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Surface hydrologic modeling becomes a problem when insufficient spatial and temporal information is available. It is common to have useful modeling periods of less than 15 years. The purpose of this work is to develop a methodology that allows the selection of meteorological and hydrometric stations that are suitable for modeling when information is scarce in the area. Based on the scarcity of data, a series of statistical tests are proposed to eliminate stations according to a decision-making process. Although the number of stations decreases drastically, the information used is reliable and of adequate quality, ensuring less uncertainty in the surface simulation models. Individual basin modeling can be carried out considering the poor data. The transfer of parameters can be applied through the nesting of basins to have information distributed over an extensive area. Therefore, temporally and spatially extended modeling can be achieved with information that preserves statistical parameters over time. If data management and validation is performed, the modeled watersheds are well represented; if this is not done, only 26% to 50% of the runoff is represented.

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The demand for mountain water resources is increasing, and their availability is threatened by climate change, emphasizing the urgency for effective protection and management. The upper Sali-Dulce watershed holds vital significance as it contributes the majority of the Sali-Dulce water resources, supporting a densely populated dry region in Northwestern Argentina, covering an area of 24,217 km2. However, the potential impact of climate change and land use/land cover change on water yield in this watershed remains uncertain. This study employs the InVEST Annual Water Yield model to analyze the average water yield in the watershed and evaluate its potential changes under future scenarios of climate and land use/land cover change. InVEST was calibrated using data from multiple river gauges located across the watershed, indicating satisfactory performance (R2 = 0.751, p-value = 0.0054). Precipitation and evapotranspiration were the most important variables explaining water yield in the area, followed by land use. Water yield showed a notable concentration in the montane area with 40% of the watershed accounting for 80% of the water yield, underscoring the importance of conserving natural land cover in this critical zone. Climate change scenarios project an increase in water yield ranging from 21 to 75%, while the effects of land cover change scenarios on water yield vary, with reforestation scenarios leading to reductions of up to 15% and expansions in non-irrigated agriculture resulting in increases of up to 40%. Additionally, water yield distribution may become more concentrated or dispersed, largely dependent on the type of land cover. The combined scenarios highlight the pivotal role of land cover in adapting to climate change. Our findings provide valuable insights for designing future studies and developing policies aimed at implementing effective adaptation strategies to climate change within the Salí-Dulce watershed.

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Introdução: As mudanças climáticas podem afetar a qualidade e a disponibilidade dos recursos hídricos. Objetivo: Avaliar a tendência das séries temporais de precipitação e vazão e o impacto dos cenários climáticos projetados para o período de 2020-2050 na bacia hidrográfica Sorocaba- Médio Tietê-BHSMT e suas repercussões no abastecimento público de água. Método: Estudo de revisão narrativa sobre os impactos das mudanças climáticas na disponibilidade e qualidade da água. Um estudo de tendência dos dados históricos de precipitação e vazão do período de 1980 a 2020 de quatro estações localizadas na BHSMT, utilizado os métodos de Man-Kendall e de Pettitt. Aplicação do modelo SWAT (Soil Water Assessment Tool) para avaliar o impacto dos cenários climáticos RCP4.5 e RCP8.5 para o período de 2020 a 2050, no ciclo hidrológico da bacia e na disponibilidade de água para abastecimento público. Resultados: Existem muitas lacunas para compreender os impactos dos cenários climáticos nos recursos hídricos e suas repercussões na saúde da população. A análise de tendência dos dados de vazão e precipitação mostrou estacionariedade. A análise dos impactos dos cenários climáticos mostrou importante redução na precipitação e vazão, para ambos os cenários, em especial para o período de 2020-2030 e 2030-2040, oferecendo riscos ao abastecimento de público e segurança hídrica na região. Conclusão: Estratégias envolvendo ampla gama de áreas temáticas e perspectivas para garantir segurança hídrica e ampliar a resiliência das bacias frente aos efeitos das mudanças climáticas são necessárias.

