Hydraulic Planning in Insular Urban Territories: The Case of Madeira Island—São Vicente

This study aims to examine the flood propensity of the main watercourse of São Vicente drainage basin and, if relevant, to propose two methodologies to alleviate the impacts, i.e., detention basin sizing and riverbed roughness coefficient adjustment. Geomorphological data were obtained from the watershed characterization process and used through the SIG ArcGIS software for the flood propensity assessment and then for the calculation of the expected peak flow rate for a return period of 100 years through the Gumbel Distribution. Subsequently, the drainage capacity of the river mouth was verified using the Manning-Strickler equation, in order to establish whether the river mouth of the watershed has the capacity to drain the entire volume of rainwater in a severe flood event. In summary, it was possible to conclude that São Vicente’s watershed river mouth is not able to completely drain the rain flow for the established return period. Thus, its drainage capacity was guaranteed by modifying the walls and streambed roughness coefficient and by sizing the detention basin using the Dutch and the Simplified Triangular Hydrograph methods.

Maintenance Time of Permeable Asphalt Pavement Based on Entropy–Analytic Hierarchy Process Analysis

Dust, sediment, and stone chips often block the rainwater-infiltration paths of permeable pavements, which, in conjunction with vehicle load, reduces drainage capacity. To restore this capacity, a reasonable maintenance time and suitable maintenance measures must be determined. Therefore, we investigated the void attenuation and decline in drainage capacity of permeable asphalt pavements under the combined action of dust blockage and vehicle load. First, the water seepage coefficient decay and the decay rate under blocking and compaction were determined via clogging and compaction experiments. Second, experimental data were incorporated into an entropy–analytic hierarchy process analysis model, with the gross domestic product ratio, wind scale, and maximum five-year rainfall for the area. Finally, three test roads were studied as the weight to rank the maintenance urgency and predict the maintenance timing for each road under different rainfall conditions. The results demonstrate that the drainage capacity of permeable pavements obeys the parabolic exponential attenuation law. From the findings regarding road water storage capacity, the latest pavement maintenance time at different rainfall levels were obtained. This predicted maintenance time enables better decisions than regular time on code, which is the effect of drainage caused by multiple factors.

Sustainable Restoration of Degraded Farm Land by the Sheet-Pipe System

For the sustainable restoration of wet farm land degraded by the climate change-induced rise of ground water level (GWL) and soil salinity etc., the sheet pipe system is one of the most useful technologies which reduces cultivation obstacles due to the poor drainage by controlling the rapid drainage function and enabling farmers to produce profitable crops. This system is characterized mainly as a perforated polyethylene rolled-band sheet 180 mm in width and 1 mm thick which is drawn into the subsurface layer while transforming a drainage pipe with φ = 50 mm. The major advantage of this system is that since the sheet pipe is installed without trenching, the disturbance of land is minimized and the construction period can be shortened to about 1/4 (which reduces the cost approximately by 50%). In this study, by using the sheet pipe installed miniature-type model soil box, the drainage capacity of the sheet pipe was confirmed as being the same as the pipe-shaped standard drainage pipes. Based on the observations of the saturated–unsaturated flow and the maximum lowering rate of GWL was predicted. Finally, at the farm land wherein the free board of the adjoining canal was limited, the effectiveness of the sheet-pipe system was confirmed.

Study on the Contribution of Normalization to Reducing Flood Risk in the Ciliwung River, Tebet District, Jakarta

Jakarta is the capital city of the State of Indonesia and fast economy and population growth rate. With these, urbanization continues to increase every year. In this study, we analyse the effect of river normalization on reducing flood risk on the MT. Haryono - Manggarai section based on the Hec-RAS hydraulic model. Boundary Condition applied in upstream river is flow hydrograph with a peak discharge of 561.48 m3/s. In the upstream part, a rating curve is applied from the water level measurement data for the Manggarai Sluice Gate. While in the middle, the lateral flow from the urban drainage channels is inserted. The simulation results show that normalizing the channel can increase the drainage capacity as implied by the decrease in the flood water level. However, downstream there is backwater due to the lack of capacity of the Manggarai floodgate.

