Showing papers by "Simon Beecham published in 2005"

Friction Factors for Spatially Varied Flow with Increasing Discharge

Abstract: This paper describes an experimental investigation of how friction factors change for spatially varied flow in sloping channels receiving lateral inflow. The results are compared with those of Beij in 1934, and it is concluded that uniform flow resistance coefficients are not always appropriate for spatially varied flow. Moreover, the common technique of assuming a constant friction factor over the entire length of the channel has been found to have little theoretical justification. The method of Keulegan in 1952 for calculating friction factors in spatially varied flow gives a better estimate, but does not explicitly take account of the lateral inflow rate or velocity. Beij’s 1934 experimental data, which was used by Keulegan does not show a systematic variation of friction factor with lateral inflow rate for a constant Reynolds number although this may be due to the low flowrates used. The results of the present study indicate that the friction factor increases with lateral inflow rate for a constant Re...

Modelling on-site detention on a catchment-wide basis

Abstract: Many countries are either currently using or considering the use of on-site detention (OSD) as a structural flood mitigation method. On-site detention is a structural element of a property drainage system that limits the site discharge of stormwater using outlet restriction devices. The excess stormwater runoff is temporarily stored on site in underground tanks or above-ground storage areas until the storm event recedes. Sydney, Australia, has a stormwater system that is completely separate from the sewerage system. The stormwater systems are mainly managed by the 43 local councils and most of these use OSD as a means of reducing site discharge of stormwater, thereby relieving catchment flooding. Sheas Creek is an urbanized catchment that lies within the South Sydney City Council Local Government Area. Since 1984 an OSD policy has been implemented in the Sheas Creek catchment. The associated design code, like most others in Sydney, is based on discharge from individual properties without consideration of ...

Boundary Shear Stress in Spatially Varied Flow with Increasing Discharge

Abstract: The distribution of the wall shear stress on the bed and sidewalls of an open channel receiving lateral inflow was obtained from experimental measurements of the distribution of the velocity in the viscous sublayer using a laser doppler velocimeter. The experiments were conducted in a 0.4 m wide by 7.5 m long flume. Lateral inflow was provided into the channel from above via sets of nozzles positioned toward the downstream end of the flume. Lateral inflow was provided over a length of 1.9 m. The results indicate that the local boundary shear stresses are significantly influenced by lateral inflow. The significant variation occurs near and around the region where the lateral inflow enters the channel. At various measurement positions along the lateral inflow zone, mean boundary, mean wall, and mean bed shear stresses were obtained and compared. The results indicate that the mean boundary shear stresses increase from the upstream to the downstream ends of the lateral inflow zone. The results also indicate t...

Water Sensitive Urban Design at an Agricultural High School

Abstract: The deleterious effects on receiving water bodies of stormwater runoff from urban areas have been studied extensively. However, impacts of runoff from mixed land-use institutions such as schools is less understood. This paper describes a project that arose from a NSW Environmental Protection Authority Stormwater Trust grant that was received by the Upper Parramatta River Catchment Trust (UPRCT). This funding was used to develop Water Sensitive Urban Design (WSUD) demonstration sites, including one at Model Farms High School in Baulkham Hills. The quality of the stormwater runoff from Model Farms High School was monitored for a period of six months. This monitoring was undertaken during the pre-construction phase, and a phase that involved the construction and retrofitting of WSUD systems into the existing school layout. One of the major features of this school is that it contains agricultural areas. A range of water quality parameters were analysed, including faecal coliforms, total nitrogen, total phosphorus and zinc. The results indicated that the stormwater runoff from the site significantly exceeded the ANZECC water quality guidelines. In particular, faecal coliform levels were high as were the zinc loadings from the school's large roof areas. The bacterial contamination was found to be associated with the agricultural activities taking place at the school, including the pasturing of cows and sheep on the school grounds. Numerous schools within Australia have an agricultural focus. The results presented in this paper give an indication of the level of pollution that is potentially leaving these urbanised agricultural sites via stormwater runoff. They also indicate the importance of looking at new ways of improving the quality of runoff from agricultural areas, prior to it reaching receiving water bodies. These include the incorporation of WSUD features that can be readily retrofitted into school grounds. Bioretention systems and rainwater tanks were both used at Model Farms High School to improve the quality of runoff and to harvest stormwater for non-potable reuse. An important component of this project was the opportunity for the education of the school children about the benefits of stormwater harvesting and WSUD. This paper discusses the education strategies employed at the school and the ways these were integrated into the maintenance requirements for the WSUD systems.