Reliability analysis of complex water distribution systems: the role of the network connectivity and tanks

A reliable water distribution network (WDN) can provide an adequate supply service to customers under both normal and abnormal working conditions. The WDN reliability analysis, therefore, is a keystone to improve the supply service efficiency. Strategies for reliability analysis are usually proved on small WDNs, which do not compare with large real complex systems in terms of number of water tanks, pressure reduction valves, variable speed pumps, controlled devices and possible alternative water supply schemes. The topological changes due to pipeline interruptions impact on emptying–filling of water tanks and network pressure status. This work proposes a two-level procedure for mechanical reliability assessment, suited for large real WDNs. It leverages a path/connectivity-based approach to set up reliability indicators for global-level analysis and local screening of the most critical scenarios. The employed advanced hydraulic model includes the automatic detection of topological changes and the robust modelling of water level in tanks using the generalized global gradient algorithm. The extended period simulation enables the reliability assessment of alternative water supply schemes and the sensitivity of tanks and controlled devices to single failure events. The procedure is demonstrated on a real complex network, being consistent with the ongoing digital transition in the WDN management sector.

Assessment of Hydrogeoelectrical Characteristics of Crystalline Aquifers and Groundwaters Quality in Adamawa Plateau: Case of Mbakaou (Adamawa - Cameroon)

Population in Adamawa Plateau faced to borehole failure and return to alternative water supply structures (wells and catchments) with a doubtful quality. This study was carried out to highlight the location of aquifers, their hydrodynamics characteristics and groundwaters quality in Mbakaou locality, which belong to the Adamawa Region. Combination of geological and geoelectrical surveys at 10 stations, with hydrodynamic study of 4 boreholes were carried out to characterize aquifers. Hydrochemical analysis of 10 waters samples has been done to determine physico-chemical water quality and origin of waters mineralization. Geological studies show that basement rocks, which constitute fractured aquifers, consists of a large assemblage of granitoid. Geophysics and drilling data highlight superficial aquifers located between 2 and 17 m and fractured aquifers located between 11 and 74 m, with resistivity ranging from 50 to 671 Ω.m. The borehole have yield varying between 2.80 and 5.14 m3/h. Transmissivity and permeability ranging from 10-6 to 10-5 m2/s and 10-7 to 10-6 m/s respectively, indicating that aquifers are semi-permeable. Waters are of good quality compared to WHO norms and weakly mineralized (35 to 247.9 mg/l). Piper diagram show that calcium and magnesium bicarbonate facies is dominant. Mineralisation of water is mainly influenced by water-rock interaction through silicate weathering.

Addressing the Scarcity of Traditional Water Sources through Investments in Alternative Water Supplies: Case Study from Florida

This paper examines the capital costs for alternative water supply projects in Florida, the third most populous state in the United States. The increasing scarcity of fresh groundwater in Florida has led to investments in alternative water supply sources, including brackish groundwater, surface water capture and storage, reclaimed water, and stormwater. Expenditures to meet the growing water demand for the 20-year planning horizon are estimated using water demand projections and existing supply estimates from Florida’s five water management districts. In the regions where demand projections exceed the existing supply, the districts are required to identify project options to meet the growing water demand while protecting the natural systems. This study uses the database of 645 projects implemented in the past or considered for the future. The Ordinary Least Squares regression model shows that project implementation costs depend on project capacity, type, implementation status, and implementation region. Given the most common project types and project sizes, the total investments to meet the state’s future water demand could reach almost $2 billion in the next 20 years. The expenditures necessitate more cost-effective options (such as expanding stormwater use and water conservation).

Water supply regulation in Nigeria: problems, challenges, solutions and benefits

Even though Nigeria is recognized for her rich vegetation and tropical weather and blessed with surplus water resources, the country still faces challenges on getting clean water supply around the country and mostly depend on alternative water supply like well, borehole and river. These alternative water supply systems are not efficient and viable enough for water supply systems especially in a country with large population. The country is characterized by irregular water supply and water management laws are also weak and mostly not in conformity with today's standard and needs. Proper management and conservation of the water supply services and resource has not given adequate attention by the government. It is, therefore, important to identify such factor that inhibits the implementation of water regulations and proffer a solution to these. In a bid to provide an understanding of the effect of implementing and enforcing stringent water regulation and providing adequate water supply, we compare forecasted population with investment capital expenditure (CAPEX) for water supply by Millennium Development Goal (MDG+) targets. The result shows that in year to come, the country will significantly benefit from investing and providing regular water supply through employment availability and revenue generated through utility water bills, spending less on epidemic of water-borne diseases thereby improving the lives and health of its citizen.