付記する学位プログラム名: グローバル生存学大学院連携プログラム / 京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21058号 / 工博第4422号 / 新制||工||1687(附属図書館) / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 寶 馨, 教授 堀 智晴, 准教授 佐山 敬洋 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Climate change is expected to increase the frequency, intensity and duration of droughts in all parts of the United States (US). Snow packs are disappearing earlier in the spring and summer, with reduced stream-flow. Lower reservoir levels, higher temperatures, and greater precipitation variability have been observed. Drought events in the US have threatened drinking water supplies for communities in Maryland and Chesapeake Bay as observed in 2001 through September 2002; Lake Mead in Las Vegas in 2000 through 2004; Peace River and Lake Okeechobee in South Florida in 2006; and Lake Lanier in Atlanta, Georgia in 2007. ENSO influences the climate of Florida; where El Niño years tend to be cooler and wetter, while La Niña years tend to be warmer and drier than normal in the fall through the spring, with the strongest effect in the winter. Both prolonged heavy rainfall and drought potentially have impacts on land uses and many aspects of Florida's economy and quality of life. Drought indices could integrate various hydrological and meteorological parameters and quantify climate anomalies in terms of intensity, duration, and spatial extent, thus making it easier to communicate information to diverse users. Hence, understanding local ENSO patterns on regional scales and developing a new land use drought index in Florida are critical in agriculture and water resources planning and managements. Current drought indices have limitations and drawbacks such as calculation using climate data from meteorological stations, which are point measurements. In addition, weather stations are scarce in remote areas and are not uniformly distributed. Currently used drought indices like the iv PDSI and the Standardized Precipitation Index (SPI) could not fully demonstrate the land use effects. Other limitations include no single index that addresses universal drought impact. Hence, there is a renewed interest to develop a new “Regional Land Use Drought Index (RLDI) that could be applied for various land use areas and serve for short term water resources planning. In this study, the first and second research topics investigated water and energy budgets on the specific and important land use areas (urban, forest, agriculture and lake) in the State of Florida by using the North American Regional Reanalysis (NARR) reanalysis data. NARR data were used to understand how drought events, EI Niño, La Niña, and seasonal and inter-annual variations in climatic variables affect the hydrologic and energy cycle over different land use areas. The results showed that the NARR data could provide valuable, independent analysis of the water and energy budgets for various land uses in Florida. Finally, the high resolution land use (32km×32km) adapted drought indices were developed based on the NARR data from 1979 to 2002. The new regional land use drought indices were developed from normalized Bowen ratio and the results showed that they could reflect not only the level of severity in drought events resulting from land use effects, but also La Niña driven drought impacts.

Anthropogenic activities including urbanization, rapid industrialization, deforestation and burning of fossil fuels are broadly agreed on as primary causes for ongoing climate change. Scientists agree that climate change over the next century will continue to impact water resources with serious implications including storm surge flooding and a sea level rise projected for North America. To date, the majority of climate change studies conducted across the globe have been for large-sized watersheds; more attention is required to assess the impact of climate change on smaller watersheds, which can help to better frame sustainable water management strategies. In the first of three studies described in this dissertation, trends in annual precipitation and air-temperature across the Commonwealth of Kentucky were evaluated using the non-parametric Mann-Kendall test considering meteorological time series data from 84 weather stations. Results indicated that while annual precipitation and mean annual temperature have been stable for most of Kentucky over the period 1950-2010, there is evidence of increases (averages of 4.1 mm/year increase in annual precipitation and 0.01 °C/year in mean annual temperature) along the borders of the Kentucky. Considered in its totality, available information indicates that climate change will occur – indeed, it is occurring – and while much of the state might not clearly indicate it at present, Kentucky will almost certainly