The past three issues of Water Management have been themed issues, focusing on specific pertinent themes. Some of you may therefore, welcome the return to the normal variety of topics with this issue. However, it does pose a greater challenge in the production of an editorial: how does one link the advances in understanding of triangular labyrinth spillways1 with the prediction of water use by neural networks?2 The answer is that one probably shouldn't try. The links will be tenuous, at best. In any case, one of the most interesting aspects of water management is its diversity. For me, the regular discovery of emerging areas of knowledge and new techniques is always refreshing.
So there are no intentional links between the seven papers presented here, save the mutual aim of improving the way we deal with water, its availability for consumption, its impact on the environment and its interaction with man-made systems. Nonetheless, there is the urge to categorise the contents. Several papers could be grouped within a ‘predictive methods’ category.
The technique presented by Takebayashi and Okabe3 for braided streams in unsteady flow capitalises on the power of numerical models to enhance understanding of river bed deformation and sediment deposition, taking into account the impact of vegetation.
The work of Afshar and Rohani4 using the modified Euler method for extended period simulation of flow in pipe networks under dynamic loading aims to demonstrate improved accuracy over conventional methods and gains in efficiency over other improved methods of dynamic simulation. The ease of embedding the procedure into existing pipe network simulation codes is cited as an advantage of the method.
The aforementioned prediction of water consumption by neural networks (Yurdusev et al.2) reflects a growth in applications for this still relatively new technique. The paper covers the use of feed forward neural networks (FFNNs) and radial basis neural networks (RBNNs), both explained for those less familiar with workings of artificial neural networks – to predict monthly water use where a range of several socio-economic and climatic factors affect consumption. The performance of the models is compared with observed water consumption in the city of Izmir, in Turkey.
While the academic research value of the above papers is clear, the potential for application of each method is also noted.
A second category might then contain those papers where field and laboratory observations have contributed to the findings.
The study by Pezzaniti et al.5 on clogging of permeable pavements comes within the area of water sensitive urban design (WSUD), the principles of which are analogous to the UK sustainable drainage systems (SuDS). One of the aims of WSUD is a reduction in the adverse effects of stormwater runoff. This paper addresses the hydraulic performance of systems that have been introduced in Australia over recent years with this in mind.
In a paper undoubtedly driven by the floods that have caused destruction across Europe in recent years, Dyer et al.6 present the result of field surveys and laboratory tests conducted to improve understanding of the impact of desiccation fissuring on flood embankments and its contribution towards embankment failure. In a document which is relevant to water engineers and geotechnical engineers alike, the authors indicate that it is possible to assess the susceptibility of a fill material to desiccation fissuring from the soil water characteristic curve.
In contrast to the above, Ghodsian1 describes experiments to establish the stage-discharge relationship of a triangular labyrinth spillway with various crest shapes. The spillway, which allows substantial increases in discharge per unit width for a given head over conventional spillways, was tested under laboratory conditions and an equation developed to define the coefficient of discharge.
The paper by Chahar and Basu7 on optimal design of circular and parabolic canal sections does not fall neatly within either of the above (rather arbitrary) categories. It addresses, however, an issue not mentioned quite so explicitly elsewhere in this issue: cost. This study, which refers to current practice for lined canals within India, focuses specifically on the issues of earthwork cost and lining cost. The technique relies on widely-available software. In today's economic climate, cost must surely be of interest to most readers. If canal design is not within your remit, then perhaps the principles can be adapted for other fields?
Reiterating the aim of Water Management, ‘to provide authoritative, stimulating and informative papers of use to practitioners (including consultants, contractors, managers and planners) and applied researchers’, I trust that most of our readers will find something relevant and stimulating within the June 2009 issue.
Water Management includes a request for comments (within a 500-word limit), but relatively few are received. We welcome, indeed encourage, your comments on the material within this and other issues: the greatest benefits will undoubtedly be achieved through discussion of the topics published.