Introduction: Climate change can affect the quality and availability of water resources. Objective: To evaluate the trend of precipitation and flow time series and the impact of climate scenarios projected for the period 2020-2050 in the Sorocaba- Médio Tietê-BHSMT river basin and its repercussions on public water supply. Method: Narrative review study on the impacts of climate change on water availability and quality. A trend study of historical precipitation and flow data from 1980 to 2020 from four stations located in the BHSMT, using the Man-Kendall and Pettitt methods. Application of the SWAT model (Soil Water Assessment Tool) to evaluate the impact of the RCP4.5 and RCP8.5 climate scenarios for the period from 2020 to 2050, on the basin's hydrological cycle and on the availability of water for public supply. Results: There are many gaps in understanding the impacts of climate scenarios on water resources and their repercussions on the population's health. Trend analysis of flow and precipitation data showed stationarity. The analysis of the impacts of the climate scenarios showed an important reduction in precipitation and flow, for both scenarios, especially for the period 2020-2030 and 2030-2040, posing risks to public supply and water security in the region. Conclusion: Strategies involving a wide range of thematic areas and perspectives to ensure water security and increase the resilience of basins to the effects of climate change are necessary.

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Drought variability analysis is of utmost concern for planning and efficiently managing water resources and food security in any specific area. In the current study, drought spell occurrence has been investigated in the Balochistan province of Pakistan during the past four decades (1981-2020) using standardized precipitation index (SPI), reconnaissance drought index (RDI), and precipitation deciles (PD) at an annual timescale. Precipitation and temperature data collected from 13 synoptic meteorological stations located in Balochistan were used to calculate the SPI, the RDI, and the PD for calculation of drought severity and duration. Based on these indices, temporal analysis shows adverse impacts of drought spells in Nokkundi during 1991-1993, in Barkhan, Dalbandin, Quetta stations during 1999-2000, whereas Barkhan, Dalbandin, Lasbella, Sibi during 2002-2003, Zhob during 2010-2011, Kalat and Khuzdar during 2014-2015, and Panjgur during 2017-2018. Also, the aridity index for each station was calculated based on the UNEP method shows that major part of Balochistan lies in the arid zone, followed by the hyper-arid in the southwestern part and the semi-arid zones in the northeastern part of the province. SPI and RDI results were found more localized than PD, as PD shows extensive events. Furthermore, principal component analysis shows a significant contribution from all the indices. For SPI, RDI, and PD, the first three principal components have more than 70% share, contributing 73.63%, 74.15%, and 72.30% respectively. By integrating drought patterns, long-term planning, and preparedness to mitigate drought impacts are only possible. The RDI was found more suitable and recommended in case of temperature data availability.

A análise da variabilidade da seca é de extrema importância para o planejamento e gestão eficiente dos recursos hídricos e da segurança alimentar em qualquer área específica. No estudo atual, a ocorrência de períodos de seca foi investigada na província do Baluchistão, no Paquistão, durante as últimas quatro décadas (1981-2020), usando índice de precipitação padronizado (SPI), índice de seca de reconhecimento (RDI) e decis de precipitação (PD) em uma escala anual. Dados de precipitação e temperatura coletados de 13 estações meteorológicas sinóticas localizadas no Baluchistão foram usados ​​para calcular o SPI, o RDI e o PD para cálculo da severidade e duração da seca. A análise temporal mostra os impactos adversos dos períodos de seca em Nokkundi durante 1991-1993 e na maior parte da província de 1999 a 2004. Além disso, o índice de aridez para cada estação foi calculado com base no método do PNUMA. Os resultados de SPI e RDI foram encontrados mais localizados do que PD, pois PD apresenta eventos extensos. Além disso, a análise de componentes principais mostra uma contribuição significativa de todos os índices. Para SPI, RDI e PD, os três primeiros componentes principais têm mais de 70% de participação, contribuindo com 73,63%, 74,15% e 72,30%, respectivamente. O planejamento e a preparação de longo prazo para mitigar os impactos da seca só são possíveis por meio da integração dos padrões de seca.

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Changes in land use have been occurring in a continuous and disorderly way in recent decades due to rapid population growth and the growing demand for food. These constant changes result in a series of harmful effects to the environment, especially to water resources, significantly changing their availability and quality. This study aims to evaluate the degradation potential of watersheds through an evaluation of some environmental indicators using arithmetic means to construct an index called in this research "index of potential environmental degradation" (IPED). To form the IPED, the hydrographic sub-basins of the Sorocabuçu River, located in the central west of the State of São Paulo, Brazil, comprised the study area. The results showed that most hydrographic sub-basins, that is, eight units, present degradation values ranging from moderate to very high, resulting mainly from low conservation values of forests plus a use destined to the planting of temporary cultures depending on good physical conditions. On the other hand, only one sub-basin showed a low degradation value. The methodology used for the development of the IPED is easy to apply and an effective tool for environmental analyses. It may contribute to studies and forms of planning and land use management aiming the conservation of water resources and protected areas and reduction of degradation.

