediction of the onset and magni-tude of drought problems can now be done from readily availabledata on precipitation deficiencies. Newspapers were found to bereliable indicators for the timing of drought impacts and adjust-ments as precipitation deficiency develops. A review of local andstate adjustments during two recent droughts revealed most deci-sion makers lacked information and experience in dealing withdrought.(KEY TERMS: drought; socio-economic impacts; streamfiow; pre-cipitation; reservoirs; wells; water policy.)

INTRODUCTION

Quantification of drought impacts, and the actionsthat result to lessen their effects, offer a basis for for-mulating intelligent drought policies at the local,state, and federal levels. This paper is a synthesis ofdrought impact and adjustment findings from a majorstudy of Illinois droughts (Changnon, et til., 1987). Agoal was to learn whether levels of precipitation defi-ciencies could be related to varying levels of impactsand adjustments. Such relationships would allowmeaningful quantitative assessments of drought pres-ence and severity using readily available precipitationdata as an index.

One of the obstacles to an objective and reasonedreaction to drought is uncertainty over its definition.Drought is complex physically and socially, and gener-ally of widespread significance. There is no universal-ly accepted definition because: 1) drought, unlike

flood, is not a distinct event; and 2) drought is oftenthe result of many complex factors acting on andinteracting within the environment (Changnon,1980). Complicating the problem of drought defini-tion are the facts that drought often has neither a dis-tinct start nor end, becoming recognizable only after aperiod of deficient precipitation, and because droughtmay be interrupted by spells of above normal precipi-tation for one or moire months, its termination is oftendifficult to recognize. Drought is also an occasionalfeature of the climate of Illinois and most humid cli-matic zones.

Natural factors commonly assessed to determinethe presence of drought include weather conditions,soil moisture, water table conditions, water quality,and streamfiow. Their interactions and the areas ofimpact caused by drought are illustrated in Figure 1.Some of the impacts affecting people involve loweredsupplies in water storage systems; diminished groundwater in shallow wells; decreased water use per capi-ta; decreased water services; and a myriad of econom-ic considerations (Changnon, et al., 1982).Consequently, a wide variety of criteria have beenused in defining drought. In essence, the termdrought is generally associated with a sustainedperiod of abnormally low water or moisture supply. Aprecise definition of a "sustained period" is not attain-able and varies, as this study shows, with the typicalimpacts. For example, in a humid environment likethat of Illinois, where precipitation is usually well dis-tributed throughou.t the growing season, a summerdry period lasting several weeks may constitute a"crop drought." Conversely, it may take one or moreyears of deficient precipitation before certain waterdemand areas such as urban water supplies aredrought affected (Changnon, 1980). The most com-monly used drought definitions found in illinois andelsewhere are based on 1) meteorological conditions,2) agricultural problems, 3) hydrological conditions,

'Paper No. 88051 of the Water Resources Bulletin. Discussions are open until October 1, 1989.2Respectively, Chief Emeritus, Climate and Meteorology Section, Illinois State Water Surve3; 2204 Griffith Drive, Champaign, illinois

61820; and Professional Scientist, Resources for the Future, Washington, D.C.

27 WATER RESOURCES BULLETIN

WATER STORAGE ZONES I

WATER FLOWS (AND IMPACTS)

Changnon and Easterling

IATMOSPHERIC MOISTURE I

and 4) socio-economic considerations (Wilhite andGlantz, 1985). In the study of Illinois drought during1901-1983 we developed three measures of precipita-tion conditions that defined Illinois "precipitationdroughts" for 12- and 24-month periods (Easterlingand Changnon, 1988). In a 12-month drought, thestatewide mean precipitation was 80 percent of aver-age or less, at least one locale experienced <50 per-cent, and �15 percent of the state experienced lowprecipitation values expected to occur in only 10percent of the years. In a 24-month drought wherethe statewide mean was �90 percent, one localeachieved <60 percent, and �18 percent of Illinois expe-rienced low precipitation values expected to occur in10 percent of the two-year periods.

This study measured drought impacts, using cer-tain unique data sets available in Illinois, to illustratewhat constitutes the onset and severity of drought asreflected in surface water, shallow ground water, andin other areas like agriculture. Relationshipsbetween drought impacts/adjustments and theamount of precipitation deficiency were developed.

The first section of the paper addresses the rela-tionships of the physical and human impacts. This isfollowed by a section that examines the incidence ofrequests to the Water Survey for assistance on wellsfor any purpose, and the 25-year record reflects

WATER RESOURCES BULLETIN 28

drought-induced problems. A third section utilizes a45-year record of reservoir problems and the relation-ship of these problems to deficient precipitation as ameans to delineate drought. The fourth section pre-sents results of studies of news accounts of droughts,from drought and non-drought areas, to estimate dif-ferences as to what impacts are reported and when.Adjustments to droughts made by local and stateinstitutions are examined in the next section, and thefinal section summarizes the findings.

Structure of Impacts

It is important when considering the social and eco-nomic impacts of droughts (and subsequent adjust-ments) to initiate the examination at the physicallevel, and hydrologic cycle. As noted in Figure 2,droughts begin with precipitation deficiencies. Sincethe evapotranspirative demands of the atmospherefor water must be served, the effects of lowered pre-cipitation are delayed, and the ensuing decreases inrunoff and shallow ground water are greater percent-agewise than those in precipitation. This means thathuman activities dependent upon water capturedfrom runoff or in shallow ground water aquifers are

(evapotranspiration)

IPRECIPITATION I

Crops &Plants

FarmIncome

IMPACTS Erosion

Municipal Water Supplies

Figure 1. Hydrologic Conditions Affected by Droughts and Related Impacts.

Measuring Drought Impacts: The Illinois Case

most apt to be seriously impacted by long-termdroughts. Conversely, deficient precipitation duringcritical periods of the growing season, leading to soilmoisture deficits, puts stress on crops, reduce yields,and results in "agricultural drought."

Figure 2. A Schematic Showing How Precipitation DeficiencyDuring a Hypothetical Four-Year Period are Translated,

in a Delayed Fashion, Over Time Through OtherComponents of the Hydrologic Cycle.