Analisa sumur resapan untuk mereduksi limpasan permukaan pada Perumahan Hang Tuah Cipta Residence Pekanbaru

Changes in land use, namely from cultivated land to closed land or settlements, make the water demand in the area increase, if the water that comes out is not balanced with the water that enters the ground, it will cause a decrease in the ground water level. Another problem that arises due to changes in land use is runoff, where runoff occurs due to rainfall exceeding the suction power or infiltration of the soil, so that over time the runoff becomes a puddle and can even cause flooding. One way to overcome these problems is to apply infiltration wells. This case study takes place in the Hang Tuah Cipta Residence Housing Area, Pekanbaru. From the results of field research and Hydrological data analysis revealed that the main existing drainage channel discharge with a discharge capacity of 0.923 m³/s is unable to accommodate the discharge that occurs at 1.19 m³/s. Segment or secondary drainage channels Q12 and Q13 are also unable to accommodate the discharge that occurs at 0.085 m³/s with a capacity of 0.06 m³/s. Based on the analysis results it is planned that the infiltration well with a radius of 0.5 m and a depth of 9 m which has a capacity of 0.0022 m³/s. After the planned discharge infiltration well comes out to be 0.88 m³/s, it means that the discharge does not exceed drainage capacity of 0.923m³/s.

Study on Air Void Characteristics and Hydraulic Characteristics of Porous Asphalt Concrete Based on Image Processing Technology

The appearance of porous asphalt (PA) pavement is to solve the problem of road ponding in rainy days. The internal air voids in PA pavement are the main functional structure that determines its drainage performance. It is of great practical significance to find out the relationship between void drainage capacity and air voids. This paper is aimed at researching the relationship between three-dimensional (3D) pore structures and drainage performance of PA concrete. Four samples were formed and scanned by CT equipment to obtain the internal cross-sectional CT images. Image dodging algorithm and OTSU method were conducted to deal with these CT images for segmenting them into three subimages (void image, asphalt mortar image, and aggregate image) according to the three components of PA concrete. The voids on void images were identified and classified into three groups according to the three kind of pores (interconnected pore, semi-interconnected pore, and closed pore) and reshaped them into 3D pore structures according to the overlapping principle. Then, the volume and size distribution of the pores was analyzed. Besides, this research mainly focused on the influence of several parameters obtained from interconnected pores on the drainage performance of PA concrete at last. The permeability coefficient of PA concrete samples was tested, and equations between permeability coefficient and void content were fitted linearly. The distribution of hydraulic radius and cross-sectional area ratio was calculated and researched by statistical methods. A new parameter, perimeter variation coefficient, is proposed to study the influence of boundary wall roughness on the drainage performance. At last, equivalent drainage channel was drawn to reflect the drainage capacity of PA concrete.

ASSESSING THE IMPACT OF THE SLOPES ON RUNWAY DRAINAGE CAPACITY BASED ON WHEEL/PATH SURFACE ADHESION CONDITIONS

Aircraft braking distance is dependent on the friction between the main gear tires and runway pavement surface.Pavement texture, which is divided into macrotexture and micro-texture, has a noticeable effect upon friction, especially when the surface is wet. A risk analysis framework is developed to study the effects of longitudinal and transverse slopes on the aircraft braking distance in wet runway conditions and their influences on the probability of landing overrun accidents.This framework is operating under various water-film thicknesses, Maximum Landing Weights (MLW), and touchdown speed probability distributions for an acceptable range of longitudinal/transverse slopes and pavement texture depths.A simulator code is developed that initially computes the existing water-film thickness, as the result of intense precipitation,under aircraft main gear (depend on aircraft category) and then applies this variable as one of the main inputs to the aircraft braking distance computation. According to the obtained results, longitudinal gradient does not have a significant effect on the existing water depth on the surface although it affects the flow path length. Furthermore, 1% to 1.5% transverse slope causes rapid drainage of water from the runway surface and considerably decreases the probability of runway excursion accidents.