٨Research Trends and Results

Evaluation of degree of tolerationof drought by a social experiment


MITSUISHI Shinya, HeadTOYODA Tadahiro, ResearcherWater Management and Dam Division, River Department
1. Introduction
In Japan, normal responses in drought periods arerestrictions on water intake according to river flowrate or dam reservoir storage percentage from thestandpoint of managers, but responses from theperspective of water users considering their toleranceof droughts are rare. Therefore, the author’s performed
a water stoppage social experiment to survey andanalyze drought damage to clarify tolerance ofdrought in order to more rationally perform drought
adjustments including the perspective of the water
users in the future.
2. Outline of the water stoppage social experiment
The water stoppage social experiment wasperformed with the cooperation of Hirakata City inOsaka Prefecture. Artificial water stoppages todeliberately prevent water use by 60 households with153 members were performed for a total of 8 days,
with the water stopped for 6 hours for 3 days, 9 hours
for 3 days, and 12 hours for 2 days. The water
stoppage social experiment was short, so aquestionnaire survey based on the premise the drought
continued for a long period was carried out.
3. Analysis of the results of the survey
The results of the survey were analyzed in order tospecify the attributes with high impact on droughttolerance and to abstract attributes of weak toleranceof droughts. This analysis was performed using
quantification II type as the statistical method in orderto handle data which cannot be quantified, which is
the level of tolerance. Tolerance/non-tolerance was set
as the objective variable and the attribute as theexplanatory variable and a model formula shown as
formula (1) was prepared by stoppage time and byrestricted period.
Y: objective variable (tolerance/non-tolerance)
Xij: explanatory variable (each attribute)
X1j: sex, X2j: family constitutionai, bi, ci ---: category score (degree of impact onobjective variable)
A relational formula was prepared by treating theobjective variable Y as tolerance/non-tolerance, andthe explanatory variable Xij as monitor attribute, andsetting 1 in a case where each corresponds, and 0 in acase where each does not correspond. A simultaneous
equation was solved to maximize the correlation ratio,
and if the category score obtained was positive it wasjudged to be a factor working tolerably, and if it wasnegative, a factor working intolerably. As a result of
the analysis, “household with many members” and“household with all members 65 or older” were seen
to be factors acting intolerably.
4. Drought tolerance level
Next, in order to evaluate the level of tolerance fordroughts, water stoppage period and water stoppage
hours were organized based on a matrix. In responsesto the questionnaire survey, a regression curve on
which the percentage of “harsh” and the percentageof “harsh” and “a little harsh” are over 50% wasobtained based on the interpolation method, and set as
the boundary of each tolerance level. Figure 1 shows
the tolerance level curve. Tolerance
level 3: unbearable (overฃᔋ䊧䊔䊦㪊䋺ᚒᘟ䈪䈐䈭䈇
tolerationboundary) ㆊ䋩 [Z
䇭䋨ฃᔋ㒢⇇⿥ 4 
 Tolerance
level 2: suffers fromฃᔋ䊧䊔䊦㪉䋺ਇଢ⧰∩䉕
the inconveniencebut bearableᗵ䈛䉎䈏ᚒᘟ䈪䈐䉎  [Z
4 
 Tolerance
level 1: normal life 䈇↢ᵴฃᔋ䊧䊔䊦㪈䋺᥉Ბ䈫ᄌ䉒䉌䈭 “Littleharsh”‫ޟ‬߿߿෩ ߒ answer޿ ‫ ޠ‬࿁ rate:╵ Ყ50%₸ 㧑
“Harsh”
answerrate‫ޟ‬෩ߒ޿‫ޠ‬࿁╵
Ყ50%
₸ 㧑 ᢿ᳓ᦼ㑆㧔ᣣ㧕
Water stoppage
period (days)

Figure 1. Tolerance Level Curve
5. ConclusionBased on the results of analysis performed in thisresearch, persons requiring protection during a disaster
caused by a drought were specified, and tolerance
levels for droughts were set. We are counting on thefacts learned from this research being the basis for a
proposal for a study of a drought adjustment method
Water stoppage
time (hr/day)
ᢿ᳓ᤨ㑆㧔JTᣣ㧕

Research Trends and Results(Key words) Water stoppage social experiment, drought disaster, drought toleration level 㪈㪈㩼 㪉㪌㩼㪍㪋㩼 㪐㪇㩼㪍㪈㩼㪐㪎㩼㪉㩼 㪌㩼㪈㪐㩼㪊㪐㩼㪉㪉㩼 㪌㪉㩼㪏㪊㩼㪏㪎㩼㪈㩼 㪈㩼㪊㩼 㪈㪈㩼㪌㩼㪊㪊㩼㪎㪉㩼㪐㪎㩼㪈㪊㩼㪋㪌㩼including the perspective of water users to be applied
when future droughts occur.
http://www.nilim.go.jp/lab/fdg/index.htm (WaterManagement and Dam Division)

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