We know from extensive studies of recent Illinoisdroughts (Changnon, et al., 1987), that they have aseries of first-order impacts (changes in the hydrologiccycle), then second-order impacts, and finally third-order impacts. The "second-order impacts" typicallyaffect activities in urban communities, farming,transportation, and industry. For example, second-order impacts for transportation are primarily relatedto low flows in major rivers (low flows are considereda direct or first-order impact) used for barge trans-portation. In this example, one third-order impact isthe reduced income to barge owners and shippersresulting from limited barge movements. An exampleof second-order urban impacts, which are obviouslysimilar to industrial impacts, is reduced surface watersupplies, both in small and large municipal reser-voirs. A third-order impact in the urban sequencerelates to adjustments involving reductions in highwater use activities such as lawn irrigation and car

washing. Third-order impacts are actually often"adjustments" to the impacts being felt at the first-and second-order levels. Impacts on government areusually classified as "third-order impacts"

The 1976-1977 and 1980-1981 droughts, althoughnot among Illinois' most severe precipitation droughtssince 1900, were subject to impact summarizationafter they occurred (Illinois Task Force on Drought,1977; Changnon, et al., 1982). The assessment ofthese impacts, done at the request of the Governor ofIllinois, was motivated by a desire to make moreappropriate responses to future drought, i.e., to makewise future "adjustments" to drought impacts.Table 1 lists the primary impacts, generally not quan-tified and as summarized by state officials, for the1980-1981 drought. They are typical major droughtproblems, but they do not provide the basis for under-standing how the impacts developed. A variety of sec-ondary impacts we:re noted in the 1980-1981 drought,and in particular, several institutional impacts onlocal, state, and the federal government were identi-fied (Changnon, et cii., 1982). The drought resulted ina variety of impacts on state agencies with responsi-bilities relating to water.

TABLE 1. Notable Impacts on the 1980-1981Drought in Southern illinois.

Public Water Supplieu

1. Thirteen communities had problems2. Various restrictions on usage were employed3. Various temporary and permanent means to increase

supplies were 'used

Impacts on Agricultuire and Rural Dwellers

1. Crop yields were severely reduced in 19802. Dust storms in spring of 1981 caused soil loss3. Wells and ponds dried up; hauled water for livestock4. Economic effects were sizable

Impacts on Transportation

1. Increased water hauling2. Barge traffic on illinois River was restricted3. Blowing dust affected visibility and led to accidents

Impacts on Recreation and Environment

1. Fishing was reduced2. Fish populations were reduced; certain insects flourished

Effects on Social Behavior and Health

1. Anxiety of public occurred in severely affected areas2. Farm incomes were reduced3. Conflicts over proposed adjustments to community

shortages occurred4. Temperature and humidity (July 1980) affected humans

and animals leading to heart attacks5. Certain businesses were hurt, others helped


C0VC0

awOz=D00

TIME, years

Changnon andEasterling

In some instances, benefits have accrued fromdroughts. Several cities, particularly in the southernthird of Illinois, have developed more adequate sur-face water supply systems over the last 35 years as aresult of drought impacts (van Es, et al., 1980;Changnon, et al., 1982). Other communities improvedtheir water supply systems as a result of drought, andin some cases, water rates have been increased tomore adequate levels, reflecting a truer value ofwater. In all these instances, these drought responseshave helped make these communities more "drought-resistant."

SHALLOW GROUND WATER DROUGHTS:WELL PROBLEMS

Data andAnalysis

The Illinois State Water Survey has served as aninformation source for Illinois residents with wellproblems more than 25 years. Careful records ofrequests for assistance have been kept since 1960,and those for 1961-1985 were used in this analysis.The annual frequency of requests was determined ona county basis, and a 25-year annual average countyvalue calculated. During this 25-year period, Illinoisexperienced four precipitation droughts lastingbetween 6 and 12 months. The requests for wellinformation during the two years embracing each ofthese droughts (usually a deficient precipitationperiod of 12 months) were used as a measure ofimpacts resulting from lowered ground water levels.The requests were either for information about modi-fying an existing well, or drilling a new well.

A quasi-experimental design was used in this anal-ysis. Specifically, to assess the potential impacts ofthe drought problems on shallow ground water, asreflected in these requests for assistance, we per-formed three comparisons. First, examination of theprecipitation patterns for the drought periods,expressed as percent of normal values, revealed thatin each drought period there were two to four discreteareas within the state having very low precipitationvalues, less than 40 percent of the long-term averagefor six months. Counties were selected within theseareas with two, three, or four counties per discretearea for each drought. As a result, for each of the fourdroughts in 1961-1985, between 7 and 14 countieswere identified (see Table 2).

Then, an equal number of adjacent counties withmuch less severe precipitation departures, but still


with below normal values, were chosen for eachdrought. It was considered important to select"adjacent" counties located 30 to 80 km distant,rather than counties farther away where much less(or no) drought had occurred. This was to ensurecomparable physical and socio-economic environ-ments. Where possible, attention was paid to select-ing control counties that had subsurface geologicconditions comparable to those in the severe droughtcenters, so that problems related to shallow groundwater deficiencies in well supplies would be similar.The selected "severe drought" counties became the"target" counties, and those in the selected adjacentcounties were considered the "control" counties. Theirnumbers of requests for well assistance, expressed aspercentages of their 25-year averages of any county,were compared, target versus control.

A second comparison, related with the first,involved the percentage of normal (1901-1985 baseperiod) precipitation values. This comparison usedthe same counties as selected abOve, the target andcontrol counties. The ratios of the precipitationdepartures (percent of normal) for the target and con-trol counties in each drought were compared. Theresulting ratios of target-control precipitation depar-tures were compared with the target-control ratiosbased on the requests for well information, providinga measure of how the degree of precipitation depar-ture led to changes in requests.

A third comparison was also of a target-controlnature, but had a temporal rather than spatialnature. For each of the four droughts, the frequencyof requests in the two years of the drought periodwere compared with 1) the frequency of well requestsin the two years "before the drought," and 2) therequests received in the two years after the droughthad ended. The number of requests were expressedas a percent of each county's 25-year average number.In this comparison, the before and after values werethe "control" values, and the values in the droughtremained as the "target" values.

Findings

Table 2 presents the statistics on the requests forwell information (expressed as a percent of the aver-age number of requests) and drought-related informa-tion for the four droughts in the 1961-1985 period.Relevant aspects of the four droughts, based on thesix-month period of greatest precipitation departure,include the number of discrete severe drought centersfound in each drought, ranging from two in the 1980-1981 drought, up to four areas in two other droughts.The number of counties selected in each of the four


Drought Periods

Number ofCounties Selected

Number of DiscreteSevere Drought

Centers in Target

Percent AveragePrecipitation

Percent AverageRequests

T C Ratio, PC+PT* T C Ratio, Rr+RT C

September 1962-February 1963September 1963-February 1964August 1976-January 1977October 1980-March 1981

11 118 8

14 147 7

3442

39404138

77 1.9767 1.6766 1.6161 1.60

144138138151

79 1.8282 1.6888 1.5768 2.22

Averages — — 3 40 68 1.71 143 79 1.82

droughts is also indicated in Table 2, ranging fromseven counties in the 1980-1981 drought (four in onediscrete severe drought area, and three in the other),up to 14 test counties for the 1976-1977 drought. Alsoshown in Table 2 are the comparable values for thecontrol area counties selected from the four droughts.

