Gunasekara Nilupul Kalpana

English

博士学位論文の要旨及び審査結果の要旨 (Summary of Thesis(DR))othe

Gunasekara, Nilupul Kalpana

Tohoku University Repository (TOUR) / 東北大学機関リポジトリ

The impacts of climate and population changeon water conflicts estimated by theinequalities in water resource distributions著者 Gunasekara Nilupul Kalpana号 10学位授与機関 Tohoku University学位授与番号 環博第70号URL http://hdl.handle.net/10097/59064氏 名授 与 ザ戸4ー 位学位 記 番 号学位授与年月日学位授与の根拠法規研究科，専攻の名称学位論文題目ニルプル カルパナ グナセカラNilupul Kalpana Gunasekara 博士(環境科学)環博第 7 0 号平成 24 年 9 月 2 5 日学位規則第 4 条第 1 項東北大学大学院環境科学研究科(博士課程)環境科学専攻The impacts of climate and population change on water conflicts estimated by the inequalities in water resource distributions (水資源分布の不均一性から推定された水紛争への土地利用と人口変化の影響)指 導 教 員東北大学教授風間聡論文審査委員主査東北大学教授風間聡東北大学教授田中仁(工学研究科)論文内容要東北大学准教授李玉友ヒ二A日The rationale of this research is to assess the vulnerability and impacts of climate change and population change to the societ子 The social impact of climate change considered under this study is the increasing risk of water conflicts. The future vulnerability to the increased risk of water conflicts under climate change was assessed in terms of sensitivity and adaptability of countries to the risk of water conflicts. As employed in this research, a water conflict is a conflict which necessarily has its root causes in water related issues. However, the use of the term “Conflict" ranges from the situation commonly referred to as an argument, also to armed situations as well. Water availability was assumed as the simulated annual average river discharges of horizontal resolution 0.5 degrees, which is the potentially available water for the use by the population in the 0.5 degree grid. Data were obtained from the University of Tokyo, from the Total Runoff Integrating Pathways (TRIP) global river routing scheme under four climate scenarios, 20c3m for the present climate until 1999, and for future scenarios A1b, B1 and A2 until 2100, under four GCMs: CCSM3, MIROC3.2, CGCM2.3.2 and UKMO. The countries with different adaptabilities to the increased risk ofwater conflicts were first identified using a classification method (Table 1), which considers economic, social and physical parameters other than simple water availability directly affected by climate change. Table 1 The employed classification to identify different adaptabilities of countries to the increased risk of water conflicts -12-同ω芯556仏ロ。Z60出何回目c-h)3rd level Aquastat 2nd level 1 st level (Multivariate c1assification) World Bank Observed no conflicts estimated as the same 口 bservedviater ∞nfticts (low !evel or vota1ile) estimat凶 aswaもer confl兤t Observed no conflict estlmated aswater conf!ict O bse問dwater conflict (Iow 出 el Of VO凶le) estrnated as no ∞n時 IctNo data Fig. 2 The accuracy of the water conflict models in different regions. Within these conflict adaptability country groups, the inter-relation of water availability and the inequality of the water resources distribution, which are factors directly affected by climate change with the probability of water conflicts was investigated. Water conflicts models were derived and were validated for each water conflict adaptability country group , aiming to estimate the probability of water conflicts and the change in the likelihood of water conflicts thereby, because of climate change. Utilizing the validated water conflict models, the future vulnerabilities of countries to the increased risk of water conflicts were estimated. The plausibility of the results was confirmed across scenarios and in confirmation with the IPCC terminology for the classification of likelihood of an event. Within the 136 countries classified, only 116 countries of the classification could be confirmed, with a comparison to present conflict occurrences. Thirteen water conflict adaptability groups were identified (Fig. 1). The two highest