Applying the Water-Energy Nexus for Water Supply—A Diagnostic Review on Energy Use for Water Provision in Africa

Analysis, design, and maintenance of isolation valves in water distribution networks: State of the art review, insights from field experiences and future directions

Isolation valves play a primary role in water distribution networks as their operation enables isolating the part of the network undergoing planned or extraordinary maintenance, in the context of rehabilitation or pipe break repairs, respectively. This paper presents a review of the current state of the art of isolation valves, with a focus on the problems of analysis, e.g., assessment of the performance of the network in segment isolation scenarios, design of optimal valve locations, and selection criteria/methods for identification of the valves to maintain. After describing and classifying the main scientific contributions, the paper proceeds by reporting the results of a survey to water utility staff in the United States, Italy, Portugal, and Iran, aimed at analysing the current practices adopted for the positioning and maintenance of isolation valves in real case studies. The paper ends with a discussion on the analysis of scientific literature and results of on-field surveys, highlighting critical points for potential future developments, including the connection between the design and maintenance of isolation valves, the trade-off between increasing validity and reducing complexity of reliability assessment methods, and more precise modeling of isolation valves systems.

Complexities of the urban drinking water systems in Ethiopia and possible interventions for sustainability

Rapid urbanization in developing countries has imposed threats and challenges to basic urban infrastructures like drinking water, transportation, and energy systems. The existing urban drinking water systems (UDWS) are highly stressed and unsustainable, particularly under changing hydroclimatic conditions, population growth, changing socioeconomic conditions, government decisions, and various policies. This study focuses on the complexities of UDWS in Sub-Saharan African countries, especially in Ethiopia. The objective of this study is to investigate the issues and challenges of urban drinking water systems (UDWS) in Ethiopia, specifically, to assess the gap between water supply and demand, water loss/non-revenue water, environmental, technical, institutional, and governance, etc. and propose sustainable interventions to deal with such issues so as to improve. For this purpose, a mix of methods involving primary data (including key informant interviews, field observations, and field measured data) and secondary data (including published articles, books, various reports, and design documents), as well as various computer-aided applications (mainly, ArcGIS and WaterGEMS) are used to collect data. The issues are deliberated through the UDWSs of Addis Ababa, Adama, Mekelle, and Dire Dawa cities in Ethiopia. Complexities like water shortage, high and low pressure in the water distribution network (WDN), non-revenue water (NRW)/water loss, source pollution, ineffective policies and governance, and weak institutions are the main challenges to Ethiopian cities' water utilities. Further, the case study noticed that in Addis Ababa alone, potable water is only accessible to 66% of the city population. A significant water supply deficit was observed in Mekelle city, where only half of the city population has access to potable water from the system. Additionally, in Addis Ababa, Adama, Mekelle, and Dire Dawa, above 35% of the freshwater produced is either NRW, unaccounted for, or lost, which is significantly higher than the upper 25% limit suggested by the World Bank. Therefore, it is recommended to adopt certain sustainable interventions, such as integrated water resource management, installing appurtenances like pressure-reducing valves, check valves in the WDN, controlling and monitoring of WDN through supervisory control and data acquisition and Internet of Things, effective and long-term planning and policy, etc. It is felt that the study will help the decision-makers and the operators of the UDWS utilities to run the water supply schemes in a sustainable manner.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10668-022-02901-7.

U.S. national water and energy land dataset for integrated multisector dynamics research

Understanding resource demands and tradeoffs among energy, water, and land socioeconomic sectors requires an explicit consideration of spatial scale. However, incorporation of land dynamics within the energy-water nexus has been limited due inconsistent spatial units of observation from disparate data sources. Herein we describe the development of a National Water and Energy Land Dataset (NWELD) for the conterminous United States. NWELD is a 30-m, 86-layer rasterized dataset depicting the land use of mappable components of the United States energy sector life cycles (and related water used for energy), specifically the extraction, development, production, storage, distribution, and operation of eight renewable and non-renewable technologies. Through geospatial processing and programming, the final products were assembled using four different methodologies, each depending upon the nature and availability of raw data sources. For validation, NWELD provided a relatively accurate portrayal of the spatial extent of energy life cycles yet displayed low measures of association  with mainstream land cover and land use datasets, indicating the provision of new land use information for the energy-water nexus.

Measurement(s)	land use of renewable and nonrenewable technologies
Technology Type(s)	Esri Arcmap
Sample Characteristic - Environment	terrestrial; • aquatic
Sample Characteristic - Location	United States