Comparison of the percent of average precipitationvalues in Table 2 reveals that the average of the fourdroughts in the target area was 40 percent of normal,compared to 68 percent of normal in the adjacent con-trol areas. Comparison of the percent of averagerequests values (in Table 2) for the four droughtsshows that the requests were much above normal ineach of the four droughts (138 percent, 138 percent,144 percent, 151 percent). Furthermore, in the con-trol area the values were all below average including68 percent of average, 79 percent, 82 percent, and 88percent. The average value for the target areadroughts was 142.8 percent, as compared with 79.3percent of average for the control areas in the fourdroughts. Their ratios are also shown in Table 2. AllRT/RC ratios in Table 2 were much greater than one,and the average ratio was 1.82. In summary, the spa-tial comparison of requests for well assistancerevealed that the values in the drought cores (target)were always much higher, being nearly double theaverage number of requests in the adjacent controlareas.

Relevant to these request differences is the magni-tude of the precipitation departures by the target andcontrol areas, recognizing that the control areasselected were also areas of deficient precipitation. Ineach of the four droughts, the percent of average pre-cipitation in a target area was much less than that inthe control area, as revealed by comparing individualdrought values (Table 2). As previously noted, theaverages ranged from about 40 percent of average inthe target to about 68 percent of average precipitationin the control. The precipitation ratios, PC/Pr, reveal

sizable differences with a four-drought average of1.71. This value approximates the target-control ratioof requests of 1.82, suggesting that the extent (num-ber) of ground water problems in drought are wellrelated to the departure of precipitation over a six-month dry period.

The values from this analyses indicate that defi-cient precipitation for 6 to 12 months of 65 to 80 per-cent of average do not produce well supply problemsleading to above normal number of requests for wellinformation. However, the shift from 60 percent ofaverage precipitation (over six months) downward to40 percent of average brings on shallow ground watershortages sufficient to lead to actions to remedy short-ages.

The third investigation related to comparisons ofthe frequency of requests for well information in thetarget counties before and after the droughts with thenumber during the drought period. The drought peri-od was defined as the two calendar years embracingthe six-month period of greatest precipitation defi-ciency. For example, the six-month drought ofSeptember 1962-February 1962 was considered adrought period for 1962 and 1963, at least as far ascounting the number of well requests. This type ofdefinition likely incorporates all the problems andactions needed to correct well problems after the low-est precipitation period ended. It thus conservativelyisolates the impacts as reflected in well requests.

The number of requests for well information in thetwo calendar years prior to the two-year droughtperiod, and those in the two calendar years after thedrought period ended, were counted and expressed aspercent of average. These values for each of the fourdroughts are shown in Table 3. Values after the 1962-1963 drought could not be considered control sincethat overlapped wit;h the 1963-1964 drought, and sim-ilarly, there was no control "before" value for the1963-1964 drought;. The sample size is small, only


TABLE 2. Comparison of Precipitation Departures (six-month periods) and Frequency of Requests for Well InformationFound in Intense Drought Zones (Target) and in Adjacent Areas of Less Severe Drought (Control).

=

R=

PrecipitationControlTargetRequests


TABLE 3. Requests for Well Information in Target Counties, for Two Years Before,Two Years During, and Two Years After Drought.

Droughts

Requeats Expressed as Percentof 25-Year Average

RatiosDuringBefore

DuringAfterBefore During After

1962-1963 81 144 - 1.78 -1963.1964 - 138 108 - 1.281976-1977 125 138 93 1.11 1.481980-1981 91 151 111 1.66 1.36

Average 99 143 104 1.52 1.37

four droughts, with only three "before values" andthree "after values." Nevertheless, the values inTable 3 are consistent and suggest utility. Therequests before droughts were all less than thedrought values (81 percent versus 144 percent; 125percent versus 138 percent; and 91 percent versus151 percent). The average before/during ratio is 1.52,indicating a 50 percent increase in well problems dur-ing droughts. Note that the "before drought" requestaverage was 99 percent, very near average, as com-pared to the 143 percent during droughts. The "afterdrought" values were also all less than the droughtvalues (108 percent versus 138 percent; 93 percentversus 138 percent; and 111 percent versus 151 per-cent). Their ratios were all above 1, and yielding anaverage target-to-control ratio of 1.37, as shown inTable 3. Although they decreased, they are stillslightly above average, 104 percent. This may reflecta slight carry over effect of problems from the droughtperiod.

STREAMFLOW DROUGHT: RESERVOIRPROBLEMS/ADJUSTMENTS

This study investigated the impacts (and relation-ships) of precipitation drought on public water sup-plies sustained by streamflows in Illinois. This wasfeasible because prior research had defined the rela-tionship between precipitation deficiencies and lowstreamfiows (Huff and Changnon, 1964). That studyshowed that by incorporating areal physiographicdescriptions, the precipitation-streamfiow relation-ship could be well defined mathematically for periodsof 12 months or longer duration and for precipitationdeficiencies equating to recurrence intervals of fiveyears or greater. That is, a six-year return intervalvalue in low precipitation could be related to a six-year return interval in streamfiow. Theseprecipitation-low flow relationships varied accordingto Illinois' nine major physiographic areas such thateach area had its own set of constants in its equation


relating the precipitation departure to the streamfiowdeparture. For shorter periods (< 12 months) andlesser return intervals (< 5 years), the precipitation-low flow relationships were not strong. At the greaterdepartures (>5 years return), these results signifiedthat local factors (soils, slopes, and subsurface geolo-gy) played a major role in determining the amount oflow flow.

The impacts of low flow conditions resulting fromdrought occur in several ways (Figure 1). The effectof low streamflows leading to less inflow to publicwater supply reservoirs is a critical one.

Data and Analysis

There are 133 Illinois communities that use surfacewater sources for their domestic water supply. Ouranalysis first defined the relationship betweendrought problems in public supply systems and lowflow levels. The relative departures of these levelsand problems were compared, and the type of problemand adjustment made was in turn related to the levelof precipitation deficiency.

Data from three major droughts during 1951-1985were studied. The degree of low flow for 12- and 24-month periods during the droughts was comparedwith the remedial actions pursued at public watersupply reservoirs to compensate for the low inflows.In the 1952-1955 drought (Hudson and Roberts,1956), 62 public water supply reservoirs experiencedsupply problems and made some form of adjustments.In the 1976-1977 (two-year) drought, there were 23reservoirs where adjustments were made (IllinoisTask Force on Drought, 1977), and in the 1980-198 1(12-month) drought there were 12 public water supplyreservoirs which were impacted and which had someform of adjustments (Changnon, et al., 1982). In all,there were 97 adjustments made because of 12-monthlow flows, and 85 based on 24-month low flows.

