The role of weather and climate variability on the health of Aboriginal people in Fort Albany and Toronto, Ontario, Canada is explored through four complementary research studies. The first study examined past temperature trends of Fort Albany (using climate records of Moosonee) and Toronto. Temperature variability was found to be greater in Moosonee than in Toronto, and day to day temperature minimum (Tmin) threshold exceedances of 5 degrees Celsius was found to have significantly declined in both Toronto and Fort Albany. The second study explored the effects of climate change on a rural First Nation group in Fort Albany. Observed environmental changes include changes in the timing of seasons, spring melt and ice freeze-up; warmer seasons, an increase in extreme and unpredictable weather, and changes in animal patterns. These changes have affected subsistence harvesting activities and community infrastructure, which have lead to increased health risks, though many community members have exhibited resiliency and adaptation. The third study compared current health status between an urban Aboriginal and non-Aboriginal group. Urban Aboriginal participants were found to be at greater risk to psychological distress and seasonal affective disorder (SAD) than non-Aboriginal participants. Moreover, those who self-rated their health as poor/fair were more likely to exhibit psychological distress than those who self-rated their health as good/very good/excellent. The fourth study compared the effects of weather and seasonal change among a rural First Nation group, an urban Aboriginal group and an urban non-Aboriginal group. Urban Aboriginal participants were most affected by weather while rural Aboriginal (i.e. First Nation) participants were least affected by weather. These studies demonstrate that both urban and rural Aboriginal groups may be at risk to climate change and weather-related changes; though specific implications may differ due to different lifestyles and capacities to adapt to environmental conditions.

South Asia, a land of contrasting landscapes, seasons and climates, is highly vulnerable to climate variability over intra-seasonal to decadal time scales. In winter, precipitation over the western parts of south Asia and fog over the Indo-Gangetic (IG) plains are the two major climatic features. During summer most of the region comes under the grip of monsoon. Winter precipitation over the north-western parts of South Asia is associated with eastwards propagating ‘western disturbances’ originating mostly from Mediterranean. Both observations and regional climate-model simulations show that the winter precipitation increases/decreases during the positive/negative phases of the North Atlantic Oscillation (NAO) and the warm/cold phase of the El Niño-Southern Oscillation (ENSO). During these phases, the intensification of western disturbances results from the effect of an enhanced trough visible at sea-level as well as at higher altitudes over central Asia. The inter-annual variability of fog is coupled over IG plains with a significant trend in the fog frequencies, both in observations and ERA-Interim reanalysis data. This increase shows two distinct regime shifts in 1990 and 1998 with respect to mean and variance, this in contrast to a gradual increase of the humidity over the region. The thermodynamic analysis of the intra-seasonal summer monsoon active phases (APs) over Pakistan revealed that a few days before AP, an upper-level warm anomaly appears over the northern Hindu Kush-Himalaya region and is reinforced by surface heating. The baroclinic height anomalies, with a low-level anticyclone located east of the warming, causes a moisture convergence, strong enough to overcome the preexisting stable atmospheric conditions. The extratropical dynamics also play an important role for the inter-annual variation of the South-Asian monsoon. It is found that the two leading modes between the upper-level circulation in the Atlantic/European region and monsoon rainfall are the Circumglobal Teleconnection (CGT) and the summer NAO. The positive phase of the CGT is related to a widespread increase of monsoon rainfall, and a positive summer NAO is related to a precipitation dipole with its positive anomaly over Pakistan. / At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Submitted.

