scholarly journals The role of river flow and tidal asymmetry on 1-D estuarine morphodynamics

2014 ◽  
Vol 119 (11) ◽  
pp. 2315-2334 ◽  
Author(s):  
L. Guo ◽  
M. van der Wegen ◽  
J. A. Roelvink ◽  
Q. He
Keyword(s):  
River Flow ◽  
Tidal Asymmetry

scholarly journals Role of glaciers in watershed hydrology: a preliminary study of a "Himalayan catchment"

2010 ◽  
Vol 4 (1) ◽  
pp. 115-128 ◽  
Author(s):  
R. J. Thayyen ◽  
J. T. Gergan
Keyword(s):  
Mass Balance ◽  
River Flow ◽  
Initial Increase ◽  
Glacier Mass Balance ◽  
Mountain Range ◽  
Humid Climate ◽  
Flow Response ◽  
Sustainable Water Resources Management ◽  
South West Monsoon

Abstract. A large number of Himalayan glacier catchments are under the influence of humid climate with snowfall in winter (November–April) and south-west monsoon in summer (June–September) dominating the regional hydrology. Such catchments are defined as "Himalayan catchment", where the glacier meltwater contributes to the river flow during the period of annual high flows produced by the monsoon. The winter snow dominated Alpine catchments of the Kashmir and Karakoram region and cold-arid regions of the Ladakh mountain range are the other major glacio-hydrological regimes identified in the region. Factors influencing the river flow variations in a "Himalayan catchment" were studied in a micro-scale glacier catchment in the Garhwal Himalaya, covering an area of 77.8 km2. Three hydrometric stations were established at different altitudes along the Din Gad stream and discharge was monitored during the summer ablation period from 1998 to 2004, with an exception in 2002. These data have been analysed along with winter/summer precipitation, temperature and mass balance data of the Dokriani glacier to study the role of glacier and precipitation in determining runoff variations along the stream continuum from the glacier snout to 2360 m a.s.l. The study shows that the inter-annual runoff variation in a "Himalayan catchment" is linked with precipitation rather than mass balance changes of the glacier. This study also indicates that the warming induced an initial increase of glacier runoff and subsequent decline as suggested by the IPCC (2007) is restricted to the glacier degradation-derived component in a precipitation dominant Himalayan catchment and cannot be translated as river flow response. The preliminary assessment suggests that the "Himalayan catchment" could experience higher river flows and positive glacier mass balance regime together in association with strong monsoon. The important role of glaciers in this precipitation dominant system is to augment stream runoff during the years of low summer discharge. This paper intends to highlight the importance of creating credible knowledge on the Himalayan cryospheric processes to develop a more representative global view on river flow response to cryospheric changes and locally sustainable water resources management strategies.

scholarly journals Role of Runoff–Infiltration Partitioning and Resolved Overland Flow on Land–Atmosphere Feedbacks: A Case Study with the WRF-Hydro Coupled Modeling System for West Africa

2016 ◽  
Vol 17 (5) ◽  
pp. 1489-1516 ◽  
Author(s):  
Joel Arnault ◽  
Sven Wagner ◽  
Thomas Rummler ◽  
Benjamin Fersch ◽  
Jan Bliefernicht ◽  
...  
Keyword(s):  
West Africa ◽  
Overland Flow ◽  
River Flow ◽  
Efficiency Coefficient ◽  
Wet Season ◽  
Coupled Modeling ◽  
Study Region ◽  
Outer Domain ◽  
Terrestrial Water

Abstract The analysis of land–atmosphere feedbacks requires detailed representation of land processes in atmospheric models. The focus here is on runoff–infiltration partitioning and resolved overland flow. In the standard version of WRF, runoff–infiltration partitioning is described as a purely vertical process. In WRF-Hydro, runoff is enhanced with lateral water flows. The study region is the Sissili catchment (12 800 km2) in West Africa, and the study period is from March 2003 to February 2004. The WRF setup here includes an outer and inner domain at 10- and 2-km resolution covering the West Africa and Sissili regions, respectively. In this WRF-Hydro setup, the inner domain is coupled with a subgrid at 500-m resolution to compute overland and river flow. Model results are compared with TRMM precipitation, model tree ensemble (MTE) evapotranspiration, Climate Change Initiative (CCI) soil moisture, CRU temperature, and streamflow observation. The role of runoff–infiltration partitioning and resolved overland flow on land–atmosphere feedbacks is addressed with a sensitivity analysis of WRF results to the runoff–infiltration partitioning parameter and a comparison between WRF and WRF-Hydro results, respectively. In the outer domain, precipitation is sensitive to runoff–infiltration partitioning at the scale of the Sissili area (~100 × 100 km2), but not of area A (500 × 2500 km2). In the inner domain, where precipitation patterns are mainly prescribed by lateral boundary conditions, sensitivity is small, but additionally resolved overland flow here clearly increases infiltration and evapotranspiration at the beginning of the wet season when soils are still dry. The WRF-Hydro setup presented here shows potential for joint atmospheric and terrestrial water balance studies and reproduces observed daily discharge with a Nash–Sutcliffe model efficiency coefficient of 0.43.

