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Sediment deposition in storm drains is one of the most common problems affecting the hydraulic behavior of sewage systems. Sediments are deposited with the passage of time and in the time of drought in particular, the long-term retention of sedimentary solids in the sewer increases the risks of changes in sediment, uniformity and cohesion as the sediments change the surface roughness of the pipes and reduce the flow capacity and change in velocity. In this study, the characteristics of storm sediments were studied in the center of Ramadi city, where 6 samples were collected from rainwater collection holes (manholes) and the main collection basin from three rain networks in different areas (Al-Moalemeen neighborhood, Al-Malaab neighborhood and Al-Shurta neighborhood) and they are of a separate type. It is not hydraulically connected to the sewage network. The samples were examined in the laboratories of the University of Anbar - College of Engineering and included particle size distribution, average particle size (d50), specific gravity (Gs), moisture content and organic content. The sedimentation analysis results showed that sand was the main component except for one sample in which gravel was the main component, and clay and silt were minor components in the samples. High organic content was found in two samples, indicating an overrun on the network. [ABSTRACT FROM AUTHOR]

In recent decades, African cities have been confronted with series of floods linked to rapid urbanisation, intensification of heavy rains and the failure of the storm drainage system. Developing tools to characterise floods and reduce their impact is essential to facilitate decision support in a complex and vulnerable context. This study, conducted in the urban periphery of the Dakar metropolitan area, aims to propose a fine resolution (5 m) model of flows and overflows of rainwater drainage network in a pilot area. Two methodological steps are combined to achieve this objective: (1) the construction of the urban drainage topology to reconstitute the water drainage directions, taking into account the buildings, artificial channels and retention basins, using algorithms developed for this purpose, (2) simulations of the flows in real time or in project mode, using a parsimonious spatial model adapted to the local context, coupling a hydrological model (SCS-LR) on the scale of small basins with a hydraulic model (kinematic wave) for the propagation through the hydrological network. The former ensures the speed of the calculation, and the latter provides precise information on the behaviour of the network during a rainfall event. The overflow points of the network are detected by the difference between the maximum flow and the capacity of the network to evacuate floods. This modelling provides sufficiently informative simulations to guide the deployment of emergency services in the field, in real time, or to evaluate the efficiency of infrastructures in project mode, in a context of limited data. The model also provides boundary conditions for applying more complex hydraulic models to determine the impact of overtopping on limited areas. [ABSTRACT FROM AUTHOR]

Design of hydraulic structures or elements such as check dams, weir, storm water drains, flood levels etc. are carried out for design basis Return period (RP). Hence, historical database is used to estimate Probable Maximum Precipitation (PMP) or statistically analysed to generate design parameters through extreme value analyses (EVA). Generally, such studies are carried out by Expert agencies of Central/State Authorities or Academic Institutions for important zones in the country. However, independent analysis will be required for any project at a virgin site which might have not been covered under these institutional studies. At times, a regional study may not fully capture the uniqueness of a site and may not be able to provide a sustainable design basis. This becomes more critical for important industrial structures, say, nuclear power plants or major dam, which have more conservatism in design and cannot risk any under-design of the system. Present paper presents such a case study of a site on western coast of India wherein EVA has been carried out for site specific rainfall data for different return periods. PMP of the site was also estimated. Findings of the analyses were then compared with available regional study to assess the deviation in design basis. [ABSTRACT FROM AUTHOR]

At present, surface runoff represents serious environmental problems in the urban environment, causing adverse effects on socio-economic and natural systems. Surface runoff is a complex source. The creation of surface runoff is described by various hydraulic hydrological processes, from the impact of water on the surface to the mouth into the sewer network or recipient. The formation of the precipitation-runoff process depends on several factors. Land-use change is a key factor that significantly affects the quality and quantity of surface runoff. In addition, the quality of surface runoff is also influenced by precipitation characteristics and air quality. In the last few years, the air quality is significantly worsened. The reason for this is the rapid development of urban areas, transport, and technical infrastructure. As a result of these phenomena, excessive gases, particularly carbon dioxide, methane, sulfur dioxide, and nitrous oxide, were produced. Due to many research, emission in the atmosphere accounts more than 50 % of atmospheric precipitation pollution. In recent decades, attention has been paid to rainwater quality due to the water crisis. The current use of large amounts of quality water and the removal of heavily polluted water causes significant damage to the aquatic ecosystem. Given the facts, the paper focuses on analyzing the quality of surface runoff captured in urban areas. Subsequently, a comparison of the influence of air quality on the quality of surface runoff is performed. The study results could help design the proper management of surface runoff in urban agglomerations concerning environmental protection and the possibility of rainwater reuse. [ABSTRACT FROM AUTHOR]

Municipalities can take various measures to prevent damage from extreme rainfall events like increasing the dimension of the combined sewer system, separate them into foul and storm sewer systems, increase the infiltration capacity of the subsoil by reducing the (poorly permeable) paved surface, increase the infiltration surface in (underground) facilities or increase the permeability of the paving, install green / blue roofs to ensure delayed drainage and evaporation of water to the atmosphere or by building storage tanks / rain barrel for collecting rainwater that can be reused later. To identify which one is most efficient the extreme rainfall with an intensity of 94mm in 70 minutes has been simulated. This showed that substantial measures are required on site to prevent rainwater nuisance in public areas during extreme showers. In existing situations with low building levels, it is important to realize water storage in low areas in the site or underground. Measures such as a simple green roof and the reduction of paved garden area are the least effective. Most effective seems to be the construction of infiltration boxes underground. It also appears that an emergency overflow to the public area can be important, partly with a view to damage and liability. For dimensioning measures on your own site without overflow, it is wise to take very extreme rainfalls into account. The criterion for a facility on site is that it can handle a local extreme downpour without nuisance in the home. [ABSTRACT FROM AUTHOR]