Esta tese investiga se eventos anômalos de precipitação pluviométrica (PP) na Planície Costeira do Rio Grande do Sul (PCRGS) estão relacionados a modos de variabilidade climática e como essa relação pode afetar o ambiente costeiro. A PP e suas anomalias foram estatisticamente correlacionadas aos modos de variabilidade climática, o Modo Anular do Hemisfério Sul (SAM) e El Niño - Oscilação Sul (ENOS). O índice do ENOS utilizado foi o Multivariate ENSO Index (MEI) e do SAM foi o de Nan e Li (2003). Para o cálculo das anomalias de PP foram utilizados dados do satélite Tropical Rainfall Measurement Mission, entre 1998 e 2013. As correlações foram calculadas por meio de matrizes de classificação, e suas significâncias pelo teste-t de Student. A área de estudo foi dividida em costas sul (33°44’39” – 32°09’36”S), central (32°09’36” – 30°10’12”S) e norte (30°10’12” – 29°19’34”S) e para cada uma delas foi escolhido um geoindicador (sangradouros ou lagunas), examinados em imagens de satélite. Comparouse os geoindicadores em períodos de PP anomalamente positiva e negativa. Para destacar as variações nos geoindicadores foram utilizadas composições RGB 543 dos sensores Thematic Mapper (TM) e Enhanced Thematic Mapper Plus (ETM+) do Landsat. Os resultados apontam para correlação negativa entre as anomalias de PP nas costas sul e central com o SAM e correlação positiva das anomalias de PP da costa sul com o MEI. A PP na costa norte não apresenta correlação com nenhum dos dois índices. Foram identificados 28 eventos anômalos de PP no período 1998-2013. Nas imagens de satélite todos geoindicadores apontaram para variações morfológicas e hídricas entre os períodos PP acima e abaixo da média, sendo a costa norte a que apresenta menor variação visível. A costa sul tem a menor média de PP e o maior número de eventos anômalos de PP, dos quais 67% eram de PP negativa. A maioria dos eventos são de PP negativa (78%) e podem estar relacionados simultaneamente ao SAM positivo e MEI negativo, ou somente ao MEI positivo. Todos eventos de PP positiva foram concomitantes ao MEI positivo. As costas sul e central mostram uma redução na PP média. Essa tendência pode estar relacionada as mudanças climáticas globais, pela intensificação do SAM positivo e de eventos El Niño e La Niña. As variações observadas nos geoindicadores (sangradouros ou lagunas) indicam que a redução na PP média resulta em menor volume de sedimentos transportados do pós praia para a zona de arrebentação e face praial, alterando o balanço sedimentar. As areias secas dos campos de dunas transportadas pelo vento podem assorear lagos e lagunas da área de estudo, desequilibrando o ecossistema. / This thesis investigates whether anomalous events of precipitation (PP) in the Coastal Plain of Rio Grande do Sul (RGSCP) are related to climate variability modes and how this relationship can affect the coastal environment. The PP and its anomalies were statistically correlated to climate variability modes, the Southern Annular Mode (SAM) and El Niño-Southern Oscillation (ENSO). The used ENSO index was the Multivariate ENSO Index (MEI) and SAM is the one defined by Nan and Li (2003). For the calculation of the PP anomalies, we used data from the Tropical Rainfall Measurement Mission satellite, from 1998 to 2013. Correlations were calculated using classification matrices, and their significance by the the Student t-test. The study area was divided into south (33°44'39" – 32°09'36"S), central (32°09'36"– 30°10'12"S) and north (30°10'12"– 29°19'34"S) coasts and for each one it was chosen a geoindicador (washouts or lagoons), examined on satellite images. This investigation compared the geoindicators in positive and negative anomalous PP periods. To highlight variations in the geoindicators, it was used the RGB 543 composition of the Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) Landsat sensors. The results point to a negative correlation of the PP anomalies in the southern and central coasts with the SAM and a positive correlation of PP anomalies in the south coast with the MEI. The north coast PP is not correlated with any of the two indexes. Twenty-eight anomalous PP events were found in the 1988–2013 period. In satellite images, all geoindicators pointed to morphological and hydrological variations between periods of PP above and below the mean, the northern coast has the least visible variations. The south coast has the lowest mean PP and the largest number of anomalous events, of which 67% were negative PP. The majority of events are negative PP (78%), they could be simultaneously connected to a positive SAM and a negative MEI, or only to a positive MEI. All positive PP events were concomitant to a positive MEI. The central and southern coasts show a decrease in the men PP. This trend may be related to global climate change, by the intensification of the positive SAM and of El Niño and La Niña events. The variations observed in geoindicators (washouts or lagoons) indicate that the reduction in the mean PP results in lower volume of sediments transported from the backshore to the surf zone and the shoreface, changing the sedimentary balance. The dry sands from the wind-transported dune fields could silt up lakes and lagoons of the study area, unbalancing the ecosystem.

