Preliminary rainfall runoff management for developments - R&D Technical Report W5-074/A/TR/1

This Guide is aimed at Regulators, Developers and Local Authorities to advise on the management of stormwater drainage for developments and in particular to assist in sizing of storage elements for the control and treatment of stormwater runoff. It is based on the requirements of the Interim Procedure produced by the Environment Agency which is reproduced in this document following on from this summary. This Guide may be used to form part of a Flood Risk Assessment to comply with PPS25, but it does not address issues such as risk of flooding from a watercourse, effects of changes in floodplain storage or in floodplain conveyance

An artificial neural network-based rainfall runoff model for improved drainage network modelling

This Presentation is brought to you for free and open access by the City College of New York at CUNY Academic Works. It has been accepted for inclusion in International Conference on Hydroinformatics by an authorized administrator of CUNY Academic Works. For more information, please contact [email protected] th International Conference on Hydroinformatics HIC 2014, New York City, USAModelling rainfall-runoff processes enables hydrologists to plan their response to flooding events. Urban drainage catchment modelling requires rainfall-runoff models as a prerequisite. In the UK, one of the main software tools used for drainage modelling is InfoWorks CS, based on relatively simple methods which are relatively robust in predicting runoff. This paper presents an alternative approach to modelling runoff that will allow for the complex inter-relation of runoff that occurs from impermeable areas, permeable areas, local surface storage and variation in rainfall induced infiltration. Apart from the uncertainties associated with the measurement of connected surfaces to the drainage system, the physical processes involved in runoff are nonlinear, making artificial neural networks (ANNs) an ideal candidate for modelling them. ANNs have been used for runoff prediction in natural catchments, and recently on a study for predicting the performance of urban drainage systems. This study seeks to determine an input set that predicts sewerage flow in urban catchments where the runoff is dominated by infiltration, a major issue for the water industry. A framework is proposed in which an ANN is trained by an evolutionary algorithm, which optimises ANN weights; results are assessed using the Nash-Sutcliffe Efficiency Coefficient. The model is demonstrated on a real-world case study site for which rainfall, flow, air temperature and groundwater levels in three boreholes have been measured. Various combinations of these data are used as model inputs, examining a mixture of daily and sub-daily timesteps. The best predictions are generated from daily linearly combined antecedent rainfall and air temperature, although sub-daily information improves the worst-case performance of the model. Although infiltration is affected by groundwater levels, incorporating groundwater into the model does not improve predictions. The proposed ANN model is capable of producing acceptable predictions, thus avoiding many of the uncertainties involved in traditional infiltration modelling

The Wallingford Procedure - for design and analysis of urban storm drainage

The Wallingford Procedure is a complete methodology for the design and analysis of urban drainage systems. It is invaluable for all those engaged in or responsible for urban drainage. Of the original 5 volumes published in 1981, only 3 volumes are still relevant today. All documents are available in pdf format. The Principles Methods and Practice (Volume 1) describes the background and development of the Wallingford Procedure. Four methods, incorporated within an economic framework are used to design sewer dimensions, depths and gradients and to simulate the behaviour of a system under surcharge and with surface flooding. The UK Maps (Volume 3) are four large scale maps of the UK giving meteorological and soil data. To a scale of 1:1 million, the maps can be used to obtain the most accurate values of various parameters for a given location. The soil map also includes Scotland and Northern Ireland. The Modified Rational Method (Volume 4) presents a hand calculation for a modified version of the Rational Method for use in the UK. This volume is suitable for those designing or analysing small sewer systems or for planning urban drainage schemes

SuDS study summary - Interception of 5 mm of rainfall

Sustainable Drainage Systems do more than reduce runoff from rainfall. SuDS add value by using rainwater as a resource, treating the surface water runoff to reduce pollution, and enhancing biodiversity and amenity. One of the most important criteria for designing sustainable drainage is Interception – the capture and retention of the first 5 mm of any rainfall event

Storage requirements for rainfall runoff from greenfield development sites

The research output for this study was to provide a detailed analysis of the problem and to determine the most appropriate method of approach to achieve the objectives of sustainability and river flood protection. An official guide for use by the regulators, developers and consultants may be produced to provide a national consensus of approach to the provision of storage once the Environment Agency has approved or modified this recommended procedure

Stormwater management using rainwater harvesting: testing the Kellagher/Gerolin methodology on a pilot study

This project is aimed specifically at demonstrating the effectiveness of a new methodology for designing rainwater harvesting systems for controlling stormwater runoff. It applied the new procedure developed by Gerolin and Kellagher which has been developed specifically for rainwater harvesting system to provide effective stormwater management

The Wallingford Procedure for Europe - best practise guide to urban drainage modelling

The theory and practical aspects of urban drainage modelling and includes the Wallingford Procedure maps in digital form

SuDS design for catchment flood protection – are current criteria appropriate?

Current criteria on the design of runoff storage for developments can result in surface water attenuation storage volumes in excess of 1000m3 or more per hectare which is of the order of 20m3 to 40m3 per property for large developments. The use of up to 40% increase in rainfall intensity, based on the latest guidance from the Environment Agency, for addressing expected future climate conditions, results in volumes being twice what they would be if designed for the present day. The cost of the attenuation storage is therefore a very significant component of development construction costs. Considering the expected investment in housing stock is of the order of 250,000 dwellings per year for many years ahead, this is a massive investment. So it is therefore reasonable to ask: Is there evidence that this investment is effective in protecting catchments from flooding? Are the design rules suitable for addressing flooding problems in the specific catchments in which the developments are located? Are methods of assessing runoff from small development sites accurate? If there is any doubt that current methods are not cost-effective in achieving the intended goal of effective catchment flood protection, then appropriate research should be carried out and a new approach should be developed to provide the appropriate control of site runoff which minimises this investment in storage, is targeted at catchment specific issues and uses suitable technology. This presentation will explain how drainage design criteria have evolved in the last 30 years, discuss the limitations these have and explore possible options for a new approach