The reactions included relatively minor adjust-ments including altered water treatments, enforcedconservation, and altered storage. The more major

Measuring Drought Impacts: The illinois Case

(and expensive) adjustments involved the raising ofdams and/or spiliways, developing new reservoirs,installation of pipelines, etc. After inspection of therange of adjustments, we identified two levels ofadjustments: 1) those 71 adjustments considered adhoc, short-term adjustments (and generally inexpen-sive); and 2) those 26 involving major capital outlaysfor new facilities, including dams, spiliways, orpipelines.

This separation of impacts into a "temporary" lowcost and "permanent" high cost classes was used inturn, to categorize precipitation droughts as "moder-ate" and "severe," 'respectively. For these two sets ofadjustments for the 12-month and 24-month reservoirevents, the lowest streamfiow values (averages)attained over a 12-month and 24-month period for thestreams that supplied the reservoirs was identifiedand their departures from average were determined.Each of these departures from average for each of thereservoirs was then equated to its recurrence interval.

Findings

The streamfiow flow departures (percent) and theirrecurrence intervals of given streams were comparedwith the type of reservoir adjustments in their basins.Inspection of the 97 sets of values revealed that most(84 percent) of the 71 moderate (temporary) adjust-ments occurred with streamfiow values equating torecurrence intervals between 5 years to 20 years. Afew (11 adjustments) equated to longer intervals, 20-to 35-year returns.

The 26 reservoir impacts classified as indicative of"severe" drought (major capital expenditures for facil-ities) were all associated with very low streamfiows.All flow values were classified as exceeding their 20-year recurrence interval values. By this process,"streamflow droughts" were defined based on theirreturn intervals. "Moderate droughts" were thoseranging from 5- to 20-year return interval values, and"severe droughts" were those having return intervalsgreater than 20 years,.

These findings, coupled with the established fre-quency relationships of precipitation departures andlow flows (with physiographic delineations), allowedus to define the association between precipitationdrought, streamfiow drought, and reservoir impacts(adjustments). That is, precipitation droughts in the"moderate category" were defined as those achieving12-month (or longer) departures equating to 5- to 20-year return intervals. "Severe precipitation droughts"were those relating to precipitation deficiencies (over12 months or longer) having greater than 20-yearreturn intervals. Precipitation amounts equating to

moderate and severe streamfiow droughts vary acrossIllinois (Changnon, et al., 1987). The values, as per-cents of normal, for the three major divisions ofIllinois are listed in Table 4.

TABLE 4. PrecipitatLon Depaturea, in Percentages, DefiningModerate and Severe Streamfiow Droughts in the Three

Areas of illinois for 12- and 24-Month Periods.

StreamfiowReturn Interval/ North CentralDrought Severity (percent) (percent)

South(percent)

12-Month Periods

5-Year/Moderate Drought �8020-Year/Severe Drought �71

�74�60

24-Month Periods

5-Year/Moderate Drought �9020-Year/Severe Drought �82

�88�70

The tabular values can be used to equate precipita-tion departures in any area of Illinois to droughtimpacts/adjustment;s in typical supply reservoirs. Forexample, in the northern third of Illinois, a basin witha mean 12-month precipitation value representing 80percent of average (or less) would be equivalent to afive-year return interval; labeled as a moderatestreamflow drought; and produce sufficient supplyproblems to lead to temporary adjustments. A valueof 71 percent or less would create problems potential-ly leading to some form of permanent adjustment. Bythese means, amounts of deficient precipitation for12-month (or longer) periods can be used to classifrmoderate or severe streamfiow droughts, and to pre-dict the supply deficiencies in reservoirs that lead tovarying levels of response.

SPATIAL AND TEMPORAL VARIATIONSIN DROUGHT :[MPACTS: NEWS ACCOUNTS

Historical records of well information and/or reser-voir problems to quantifr droughts do not exist inmany locales as they do in Illinois. However, mostareas have had newspapers for many decades, andpast articles after droughts in newspapers provide asource of information potentially useful in identifying:1) the type of impacts in various socio-economic sec-tors (agriculture, public, domestic, commercial; and 2)the timing of impacts in relation to precipitation defi-ciencies. Hence, a study of newspapers was made todiscern the type and utility of information aboutdroughts contained in news accounts. The newspaper



content study was used to shed light on two ques-tions. First, how well does the incidence of drought-related articles correspond with the presence ofknown precipitation deficiencies? Second, what is thetypical elapsed time between the onset of precipita-tion deficiency and the "first mention" in newspapersof particular types of drought impacts and/or adjust-ments?

Data and Analysis

Newspapers can be criticized for being inaccuratein reporting; for being too quick in reporting droughtconditions or, in some cases, for reporting droughtconditions when none exist. However, droughts havebeen declared on the basis of physical drought indices,such as the Palmer Drought Severity Index, only tolearn later that drought-sensitive activities were vir-tually unaffected when impact evidence was obtained(Changnon, 1980).

Regardless, newspapers in an area report what isdeemed newsworthy, and there can be subjectivityinvolved. However, if several newspapers consistentlyreport drought-associated problems, there is no com-pelling reason to believe that these problems are notreal and that drought does not exist. The validity ofnews accounts as drought data was evaluated by com-paring them with precipitation departures. Thisstudy was designed to compare newspaper accounts,on both a temporal and spatial basis, with precipita-tion information.

Data were analyzed for the three most recent 12-month droughts in Illinois including those beginningin November 1970, Ap'ril 1976, and April 1980.Patterns of precipitation (percent of average) in eachdrought appear on Figure 3. Each drought wasstatewide in that it met criteria used to define a 12-month occurrence during 1901-1983 (Easterling andChangnon, 1988).

Newspapers from two locales were selected toexamine regional differences between one site thatexperienced moderate precipitation deficiency duringthe November 1970-October 1971 drought(Springfield), and a site (Decatur) 64 km away thatexperienced normal precipitation during the samedrought period (Figure 3). A detailed newspaperrecording form was completed for each Illinoisdrought-related article appearing in either paper fora) the year before the drought, and b) the year of thedrought (Changnon, et al., 1987). The Springfieldpaper was considered to represent the "target," ortotally in the drought area conditions, and theDecatur paper represented the "control" or non-drought area conditions although part of its


circulation area was in the drought area. The dualpremise was that increased reporting of droughtshould occur in both newspapers during the droughtyear, as opposed to the preceding non-drought year,and that the (target) newspaper should have a higherrate of reporting than the (control) newspaper duringthe drought year, November 1970-October 1971. Thisdesign allowed an assessment of how well the level ofreporting was related to different precipitation condi-tions.

