城市雨洪利用的设计降雨分析方法探讨

针对城区降雨径流和雨洪利用工程建设特点,提出了雨洪利用工程规划设计应采用的降雨分析方法.包括:降雨资料选择与统计分析方法,降雨时空分布和时程分配以及设计降雨过程等内容,可供城市雨洪利用工程和市政排水工程规划设计时参考.     

Design and Performance of Multipurpose Constructed Wetland and Flow Equalization Basin

Stormwater runoff from a portion of a 273?ha (675?acres) Midwestern rail yard contacts industrial facilities including fuel storage tanks and fueling and servicing operation areas. Stormwater draining from a smaller 64?ha (159?acres) sub-basin containing the industrial facilities previously flowed into a retention pond within the rail yard. The retention pond had a surface area of 607?m2 (0.15?acre) and a maximum storage capacity of 1.4?million?L (370,000?gal). Given the large drainage area of the pond the retention time within the pond was shorter than optimal, limiting its potential effectiveness for improving water quality. To address these issues the pond was redesigned to have a 6.25?million?L (1.65?million?gal) storage capacity and configured into a constructed wetland to control a 50-year storm event and increase its ability to treat stormwater runoff. A network of riparian plants (5,700) was placed within the stormwater wetland to treat runoff prior to discharge off-site. Evaluating the performance of both the former and current retention basins revealed significant improvements in the retention and treatment ability when comparing the two structures. Mean total suspended solid concentrations and oil and grease concentrations were reduced approximately 45% when comparing pre- and postconstruction flow analysis. This innovative multiuse approach has demonstrated effectiveness in controlling storm flows and treating runoff from the rail yard.     

Expanding Disk Rain Sensor Performance and Potential Irrigation Water Savings

Rain sensors (RSs) appear to be a useful tool for water conservation at a relatively low cost. However, little evidence related to RS performance and/or reliability exists. The objectives of this experiment were to: (1) evaluate two RS types with respect to the following: Accuracy of their set point, number of irrigation cycles bypassed, and duration in bypass mode; (2) quantify the amount of water that RSs could save; and (3) estimate their payback period. Mini-click (MC) and wireless rain-click (WL) rain sensor models were monitored. For the WL treatment, the dry-out ventilation windows were set half open, and for the MC treatments, rainfall set points of 3, 13, and 25?mm were established. On average, all treatments responded close to their set points with the WL, 3?mm MC, 13?mm MC, and 25?mm MC treatments averaging 1.4, 3.4, 10.0, and 24.5?mm, respectively. However, some replicates showed variable behavior. The number of times that these sensors shut off irrigation (81, 43, 30, and 8 times, respectively) was inversely proportional to the magnitude of their set point, with potential water savings following a similar trend. Where water costs exceed $0.53 per cubic meter ($2.00 per thousand gallons), the payback period is less than a year for WL and MCs set at 13?mm or less.     

Modelling a viscous rock joint activated by rainfall: Application to the La Clapière landslide

The continuous evolution of sliding rock masses activated by rainfall combined with snowmelt will be discussed in this paper. The effects of precipitation on slip velocities during the periods separating failure events have already been studied in the literature by means of either pure statistical approaches or sophisticated numerical codes. A simple schematic model will be presented in this paper based on a crude physical and geometrical simplification of the rock mass hydromechanical system. This model enables simulating the correlations between rainfall/snowmelt data and slip velocities with relative efficiency. This model may be considered as an intermediate tool between purely statistical and more sophisticated numerical models; moreover, it is potentially useful for assessing the stability of civil engineering and open-pit mining slopes.     

Measurement Accuracy Analysis of Sprinkler Irrigation Rainfall in Relation to Collector Shape

Sprinkler irrigation is a widely studied subject in scientific and technical literature. Initially studies were mainly conducted experimentally, whereas more recently we can say that the use of simulation models is the rule. To calibrate such models, experimental data of high precision are required to prevent possible errors in simulations. In sprinkler irrigation evaluation the collectors play a central role and should be designed to minimize the perturbation of water application it is measuring. Using the fluid dynamics software program Fluent, several designs of collectors have been analyzed to assess their capabilities for precise water collection under a horizontal wind. The analysis was performed in two steps: (1) evaluation of airflow perturbation due to collector and (2) calculation of collection rate for different droplet diameters and wind velocity on two selected collectors (one minimizing airflow perturbations, one easy to manufacture). The collector design producing the best results was used to create a mold for manufacturing collectors out of injected plastic material.     

Hydrologic Modeling Inventory: Cooperative Research Effort

The hydrologic modeling inventory developed at the Bureau of Reclamation and posted at its website ?http://www.usbr.gov/pmts/rivers/hmi? is described. The inventory comprises a large number of state-of-the-art watershed models developed by government (federal, state, and local) agencies, universities, and private companies in the United States and elsewhere. This inventory is among the first of its kind and is useful not only for modelers but water resources planners and managers.     

小面积区的集水径流计算方法

曲线数值法考虑了径流与土壤特性和土地利用情况的关系，所需参数少，是一种较好的小型集水区径流计算方法，可用于小面积集水区可集雨量的计算。     

NRCS Design Storm Erosivity

Two methods are developed to estimate rainfall erosivity indices produced by four standard design storms developed by the National Resource Conservation Service (NRCS), which are used widely throughout the United States. The first method is based on regression analysis of erosivity indices calculated from the actual 24-h duration rainfall distributions and is presented in an uncomplicated form. The second method is founded on fits of an exponential distribution to the ordered rainfall intensities obtained for 6-min (0.1-h) intervals for each of the design storm types. Subsequent integration of the unit kinetic energy equation used over the storm durations, which makes use of the exponential expression for rainfall intensity, leads to an analytical approximation of the rainfall erosivity index. Although the regression equations estimate erosivity design storms accurately and are easy to apply, they are limited to durations of 24?h. The analytical solution, on the other hand, can be used to estimate erosivity indices from the four storm types for any duration of 24?h or less.     

Triggering factors of landslides in Campos do Jordão city,Brazil

This paper focuses on the identification and analysis of the mechanisms and triggering factors of some landslides which have occurred in Campos de Jordão city, Brazil. The methodological procedures were based mainly on the recognition of the weathering profiles, recording of the landslide features, elaboration of the map of unconsolidated materials and slope and mass flow direction charts. In addition, an analysis of the rainfall data of the last 23 years was carried out. The translational type was the most common landslide that occurred, with failure surfaces between the sandy silt and sandy clay layers. Most landslides occurred in areas with slopes steeper than 30°. The rainfall data analyzed also showed that the distribution is a more important triggering factor than the amount of precipitation, such that landslides occur preferentially in the period from December to January.