urban drainage; Hill; gutters; water descents

The intensification of the urbanization process in large urban centers has increased the demand for

infrastructure, sanitation and housing. In this way, the result is transformations in the earth's surface,

mainly with regard to changes from vegetated surfaces, considered permeable, to urbanized surfaces, considered impermeable. Meireles (2023) cited a series of environmental, social and economic problems as a consequence of urbanization, highlighting the need for greater urban planning for the balanced and sustainable growth of urban centers. Song et al. (2018) highlighted that changes in land use and cover considerably alter the dynamics of the Earth's functioning and its biochemical cycles, contributing to climate change and affecting the properties of the Earth's surface. As a result, there is the occurrence of natural disasters, which, combined with extreme precipitation events, can generate risky situations and cause a series of losses for society. This work aims to analyze the surface drainage system of a hill area located in the municipality of Recife-PE, which presented great vulnerability to the impacts resulting from high precipitation in the extreme precipitation event that occurred on May 28, 2022, which caused a series of negative impacts on the municipality. Therefore, the work will be focused on the study and hydraulic evaluation of surface drainage devices, as well as possible suggestions for greater system efficiency. Two main types of microdrainage devices were evaluated: 3 gutters, based on the difference between the admissible flow (Izzard Equation) and design flow (Rational Method) and 4 water drops, using the SISCCOH software – System for Water Calculations. Hydraulic Components. For gutters, problems were found in relation to the capacity of gutter S2, in which the design flow (generated by the extreme event) was higher than the allowable flow (flow that the device is capable of supporting). It should be noted that this situation is mainly linked to the impact of the external contribution to thedevice, since the inclusion of this area substantially increases the relative design flow (0.189 m³/s). The AHP methodology was applied to determine the best compensatory technique in the gutter contribution area to be adopted with a view to reducing the water flow coming from the urbanized contribution areas of the hill, three alternatives being evaluated: (1) green roofs with vegetation; (2) storage of rainwater in a reservoir (water tank); and (3) low-cost green roofs. The Analytic Hierarchy Process (AHP) was used to assist in decision making, carrying out joint analysis with data collection from the Google Forms platform and evaluation of alternatives based on qualitative and quantitative analyzes carried out in studies previous ones. It was concluded that Alternative 2 (implementation of water tanks) is considered the most appropriate alternative based on the application of the AHP analysis, as it presented a higher final score than the other alternatives (2.18) and consequently the highest-ranking order. In relation to waterfalls, the results pointed to the Nappe Flow regime, with a subregime of partial development of the hydraulic rebound. It is noteworthy that the devices presented jet drop lengths with very close values, which causes air pockets to be formed on each step, with successive drops in which a hydraulic jump may or may not be generated on each step.