Another analysis focused on the onset of impactsand involved data from a sample of weekly and dailynewspapers chosen from severe precipitation deficien-cy areas in the three droughts (Figure 3). Dates offirst mentions of drought-related problems werenoted, and the span of time between the first mentionof a type of impact (say crop loss) in any given news-paper, and the last of the first mention in a givenpaper in the area provided a "range of onset time" fora given type of impact. Impacts were classed intothree sectors (agriculture, public sector, and domes-tic/commercial), and within each, impacts werelabeled according to commonly reported problems.

Target-Control Findings

The 1970-1971 precipitation drought was used toassess the relationship between precipitation deficien-cy and the level of reports of drought impacts andresponses. The state averaged only 75 percent ofaverage precipitation, but the control newspaper wasin a small region that received nearly 100 percent ofits average precipitation during the drought period.As shown on Figure 3, the target newspaper was in aregion with 60 percent to 75 percent of average.

Differences in target and control precipitation andresulting effects were found in corn yield and stream-flow statistics. The 1970 corn yields for the sevencontiguous counties around Springfield, the targetregion, averaged 76 percent of the five-year regionmean, whereas yields for all six contiguous countiesin the control region averaged 86 percent of the five-year mean. Streamfiow in a target area basin was 43percent of the long-term mean for 1968-1982, whereasa basin near the center of the control area had 63 per-cent of its mean flow during the drought. Thus, boththe target and control areas experienced below nor-mal yields and flows during the drought, but thecontrol area had relatively smaller departures thandid the target. The close proximity of the two news-paper cities increases the likelihood they representregions of similar physical and agriculturalcharacteristics which increases the potential of thetarget-control design to isolate a drought "signal" in

Measuring Drought Impacts: The flilnois Case

a. November 1970 b. April 1976 c. April 1980

the level of newspaper reporting. However, theirproximity also meant that the control paper may havebeen reporting regional drought problems becausethey were sufficiently close to Decatur to benewsworthy.

Newspaper article frequencies for the year ofdrought and the year before appear in Table 5. Onlysix articles appeared during the entire pre-droughtyear, and all were in the target area suggestinggreater local concern over the subject, particularly inthe public sector since Springfield is the state capitol.Table 5 reveals that 51 drought-related articlesappeared in the two newspapers during the drought.The difference between 6 and 51 establishes that a12-month precipitation deficiency of 75 percent ofaverage produced a drought of sufficient magnitude tocause many problems that newspapers reported.During the year of the drought, articles (in bothpapers) were largely devoted to agricultural (30 arti-cles) and public sector (13) problems. Few concerneddomestic (home) issues and none addressed commer-cial issues.

Comparison of the target and control frequenciesindicates that the target had more articles on droughtin each category than did the control paper with one-year totals of 37 (target) to 14 (control). All public

and domestic sector drought articles were in the tar-get newspaper. The most frequently reported cate-gories for either sector were mentions of "drought"and "water conservation."

These results suggest that the newspaper-basedmeans of measuring drought impacts has promise inisolating drought problems occurring within newspa-per circulation regions. However, the small differencein agricultural articles (16 versus 14) revealed thatagricultural-oriented problems are more pervasiveand not just related to droughts in specific circulationareas. Analysis of these 30 articles reveals the target-control approach was partly overwhelmed by thereporting of agricultural problems in regions outsidethe circulation region. This likely results because thecontrol and target newspapers represent a broad agri-cultural region that is strongly tied to agribusinessand whose aggregate interest in agricultural droughtextends widely and encompasses most portions ofIllinois. Second, the control newspaper city had 100percent of average precipitation but the circulationregion was not entirely drought-free, as revealed bythe below-average crop yields and streamfiow. Thissituation contaminated the control region in an agri-cultural sense.


Figure 3. Three 12-Month Droughts Showing Starting Month, Precipitation Expressed as Percent of Normal (190 1-1985),and Sites Where Newspaper Accounts Were Analyzed (W = weekly; D = daily publication).


TABLE 5. Number of Newspaper Articles Referring to Drought-Related Impacts and Adjustment, Sorted by Sectoral Perspective:November 1970-October 1971. Values for pie-drought year (November 1969-October 1970) shown in brackets.

CommC

ercialT AgriC

cultureT

DomC

esticT

PublicC

SectorT

Impact• Drought - - 8 6 - 3(1) - 4(1)• Water Shortage - - - - - 1(1) - 1(1)• DryWells - - - - - - - -• Crop Stress • - 3 6 - 1 - 1• StreamflowlReservoir Reduction • - - - - - - 1(1)• Blowing DustlSoil Erosion - - 2 1 - - . 1• Water Quality - - -

Adjustment• Hauled Water/Alternative Supply - - - 1(1) - 1 - -• New Well Construction - - - - - - - -• Water Conservation - - - - 2 4• Irrigation - - - - - - - -• Weather Modification - - - - -• Pest Management . - 1 2 - - - 1

TOTALS 0 0 14 16 0 8 0 13 51

PRE-DOUGHT YEAR ( ) (0) (0) (0) (1) (0) (2) (0) (3) (6)

*Contrel Newspaper**Target Newspaper

The exclusive appearance of domestic and publicsector articles within the target newspaper (Table 5)suggests that these sectors, unlike agriculture, tendto focus on local problems in the circulation area.Water conservation and reduced water suppliesbecome manifest more readily in urban settings thanrural settings because of the high consumptive use ofwater in the urban setting.

Relations of First Mention of Impacts andPrecipitation Deficiency

The question of when drought impacts and adjust-ments emerge, relative to the onset of precipitationdeficiency, was addressed by examining the dates ofthe first mention of articles concerning any givenimpact, or adjustment, for three droughts.

Agricultural Perspective. There was good gen-eral correspondence between the 1976 and 1980droughts (both began in April) as to the order inwhich the agricultural impacts and adjustments werereported, especially for the earliest declared problems.As shown in Figure 4a and 4b, initial drought-relatedarticles concerned crop stress, and in 1976, articlesappeared within two weeks after the dry periodbegan. In 1980, the first drought articles did notappear until early May, five weeks after the droughtbegan.


The order of impacts and attempts to cope withthose impacts were not always in the expected order.Crop stress reports (impact) were followed by reportsof increased irrigation and weather modification(adjustments) as shown for 1976 and 1980 (Figure 4).However, initial reports of hauled water and/or alter-native supplies (adjustment) preceded initial reportsof dry wells (impact). Thus, where certain impactscan be anticipated and adjustments are possible,there were some attempts to mitigate the impactsapparently before they fully developed.