Esta tese investiga se eventos anômalos de precipitação pluviométrica (PP) na Planície Costeira do Rio Grande do Sul (PCRGS) estão relacionados a modos de variabilidade climática e como essa relação pode afetar o ambiente costeiro. A PP e suas anomalias foram estatisticamente correlacionadas aos modos de variabilidade climática, o Modo Anular do Hemisfério Sul (SAM) e El Niño - Oscilação Sul (ENOS). O índice do ENOS utilizado foi o Multivariate ENSO Index (MEI) e do SAM foi o de Nan e Li (2003). Para o cálculo das anomalias de PP foram utilizados dados do satélite Tropical Rainfall Measurement Mission, entre 1998 e 2013. As correlações foram calculadas por meio de matrizes de classificação, e suas significâncias pelo teste-t de Student. A área de estudo foi dividida em costas sul (33°44’39” – 32°09’36”S), central (32°09’36” – 30°10’12”S) e norte (30°10’12” – 29°19’34”S) e para cada uma delas foi escolhido um geoindicador (sangradouros ou lagunas), examinados em imagens de satélite. Comparouse os geoindicadores em períodos de PP anomalamente positiva e negativa. Para destacar as variações nos geoindicadores foram utilizadas composições RGB 543 dos sensores Thematic Mapper (TM) e Enhanced Thematic Mapper Plus (ETM+) do Landsat. Os resultados apontam para correlação negativa entre as anomalias de PP nas costas sul e central com o SAM e correlação positiva das anomalias de PP da costa sul com o MEI. A PP na costa norte não apresenta correlação com nenhum dos dois índices. Foram identificados 28 eventos anômalos de PP no período 1998-2013. Nas imagens de satélite todos geoindicadores apontaram para variações morfológicas e hídricas entre os períodos PP acima e abaixo da média, sendo a costa norte a que apresenta menor variação visível. A costa sul tem a menor média de PP e o maior número de eventos anômalos de PP, dos quais 67% eram de PP negativa. A maioria dos eventos são de PP negativa (78%) e podem estar relacionados simultaneamente ao SAM positivo e MEI negativo, ou somente ao MEI positivo. Todos eventos de PP positiva foram concomitantes ao MEI positivo. As costas sul e central mostram uma redução na PP média. Essa tendência pode estar relacionada as mudanças climáticas globais, pela intensificação do SAM positivo e de eventos El Niño e La Niña. As variações observadas nos geoindicadores (sangradouros ou lagunas) indicam que a redução na PP média resulta em menor volume de sedimentos transportados do pós praia para a zona de arrebentação e face praial, alterando o balanço sedimentar. As areias secas dos campos de dunas transportadas pelo vento podem assorear lagos e lagunas da área de estudo, desequilibrando o ecossistema. / This thesis investigates whether anomalous events of precipitation (PP) in the Coastal Plain of Rio Grande do Sul (RGSCP) are related to climate variability modes and how this relationship can affect the coastal environment. The PP and its anomalies were statistically correlated to climate variability modes, the Southern Annular Mode (SAM) and El Niño-Southern Oscillation (ENSO). The used ENSO index was the Multivariate ENSO Index (MEI) and SAM is the one defined by Nan and Li (2003). For the calculation of the PP anomalies, we used data from the Tropical Rainfall Measurement Mission satellite, from 1998 to 2013. Correlations were calculated using classification matrices, and their significance by the the Student t-test. The study area was divided into south (33°44'39" – 32°09'36"S), central (32°09'36"– 30°10'12"S) and north (30°10'12"– 29°19'34"S) coasts and for each one it was chosen a geoindicador (washouts or lagoons), examined on satellite images. This investigation compared the geoindicators in positive and negative anomalous PP periods. To highlight variations in the geoindicators, it was used the RGB 543 composition of the Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) Landsat sensors. The results point to a negative correlation of the PP anomalies in the southern and central coasts with the SAM and a positive correlation of PP anomalies in the south coast with the MEI. The north coast PP is not correlated with any of the two indexes. Twenty-eight anomalous PP events were found in the 1988–2013 period. In satellite images, all geoindicators pointed to morphological and hydrological variations between periods of PP above and below the mean, the northern coast has the least visible variations. The south coast has the lowest mean PP and the largest number of anomalous events, of which 67% were negative PP. The majority of events are negative PP (78%), they could be simultaneously connected to a positive SAM and a negative MEI, or only to a positive MEI. All positive PP events were concomitant to a positive MEI. The central and southern coasts show a decrease in the men PP. This trend may be related to global climate change, by the intensification of the positive SAM and of El Niño and La Niña events. The variations observed in geoindicators (washouts or lagoons) indicate that the reduction in the mean PP results in lower volume of sediments transported from the backshore to the surf zone and the shoreface, changing the sedimentary balance. The dry sands from the wind-transported dune fields could silt up lakes and lagoons of the study area, unbalancing the ecosystem.