not be exempt from its effects. Spatial analysis of the trend results indicated that eastern part of the state, which is characterized by relatively high elevations, has been experiencing decreasing trends in precipitation. In the second study, trends and variability of seven extreme precipitation indices (total precipitation on wet days, PRCPTOT; maximum length of dry and wet periods, CDD and CWD, respectively; number of days with precipitation depth ≥20 mm, R20mm; maximum five-day precipitation depth, RX5day; simple daily precipitation intensity, SDII; and standardized precipitation index, SPI were analyzed for the Kentucky River Basin for both baseline period of 1986-2015 and the late-century time frame of 2070-2099. For the baseline period, the majority of the indices demonstrated increasing trends; however, statistically significant trends were found for only ~11% of station-index combinations of the 16 weather stations considered. Projected magnitudes for PRCPTOT, CDD, CWD, RX5day and SPI, indices associated with the macroweather regime, demonstrated general consistency with trends previously identified and indicated modest increases in PRCPTOT and CWD, slight decreases in CDD, mixed results for RX5day, and increased non-drought years in the late century relative to the baseline period. The study’s findings indicate that future conditions might be characterized by more rainy days but fewer large rainfall events; this might lead to a scenario of increased average annual rainfall but, at the same time, increased water scarcity during times of maximum demand. In the third and final study, the potential impact of climate change on hydrologic processes and droughts over the Kentucky River basin was studied using the watershed model Soil and Water Assessment Tool (SWAT). The SWAT model was successfully calibrated and validated and then forced with forecasted precipitation and temperature outputs from a suite of CMIP5 global climate model (GCMs) corresponding to two different representative concentration pathways (RCP 4.5 and 8.5) for two time periods: 2036-2065 and 2070-2099, referred to as mid-century and late-century, respectively. Climate projections indicate that there will be modest increases in average annual precipitation and temperature in the future compared to the baseline (1976-2005) period. Monthly variations of water yield and surface runoff demonstrated an increasing trend in spring and autumn, while winter months are projected as having decreasing trends. In general, maximum drought length is expected to increase, while drought intensity might decrease under future climatic conditions. Hydrological droughts (reflective of water availability), however, are predicted to be less intense but more persistent than meteorological droughts (which are more reflective of only meteorological variables). Results of this study could be helpful for preparing any climate change adaptation plan to ensure sustainable water resources in the Kentucky River Basin.

Made available in DSpace on 2015-03-26T13:49:59Z (GMT). No. of bitstreams: 1 texto completo.pdf: 815766 bytes, checksum: bf680fb880109e605257b542185cf6cf (MD5) Previous issue date: 2008-07-21 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This study investigates the relationship between agricultural yield and drought in the state of Minas Gerais. Climate changes have warned to possible increases in meteorological extremes worldwide, as well as have uncertainties on how the climatic events might change the environment and affect world agricultural production in the future. Meteorological data from 1973 to 2004 and data projected by the ECHAM5/MPI-OM model for 2008 to 2020 based upon the scenario A1B. During the period from 1973 to 2004, corn productivity data obtained from the IBGE was used and future productivity estimates were performed using the Agro-ecological Zone (AEZ) methodology. The Palmer drought severity index (PDSI) and the Z index were used in a regression model which considered productivity as a dependant variable and the indices as independent variables. The performance of these models was verified by the following statistical coefficients: determination coefficient (r2), root mean squared error (RMSE), mean absolute error (MAE) and the Willmott index of agreement (d). The results demonstrated variation in the observed productivity (IBGE data) were poorly explained by the PDSI and Z index, as all model predictions for the different regions presented agreement values less than 0.5 with the observed values as well as extremely low determination coefficient values. Scenario A1B illustrated Willmot agreement values ranging from 0.48 to 0.90 as well as slightly more significant r2 values. However, productivity estimated by the AEZ presented significant loss