A review of recent developments on drought characterization, propagation, and influential factors.

Droughts have impacted human society throughout its history. However, the occurrence of severe drought events in the last century and the concerns on the potential effects of climate change have prompted remarkable advances in drought conceptualization and modeling in recent years. This review intends to present the state-of-the-art on drought characterization and propagation, as well as providing insights on how climate dynamics and anthropogenic activities might affect this phenomenon. For this purpose, we first address the distinct concepts of droughts and their relationships. Next, we present two frequently utilized methods based on the run theory for drought characterization and explain the development and recovery stages of droughts. Then, we discuss potential drivers for drought occurrence and propagation, with focus on meteorological factors, catchments' physical characteristics and human activities. Later, we describe how droughts can affect several parameters of water quality. This review also addressed flash droughts, encompassing their definitions, commonly used indices, and potential drivers. Finally, we briefly address the roles of climate change and long-term persistence on future drought scenarios. This review may be useful for researchers and stakeholders for attaining a broader understanding on drought dynamics and impacts.

Proposal of a regulatory index of quality of water supply services-RIQS.

Among the challenges faced by regulatory authorities in the water sector, the large number of municipal supply services to be inspected and the cost of on-site inspections are prominent. To overcome these issues, decisions regarding the priority of inspections based on indicators is an alternative. Therefore, this research aims to propose and evaluate the Regulatory Index of Quality of Water Supply Service (RIQS) to triage on-site inspections of water supply systems in cities of the state of Minas Gerais. The study was conducted with information from the Regulatory Agency of Water Supply and Sanitation Services of Minas Gerais (Arsae-MG). The methodology followed seven steps: (i) selection of available indicators; (ii) grouping of indicators according to their typology; (iii) screening of indicators; (iv) establishment of standardized scale; (v) evaluation of the relative importance of typologies and indicators, through the adaptation of the analytic hierarchy process (AHP); (vi) determination of the RIQS; and (vii) analysis of results. As a result, we selected 12 indicators to compose the RIQS, which deal with efficiency, effectiveness, and customer relationship. We noticed that the indicator of water supply service coverage (17.2%) had the highest weight in the calculation of the RIQS, and the index of requests for an inspection of the water connection served on time (2.1%) had the lowest weight. In addition, 95.1% of the 591 municipalities evaluated presented excellent or good performance. Based on these results, we show that the RIQS can be used to identify cities with low performance and prioritize inspections in the most urgent water systems. Furthermore, these outcomes reveal the possibility of extending and adapting the methodology to other regulatory agencies around the world for identifying the priority of inspections in water supply systems at a municipal level.

Assessment of performance indicators for different sizes of water supply systems in Minas Gerais, Brazil.

Indicators are important tools to improve the efficiency of water supply systems. Considering that the performance could vary according to the systems' sizes, this research proposed financial, operational, and water quality indicators for water supply systems of municipalities with different populations in Minas Gerais, Brazil. The organisation and selection of the sample were based on available information in the National Sanitation Data System of 2014. We selected 363 municipalities of Minas Gerais and 56 predictors. Through multiple linear regression (MLR), we found that the commitment of revenues with expenditures and the ratio among revenues and expenses are the most relevant variables to describe the financial performance. Furthermore, water loss per connection and water-billing index were the most important to describe the operational performance. Finally, models related to water quality performance could not be established due to the low value of the coefficient of determination. We observed that supply systems have distinct variables to describe their financial and operational performance, according to their sizes. Small municipalities have a strong relationship with financial performance and expenses. Large counterparts have their performance related to the collection, which can be explained by the economy of scale. Considering the operational performance, we observed that larger municipalities have a strong relationship between their operational performance and water loss. These models are potential tools in the decision-making processes, which can be used to promote improvements in water supply systems.

Avaliação de indicadores aplicados a sistemas de abastecimento de água de pequeno porte / Evaluation of indicators applied to small water supply systems

RESUMO O presente trabalho visou avaliar, por meio de regressão linear múltipla (RLM), os indicadores que melhor exprimem a realidade dos sistemas de abastecimento de água de municípios de pequeno porte, com base nos desempenhos financeiro, operacional e de qualidade da água como variáveis de resposta. A organização e a seleção dos dados fiaram-se no Sistema Nacional de Informações sobre Saneamento de 2014, tendo sido selecionados os referentes a 182 municípios de Minas Gerais com população inferior a 10 mil habitantes e 56 indicadores como variáveis explicativas. Por meio da RLM, verificou-se que o comprometimento das receitas com a despesa (margem da despesa de exploração) e a razão entre a arrecadação e as despesas (índice de suficiência de caixa) são as variáveis mais relevantes para descrever o desempenho financeiro. Para descrição do desempenho operacional, os índices de perdas por ligação e de faturamento de água foram os mais recorrentes. Por fim, no que tange ao desempenho de qualidade da água, os modelos apresentaram baixos coeficientes de determinação e a não aderência dos resíduos à distribuição normal.

ABSTRACT The aim of this study was to evaluate, by means of multiple linear regression (MLR), the indicators that best express the reality of small municipalities water supply systems, based on financial, operational and water quality performance as response variables. The organization and selection of the sample were based on the information available in the National Sanitation Information System of 2014, selecting 182 municipalities in Minas Gerais with population below 10,000 inhabitants and 56 indicators as explanatory variables. Through MLR, it was found that the commitment of revenue to expenditure (operating expense margin) and the ratio of collection to expenses (monetary sufficiency index) are the most relevant variables to describe financial performance. For the description of operational performance, the water loss per connection and water billing rates were the most recurrent. Finally, with regard to the performance of water quality, the models presented low determination coefficients and non-adherence of the residues to normal distribution.