nÃo hà / As peculiaridades de cada paÃs levam à utilizaÃÃo de mecanismos variados de alocaÃÃo de recursos hÃdricos, nÃo havendo uma regra geral para a resoluÃÃo do problema de escassez de Ãgua. O conhecimento dos modelos experimentados internacionalmente, com a identificaÃÃo de suas respectivas vantagens e desvantagens, sÃo de grande utilidade. O objetivo principal da gestÃo dos recursos hÃdricos à satisfazer a demanda, considerando as possibilidades e limitaÃÃes da oferta de Ãgua. Entretanto, para isso, à necessÃrio o conhecimento de todos os aspectos hidrolÃgicos, climatolÃgicos e fÃsicos da regiÃo para realizar um planejamento adequado de oferta hÃdrica, alÃm do conhecimento da populaÃÃo e dos mÃltiplos interesses, para um bom dimensionamento da demanda. Entretanto, quando o sistema hÃdrico à alimentado por influxos espacial e temporalmente variÃveis, que à o que ocorre em regiÃes semiÃridas, a escolha de um modelo eficaz de gestÃo dos recursos hÃdricos torna-se ainda mais complexa, devido Ãs incertezas presentes na avaliaÃÃo dos futuros nÃveis de Ãgua. Nestes casos, as incertezas tÃm um importante papel na gestÃo dos recursos hÃdricos. Em busca de um estudo mais profundo da gestÃo dos recursos hÃdricos nessas regiÃes de alta variabilidade climÃtica, foram tomados como anÃlise os modelos aplicados no Nordeste Brasileiro e na AustrÃlia. O presente trabalho apresenta a semelhanÃa nas caracterÃsticas do clima dessas regiÃes, a semelhanÃa nos problemas enfrentados por cada uma delas e, finalmente, traÃa um paralelo, atravÃs da anÃlise e comparaÃÃo dos diferentes mÃtodos de gestÃo dos recursos hÃdricos disponÃveis. / The peculiarities of each country lead to the use of various mechanisms of water allocation. There is no general rule for solving the problem of water scarcity. Understanding the models experienced internationally, identifying their respective advantages and disadvantages are very useful. The main objective of water management is to attend the demand, considering the possibilities and limitations of water supply. However, for this, it is necessary to know all hydrological, climatological and physical aspects of the region to conduct a proper planning of water supply, beyond the knowledge of the population and the multiple interests, to a good demand sizing. However, when the water system is supplied by spatial and temporal variability of inflows, as in semiarid regions, the choice of an effective model for water management becomes more complex, due to the uncertainties presented in evaluating future water levels. In these cases, uncertainties have an important role in water resources management. In the matter of a deep study of water resources management in these regions of high climate variability, models applied in Northeast Brazil and Australia were used as analysis. This paper presents the similarity of climate aspects, the similar problems faced by each region, and finally draws a parallel comparing different methods of available water management.

