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For over a century there have been many studies that describe the use of rain drop measurement techniques. Initial manual measurement methods evolved due to improved technology to include photographic and, more recently, automated disdrometer and laser measurement techniques. Despite these numerous studies, there have been few comparative reviews of the range of methodologies, and their relative performance. This review explores the raindrop measurement techniques available, and summarizes and classifies the techniques according to the method or principle involved. The requirements of a robust raindrop measurement technique are suggested, and these are reviewed against existing rain drop measurement techniques to provide a comparative guide to the use of the range of techniques available for any research study. This review revealed that while advances in technology have allowed many of the deficiencies of early techniques to be eliminated, challenges remain in relation to the precision of the measurement of the size, shape, and velocity of rain drops.

An international literature review was undertaken to identify the most appropriate design for a pervious paving system. The literature review revealed that information contained in design guidelines is often unclear and occasionally conflicting and this can be confusing for designers and other stormwater professionals. This literature review was to form the basis of a design for a new research study on the benefits of using pervious pavements to promote street tree health has recently commenced at the University of the Sunshine Coast in Australia. The review identified four typical pervious paving surfaces porous concrete porous asphalt, permeable inter locking concrete pavers, and concrete and plastic grid pavers. All four pavement surfaces were found to have high stormwater pollutant removal performance in a variety of conditions, with a wide range of designs. Maintenance procedures can have a significant impact on the rate of clogging of pervious pavements which can impact on the effective life span and there is conflicting and unreliable evidence to support the inclusion of a geofabric layer within pervious paving systems. This paper summarises the literature review findings and is intended as a practical resource for designers and researchers of pervious pavement systems.

The use of decentralised, sustainable urban drainage systems (SUDS) for the treatment of stormwater runoff is becoming increasingly prevalent in Germany. Decentralised SUDS can offer a viable and attractive alternative to end of pipe treatment systems for stormwater runoff from urban areas. However, there is still some uncertainty regarding the long-term performance of SUDS, and the general legislative requirements for SUDS approval and testing. Whilst the allowable pollution levels in stormwater runoff that infiltrate into ground and/or water table are regulated across Germany by the Federal Soil Protection Law, there is presently no federal law addressing the discharge requirements for surface water runoff. The lack of clear guidance can make it difficult for planners and designers to implement these innovative and sustainable stormwater treatment systems. This study clarifies the current understanding of urban stormwater treatment requirements and new technical approval guidelines for decentralised SUDS devices in Germany. The study findings should assist researchers, designers and asset managers to better anticipate and understand the performance, effective lifespans , and the planning and maintenance