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Porous basin
Published in James C.Y. Guo, Wenliang Wang, Junqi Li, Urban Drainage and Storage Practices, 2023
James C.Y. Guo, Wenliang Wang, Junqi Li
The Q-problem is represented by the changes in the flow-frequency curve that depicts the relationship between the flow and its probability of recurrence. Preservation of a flow-frequency curve implies that the development does not change the expected flood damage. In practice, a well-designed stormwater detention basin may reduce the peak flow as illustrated in Fig. 19.29, but the stored water volume will have to be released at a higher rate for a long time. Prolonged high flows do induce erosion to the stream bed and scour to the channel banks. These are typical changes in stream morphology. It is important to recognize the fact that a detention basin provides a solution to Q-problems by reducing the peak flow, but it does not reduce the runoff volume at all. Therefore, the V-problems can only be alleviated with infiltration basins that are designed to reduce runoff volumes (EPA 1983, EPA 2006).
Agricultural Runoff
Published in Brian D. Fath, Sven E. Jørgensen, Megan Cole, Managing Soils and Terrestrial Systems, 2020
Matt C. Smith, David K. Gattie, Daniel L. Thomas
A second concern is that many of these sediments are heavy and will settle out in slow moving portions of streams or in reservoirs. The settled sediments can dramatically alter the ecology of the streambed. Aquatic plants, insects, and fish all have specific requirements related to composition of the streambed for them to live and reproduce.[6] Sediments in reservoirs reduce the volume of the reservoir available to store water. This may result in reduced production of hydroelectric power, reduced water availability for municipal supply, interference with navigation and recreation, and increased dredging requirements to maintain harbor navigability.
New Insights Offered by UAS for River Monitoring
Published in J.B. Sharma, Applications of Small Unmanned Aircraft Systems, 2019
Salvatore Manfreda, Silvano Fortunato Dal Sasso, Alonso Pizarro, Flavia Tauro
Furthermore, UAS platforms have the potential to generate remote and distributed hydrometric data over any river system, also under difficult-to-access environments. Accurate topographic data from the riverbed and floodplain areas are essential for simulating flow dynamics and forecasting flood hazards, predicting sediment transport and streambed morphological evolution, and monitoring instream habitats (Bandini et al. 2018). From this point of view, UASs can fill the gap between satellite/aerial imagery and ground-based measurements. Whereas exposed floodplain areas can be directly monitored from aerial surveys, riverbed topography is not directly observable. At the same time, satellite methods have been successfully applied in monitoring water surface elevation in large rivers, but are ineffective for smaller streams due to low spatial resolution.
Role of roughness geometry function on spatially averaged form induced shear stresses and pressure energy diffusion rates in gravel-bed stream
Published in ISH Journal of Hydraulic Engineering, 2021
Mithun Ghosh, Pritam Malakar, Ratul Das
The understanding of flow-stream bed interactions in natural and artificial porous media has always been in the focus of many river engineering applications. The surface topography and complex geometry of stream-bed porosity are considered to be the dominant factors on the near-bed hydraulics. The recent research advances underpin the interactions of flow-stream bed mechanisms which corroborate the overall development of stream health and therefore recognised as fundamental to river ecology. Several publications have appeared in recent years and there has been less evidence where the gravel-bed porosity at different vertical scales is directly addressed to interpret the spatial flow structures. In this regard, the roughness geometry function, ø(z) put forward the claim to act as an inherent tool addressing the issue. In general, the ø(z)-function is defined as the fractional fluid volume occupied at an elevation to the total volume considered for averaging in the interfacial sub-layer. Estimation of ø(z)-function in gravel bed stream is a complex task and many researchers (Nikora et al. 2001; Aberle et al. 2008) attempted measuring the best possible surface textures by point gauges and laser scans. Most significantly, measuring of inter-gravel fluid volume below the lower curvature of gravels is very difficult and water displacement method may overcome the constraints of point gauge measurement. In order to demonstrate the near-bed spatial flow structures, the double-averaging (DA) methodology may be an appropriate tool by which the governing equations of fluid flows are averaged in both temporal and spatial domains. The theory and applications of DA methodology are well explained in many literatures (Nikora et al. 2007a, b; Cooper et al. 2018; Aberle et al. 2008; Dey and Das 2012). Here, the time-averaged variables are decomposed into two parts as
A systematic approach for effective storm water management at building level during extreme rainfall events – a case study
Published in Urban Water Journal, 2022
Vasantha Kumar S., Shishodiya Ghanshyam Singh
Constructing gutters, pipes and stormwater drains to collect and carry the stormwater to the nearby streams or rivers is the traditional practice of stormwater management. While this can reduce the chances of local flooding, however, flooding is more likely to happen on the downstream side, especially when high flows from many streams converge. Also, as the water moves faster in a channelized stream, erosion of the stream bed and bank can occur. Sometimes, the storm sewers may overflow and cause flooding on the streets. The tanks are also not effective nowadays for storm water management due to the reasons stated before. Hence in recent years, more focus is given to new stormwater management techniques like low impact development, green infrastructure where the idea is to keep the stormwater close to where it falls and use it for purposes like infiltration, gardening, etc (Tan et al. 2019; McPhillips et al. 2021; Shandas et al. 2020; Junqueira, Serrao-Neumann, and White 2020; Neupane, Vu, and Mishra 2021; Ureta et al. 2021; Yang et al. 2021; Ying et al. 2021). Though this green infrastructure concept of decentralized stormwater management is popular in many developed countries as witnessed from the studies listed above, however it is still in initial stage in developing countries like India as studies on this topic could not be found much (Mankikar and Driver 2021). Studies on stormwater management are mostly focused on city level (Zhang et al. 2017; Fitzgerald and Laufer 2017; Tredway and Havlick 2017; Finewood, Matsler, and Zivkovich 2019; Thorsby, Miller, and Treemore-Spears 2020; Sheikh and Izanloo 2021; Walker 2021) whereas studies that addresses the stormwater management at building level was not found much. The study of stormwater management at building level is very important because if the water level surrounding the building is raised during excess rainfall, it may go inside the building basement and this may cause severe damage to the infrastructure in the basement. This case study work presented in this paper primarily aims to address this particular issue. Because during the floods in Chennai in 2015, many buildings faced the similar issue as the basement and ground floors have submerged (Kotteswaran 2015). The damages and losses due to Chennai floods were worked out to be 50,000 crores or US$7 billion (NITI Aayog 2021). This clearly indicates the need for stormwater management at building level especially in countries like India which lacks proper stormwater management system. The objectives of this study are: (1). To perform total station survey surrounding a case study building which experienced water stagnation issues during an extreme rainfall and prepare the topographic maps (Reduced level (RL), contour, digital elevation model (DEM)) and maps of hydrologic parameters (flow direction & accumulation), (2). To identify the low-lying areas through the analysis of maps prepared, for use by the estates department in order to devise an effective stormwater management plan for the case study building considered, (3). To perform hydrological analysis to find the extreme rainfalls and their peak runoffs for checking the effectiveness of the recharging structure.