conflict adaptability groups, with countries of low groundwater dependency (<50%) and high external water dependency (>30%) together with the lowest adaptive capacity (GNI per capita く 13 195 International Dollars, ppp) were classified with above 54% accuracy. The five adaptability groups with lowest water conflict adaptability have a total ability to address water conflicts in south and Southeast Asia, Mrica and South America. Inside the country groups similar in adaptability to the increased risk of water conflicts, the inter-relation of per capita water resources of a country and the inequality in distribution of the resource was explored. Conflict model derivation was conducted for 1990, and validation was conducted for the year 2000. Country groups with the lowest adaptability to water conflict incidence, the CG 1, CG2, CG3 and CG4 groups, showed significant associations with model 13 coefficients for Logit regressions on the near-future water-conflict indicators 5-year conflict and 5・year conflict risk. Inequality in per capita water distributions was highly associated with these two water-conflict variables. Country groups classified as having both the lowest economic capacity (per capita GNI (ppp) lower than 13195 International Dollars) and the lowest per capita water availability (CG 1 and CG3) showed an increasing probability of low-level and volatile water conflicts with increasing inequalities. Inequalities were highly significant in estimating volatile water conflicts in these two adaptability groups, whereas the odds of low-level conflict incidence were higher than those for the incidence of volatile water conflict. In indicating the incidence of water conflicts, the interactive country groups CG 10, CG 11 and CG 12 were the best modeled (Fig. 1 and Fig. 2), with an overall accuracy of 85.7% and a false-negative rate of 0.0%, whereas CG2 had the most modeling errors (a false-negative rate of 66.7% and a false-positive rate of 87.5%). However, CG2 produced an overall accuracy of 74.0%. The overall modeling of the incidence of water conflicts had an accuracy of 54.1% along with a false-positive rate of 34.0% and a false-negative rate of 11.9%. The sensitivity of the countries utilized for the classification to the parameters governing the water conflict models were explored next. The effectiveness of population policy to reduce the stress on per capita water was also explored. The risk of low-level water conflicts is more sensitive to the population changes than the risk of volatile water conflicts (Fig. 3). In reducing the population stress on the available water resources, population policy was proposed as a low-regret adaptation measure in the study. The fertility-reduction policy assumed (SC2) was very effective in reducing water stress in the countries suffering from water scarcity. They were effective in reducing the area stressed inside countries as well. By reducing the population stress on the available water resources, the risk of water conflicts, especially the risk of low-level water conflicts can be reduced (examples shown in Fig. 4 for Iraq and Kenya). The sensitivity of the countries to climate change impacts on water resources is lower than the sensitivity to population stress. By combining the adaptability of countries and the sensitivity to climate cha 14 0.45 0.16 一一ー一一一 、一一---"---~=一一一、、、、、, 、、、、、一一一一 守、、、、、0.12 0.4 0.14 • 0.35 一一一一ーー......_-----司惨ー--鳴ーーーー酔--'-----­a..…・-ー-，一、7' /' 0.3 酬。.25H U ?" 0.2 0.15 I 一一間b~~C1_1ra可I 一--A1b_SC2Jraq 0.1 -~一一一 一一-.ßl-_5C8惜守/ ---81ω5C2J日q0.05 !