scholarly journals MORPHOLOGICAL CHARACTERISTICS OF THE GIANH RIVER (FROM CO CANG TO CUA GIANH) IN RELATION TO THE EROSION AND ACCUMULATION

2019 ◽  
Vol 18 (4) ◽  
pp. 384-392
Author(s):  
Hai Nguyen Tien ◽  
Dang Vu Hai ◽  
Phuc La The ◽  
Ha Nguyen Thai
Keyword(s):  
River Flow ◽  
Dominant Role ◽  
Morphological Characteristics ◽  
Straight Channel ◽  
Meandering Channel ◽  
Braided Channel ◽  
River Bed ◽  
Erosion And Accretion ◽  
Channel Bar

On the basis of morphological characteristics and erosion - accumulation of sediment, it is possible to divide the stretch of the Gianh River from Co Cang to Cua Gianh (about 54km in length) into 3 sections as follows: Meandering channel (from Co Cang to Tien Xuan Isles): the length of the channel is 27.69km and the width of the channel is 80-250m. The channel is in the form of a meandering, narrow riverbed, flow plays a dominant role, deposition activities develop strongly at the convex side, while erosion occurs strongly in the concave side (cut side); Braided channel (from Tien Xuan Isles to Quang Phu): the length of the channel is 17.06km and the width of the channel is 800-2,200m. The channel is straight, the river bed is large and the depth of the river bed is 2-11m. Sedimentation occurs mainly at the bottom of the channel and creates bar in the middle of the channel; Straight channel (from Quang Phu to Cua Gianh): the length of the channel is 9.23km and the width of the channel is 800-1,000m. The channel is straight and the depth of the river bed is 8-12.5m. In addition to the role of river flow, it is strongly influenced by marine dynamics. The erosion and accretion activities occur mainly in estuaries. The results above show trend of river development: i) Meandering channel is the most vulnerable to changes for morphology of channel by erosion and accretion of sediment and can create 1-2 horseshoe pools by the river change line; ii) Braided channel mainly changes in the bottom of channel by the formation of channel bar; iii) Straight channel mainly changes in the estuary (the mouth of the river can be moved, enlarged or narrowed).

Tidal asymmetry in the Sylt-Romo Bight, south-eastern North Sea

2020 ◽  
Author(s):  
Vera Fofonova ◽  
Alexey Androsov ◽  
Lasse Sander ◽  
Ivan Kuznetsov ◽  
Felipe Amorim ◽  
...  
Keyword(s):  
Circulation Pattern ◽  
Tidal Energy ◽  
Tidal Asymmetry ◽  
Residual Circulation ◽  
Linear Processes ◽  
Bathymetric Data ◽  
Full Analysis ◽  
Bathymetric Map

<p> </p><p>The study is dedicated to the tidal dynamics in the Sylt-Rømø Bight with a focus on the non-linear processes. The FESOM-C model was used as the numerical tool, which works with triangular, rectangular or mixed grids and is equipped with a wetting/drying option. As the model’s success at resolving currents largely depends on the quality of the bathymetric data, we have created a new bathymetric map for an area based on recent studies of Lister Deep, Lister Ley, and the Højer and Rømø Deep areas. This new bathymetric product made it feasible to work with high resolution grids (up to 2 m in the wetting/drying zone). As a result, we were able to study the tidal energy transformation and the role of higher harmonics in the domain in detail. The tidal ellipses, maximum tidally-induced velocities, energy fluxes and residual circulation maps were constructed and analysed for the entire bight. Additionally, tidal asymmetry maps were introduced and constructed. The full analysis was performed on two grids with different structures and showed a convergence of the results as well as fulfillment of the energy balance. The tidal residual circulation and asymmetric tidal cycles largely define the circulation pattern, transport and accumulation of sediment and the distribution of bedforms in the bight, therefore the results are necessary and useful benchmarks for further studies in the area, including baroclinic and sediment dynamics investigations.</p>

scholarly journals LARGE AND SMALL RESERVOIRS OF UKRAINE: REGIONAL AND BASIN DISTRIBUTION FEATURES

