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Can stream and river restoration solve the excess nitrogen problem?
Published in Wim Uijttewaal, Mário J. Franca, Daniel Valero, Victor Chavarrias, Clàudia Ylla Arbós, Ralph Schielen, Alessandra Crosato, River Flow 2020, 2020
E.T. Hester, D.T. Scott, D.L. Azinheira, K.E. Brooks, M. Calfe, C. Guth, B. Hammond, A.Y. Lin, C.W. Tsai
Excess nutrients are widespread, for example nitrogen and phosphorous that run off lawns and agricultural fields (Novotny 2002). These cause eutrophication of downstream waterways, including algae blooms, reduced oxygen, fish kills, and toxic dinoflagellates (Vilmin et al. 2018). The two main remedies are reducing nutrient use and treatment, and here we focus on the latter. Water treatment plants are important in that regard, but are expensive for removing low concentrations. Stream/river restoration is a practice where streams/rivers that have been damaged by human activities such as straightening, lining with concrete, burying in pipes, and changes in flow/sediment regime are re-naturalized to help aquatic and riparian ecological communities as well as improve human aesthetics and connection to the landscape (Bernhardt et al. 2005). Stream restoration can also improve water quality by increasing exchange of water between the channel and off-channel storage zones including floodplains and hyporheic zones (shallow groundwater) (Craig et al. 2008). This exchange of pollutants from channel into and back out of these off-channel zones slows river water down, allowing more time for plants and bacteria to remove pollutants. For excess nitrogen in particular, both floodplains and hyporheic zones are areas of heightened denitrification and plant uptake (Jones et al. 2015, Hester et al. 2016, Hester et al. 2018).
Minerals of precious metals
Published in Francis P. Gudyanga, Minerals in Africa, 2020
Direct recovery of gold ‘placer’ deposits of free gold is usually done by gravity concentration techniques such as gold panning, washing tables and sluicing. These are normally used by small scale or artisanal miners. In gold panning, wide, shallow pans are filled with sands and gravel that may contain gold. Shaking the submerged pan in water sorts the gold from the gravel and other material as it quickly settles to the bottom of the pan as a consequence of its greater density. In sluicing, a box with riffles set in the bottom designed to create dead zones is placed in the stream of water flow. As the gold-bearing material is placed at the top of the box carried by the current through the volt, gold settles out behind the riffles. The less dense material flows out of the box.
GPU-based Medical Image Segmentation: Brain MRI Analysis Using 3D Slicer
Published in Mitul Kumar Ahirwal, Narendra D. Londhe, Anil Kumar, Artificial Intelligence Applications for Health Care, 2022
A watershed is a geographical area that aids in the drainage of water (typically rainfall) into a river or stream. It is a highland region through which water flows into a river or stream. Watershed transformation uses a similar concept to treat the picture as a topographic map, with the intensity of each pixel indicating the height. Dark regions, for example, are intuitively seen to be “lower” in height and can indicate troughs. Bright regions, on the other hand, might be regarded as “upper”, functioning as hills or a mountain range. The watershed technique to image segmentation assumes that a picture is seen as a three-dimensional object. The height is determined from the intensity of the pixel/voxel (see Figure 6.2).
A scoping review on Water Sensitive Urban Design aims and achievements
Published in Urban Water Journal, 2022
Samira Rashetnia, Ashok K Sharma, Anthony R Ladson, Dale Browne, Ehsan Yaghoubi
There is a widespread recognition of urban stormwater runoff influence on stream ecosystems; hence, it is necessary to mitigate these impacts by adopting stormwater control measures (Fletcher, Vietz, and Walsh 2014). Streams, in urban development, provide significant ecological, economic, and social benefits even though they are often degraded physically. The main reason for degradation has been the excess runoff of conventional drainage systems (Walsh et al. 2015). WSUD approaches provide an alternative by addressing the causes of urban-induced physical degradation of streams rather than patching the symptoms (Vietz and Hawley 2019).
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.