A general correspondence was obvious between thetiming of certain impacts and adjustments, and thelevel of natural drought buffering of the impacted pro-cesses. The earliest reports of impacts (crop stressand pest management problems) concerned processesat the surface-atmosphere interface which inherentlytend to respond quickly to dry conditions. Later agri-cultural problems (water shortage, dry wells, loweredstreamfiow and/or pond levels, water conservation)concerned problems associated with diminishing on-farm supply systems, natural or man-made, whichoffered some initial drought protection.

Lag times in the span from the earliest newspapermention to the last newspaper mention of specificimpacts and adjustments revealed great diversity.For example, crop stress reports appeared in all ana-lyzed papers within three months (after the initialreport) for both 1976 and 1980 droughts. As shown inFigure 4a, declarations of "agricultural drought" hada lag time of six months in 1976 and three months in


Figure 4. Dates of Earliest First Mention of an Impact and of Latesi; First Mentionfor News Articles Written from Agricultural Secthr Perspective.


6/6

4/22

10/2

8/5

1/13

1/1012/8

7/22

3/10

7/10

12/8

10/6

7/22

1/13

1/20

7/16

6/14 7/29

7/16

4/23

3/10

3/24

Drought

Water shortage

Dry wells

Crop stress

Streamllow/Reservoir levels

Blowing dust/Soil erosion

Water guality

Hauled water/Alternative supply

New wellconstruction

Water cooservation

Irrigation

Weathermodilication

Pest management

Drought

Water shortage

Dry wells

Crop stress

Stream? low/Reservoir levels


Water quality

Hauled water!Alternative supply

New wellConstrUCtiOn

Water Conservation

Irrigation

Weathermodilication

Pest management

8/S

12/16

(a)

APR MAY JUN JUL AUG SEP OCT NOV DEC AN PBS MAR1976 1977

5/8 8/13

3/2

3/16

8/10

5/9 7/24 .

1/5 2/1

8/7

10/1 3/2

.

7/25

9/11 2/16

3/2

.

10/1

6/13 6/19

5/29 9/6

I(b)

APR MAY JUN JUL AUG SEP OCT NOV DEC .iAN PE8 MAR

1960 1981

Water shortage

Dry wells

Streamtlow/Reservoir levels

Blowing dust!Soil erosion

Water guality

Hauled water/Alternative supply

New wellconStruCtion

Water Conservation

Irrigation

WeathermodilicatiOe

Pest management

11/1 4/7

4/17 4/18

4/20

11/1 4/17

4/23 10/8

4/17 4/20

4/17 4/18

4/174/16

5/2

6/20 9/5

FEB MAR APR MAY JUN JUL AUG SEP OCT1971

NOV DEC JAN1970


1980. This spread is not surprising since droughtconditions do not develop with spatial or temperaluniformity.

The drought beginning in November 1970(Figure 4c) offered an opportunity for comparisonwith those in 1976 and 1980 for seasonal differencesin timing of impacts. There was little difference inthe timing of some impact reports, but for others, thedifference was sizable. For example, reports of crop(winter wheat) stress appeared within days of the1970 dry conditions beginning (Figure 4c), a resultcomparable with the other two droughts. However,most of the remaining impacts and adjustments inthe 1970-197 1 drought appeared in April, six monthsafter the beginning of precipitation deficiency.

These results suggest that impacts (or the potentialfor later impacts) on crops by emerging dry conditionswere quickly discerned. Most of the adjustments andthe more drought-buffered impacts, however, were notnewsworthy until the beginning of the growing seasonwhen a flurry of problems were reported in a shortperiod. This indicates seasonality in some drought-related problems, and these seasonal agriculturalproblems tend not to be reported during the non-growing season portion of the year, regardless of whendry conditions begin.

Public Sector Perspective. The types and tim-ing of impacts and adjustments in public sector arti-cles reflected various concerns over managingmunicipal water systems. In the 1976 drought, thefirst three items reported were reduced streamfiowand/or reservoir levels, water conservation, and watershortages (Figure 5a). Similarly, in the 1980 drought,two of the first three impacts reported were reducedstreamfiow and/or reservoir levels, and water conser-vation (Figure 5b).

The public sector reports of the more drought-buffered systems appeared relatively soon after thestart of dry conditions. For both the 1976 and 1980droughts, initial reports of reduced streamfiowsand/or reservoir levels appeared 1.5 to 2.5 monthsafter the drought began. The early recognition ofthese types of problems is probably attributable to therisk-adverse nature of municipal water supply sys-tems. Municipal water systems must meet a fargreater demand than rural, on-farm water systems,and thus the slightest threat of drought-impairedmunicipal water delivery becomes newsworthy soonerthan in agricultural articles.

The order of impacts and adjustments was quiteapparent. Reports of reduced streamfiow and/orreservoir levels (impact) preceded reports of waterconservation (adjustment) in both 1976 and 1980, butreports of adjustments (water conservation, hauled


water and/or alternative water supplies, and new wellconstruction) preceded initial reports of dry wells.

Results of the public sector reporting during theNovember 1970 drought (Figure 5c) closely resembledthe pattern of reporting exhibited by the agriculturesector (Figure 4c). All public impacts were recordedin either April or May of 1971. A striking dissimilari-ty of this drought with the more recent, spring-onsetdroughts, was the relatively long time lag from thedrought onset to the first appearance of drought-related impacts. The initial issues (drought andhauled water/alternative supplies) appeared six orseven months into this drought, as compared to two tothree months in the droughts beginning in April.This suggests that onset of public sector impactsrelate directly to season, being more delayed in coldseason initiations than in warm season drought initi-ations.

Domestic and Commercial Sector Perspec-tives. Domestic and commercial sector reports arediscussed together because of the paucity of newspa-per articles about them and because of the similarityin the reporting patterns. In 1976, only four cate-gories (newspaper drought, water shortage, dry wells,and hauled water and/or alternative supplies) werereported for the domestic sector, and the earliestreports (water shortage) did not appear until sevenmonths into the drought with the latest at ninemonths. Commercial sector impacts in 1976 werescarce (3) and occurred six to eight months after theonset of the dry conditions. Furthermore, commercialsector mentions of a "drought" never appeared in1976. Reporting of domestic/commercial impacts inthe 1980 drought were similar, occurring five to ninemonths into the drought. In 1970, there were noreports of drought-related impacts or adjustmentsfrom a commercial perspective, and the few domesticsector impacts were reported six to eight months intothe drought.

