Urban design-storm sensitivity and reliability

Antecedent soil moisture conditions of different soil types in South‐western Ontario, Canada

“…The sizing and design of these facilities rely on the use of either the DSA or the continuous simulation approach. Even though continuous simulation is more accurate, the DSA is still more popular due to its simplicity, limited data requirements and lower computational requirements (Beaudoin et al , 1983; Voorhees and Wenzel, 1984; Ponce and Hawkins, 1996). The four essential elements of the DSA are: (i) event depth or average event intensity; (ii) event duration; (iii) event hyetograph; and (iv) ASM conditions (Packman and Kidd, 1980; Voorhees and Wenzel, 1984).…”

“…Inaccurate estimation of ASM conditions would further weaken the foundation of this basic assumption. The critical DS concept refers to the rainfall events that produce the largest peak flow for a particular watershed (Voorhees and Wenzel, 1984; Nnadi et al , 1999). ASM affects runoff volume and peak discharge; therefore, ASM information is important for use with the DSA (Voorhees and Wenzel, 1984; Wenzel and Voorhees, 1984; Tan et al , 2008).…”

Urban sedimentology

“…Sediment movement is to be restrained, wheras stormwater runoff should be as efficient, rapid and effective as possible. Although much information is available on urban stormwater drainage design (Wanielista, 1978;Kibler, 1982;Voorhees and Wenzel, 1984;Ando et al, 1984;McCuen et al, 1984) less is available on how sediment inputs affect the efficiency and capacity of urban storm water drainage works. Unless channels have sufficient gradient, or permit high enough flow velocities, any sediment carried by runoff will aggrade the channel bed and reduce flow discharge capacity.…”

Some considerations of urban drainage design practice using experimental data

“…All three approaches have advantages and disadvantages. There have been many studies related to the problem of determining more accurate flow frequencies (e.g., Packman and Kidd, 1980;Marsalek, 1984;Voorhees and Wenzel, 1984). They all agreed in several points, one being that the historical flows approach is unfeasible in the majority of cases due to the lack of measurements.…”

“…Although today's computer technology allows any sophisticated rainfall-runoff model to be applied to any length of rainfall record, design storm concept is still appealing because of its simplicity and modest data requirements. Therefore some studies (Voorhees and Wenzel, 1984;Cao et al, 1993) were dedicated to setting up a design storm procedure which would yield design flows frequencies consistent with the true ones. Another possible approach is a compound design storm approach in which antecedent conditions are estimated using Markov renewal processes (Despotovic, 1994).…”