Editorial

Abstract

It is my pleasure to welcome you to the June issue of Water Management, which brings together a selection of papers, briefings and discussions on a diverse range of interesting topics. The two briefing papers in this issue cover gradually varied flow in circular channels (Vatankhah and Easa, 2014) and the weather generator rainfall analysis processing tool Wrapt (Tomlinson et al., 2014). The subsequent four papers focus on complex flow dynamics generated in stilling basins by submerged jets (Zhang et al., 2014) and at reservoir intakes by free surface vortices (Sarkardeh et al., 2014); sanitation issues associated with portable sewage systems (Khan et al., 2014b); and water quality modelling in clean water distribution networks (Seyoum and Tanyimboh, 2014).The accurate determination of water surface profiles for gradually varied flow (GVF) is a classic hydraulic problem of significant importance to water engineers interested in determining the upstream and downstream influence of in-stream structures or works. In their briefing paper, Vatankhah and Easa (2014) present an exact analytical solution to the simplified GVF equation for circular open channels. Their proposed method is applied to a simple numerical example to demonstrate its improved accuracy in predicting the overall length of affected backwater water surface profiles compared to existing approximate analytical and numerical methods, which underestimate this length by more than 20%. The authors state that their exact GVF solution eliminates the need for these more approximate methods and should provide a useful and simple tool for water engineering practitioners and researchers.In the second briefing paper, Tomlinson et al. (2014) describe the software tool Wrapt (weather generator rainfall analysis processing tool), created as part of a UK Water Industry Research project to provide guidance on incorporating the impacts of climate change in sewer network modelling. The tool provides the industry with a means of using outputs of climate change projections for the UK (UKCP09) without the requirement for extensive knowledge of climate modelling. The authors discuss how Wrapt can be used to assess changes in extremes of shortduration rainfall events, in relation to sewer network performance and design, as well as its potential application to water quality modelling applications.The paper by Zhang et al. (2014) presents a three-dimensional numerical modelling study of the complex flow fields generated by multi-horizontal submerged jets discharging into a stilling basin. This has been proposed as a new type of energy dissipater for hydropower stations with high water heads and large unit discharges. Numerical results are presented for the three typical operating conditions comprising of crest overflow discharges only, mid-orifice discharges only and combined crest overflow and mid-orifice discharges. Results indicate that stable vortices with horizontal axes are generated for the discharges through either the crest or mid-level orifices, while vertical axes ...