Este trabalho tem por objetivo relacionar as mudanças no comportamento climático precipitação, com o crescimento da mancha urbana do município de Taubaté. Por meio de analises estatísticas do comportamento na escala de tempo anual e mensal, comparou-se a precipitação de dados observacionais do passado (período de 1950 a 1999), coletadas junto ao pelo Departamento de Águas e Energia Elétrica (DAEE), com dados de precipitação do futuro (período entre 2000 e 2100), obtidos a partir de um modelo de Circulação Geral (modelo HadCM3 do Hadley Center do Reino Unido), utilizando-se os cenários A2 e B1 do Painel Intergovenamental para Mudanças Climáticas (IPCC). A análise do período comum (entre 1950 e 2000) mostrou que a precipitação gerada pelo modelo foi superior para os trimestres primavera e verão e inferior nos trimestres de outono e inverno. Em ambos cenários. Com os dados futuros (período de 2000 a 2099) e concluiu-se que os valores serão superiores para os cenários a A2 e B1 respectivamente, aumentando o índice do regime pluviométrico em 10,1% para o cenário A2 e em 2,6% para o cenário B1. Usando os dados do índice pluviométrico e do crescimento da mancha urbana do município de Taubaté, realizou-se uma análise sucinta dos Planos Diretores verificando o comprometimento destes com o meio ambiente e os problemas que as precipitações extremas poderão causar. / It is a known fact that the process of nature transformation became faster from the second half of the eighteenth century, with the industrial revolution, marked by the use of steam machinery. The process of urbanization triggered by industrialization caused a negative impact to the environment and climate changes. This work aims to relate changes in climatic behavior rainfall, with the growth of urban spot (area) of the city of Taubaté. Through statistical analysis of behavior in the time-scale yearly and monthly, we compared the rate of rainfall in the past observational data (period from 1950 to 1999), provided by the Department of Water and Power (DAEE) with A2 and B1 sceneries of Intergovernmental Panel for Climate Change (IPCC) and concluded that the volume of precipitation was higher for the spring and summer quarters for both sceneries. We used data from future simulation (period from 2000 to 2099) and concluded that the intense rainfall will be higher for the A2 scenery. Based on the pluviometric index data and the Taubaté city urban area growth, we carried out a succinct analysis of Taubaté city development plans evaluating its commitment to the environment and the problems that extreme precipitations could cause.

O objetivo deste trabalho é investigar a relação entre a Temperatura da Superfície do Mar (TSM) no Oceano Atlântico Sul (OAS) e a precipitação no estado de São Paulo. Para tanto, adotaram-se as escalas mensal e sazonal. A técnica estatística multivariada, chamada Análise de Componentes Principais (ACP, ou EOF em inglês) foi aplicada para definir as áreas homogêneas do oceano (de \'A\' a \'L\') e as subregiões do continente (de 1 a 7). Além da definição das áreas e sub-regiões, a ACP identificou muito bem os padrões espaciais da precipitação e da TSM em todas as escalas adotadas: mensal contínua, mensal descontínua e sazonal. Na ACP da série temporal sazonal de verão, o primeiro e o segundo modos da precipitação evidenciam a distribuição espacial típica de verão (zonal) para o estado de São Paulo, e a variância explicada por esses dois modos juntos é de 59,79% do total. Esta distribuição espacial já havia sido observada nas análises iniciais a partir das médias sazonais da precipitação, padrão que se explica pelos fluxos de umidade que, nesta estação, devido ao sistema de monções da América do Sul, movem-se mais intensamente em direção ao continente. Já na ACP da série temporal sazonal de inverno, o primeiro e segundo modos da precipitação evidenciam a distribuição meridional, com variância explicada de 39,15 e 17,77%, respectivamente. Os sistemas frontais no inverno agem como responsáveis por uma parcela considerável do total precipitado, o que explica o padrão meridional da chuva. Os coeficientes de correlação linear significativos entre as áreas oceânicas e sub-regiões continentais homogêneas demonstraram que a variabilidade sazonal da precipitação está associada à TSM, sobretudo na porção central da área estudada (próximo ao litoral sul e sudeste do Brasil), nas estações seca (abril a setembro) e chuvosa (outubro a março). Além das variáveis principais (precipitação e TSM), os campos de Radiação de Onda Longa Emergente (ROLE), Pressão no nível do Mar (PNM), e Divergência do ar em 250 e 850hPa auxiliaram na identificação dos padrões atmosféricos e na análise dos eventos extremos. As estações consideradas atípicas, ou seja, as que apresentaram média muito acima ou muito abaixo