一 一一一 Alb_5CLKeoyaー一一-A1b_SC2_Kenya 81_5C1守Kenya0.06 一一一 A1b_5CUraq/ ----A1b_5C2_lraq 0.04 . f- ュー品怠1::5亡t同可→一一 81叩SC2Jraq0.Q2 -1 で=-:A1t三Q陸型通Lーーー-A1b_5C2_Kenya --Bl_SC1_Kenya 日+2000 2020 2040 2060 Year 2080 2100 2000 2020 2040 2060 Year 2080 2100 (a) (b) 日g. 3 (a) The variations ofthe risk oflow-level (C5R=1 , C5=1) and (b) the variations ofthe risk of volatile (C5R=2), for the water conf1ict adaptability country group CG 1 under the climate scenarios Alb, B1. SCl is the no-policy population scenario, while SC2 assumes population reduction policies resu1ting in uniform population growth rates across each country. 0.45 - 一一一一一一一0.40 0.40 1 0.352功。0.30 十一e-A1b SC1 Kenva --<>-A1b_5C2_Kenya ー+ー B1_SC1Jenya0.35 • 一一一行---，.:..--t一二三宍一一一一一一一一…ぷιιLと~--'-~2000 0.25 }u∞ ? ?? 。→-Alb-::，交IJl詞-<:>-Alb二支1:.-1阻q-←ー BUCIJraCjす0.20u v a 0.15 一一一一一一一0.10 0.05 ~ 0.05 2000 ~~- B1_SC2J悶q 且0.00 十一一一一一一一一 γ 一 一一 I 0.00 • 一 号ェ2100 o 10000 20000 30000 40000 50000 60000 70000 I 0 500000 1000000 1500000 2000000 2500000 3000000 Per capita water resources/ (m3/year) Per capita water resources/ (m3/year) (a) (b) Fig. 4 (a) The reductions in the risk of low-level water conf1icts in Iraq and (b) the reductions in the risk of low-level water conf1icts in Kenya resu1ted in by the applied population reduction policy scenario SC2, over the no"policy scenario SC1. of global or regional ground water data bases and the improvement of runoff data considering reservoir operations as well. At present, the primary spatial scale considered in the research is the country level, which is the basic decision"making unit in terms of international relations over water. Therefore, the results could be readily utilized in the international river basin management. Even though at this level, the method has limited applicability in the finer spatial and temporal scales because of inadequate data, with finer data, the applicability increases. The methodology utilized in this research employed the ground water dependency of a country as a local variable which enables the correct identification of outliers 匤 regression analyses in water conf1ict research. It also utilizes the Gini Coefficient to indicate the inequality in the water resource distributions over the traditional comparative resource use employed by water conf1ict research. For climate impact assessments and climate modelers, the population scenarios used in the research provides an important feedback of considering societal adaptation to climate policy and the significance of population growth in assessing future vulnerability of water resources. 15 論文審査結果の要旨人口増加に伴う社会環境変化と気候変動によって水資源の需要と供給の不安定が顕在化しており，将来の水紛争の増加が懸念されている.食糧問題との関連から水紛争が本格的な紛争に発展することも国際機関において危倶されている.このような背景から，本論文は，全球規模の様々なデータベースを利用して，水配分の不公平性と人口を地誠毎に角軌斤し，水紛争リスクを推定する手法を開発したものである.第 l 章は序論である.第 2 章は，全球規模の水の備自民味紛争に関する既往研究を収集し，本研究の1蛤1性と新規性について言及している.第 3 章では， 解析に手l開した全球のデータセットについて説明している.第4 章では，地下水依存性，外部からの水の依存性，人口あたりの水資源量，経済発展度，人口増加率を用いて，世界各国を水紛争リスクによって 13 段階に分類した. 108 か国が水紛争の高リスク 5段階に位置し，そのうちの上位 3 段階の制bの国に実際に水紛争が 1990 年から 20ω 年に柄主した.本章で得た成果は，水i昔、争のリスクを定量的にす刊面した初めての知見である.第 5 章は，水紛争リスクを推定するモデ、ルを開発した.モデ、ルの中核として，水資源量，人口，一人あたり水資源量のジニ係数を変数として持つ様々な関数を 1990 年のデータを用いて検討を行い， logit 関数が最も優れていることを示した. 2000 年のデータによってモデ、ルの検証を行し\良好な結果を得た.全球の水紛争を水の観的も推定するそデ、ルは過去になく，極めて重要な成果である.第6 章では，得られたモデルを用いて各国の水紛争に与える影響の感度分析を行った.その結果，最も水紛争のリスクが高く分類される国において，人口当たりの水資源が最も感度の高いことが珊卒された.最もリスクの高く分類される国においてジニ係数が 0.8 以上の場合は，将来に水紛争リスクが急激に上昇することが示された.これらの結果は，気候変動と人口変化について考察されており，世界の水資源の偏在性をもたらす要因を特定した.これは世界の安全保障上，重要な知見である.第 7 章では 6 章を踏まえて，将来の気候モデル、ンナリオと人口変化シナリオを用いて，銀求の将来の水紛争リスクの銀求分布を示した.特に中国は将来の水紛争リスクが高く，ロシアl地に低いと推定された.本章で得られた水紛争リスク地図は，将来の各地誠の水厳争リスク情報を与えると同時に，各国の水資源計画と水資源管理の政策に指針を与えるものであり，極めて有用性の高い成果である.第8 章は結論である.以上要するに本論文は，様々な社会環境と水文情報のデータを用いて全球の水紛争リスクを推定する手法を開発し，将来シナリオによって将来の水紛争リスク分布図を示すことに成功した.本手法の成果は，世界各国の水資源、計画立案と将来の水資源管理に大きく貢献できる成果である.よって，材命文出専士(環境科学)の学位論文として合格と認める.-16-

The impacts of climate and population change on water conflicts estimated by the inequalities in water resource distributions

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水資源分布の不均一性から推定された水紛争への土地利用と人口変化の影響

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