for the harvests of 2008/2009, 2009/2010, 2014/2015 and 2018/2019 due to the lack of water in the Triângulo/Alto Paranaíba, Central Mineira and Jequitinhonha regions. The drought index predictions show that when working alone, these indices have not proven to be efficient to evaluate variations in productivity. Further, since the AEZ methodology only considers water limitations and one of the great uncertainties in climate models is precipitation, these results do not spare the need for further studies with more complete productivity simulation models, evaluating with different emission scenarios and more adequate agricultural drought indices. / As mudanças climáticas trazem um alerta para um possível aumento de eventos meteorológicos extremos em todas as regiões do globo, sendo crescente a preocupação sobre como os elementos climáticos vão mudar o ambiente e afetar a produção das culturas agrícolas em todo o mundo. Com isso, este estudo investiga a relação entre a produtividade agrícola e a seca em algumas mesorregiões do estado de Minas Gerais, em cenários de mudanças climáticas. Foram utilizados os dados diários meteorológicos históricos do período de 1973 a 2004, e dados projetados pelo modelo ECHAM5/MPI-OM para o período de 2008 a 2020 para o cenário A1B. No período de 1973 a 2004 foram utilizados os dados de produtividade do milho do IBGE e para estimativas da produtividade futuras utilizou a metodologia da zona agroecológica (AEZ). Os índices de severidade de seca de Palmer (PDSI) e o índice Z foram utilizados em um modelo de regressão, que considera a produtividade a variável dependente e esses índices as variáveis independentes. O desempenho desses modelos foi verificado por meio das estatísticas: coeficiente de determinação (r2), raiz do erro quadrático médio (RMSE), erro absoluto médio (MAE) e índice de concordância de Willmott (d). Os resultados mostraram que as variações na produtividade observada (dados do IBGE) não foram bem explicadas pelos índices PDSI e o índice Z, com todos os modelos preditos para as diferentes mesorregiões apresentando menos de 0,5 de concordância com os valores observados e baixíssimos valores do coeficiente de determinação. Para o cenário A1B, os resultados do índice de concordância de Willmott variaram entre 0,48 a 0,90 e os valores de r2 foram um pouco mais significativos. Contudo, a produtividade estimada pela AEZ apresentou perdas significativas devido a limitações por água para os anos agrícolas de 2008/2009, 2009/2010, 2014/2015, 2018/2019 para as mesorregiões Triângulo/Alto Paranaíba, Central Mineira e Jequitinhonha. As predições do índice de seca indicam que quando empregados sozinhos, esses índices não se mostraram muito eficientes para avaliar a variabilidade da produtividade. Além disso, como a metodologia AEZ considera apenas limitações por água e uma das grandes incertezas nos modelos de clima futuro é a precipitação, esses resultados não dispensam a necessidade de estudos posteriores, com modelos de simulações de produtividade mais completos, avaliação com diferentes cenários de emissões e índices mais adequados para seca agrícola.

Submitted by Neusa Fagundes (neusa.fagundes@unioeste.br) on 2017-09-21T14:14:56Z No. of bitstreams: 1 Luciana_Quadros2017.pdf: 3841180 bytes, checksum: d0ca719c2ed9296ba68c6d8f3de2bf4b (MD5) / Made available in DSpace on 2017-09-21T14:14:56Z (GMT). No. of bitstreams: 1 Luciana_Quadros2017.pdf: 3841180 bytes, checksum: d0ca719c2ed9296ba68c6d8f3de2bf4b (MD5) Previous issue date: 2017-02-09 / This research aims to show meteorological drought occurrences in Paraná State and to present possible future scenarios concerning this extreme weather. There was some requirement to understand better the rainfall patterns in Paraná State when data were analyzed at first, since there were an extensive series of historical precipitation data, from 1980 to 2010 and simulated data by the global model MIROC5 nestled with the Eta regional model, for the future until 2050. The first paper aims to detect analyze variability and precipitation trend in Paraná. Non-parametric tests were applied to detect precipitation trends as well as compare data from historical series with future data. The results have called the researcher’s attention due to the great variability and significant changes in the average monthly precipitation that can occurred in the studied State. Secondly, the extreme drought theme was approached based on the historical series from 1980 to 2015. The second paper aims to analyze variability and future scenarios of drought in Paraná State, using the standardized drought index. The results show that, although there is an increasing trend of precipitation in the State, there is also a change concerning the drought scenario, which warns of a possible decrease