do desvio padrão, foram separadas em quatro classes: verão chuvoso, verão seco, inverno chuvoso e inverno seco. A partir da análise desses eventos, conclui-se então que a TSM do OAS pode alterar consideravelmente o padrão sazonal de precipitação no estado de São Paulo, principalmente se estiver atrelada a padrões atmosféricos. No inverno, anomalias negativas (positivas) de TSM estão associadas com a precipitação acima (abaixo) da média climatológica nesse estado. Devido a bloqueios atmosféricos no OAS no verão, a diminuição da passagem de sistemas frontais pode intensificar anomalias positivas no oceano, as quais estão associadas aos períodos chuvosos no sul do país e de seca no estado de São Paulo. / The purpose of this paper is to study the relationship between the Sea Surface Temperature (SST) in the South Atlantic Ocean (SAO) and the precipitation in São Paulo state. So, the monthly and seasonal scales were adopted. The Principal Component Analysis multivariate statistic technic (PCA, and also called EOF) was applied to define the oceans homogeneous areas (from A to L) and the continents sub-regions (from 1 to 7). Besides defining the areas and sub-regions, the PCA has identified very well the spatial patterns of the precipitation and SST in all the adopted scales: continuous monthly, discontinuous monthly and seasonal. In the PCA of the summer seasonal temporal series, the first and the second precipitations mode evidence the summer-typical spatial distribution (zonal) for São Paulo state, and the variance explained by these two modes together is 59,79% of the total. This spatial distribution was already noted in the first analysis from the seasonal precipitation averages, and such a pattern is explained by the flow of humidity, which in the summer, owing to the South America monsoon systems, move more intensely toward the continent. On the other hand, in the PCA of the winter seasonal temporal series, the first and the second precipitations modes evidence the meridional distribution, with a variance explained from 39,15 to 17,77%, respectively. The frontal systems in the winter act as responsibles for a substantial portion of the total of precipitation, which explains the rains meridional pattern. The significative linear correlation coefficients between the oceanic areas and the homogeneous continental sub-regions demonstrate that the precipitations seasonal variability is associated to the SST, mostly in the central portion of the studied area (next to the southern and southeastern Brazilian coast), in the drought season (from April to September) and rainy season (from October to March). Besides the principal variables (precipitation and SST), the fields of Outgoing Long wave Radiation (OLR), Sea-level Pressure (SLP) and air Divergence in 250 and 850hPa has helped to identify the atmospheric patterns and to analyze the extreme events. The atypical seasons, in other words, those which presented an average too high or too low compared to the standard deviation, were divided in four categories: rainy summer, drought summer, rainy winter and drought winter. With the analysis of these events, it is possible to conclude that the SST of the SAO can change substantially the precipitation seasonal pattern in São Paulo state, mainly if it is linked to atmospheric patterns. In the winter, SSTs negative (positive) anomalies are associated to the overage (underage) climatologic precipitation in this state. Owing to atmospheric blockades on the SAO in the summer, the decreasing transit of frontal systems can intensify positive anomalies in the ocean, which are associated to the rainy periods in the Brazilian South and drought periods in the São Paulo state.

O objetivo deste trabalho de pesquisa é o de buscar entender os tempos e eventos que determinaram as grandes mudanças climáticas no Éon Fanerozoico. Técnicas são constituídas, metodologias estabelecidas, e por vezes são aceitas como sendo as verdades científicas. Com as inovações nas técnicas, com o mudar das ciências, mudam as evidências, mudam as verdades, fazendo mudar nossa percepção do passado. Este trabalho apresenta elementos para um debate sobre o clima da Terra no Fanerozoico, estabelecido a partir de pesquisas bibliográficas sobre evidências passadas e atuais. / The goal of this research work is to understand the times and events that determined the great climatic changes in the Phanerozoic Eon. Techniques are constituted, methodologies are established, and are sometimes accepted as scientific truths. With innovations in techniques, with the change of science, change the evidence; change the truths, making change our perception of the past. This paper presents elements for a discussion on the Earth\'s climate in Phanerozoic established from bibliographical research on past and current evidences.

