stream flows
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Author(s):  
R.N. Filippov ◽  
E.A. Titova

The wake vortex consists mainly of two vortices, which are formed when the stream flows around the wings of an aircraft. A semi-empirical model of a stable vortex wake is proposed and analyzed. The model allows describing the velocity field in a vortex, depending on the characteristics of the aircraft generator, as well as assessing the effect of the vortex on the subsequent aircraft. Statistical modeling was carried out to determine the safe interval between the aircrafts for the characteristic sections of the trajectory. When moving over the sea, a straight-line route, a trajectory with turns and an ascent to an altitude for flying around the island were chosen; on the land section of the movement, a flight over the relief was simulated. A significant influence of the ruggedness of the relief on the probability of an aircraft falling when it enters a wake vortex is shown. The effect of the displacement of the aircraft trajectories in the vertical and horizontal planes and the increase in the average flight speed on the safe interval between the aircrafts is investigated.


2021 ◽  
Vol 9 ◽  
Author(s):  
Catherine R. Moore ◽  
John Doherty

This paper explores the adequacy of steady-state-only calibration as a precursor to use of a groundwater model for decision-support. First, it reviews metrics by which a decision-support model should be judged. On the basis of these metrics, it establishes the shortcomings that a decision-support model may incur through foregoing transient calibration. These are 1) failure to reduce the uncertainties of management-salient model predictions to the extent that available data allows, and 2) creation of unquantifiable bias in management-salient predictions. Two methodologies for quantification of these deficiencies are proposed. The first of these addresses uncertainty reduction. This is relatively easy to implement, as it requires only that sensitivities of pertinent model outputs to a model’s parameters be calculated. The second methodology addresses predictive bias. Implementation of this second methodology is more expensive as it requires repeated calibration of a steady state model against stochastic realizations of a transient model.These methods are demonstrated using a synthetic case which explores the viability of steady-state-only calibration of models deployed to examine the impacts of pumping on stream flows and groundwater levels. It is demonstrated that, for some predictions of management interest, steady-state-only calibration is more than sufficient for this kind of decision-support modelling.


2021 ◽  
Vol 13 (9) ◽  
pp. 4833
Author(s):  
Ahmad Zeeshan Bhatti ◽  
Aitazaz Ahsan Farooque ◽  
Nicholas Krouglicof ◽  
Qing Li ◽  
Wayne Peters ◽  
...  

Climate change is impacting different parts of Canada in a diverse manner. Impacts on temperature, precipitation, and stream flows have been reviewed and discussed region and province-wise. The average warming in Canada was 1.6 °C during the 20th century, which is 0.6 °C above the global average. Spatially, southern and western parts got warmer than others, and temporally winters got warmer than summers. Explicit implications include loss of Arctic ice @ 12.8% per decade, retreat of British Columbian glaciers @ 40–70 giga-tons/year, and sea level rise of 32 cm/20th century on the east coast, etc. The average precipitation increased since 1950s from under 500 to around 600 mm/year, with up to a 10% reduction in Prairies and up to a 35% increase in northern and southern parts. Precipitation patterns exhibited short-intense trends, due to which urban drainage and other hydraulic structures may require re-designing. Streamflow patterns exhibited stability overall with a temporal re-distribution and intense peaks. However, surface water withdrawals were well under sustainable limits. For agriculture, the rainfed and semi-arid regions may require supplemental irrigation during summers. Availability of water is mostly not a limitation, but the raised energy demands thereof are. Supplemental irrigation by water and energy-efficient systems, adaptation, and regulation can ensure sustainability under the changing climate.


2021 ◽  
Author(s):  
Nafsika-Ioanna Spyrou ◽  
Eirini Spyridoula Stanota ◽  
Emmanuel Andreadakis ◽  
Emmanuel Skourtsos ◽  
Stylianos Lozios ◽  
...  

<p>This project aims at the use of Unmanned Aircraft Systems (UAS) applications for mapping. Geomorphological mapping of features and changes with the use of UAS, in cases of floods, landslides, stream flows, etc. has been growing rapidly in recent years. It is combined with traditional mapping methods as well as modern technologies such as Geographic Information System (GIS). Our work concerns landslide hazard in the study area of Chios, in particular along the Chios - Kardamila road in the Mersinidi - Miliga region with a record of landslides and particular geological interest. During the field survey a) three-dimensional model of the slope was made across the road using UAS and the apropriate software, b) point cloud, c) a mosaic orthophotomap and d) a Digital Surface Model (DSM). After the data collection components material we followed detailed geological and tectonic mapping with enormous accuracy because the innovative technologies provided us multiple data compared to older methodologies. The exploitation of the Structure from Motion provided us with information of the inaccessible parts of the study area.</p><p> </p>


2021 ◽  
Vol 13 (4) ◽  
pp. 756
Author(s):  
Jeonghyeon Choi ◽  
Jeongeun Won ◽  
Okjeong Lee ◽  
Sangdan Kim

Using modelling approaches to predict stream flow from ungauged basins requires new model calibration strategies and evaluation methods that are different from the existing ones. Soil moisture information plays an important role in hydrological applications in basins. Increased availability of remote sensing data presents a significant opportunity to obtain the predictive performance of hydrological models (especially in ungauged basins), but there is still a limit to applying remote sensing soil moisture data directly to models. The Soil Moisture Active Passive (SMAP) satellite mission provides global soil moisture data estimated by assimilating remotely sensed brightness temperature to a land surface model. This study investigates the potential of a hydrological model calibrated using only global root zone soil moisture based on satellite observation when attempting to predict stream flow in ungauged basins. This approach’s advantage is that it is particularly useful for stream flow prediction in ungauged basins since it does not require observed stream flow data to calibrate a model. The modelling experiments were carried out on upstream watersheds of two dams in South Korea with high-quality stream flow data. The resulting model outputs when calibrated using soil moisture data without observed stream flow data are particularly impressive when simulating monthly stream flows upstream of the dams, and daily stream flows also showed a satisfactory level of predictive performance. In particular, the model calibrated using soil moisture data for dry years showed better predictive performance than for wet years. The performance of the model calibrated using soil moisture data was significantly improved under low flow conditions compared to the traditional regionalization approach. Additionally, the overall stream flow was also predicted better. In addition, the uncertainty of the model calibrated using soil moisture was not much different from that of the model calibrated using observed stream flow data, and showed more robust outputs when compared to the traditional regionalization approach. These results prove that the application of the global soil moisture product for predicting stream flows in ungauged basins is promising.


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