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abstract 577

ANALYSIS OF THE HYDRAULIC EFFICIENCY OF STORM WATER INLETS MOSTLY USED IN ARGENTINA

Author(s): Claudio Fattor, Héctor Barrionuevo, Jorge Bacchiega, Alejandro Secchi, Rosana Mazzon
Fattor Claudio: Hydraulic engineer, National Institute of Water, with main activity in the field of Hydraulic Structures and physical modeling. Barrionuevo Daniel: Hydraulic engineer, National Institute of Water, with main activity in the field of Hydr

Keyword(s): urban drainage, storm water inlets, hydraulic efficiency

Article:
Poster:

Session: Poster session 4

AbstractIn many of

the main cities of Argentina almost a unique type of storm water inlet has been used until principles of this decade,

with a technical design of early 1940´s. As a result of the severe economic situation of the country around the year

2000, the characteristics of these structures turned very expensive its replacement or his application to new areas.

This derived in the necessity to implement new and more efficient hydraulic designs, taking also into account the

advantages that may provide the use of new materials and fabrication processes. These new designs were not always

directed to maximize the hydraulic efficiency, but to guarantee good conditions of circulation for pedestrians and

vehicles, to diminish the possibilities of damage by vandalism and to avoid their robbery, among other

aspects.

The purpose of this work is to present an analysis of the incidence of storm water inlets design on its

hydraulic performance, considering additionally the incidence that obstructions like solid wastes can generate. To

such aim, an experimental device was constructed in the Laboratory of Hydraulics of the National Institute of Water,

allowing to analyze the hydraulic behavior of these structures at 1:1 length scale. The model includes an

approximation flow area with their cross-sectional and longitudinal slopes, the zone of location of the storm water

inlet, which can be positioned at the same level of the street or below that (depressed area), and the discharge flow

measurement device that allows to know the intercepted flow by each part of the inlet.

The work methodology

consisted of testing different isolated storm water inlets of approximately 1.00 m-long by 0.50 m-wide for

longitudinal street slopes of 0.1% and 0.5% and one cross-sectional slope of 2.0%, taking as an additional variable

the possibility of positioning the inlet device in a depressed zone. The water depth at the upstream section of the inlet,

the flow intercepted by the bottom grates, the flow intercepted by the lateral opening and the exceeding flow were

determined for each flow discharge being circulated in the street. The influence of total or partial obstruction of the

storm water inlet on the efficiency of the device as a consequence, for instance, of solid wastes or leaves was also

analyzed. Besides that, the efficiency experimentally obtained was compared with other criteria, like that developed

by Universidad Politécnica de Cataluña (UPC).

The hydraulic efficiency was obtained by these tests,

determining the incidence of longitudinal slopes as well as the lost of efficiency as a result of obstructions of the storm

water inlet. In addition, the estimations of hydraulic efficiency carried out with some expressions like that presented

by UPC have shown, for some designs, an important difference compared to the experimental results. These results

allow seeing a noticeable incidence of the geometry of the grate, whose hydraulic performance must be precisely

determined to know the efficiency of the storm water inlet to be installed as a fundamental part of urban drainage

system.

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ANALYSIS OF THE HYDRAULIC EFFICIENCY OF STORM WATER INLETS MOSTLY USED IN ARGENTINA