This scarcity of articles and the long time lags fromthe beginning of precipitation deficiency suggest thatthe domestic and commercial aspects are not seriouslyaffected by 12-month droughts. One explanation isthat public sector concerns over municipal water sup-plies subsume the majority share of attention news-papers give to this issue. In this issue, the publicsector absorbs most of the direct impacts of droughton water supply, whereas the domestic and commer-cial sectors absorb the secondary impacts, many ofwhich may have been filtered through public sectoradjustive strategies such as water conservation mea-sures.


Figure 5. Dates of Earliest First Mention of an Impact and of Latest First Mentionfor News Articles Written from a Public Sector Perspective.


6/18

6/8

7/16

7/22

1/13

5/27

3/17

1/20

7/16

1/20

1/20

6/8

6/17

7/29

(a)

Drought

Water shortage

Dry welts

Crolt stress

Streamflow/Reservoir levels


Water quality


New wellConstruction

Water conservation

Irrigation

Weathermodification

Pest management

Drought

Water shortage

Dry wells

Crop stress

Srreamtlow/Resernoir levels


Water qualrty

Hauled water!Alterna tiue supply

New wellConstruction

Water coeseruation

Irrigation

Weathermodification

Pet management

Drought

Water shortage

Dry wells

Crop stress

Sr rea m S low!Reservoir levels

Blow,ng dust/Soil erosion

Water quality


New weltConstruction

Water conservation

Irrigation

Weathermodification

Pest management

APR MAY JUN JUL AUG SEP OCT NOV DEC JAN FEB MAR

1976 1977

6/16 7/16

10/17 1/30

3/16

7/45/14 3/16

617

8/27 3/2

9/1 3/2

1/13

6/16 2/4

(b)

6/13 1/7

APR MAY JUN JUL AUG SEP OCT NOV DEC JAN FEB MAR

1990 1961

. 4/7 4/28

4/12

4/12

4/12 5/2

4/.7

4/12 5/2

4/17 .

5/2

(c)

NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP OCT

1970 1971

Changnon and Eaaterling

LOCAL-STATE INSTITUTIONALADJUSTMENT ISSUES

The array of drought impacts led to many publicand government adjustments which were assessed forthe 1976-1977 and 1980-198 1 droughts (Illinois TaskForce on Drought, 1977; Changnon, et al., 1982;Illinois Division of Water Resources, 1982). In severalgovernment agencies, adjustments included provisionof extra staff time and facilities, and expenditures ofstate funds beyond normal budgeted amounts. Thebasic activities of local government involved adjust-ments to local municipal water supply problems,enforcement of various local regulations relating towater use, and encouragement or enforcement of localconservation procedures. The different reactions ofsmall communities to the 1980-198 1 drought wereillustrated in case studies of a small town problems(Changnon, 1981).

Analysis revealed that because of the basic infre-quency of droughts in Illinois, many local and stated'ecision makers had no experience with drought.That is, those involved in making decisions to react todrought problems often found that it was the firsttime in their careers that a drought event hadoccurred. Hence, they had no experience to apply inthe reaction process.

In the fall of 1980, those attending a series of ninepublic forums held in Illinois to discern major waterresource issues ranked drought last in terms of over-all priority out of 11 critical water related issues(Illinois Division of Water Resources, 1983). This lowranking may have been to the fact that farmers, whoare often the first and most seriously affected bydrought, tend to face such hardships stoically and areaccustomed to taking whatever measures necessarythemselves to deal with drought problems. It is also afunction of the fact that when drought is not present,most local decision makers are not concerned; a notexpected situation when their turnover rate is consid-ered in light of prolonged periods between droughts.Many droughts do not generally affect all parts of thestate in an equally severe fashion. This condition ofpublic disinterest in planning for drought during non-drought intervals affects expenditures for neededadjustments.

The study of institutional adjustments revealedthat more useful drought information is needed forthose who will deal with future droughts. Most reme-dial actions that government entities can utilize relat-ing to water conservation and the seeking of interimor permanent water supplies are costly in both publicattitudes and economic terms. They are also difficultto employ, given the uncertain duration of a typicaldrought.


Various means are available to enable better deci-sions about drought and to lessen the effects. Thedrought severity must be quantified, and the mea-sures relating impacts to precipitation levels (whichcan be easily monitored) offered herein are a means toassess drought presence and severity. Long-rangeprecipitation predictions, even if statistically uncer-tain, are of extreme value in drought situations. Thiswas evident in a water management issue faced in a1984 dry period (Changnon and Vonnahue, 1986).State agency representatives on the Governor'sDrought Task Force utilized precipitation outlooks tohelp make a decision on the management of reser-voirs. This issue had sizable potential economic andpolitical impacts.

Weather modification to increase rainfall wasemployed and supported by agricultural interests in afour-county area in southern Illinois during the 1980-1981 drought (Changnon, et al., 1982).. The intentwas to increase rainfall during critical water demandperiods for corn and soybeans. Similarly, farmers,agribusiness, and local institutions in central Illinoisprovided funds to support cloud seeding efforts duringthe drought of 1976-1977.

SUMMARY

Drought is difficult to understand, quantify, andhence define because it represents a series of complexrelationships between physical aspects of the hydro-logic cycle, other environmental conditions, and socio-economic factors. Human impacts and adjustments todrought typically are tertiary in a structure that firstinvolves deficient precipitation (over varying timescales), then a sequence of alterations in the linkedcomponents of the hydrologic cycle, followed by out-comes like reduced crop yields with attendant lossesof farm income, or depleted reservoir supplies andthen modifications to dams and spiliways. This com-plexity of linkages and the inherent differencesbetween agricultural droughts, water supplydroughts, and economic droughts make "droughts"difficult for officials to interpret and to select properadjustments. Hence, definitive study of key impactsof droughts and how they relate quantitatively to theinitial causative conditions, deficient precipitation,was pursued using unique data sets from Illinois.The results should be transferable to other areas witha similar humid continental climate and physiogra-phy, and certain data analysis techniques testedshould prove useful in the analysis of drought impactsin other areas.


Problems with shallow ground water supplies dur-ing droughts, as reflected in the study of frequenciesof requests for well assistance over a 25-year period,are linked to the magnitude of the preciptation defi-ciency. A spatial comparison of well problems(requests) in severe drought areas and those in areaswith slight precipitation deficiencies indicated 57 to122 percent more problems (well requests) in thesevere areas. A before-and-after drought temporalanalysis revealed 50 percent more well problems dur-ing the two years embracing the drought.Furthermore, the magnitude of the problems wasdirectly related to the precipitation deficiency. Adecrease of precipitation in the driest six months of adrought from 65-70 percent of average to 35-40 per-cent, representing a mean decrease of 71 percent, wasassociated with an average increase of 82 percent inwell supply problems. In times before drought whenrequests were average, precipitation was near aver-age. These results indicate that when six-month pre-cipitation departures go below 60 percent of average,they should serve as a useful means for predictingwhen and where shallow ground water problemsoccur.

