Small Storm Hydrology and Why it is Important for the Design of Stormwater Control Practices
Small Storm Hydrology and Why it is Important for the Design of Stormwater Control Practices
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小风暴水文学及其对于雨水控制实践设计的重要性
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发表时间：
1999
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通讯作者：
R. Pitt
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作者：
R. Pitt
不同的排水设计标准和受纳水利用目标往往需要对不同类型的降雨进行审查，以进行城市排水系统的设计。雨水排放系统的这些不同（且常常相互冲突）的目标可以通过使用长期降雨记录的不同部分来解决。一些历史研究（包括 Heaney 等，1977）也考虑了对排水设计进行广泛降雨事件研究的必要性。然而，过去缺乏高效的计算机资源严重限制了长期分析。目前，计算机资源更加可用，并且能够进行更全面的调查（Gregory 和 James 1996）。除了拥有更高效的计算资源外，还需要重新审视一些基本的城市水文建模假设（Pitt 1987）。目前用于排水设计的大多数城市水文学方法已成功用于大型“设计”风暴。显然，这种方法（使城市地区免受过度洪水和相关洪水造成的损害）是城市排水最重要的目标。然而，现在可以（并且在许多地区法律要求）提供城市排水系统，这也可以最大限度地减少与城市雨水相关的其他问题。这套更广泛的城市排水目标需要更广泛的排水设计方法，以及使用具有不同假设和简化的水文学方法。本文回顾了威斯康星州密尔沃基实际监测的降雨和径流分布（数据来自 Bannerman 等人，1983 年），并研究了美国 24 个地点的长期降雨历史和预测径流。密尔沃基的观测结果表明，威斯康星州东南部的降雨分布可分为以下几类，并针对每一类降雨提供可能的管理方法：深度 0.5 英寸（12 毫米）。当与径流相关的水质违规（例如细菌）引起关注时，这些降雨是关键的降雨。在大多数地区，这些降雨产生的径流应被完全捕获，并重新用于现场有益用途或渗透到高地地区。对于大多数地区来说，这些降雨产生的径流可以相对容易地从地表排水系统中去除。
Different drainage design criteria and receiving water use objectives often require the examination of different types of rains for the design of urban drainage systems. These different (and often conflicting) objectives of a stormwater drainage system can be addressed by using distinct portions of the long-term rainfall record. Several historical examinations (including Heaney, et al. 1977) have also considered the need for the examination of a wide range of rain events for drainage design. However, the lack of efficient computer resources severely restricted long-term analyses in the past. Currently, computer resources are much more available and are capable of much more comprehensive investigations (Gregory and James 1996). In addition to having more efficient computational resources, it is also necessary to re-examine some of the fundamental urban hydrology modeling assumptions (Pitt 1987). Most of the urban hydrology methods currently used for drainage design have been successfully used for large “design” storms. Obviously, this approach (providing urban areas safe from excessive flooding and associated flood related damages) is the most critical objective of urban drainage. However, it is now possible (and legally required in many areas) to provide urban drainage systems that also minimizes other problems associated with urban stormwater. This broader set of urban drainage objectives requires a broader approach to drainage design, and the use of hydrology methods with different assumptions and simplifications. This paper reviews actual monitored rainfall and runoff distributions for Milwaukee, WI (data from Bannerman, et al. 1983), and examines long-term rainfall histories and predicted runoff from 24 locations throughout the U.S. The Milwaukee observations show that southeastern Wisconsin rainfall distributions can be divided into the following categories, with possible management approaches relevant for each category of rain: • Common rains having relatively low pollutant discharges are associated with rains less than about 0.5 in. (12 mm) in depth. These are key rains when runoff-associated water quality violations, such as for bacteria, are of concern. In most areas, runoff from these rains should be totally captured and either re-used for on-site beneficial uses or infiltrated in upland areas. For most areas, the runoff from these rains can be relatively easily removed from the surface drainage system.