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Interdisciplinary knowledge is necessary to achieve sustainable management of natural resources. However, research is still often developed in an exclusively disciplinary manner, hampering the capacity to holistically address environmental issues. This study focuses on páramo, a group of high-elevation ecosystems situated around ∼3000 to ∼5000 m a.s.l. in the Andes from western Venezuela and northern Colombia through Ecuador down to northern Peru, and in the highlands of Panama and Costa Rica in Central America. Páramo is a social-ecological system that has been inhabited and shaped by human activity since ∼10,000 years BP. This system is highly valued for the water-related ecosystem services provided to millions of people because it forms the headwaters of major rivers in the Andean-Amazon region, including the Amazon River. We present a multidisciplinary assessment of peer-reviewed research on the abiotic (physical and chemical), biotic (ecological and ecophysiological), and social-political aspects and elements of páramo water resources. A total of 147 publications were evaluated through a systematic literature review process. We found that thematically 58, 19, and 23 % of the analyzed studies are related to the abiotic, biotic, and social-political aspects of páramo water resources, respectively. Geographically, most publications were developed in Ecuador (71 % of the synthesized publications). From 2010 onwards, the understanding of hydrological processes including precipitation and fog dynamics, evapotranspiration, soil water transport, and runoff generation improved, particularly for the humid páramo of southern Ecuador. Investigations on the chemical quality of water generated by páramo are rare, providing little empirical support to the widespread belief that páramo environments generate water of high quality. Most ecological studies examined the coupling between páramo terrestrial and aquatic environments, but few directly assessed in-stream metabolic and nutrient cycling processes. Studies focused on the connection between ecophysiological and ecohydrological processes influencing páramo water balance are still scarce and mainly related to the dominant vegetation in the Andean páramo, i.e., tussock grass (pajonal). Social-political studies addressed páramo governance and the implementation and significance of water funds and payment for hydrological services. Studies directly addressing water use, access, and governance in páramo communities remain limited. Importantly, we found only a few interdisciplinary studies combining methodologies from at least two disciplines of different nature despite their value in supporting decision-making. We expect this multidisciplinary synthesis to become a milestone to foster interdisciplinary and transdisciplinary dialogue among individuals and entities involved in and committed to the sustainable management of páramo natural resources. Finally, we also highlight key frontiers in páramo water resources research, which in our view need to be addressed in the coming years/decades to achieve this goal.

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The present work presents a methodology for modeling the quality of surface water, aiming at the management of hydrographic basins and the best allocation of resources in the treatment of sanitary sewage, considering the predominant uses of water and microbiological quality. The QUAL-UFMG model was used, composed of Excel spreadsheets, where visual basic for applications (VBA) routines were implemented, enabling deterministic and probabilistic modeling through Monte Carlo simulations. The proposed methodology was applied to a Brazilian hydrographic basin, called the GD2 Planning Unit (Grande River Slopes), considering the discharges of sanitary sewage from 30 municipal seats and approximately 740,000 inhabitants. Four scenarios were studied: the current situation (C-01), the trend for the year 2033 (C-02), compliance with environmental legislation (C-03) and compliance with the main uses of the basin (C-04). The results showed that for C-01 and C-02, the water quality, in terms of thermotolerant coliforms, in most stretches does not meet the defined uses. Even complying with the provisions of environmental legislation (C-03), which do not provide for disinfection, only the largest watercourses would have adequate quality for use. Complete service would only be achieved in C-04, which provides for universal sewage treatment with disinfection for the vast majority of municipalities.

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Freshwater resources supply has always presented challenges and considering a changing climate quantifying the available water in the future is important. In the Caribbean, based on projections it is likely that the island of Trinidad would receive less intense rainfall, experience more dry days, become drier and warmer, and the water resources be decreased. In this study, the impact of a changing climate on the Navet Reservoir in Trinidad was investigated and reservoir volumes were quantified for the period 2011-2099. This period was subdivided into three time periods, 2011-2040, 2041-2070, and 2071-2099, and evaluated under the representative concentration pathways (RCPs): RCPs 2.6, 4.5, 6.0, and 8.5. Utilizing a calibrated/validated Soil Water Assessment Tool (SWAT) model for the Navet Reservoir together with projections from five general circulation models (GCMs), future monthly and seasonal reservoir volumes were estimated. The GCM precipitation and temperature data were bias-corrected using linear scaling and variance scaling methods. It was found that reservoir volumes are likely to be the lowest during the period 2041-2070 at the Navet Reservoir. Additionally, the projected reservoir volumes are reliable, resilient, and not vulnerable. These results may be used by water managers in the adaptation and mitigation of the impacts of a changing climate, thus, building resilience in the water sector.