The magnitude of precipitation deficiencies forlonger time scales, 12 to 24 months or longer, wasfound to be well related to streamfiow conditions, andin turn, these were well related to water supply prob-lems and adjustments to alleviate these. In fact, thetypes of adjustments made, classed either as minorand temporary (conservation, water treatment, ratechanges), or as expensive, often permanent modifica-tions (raised dams, enlarged spillways, pipelines),during the four droughts of 195 1-1985 were found tobe related to the magnitude of the precipitation defi-ciency. The adjustment-precipitation relationshipvaried regionally and temporally. For example, a 12-month deficiency of 75 percent (or less) of averageprecipitation in southern Illinois always led to minoradjustments to surface water supply systems, and adeparture of 60 percent (or less) resulted in majoradjustments to several water supply systems in thedrought area. These two levels (departures fromaverage) causing two types of effects increased to 88percent and 70 percent, respectively, for droughtdurations of 24 months or longer in southern Illinois.

A newspaper content analysis of impacts andadjustments during three recent 12-month droughts(one began in fall, the others in spring) assessed howwell news articles described drought issues, andallowed spatial and temporal comparisons of droughtimpacts/adjustments with precipitation deficiencies.The spatial comparison of one drought, based on onenewspaper in a severe drought area and one nearby(64 km) but in a much lesser drought zone, revealedthat: (1) newspapers may be useful indicators of the

timing of statewide impacts and adjustments as adrought develops; and (2) they may be useful for mon-itoring localized (i.e., circulation areas) incidences ofdomestic and public sector drought problems.However, newspape:r accounts of agricultural droughtproblems were found to be not area specific, andinstead reflected wide area problems.

The timing of news articles about droughtimpacts/adjustments in severe drought areas wascompared with the time of precipitation drought onsetfor varying sectors and for three droughts. Thisrevealed that agricultural stress tends to be reportedsoon (2 to 6 weeks) after drought starts, regardless ofseason of onset. Further, public sector reports largelyreflected concerns over municipal water supplies andwater management, and occurred relatively soon, oneto three months, after the onset of drought, althoughcertain public sector problems appeared six monthsafter onset of the drought that began in the fall.Reports of impacts/adjustments in the commercialand domestic sectors were infrequent and mostappeared six to nine months after onset. In certainimpacted entities or activities where some degree ofdrought buffering exists (i.e., farm ponds, new wells)related adjustments (hauling of water, digging ofwells) occurred before impacts were reported, reveal-ing public anticipation of future problems.

Study of how adjustments were made to two pastdroughts by local and state institutions revealed thatmost decision makers had little or no experience withdrought problems, and in non-drought periods, thepublic and policy makers did not rate droughts inIllinois among the more serious water problems fac-ing the state. Clearly, more useful information aboutdroughts was needed including: (1) how precipitationdeficiencies related quantitatively to impacts (i.e., dowe have a drought and of what type, and how seri-ous?); (2) where and how to get correct information(many agencies involved); (3) the range of adjust-ments available coupled with assessments of theircosts and risks; and (4) predictions of future condi-tions (worse or better?). In this context, this paperhas presented information that pertains to the firstquestion, and we believe that other areas with compa-rable climate and physiography would experiencesimilar relationships between precipitation deficien-cies and problems related to shallow ground watersupplies (wells), surface water supplied reservoirs(and adjustments), and the timing of these and allother drought impacts after a precipitation droughtbegins.



ACKNOWLEDGMENTS

This paper was a result of research conducted on three grants:one from the Illinois Department of Energy an4Natura1 Resources;one from the National Science Foundation, ATM-84 13043; and onefrom NOAA, COIvIM NA8711-D-CP119 with the National ClimateProgram Office. The comments of Peter J. Lamb and Steven Sonkaare appreciated. Robert Olson provided the well records.

LITERATURE CITED

Changnon, S. A., 1980. Removing the Confusion Over Droughtsand Floods: The Interface Between Scientists and Policymakers.Water International 3:10-18.

Changnon, S. A., 1981. The 1980-81 Drought at Eldorado: APrecursor of Future Water Problems. illinois Municipal Review,pp. 10-11.

Changnon, S. A., G. Achtemeier, S. Hilberg, V. Knapp, R. Olson,W. J. Roberts, and P. Vinzani, 1982. The 1980-1981 Drought inIllinois: Causes, Occurrences, and Impacts. Report ofInvestigation 102, Illinois State Water Survey, Champaign,Illinois, 113 pp.

Changnon, S. A., J. Angel, M. Demissie, W. Easterling, K. Hendrie,F. Huff, C.-F. Hsu, R. Raman, G. Ramamurthy, D. Schnepper,K. Singh, and A. Tsihrintzis, 1987. Droughts in illinois: TheirPhysical and Social Dimensions. illinois State Water Survey,Champaign, illinois, 318 pp.

Changnon, S. A. and D. Vonnahme, 1986. Use of ClimatePredictions to Decide a Water Management Problem. WaterResources Bulletin 22:649-652.

Easterling, W. E. and S. A. Changnon, 1988. Climatology ofPrecipitation Droughts in Illinois Based on Water SupplyProblems. Physical Geography 8:362-377.

Hudson, H. E. and W. J. Roberts, 1955. The 1952-1955 IllinoisDrought With Special Reference to Impounding ReservoirDesign. Bulletin 43, Illinois State Water Survey, Urbana,Illinois, 52 pp.

Huff, F. A. and S. A. Changnon, 1964. Relation BetweenPrecipitation Deficiency and Low Streamflows. J. Geophys. Res.69:605-613.

Illinois Division of Water Resources, 1983. Drought ContingencyPlanning. Special Report No. 3, illinois State Water Plan TaskForce, IDOT, Springfield, Illinois, 31 pp.

Illinois Task Force on Drought, 1977. Drought in Illinois: AnAssessment with Recommendations. ESDA, Springfield,Illinois, 45 pp.

van Es, J. C., L. C. Keasler, and R. L. Whillenbarger, 1980. TheResponse of Illinois Municipal Water Systems to a ProlongedPeriod of Drought. Report 152, Water Resources Center,Champaign, illinois, 82 pp.

Wilhite, D. A. and M. H. Glantz, 1985. Understanding the DroughtPhenomenon: The Role of Definitions. Water International10:111-120.

Wilhite, D. A., N. J. Rosenberg, and M. H. Glantz, 1986. ImprovingFederal Response to Drought. J. Clim. and Appl. Meteorol.25:332-342.


measuring drought impacts: the illinois case

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