Flash flood is a very dangerous type of flood that can happen with little or no warning. The flash floods becoming more frequent in the territory of the Slovak Republic, typically for last decades in Central Europe. The number of responses of regional Fire & Rescue Corps connected to the flash floods is very high nowadays. Extreme weather fluctuations due to climate change are threatening drinking water sources as well as new types of natural threats. Severe storms and tornadoes are expected to occur more frequently When there is more rain than the soil can absorb, the excess water quickly runs into rivers and creeks, overwhelming storm drains and ditches and causing a flash flood affecting millions of people every year. The paper deals with the causes of flash floods in Slovak Republic. It points up on the problematic of enormous drainage of the water in the forests due the numerous forest logging roads. The heavy harvest vehicles press the pores of the forest soil and water does not soak inside the earth, it flows away on the surface instead. The drainage effect is discussed for rapid drainage from soil causes the flash floods. Another reason of the flash flood is in the actual field management methods. Long-term absence of the deep plowing decreased the thickness of absorption layer up to twenty centimetres. Compacted soil under the thin fertile surface is unable to absorb water from the rains. Drainage channels network in the lowlands belongs to the causes of flash floods as well as the artificially created slopes. [ABSTRACT FROM AUTHOR]

Nowadays, after intervals of time without rainfall, heavy rain with very high flow rates in very short time are increasingly more often. If extreme rainfall events, storm sewer networks can not take storm water flows, which frequently occurs with flood damage large, often with loss of life. Duet o the fact that rainwater flows to the emissaries in time, the water table drops. Analyzing the frequency of extreme phenomena rainfall and using climate scenarios we can adapt technical regulations related to sizing collectors drainage, so the excess rainfall rates can be collected and stored in underground tanks and used for services utilities, agriculture or infiltrated into the ground. Incidentally land development has damaged the ground in most large cities, such water return to nature is affected by rainwater. In this paper we present solutions to prevent floods and to retain as much water in the ground as we can, in order to avoid droughts. Some of these solutions are the result of interdisciplinary cooperation with architects and roads and bridges engineers. [ABSTRACT FROM AUTHOR]

Sodium chloride (NaCl) is used as a de-icing agent in both solid and brine forms on paved surfaces. During rain and melt events, urban runoff transports the salt ions through pipes and sewer networks to stormwater management ponds. Previous studies have shown that due to densimetric stratification in the pond itself, discharging water can generate chloride (Cl-) pulses to the receiving stream that exceed thresholds of acute toxicity to aquatic biota. This study aims to investigate the prevalence of this phenomenon in the headwaters of the Lake Ontario and Lake Simcoe basins. Five headwater streams receiving flow from wet stormwater ponds in the two basins and two streams with no stormwater treatment were instrumented with conductivity sensors in October 2021. In combination with discrete sampling for Cl- analysis, fifteen-minute conductivity data is collected from monitoring stations up- and downstream of each pond outlet to develop a continuous Cl- time series for the sites. Differences in Cl- concentrations between up and downstream stations are used to identify Cl- pulses associated with flushing of the stormwater ponds. Preliminary results indicate varied behaviour in ponds as only some generate pulses that exceed acute toxicity thresholds, while receiving streams consistently exceed chronic toxicity thresholds throughout the salting season. [ABSTRACT FROM AUTHOR]

Water is essential for life on Earth. Surface water (SW) and groundwater (GW) are the main sources for drinking water supply and important resources also for industry and agriculture. These two components of the hydrological cycle are interconnected and affecting each other, as well as the natural environment. During SW-GW interaction the water quality and quantity can change considerably. The EU Water Framework Directive (WFD) addressed the need of a sustainable management of coupled GW-SW resources and their ecosystems. The WFD recommends estimating the exchange flow rates and flow directions between SW and GW. This requires an enhanced knowledge of these systems. The exchange of water, solutes and colloids between SW and GW, or the hyporheic exchange, perform through the hyporheic zone. The stream hydrology and morphology significantly influence the spatial patterns of this exchange. Moreover stream-aquifer interactions are also influenced by riverbed clogging processes. The infiltration or drainage resistance of rivers influence the duration of hyporheic exchange. The value of these two parameters primarily depends on the clogging processes and the thickness of riverbed sediments. In this study, the interaction between GW and SW and the dynamics of flow processes in the GW-SW system was modelled for different infiltration and drainage resistance parameters. The model area is situated on the Rye Island, which is a lowland area with very low slope. In this area a channel network was built up, which serves for drainage. Because of the low slope and the system of water gates built on the channels, the riverbeds are influenced by intensive clogging processes. The objective of this study was to measure the thickness of riverbed sediments and to model their influence on the GW-SW interaction in the study area. The groundwater heads and the groundwater flow direction were simulated for different infiltration/drainage resistance parameters of the rivers. [ABSTRACT FROM AUTHOR]