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Urban stream monitoring programs rarely consider the daily cycle of water quality. Furthermore, water quality indexes (WQIs) often rely on an excessive number of correlated parameters. To the best of our knowledge, no previous study used both the principal component analysis (PCA) and the daily cycle of the water quality of urban streams to create better WQIs. In this context, the present study aimed to develop a novel urban WQI (WQIurban) considering these two factors. Moreover, the main WQI in Brazil for water quality assessment for public supply (WQIcetesb) was used as a starting point (parameters: total solids (TS), temperature, turbidity, biochemical oxygen demand, pH, dissolved oxygen (DO), total nitrogen, total phosphorus, and thermotolerant coliforms (Escherichia coli)). The selected parameters to integrate the WQIurban received weights according to their importance for the conformation of water quality and a quality value was assigned to each parameter as a function of its concentration or measure. The developed WQIurban (parameters: pH, TS, E. coli, and DO) was able to maintain the seasonal and daily patterns of the urban stream water quality compared to the WQIcetesb. Nevertheless, the spatial relationship among the sampling sites was somewhat lacking. Our findings can help environmental managers, policy planners, and local researchers to improve their urban stream monitoring programs, saving money, time, and resources. Moreover, the WQIurban can be helpful during exceptional circumstances in which the water quality of urban streams must be quickly assessed.

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Em 1989 foi instituído no estado de São Paulo o sistema integrado de gerenciamento de recursos hídricos, de forma a reunir órgãos municipais, estaduais e sociedade civil e assegurar os meios financeiros e institucionais para finalidades específicas, como a utilização racional dos recursos hídricos, superficiais e subterrâneos, assegurando o uso prioritário para o abastecimento das populações. A lei foi elaborada de forma garantir a gestão descentralizada, participativa e integrada dos recursos hídricos em relação às particularidades de cada Bacia Hidrográfica. O FEHIDRO - Fundo Estadual de Recursos Hídricos tem como objetivo dar suporte a política de recursos hídricos promulgada por meio do financiamento de programas e ações na área, de modo a promover a melhoria e a proteção de corpos d´água e de suas Bacias Hidrográficas. O fundo investiu no período de 1995 a 2019 R$ 916.955.735,79 em 5.886 empreendimentos concluídos (SInFEHIDRO). O aumento da captação do fundo associado ao papel da água como recurso natural essencial à vida, ao desenvolvimento econômico e ao bem-estar social reforça a criticidade e a importância da melhoria contínua da gestão dos recursos hídricos. O objetivo desse trabalho é analisar os investimentos realizados e apresentar um diagnóstico com proposta de indicadores e subsídios para priorização de projetos a serem contemplados pelo fundo, visando atender a indicadores tidos como prioritários para a universalização da água potável e melhor índice de qualidade dos mananciais. Essa análise será fundamentada com o método de revisão bibliográfica e levantamento de dados dos empreendimentos disponibilizados pelo Sistema Integrado de Recursos Hídricos (SIGRH).

In 1989, the state of São Paulo established an integrated water resources management system, in order to gather municipal, state and civil society bodies and to ensure financial and institutional means for specific purposes, such as the rational use of water resources, surface and underground, ensuring priority use to supply the population. The law was designed to ensure decentralized, participatory and integrated management of water resources in relation to the particularities of each Hydrographic Basin. FEHIDRO - State Water Resources Fund aims to support the water resources policy enacted by financing programs and actions in the area, in order to promote the improvement and protection of water bodies and their hydrographic basins. From 1995 to 2019, the fund invested R$ 916.955.735,79 in 5,886 completed projects (SInFEHIDRO). The increase in funding from the fund associated with the role of water as a natural resource essential to life, economic development and social well-being reinforces the criticality and importance of continuous improvement in the management of water resources. The objective of this work is to analyze the investments made and present a diagnosis with a proposal of indicators and subsidies for prioritizing projects to be contemplated by the fund, aiming to meet the indicators considered as priorities for the universalization of drinking water and a better index of quality of springs. This analysis will be based on the method of bibliographic review and survey of data from the projects made available by the Integrated Water Resources System (SIGRH).

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