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2021 ◽  
Vol 13 (24) ◽  
pp. 13513
Author(s):  
Antonio J. Sanhouse-García ◽  
Jesús Gabriel Rangel-Peraza ◽  
Sergio A. Rentería-Guevara ◽  
Yaneth A. Bustos-Terrones ◽  
Zuriel D. Mora-Félix ◽  
...  

Urban development decreases infiltration, increases the runoff velocity, and reduces the concentration times. This situation increases the flood risk in urban watersheds, which represent a management challenge for urban communities and authorities. To increase the resilience of communities due to modifications of the hydrological cycle produced by climate change and urban development, a methodology is proposed to delineate flood-prone areas in urban basins. This methodology is implemented in an urban subbasin of Culiacan, Mexico, and is based on stream order. A high-resolution digital elevation model was used, which was validated independently through a photogrammetric flight with an unmanned aerial vehicle and ground control points obtained with GNSS (global navigation satellite systems) receivers. Morphometric parameters related to geometry, shape, relief, and drainage network aspects of the subbasin were determined and analyzed. Then, flood-prone area zonation was carried out based on stream-order classification and flow direction. Fieldwork was also carried out for the inspection of the sewage network conditions. This methodology simplifies the identification of the flood-prone areas in urban subbasins without carrying out complex hydraulic calculations.


2021 ◽  
Vol 13 (22) ◽  
pp. 4645
Author(s):  
Ge Pu ◽  
Lindi J. Quackenbush ◽  
Stephen V. Stehman

Riparian vegetation delineation includes both the process of delineating the riparian zone and classifying vegetation within that zone. We developed a holistic framework to assess riparian vegetation delineation that includes evaluating channel boundary delineation accuracy using a combination of pixel- and object-based metrics. We also identified how stream order, riparian zone width, riparian land use, and image shadow influenced the accuracy of delineation and classification. We tested the framework by evaluating vegetation vs. non-vegetation riparian zone maps produced by applying random forest classification to aerial photographs with a 1 m pixel size. We assessed accuracy of the riparian vegetation classification and channel boundary delineation for two rivers in the northeastern United States. Overall accuracy for the channel boundary delineation was generally above 80% for both sites, while object-based accuracy revealed that 50% of delineated channel was less than 5 m away from the reference channel. Stream order affected channel boundary delineation accuracy while land use and image shadows influenced riparian vegetation classification accuracy; riparian zone width had little impact on observed accuracy. The holistic approach to quantification of accuracy that considers both channel boundary delineation and vegetation classification developed in this study provides an important tool to inform riparian management.


2021 ◽  
Vol 67 (3) ◽  
pp. 248-262
Author(s):  
Neetesh Kumar ◽  
◽  
Jagadish Singh ◽  

The morphometric analysis of any drainage basin is considered useful for water resource studies such as flood assessment, water quality sampling, water use reporting, watershed management etc. Drainage basin is generally defined as the areal extent of land from which the surface runoff flows to a defined drain, channel, stream or river. It is mainly governed by the topography of the terrain. Geographical Information System and Image Processing Techniques can be used for the identification of morphological features and analyzing properties of the basin. The morphometric parameters include linear, areal and relief aspects. ‘Watershed Atlas of India’ (2014) on 1:50,000 scale is an important digital database for planning and monitoring of development programs on a watershed basis. It serves as a uniform baseline for developing a hydrological unit-based data bank to be used for the management of water resources in the country. Run-off, sedimentation, water balance, evapotranspiration and several other catchment characterization related studies may be taken up on a watershed basis. The present study deals with morphometric parameters such as stream order (Nu), stream length (Lu), bifurcation ratio (Rb), drainage density (D) and stream frequency (Fs) of the Betwa drainage basin. Geographically the basin (77° 30′ to 80° 12′ east longitudes and 23°30′ to 25°55′ north latitudes) is located in two states i.e. Madhya Pradesh and Uttar Pradesh occupying an area of 43780 km2. The length of the stream segment is maximum for the first-order stream and decreases as the stream order increases. This study would help in understanding the hydrological behaviour of the basin. This, in turn, may enable the local people to utilize the resources of the basin for the sustainable development of the area.


2021 ◽  
Vol 11 (7) ◽  
Author(s):  
Alemsha Bogale

AbstractGIS and remote sensing approach is an effective tool to determine the morphological characteristics of the basin. Gilgel Abay watershed is stretched between latitude 10.56° to 11.22° N and longitude 36.44° to 37.03° E which is one major contributing river of Lake Tana which is the source of Blue Nile. The present study addressed linear and areal morphometric aspect of the watershed. The study deals with emphasis on the evolution of morphometric parameters such as stream order, stream length, bifurcation ratio, drainage density, stream frequency, texture ratio, elongation ratio, circularity ratio, and form factor ratio. The morphometric analysis of the basin revealed that Gilgel Abay is firth-order drainage basin with total of 662 drainage network, of which 511 are first order, 111 are second order, 30 are third order, 9 are fourth order, and 1 is fifth-order stream. The total length of stream is longer for first order and decrease with increasing stream order. The mean bifurcation ratio is 5.16 which is greater than the standard range, and it indicates that basin is mountainous and susceptible to flooding. Low drainage density is observed which is 0.6 km−2. It indicates that basin is highly permeable and thick vegetation cover. Areal aspect of the morphometric analysis of the basin revealed that the basin is slightly potential to flooding and soil erosion, indicating that runoff generated from the upland area of the watershed is significantly infiltrated at the gentle downstream part and contributing to groundwater potential. Further studies with the help of GIS and remote sensing with high-resolution remote sensing data integrating with ground control data in the field are more effective to formulate appropriate type of natural resource management system.