in water availability, especially in the Metropolitan mesoregion. Changes in water resources management policies would be interesting to help future mitigation actions of this phenomenon. / Esse trabalho científico tem como objetivo mostrar ocorrências de seca meteorológica sobre o Estado do Paraná e mostrar possíveis cenários futuros desse extremo climático. Em uma primeira análise dos dados, como tínhamos uma série abrangente de precipitação (período de 1980 a 2010) e também dados simulados pelo modelo global MIROC5 aninhado com o modelo regional Eta (para o futuro até 2050), observamos a necessidade de se entender melhor o regime de precipitação no Estado do Paraná. O artigo 1 tem como objetivos detectar e analisar a variabilidade e a tendência de precipitação sobre o Estado, bem como comparar dados da série histórica com dados da série futura. Os resultados chamam atenção para a grande variabilidade e mudanças significativas na precipitação média mensal que poderão ocorrer no Estado do Paraná. Em um segundo momento, o tema seca extrema foi abordado, com série histórica dos anos de 1980 a 2015. O artigo 2 tem como objetivo analisar a variabilidade e os futuros cenários de seca sobre o estado do Paraná, utilizando o índice padronizado de seca. Os resultados mostram que, apesar de haver uma tendência crescente de precipitação sobre o Estado, também há mudança do cenário de seca, a qual alerta sobre uma possível redução da disponibilidade hídrica, principalmente na mesorregião Metropolitana. Mudanças nas políticas de gestão dos recursos hídricos seriam importantes para auxiliar futuras ações mitigadoras desse fenômeno.

Droughts can have far-reaching and devastating effects on all sectors of society and ecology and future changes to drought and flood patterns are uncertain. This uncertainty has led to a lax response from local officials in dealing with mitigation and adaptation, particularly in Sweden. As such, this study focused on providing more localized estimates of future drought trends in Sweden so that policy makers can make informed decisions. To assess impacts to different sectors, the results from ten different climate model simulations between 1961-2100 under different emission scenarios, along with hydrological model simulations, were evaluated throughout Sweden for 50 different catchments using a variety of meteorological and hydrological drought indices. We projected a consistent and significant increase in drought severity, duration, and intensity over the course of the 21st century in many parts of Sweden under both moderate and high emission scenarios (RCP 4.5 and RCP 8.5). However, models were in less agreement on the sign of change of drought frequency. These results are highly consistent with more regional pan-European studies on drought, but also show significant departures due to local catchment-specific variability in some forms of drought. Local impacts to agriculture, energy production, water supply, public health, and fresh-water ecosystems are briefly discussed. These results are likely underestimates of future drought due to biases in the models. Improved formulations of drought indices along with a more robust statistical handling of the model output could reduce these uncertainties. / Torka kan ha förödande effekter på samhälle och ekosystem. På grund av ökande nederbörder och temperaturer är förändringar i torka och översvämningar osäkra. Dessa osäkerheter har lett till slappa åtgärder från politiker och lokala tjänstemän vars syfte är att anpassa samhället inför torka och översvämningar. I och med detta fokuserade denna studie på att ge mer lokaliserade uppskattningar av framtida torktrender i Sverige så att beslutsfattare kan fatta välgrundade beslut. För detta utvärderades resultat från olika klimatmodeller och simuleringar av avrinnesområden mellan 1961-2100 under olika utsläppsscenarier. Dessa utfördes i hela Sverige för 50 olika avrinningsområden för att bedöma effekterna av framtida torka på olika samhällsfunktioner, så som jordbruk, energiproduktion, vattenförsörjning, folkhälsa, och ekosystem. De flesta modellerna visade en överensstämmande ökning av torkans magnitud, varaktighet och intensitet under 2007-2100 i många delar av Sverige under både måttliga och höga utsläppsscenarier. Modellerna var dock mindre överens om förändring av torkfrekvensen. Dessa resultat överensstämmer mycket väl med mer regionala studier av Europa men visar också tydliga skillnader på grund av lokal variation, vilket har olika effekter på olika samhällsfunktioner. Det visade sig även att klimatmodellerna och våra metoder hade en tendens att överskatta bland annat nederbörd, vilket innebär att dessa resultat sannolikt är underskattningar av framtida torka.

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