Land use change and climate variability are the main drivers of watershed hydrological processes. The main objective of this study was to assess the impact of land use change and climate variability on hydrology of the Mara River Basin in East Africa. Land use maps generated from satellite images were analyzed using the intensity analysis approach to determine the patterns, dynamics and intensity of land use change. Changes in measured streamflow caused separately by land use change and climate variability were separated using the catchment water-energy budget based approach of Budyko framework. The information on past impact of climate variability on streamflow was used to develop a runoff sensitivity equation which was then used to predict the future impact of climate change on streamflow. Finally, the impact of agroforestry on watershed water balance was predicted using SWAT (Soil and Water Assessment Tool) model. Deforestation and expansion of agriculture were found to be dominant and intensive land use changes in the watershed. The deforestation was attributed to illegal encroachment and excision of the forest reserve. The deforested land was mainly converted to small scale agriculture particularly in the headwaters of the watershed. There was intensive conversion of rangeland to largescale mechanized agriculture which accelerated with change of land tenure (privatization). The watershed has a very dynamic land use change as depicted by swap change (simultaneous equal loss and gains of a particular land use/cover) which accounted for more than half of the overall change. This implies that reporting only net change in land use (of MRB) underestimates the total land use change. The results show that streamflow of Nyangores River (a headwater tributary of the Mara River) significantly increased over the last 50 years. Land use change (particularly deforestation) contributed 97.5% of change in streamflow while the rest of the change (2.5%) was caused by climate variability. It was predicted that climate change would cause a moderate 15% increase in streamflow in the next 50 years. SWAT model simulations suggested that implementation of agroforestry in the watershed would reduce surface runoff, mainly due expected improvement of soil infiltration. Baseflow and total water yield would also decrease while evapotranspiration would increase. The changes in baseflow (reduction) and evapotranspiration (increase) were attributed to increased water extraction from the soil and groundwater by trees in agroforestry systems. The impact of agroforestry on water balance (surface runoff, baseflow, water yield and evapotranspiration) was proportional to increase in size of the watershed simulated with agroforestry. Modelling results also suggested that climate variability within the watershed has a profound effect on the change of water balance caused by implementation of agroforestry. It is recommended that authorities should pay more attention to land use change as the main driver of change in watershed hydrology of the basin. More effort should be focused on prevention of further deforestation and agroforestry may be considered as a practical management strategy to reverse/reduce degradation on the deforested parts of the watershed currently under intensive cultivation.

Finely laminated sediments within Bainbridge Crater Lake, Galapagos, provide a record of El Nino-Southern Oscillation (ENSO) events over the Holocene. Despite the importance of this sediment record, hypotheses for how climate variability is preserved in the lake sediments have not been tested. Here we present results of long-term monitoring of the local climate and limnology and a revised interpretation of the sediment record. Brown-green, organic-rich, siliciclastic laminae reflect warm, wet conditions typical of El Nino events, whereas carbonate and gypsum precipitate during cool, dry La Nina events and persistent dry periods, respectively. Applying this new interpretation, we find that ENSO events of both phases were generally less frequent during the mid-Holocene (similar to 6100-4000 calendar years B.P.) relative to the last similar to 1500 calendar years. Abundant carbonate laminations between 3500 and 3000 calendar years B.P. imply that conditions in the Galapagos region were cool and dry during this period when the tropical Pacific E-W sea surface temperature (SST) gradient likely strengthened. The frequency of El Nino and La Nina events then intensified dramatically around 1750-2000 calendar years B.P., consistent with a weaker SST gradient and an increased frequency of ENSO events in other regional records. This strong interannual variability persisted until similar to 700 calendar years B.P., when ENSO-related variability at the lake decreased as the SST gradient strengthened. Persistent, dry conditions then dominated between 300 and 50 calendar years B.P. (A.D. 1650-1900, +/- similar to 100 years), whereas wetter conditions and frequent El Nino events dominated in the most recent century. Plain Language Summary Sediments accumulating at the bottom of Bainbridge Crater Lake have provided a record of Galapagos climate and the frequency of El Nino events over the past similar to 6000 years. Motivated by the importance of this lake for our understanding of climate in the tropical Pacific Ocean, we have been monitoring the link between climate, lake conditions, and the physical and chemical properties of the lake sediments since 2009. Based on this long-term monitoring, we find that the Bainbridge sediment record preserves both El Nino and La Nina events. This makes Bainbridge a particularly valuable archive of past climate, as most sediment-based records typically preserve only one or the other key phase of tropical Pacific climate.