2021 ◽  
Vol 32 (2) ◽  
pp. 96
Author(s):  
Dhuha S. Al-Khafaji ◽  
Asraa Khtan Abdulkareem ◽  
Qusai Y. Al-Kubaisi

To improve the management of water resources in Iraq, there are several methods, including the use of rainwater harvesting techniques. In this study, the Digital Elevation Model (DEM) and Landsat satellite imagery were used under the GIS environment to identify the suitable zones for rainwater harvesting. The accomplishment of rainwater harvesting systems strongly depends on their technical designing and identifying the suitable sites. Six criteria have been used to identify the rainwater harvesting sites in the Diyala governorate. The procedure of identifying the suitable sites for rainwater harvesting was applied twice for the Diyala governorate. Firstly, it was applied by using the criteria of rainfall, slope, stream order, distance to roads, and land use, and secondly, rainfall, slope, stream order, distance to roads, and Normalized Difference Vegetation Index (NDVI) criteria were used for this purpose. As a result, the study area was divided into three suitability zones: low, moderate, and high according to the specific criteria that were used to identify the rainwater harvesting suitable sites. It was found that in the application of land use criterion the low suitability zone represents 26%, 58% represents the moderate, and 16% for the high suitability zone, while in the method of NDVI it was found that 29% represents the zone that has low suitability, 57% represents the moderate, and 14% represents the high suitability zone. The compared results led to conclude that the land use is the most influential criterion for identifying the rainwater harvesting suitability sites and found that most of the Eastern parts of Diyala governorate are promising areas for rainwater harvesting and ArcGIS is a very useful, time-saving, and cost-effective tool for identifying the rainwater harvesting suitable sites.


2021 ◽  
Vol 12 ◽  
Author(s):  
Yanyan Yang ◽  
Stefanos Banos ◽  
Gunnar Gerdts ◽  
Antje Wichels ◽  
Marlis Reich

Rivers are transport systems and supply adjacent ecosystems with nutrients. They also serve human well-being, for example as a source of food. Microorganism biodiversity is an important parameter for the ecological balance of river ecosystems. Despite the knowledge that fungi are key players in freshwater nutrient cycling and food webs, data on planktonic fungi of streams with higher stream order are scarce. This study aims to fill this knowledge gap by a fungi-specific 18S ribosomal RNA (rRNA) gene tag sequencing approach, investigating mycoplankton diversity in the Elbe River along a transect from shallow freshwater, to the estuary and river plume down to the adjacent marine waters (sections of seventh stream order number). Using multivariate analyses and the quantitative process estimates (QPEs) method, questions (i) of how mycoplankton communities as part of the river continuum change along the transect, (ii) what factors, spatial and environmental, play a role, and (iii) what assembly processes, such as selection or dispersion, operate along the transect, were addressed. The partitioning of mycoplankton communities into three significant distant biomes was mainly driven by local environmental conditions that were partly under spatial control. The assembly processes underlying the biomes also differed significantly. Thus, variable selection dominated the upstream sections, while undominated processes like ecological drift dominated the sections close to the river mouth and beyond. Dispersal played a minor role. The results suggest that the ecological versatility of the mycoplankton communities changes along the transect as response, for example, to a drastic change from an autotrophic to a heterotrophic system caused by an abrupt increase in the river depth. Furthermore, a significant salinity-dependent occurrence of diverse basal fungal groups was observed, with no clade found exclusively in marine waters. These results provide an important framework to help understand patterns of riverine mycoplankton communities and serve as basis for a further in-depth work so that fungi, as an important ecological organism group, can be integrated into models of, e.g., usage-balance considerations of rivers.


Water ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 158
Author(s):  
Ji Yoon Kim ◽  
Usman Atique ◽  
Kwang-Guk An

The incidence and dispersal of invasive alien fish species (IAFS) have ecological impacts on biodiversity and environmental health at regional to global scales. We identified links between the presence of largemouth bass (Lb) and bluegill (Bg), and selected indicators of environmental water quality, trophic and tolerance guilds, ecological health factors, and stream order. We used the data collected from national biomonitoring study sites in four major rivers of South Korea. IAFS occurred in eutrophic waters (Lb = total phosphorus: 140 ± 170 µg/L, chlorophyll a: 16.7 ± 27.5 µg/L; Bg = total phosphorus: 160 ± 190 µg/L, chlorophyll a: 19.43 ± 28.05 µg/L) and dominated at higher ambient ratios of total nitrogen to total phosphorus (TN:TP). At TN:TP ≤ 100, the relative abundance of Lb and Bg was highest (95.3% and 96.0%, respectively). Concerning tolerance guilds, Lb (R2 = 0.78, p < 0.0001) and Bg (R2 = 0.59, p < 0.0001) had positive relationships with tolerant species in all four river watersheds and negative relationships with the percentages of insectivores and omnivores. This indicates the harmful impacts of IAFS on the aquatic food web. These invasive fish species also influenced stream health, particularly in the Nakdong and Yeongsan/Seomjin rivers. Our findings suggest that assessing chemical water quality can help identify the optimal and suboptimal survival and spread ranges of IAFS (Lb and Bg), as they directly influence tolerance and trophic guilds in the aquatic food web. In conclusion, these IAFS could be a major factor in the deteriorating ecosystem health, which had negative relationships with the abundance and occurrence of IAFS. Therefore, approaches that use appropriate water chemistry factors and species tolerance may provide critical insights into the efficient management of river health that has been perturbed by the presence of IAFS.


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