2021 ◽  
pp. 6-17
Author(s):  
V.K. KHILCHEVSKYI ◽  
V.V. GREBIN
Keyword(s):  
River Basin ◽  
River Flow ◽  
River Basins ◽  
Small Reservoirs ◽  
National Importance ◽  
Distribution Features ◽  
The Status ◽  
Rental Rate

The aim of the study was to establish the territorial patterns of the distribution of reservoirs in administrative regions and river basin districts, to identify the role of large, medium and small reservoirs in the balance of river flow regulation in Ukraine. In Ukraine, there are only 1054 reservoirs, among which there are six large reservoirs of the Dnieper cascade and the Dniester reservoir, and all the remaining 99.3% (1047 reservoirs) belong to the middle (M), small (S) and very small (VS) categories. For convenience, we call this group with the abbreviation MSVS-reservoirs. All reservoirs have a total volume of 55.13 km3. Thus, reservoirs regulate 32% of the total river flow of the country, amounting to 170.3 km3 per year. There are two main patterns of territorial distribution of reservoirs: large reservoirs are located on large rivers (Dnieper and Dniester) and are of national importance; MSVS-reservoirs – were created to provide water to industrial regions (for example, Donetsk, Kharkiv) and have regional or local significance. In terms of the volume of accumulated water, Ukraine is a country of large reservoirs. The six reservoirs of the Dnieper cascade contain 79% of the water, in the Dniester – 6%, in the MSVS-reservoirs – 15%. The volume of reservoirs in the Dnieper cascade is 43.71 km3, which is 82% of the average long-term runoff of the Dnieper (53.5 km3 per year). The operation of the Dniester reservoir (3.0 km3), which was created in the transboundary city of Dniester (Ukraine – Moldova), is carried out taking into account the water management interests of the two countries. MSVS-reservoirs are unevenly distributed over the territory of Ukraine. The largest number of them is concentrated in the arid central and southeastern regions of Ukraine, 45% of the total number of MSVS-reservoirs is located in the region of the river basin Dnieper. The largest total values of the total volume and area of MSVS-reservoirs is in the Odesa region due to the Danube lakes, which have been granted the status of reservoirs. In the use of territorial communities in Ukraine, there are 72% of the MSVS-reservoirs, 28% – leased. Among the regions of Ukraine, most of all are rented MSVS-reservoirs in the Transcarpathian region – 78%. In the Zaporizhye region, 56% of the MSVS-reservoirs are leased, in the Ternopil region – 54%. There are leases of MSVS-reservoirs in Ivano-Frankivsk and Lviv regions. Low values of the lease indicator were in the Autonomous Republic of Crimea (4%), in Kherson (7%), Vinnitsa (8%) and Volyn regions (10% each). Among the regions of river basins, there are more leased MSVS-reservoirs in the regions of the river basins. Southern Bug – 35%, Dnieper – 32%. The minimum rental rate was in the region of the Crimean river basin (4%). There is a lease of MSVS-reservoirs in the area of the river basin. Vistula.

The role of tidal asymmetry in characterizing the tidal energy resource of Orkney

2014 ◽  
Vol 68 ◽  
pp. 337-350 ◽  
Author(s):  
Simon P. Neill ◽  
M. Reza Hashemi ◽  
Matt J. Lewis
Keyword(s):  
Energy Resource ◽  
Tidal Energy ◽  
Tidal Asymmetry

Water Security in Pakistan

2018 ◽  
pp. 58-84
Author(s):  
Sofia Idris
Keyword(s):  
Water Scarcity ◽  
River Flow ◽  
Agricultural Land ◽  
Water Security ◽  
International Community ◽  
International Treaty ◽  
China And India ◽  
Water Treaty

Pakistan largely faces water scarcity, and the arid agricultural land of Pakistan is mainly due to the violation of the Indus Water Treaty by its neighbor India. By blocking the river flow towards Pakistan from the head-works, India has been building excessive dams, barrages, and power projects which are illegal according to the above-mentioned international treaty, and Pakistan has many times appealed in the UN to take action against this unfair act. However, so far, nothing could be done in this regard. The study will be helpful to understand the various challenges facing Pakistan to cater the insufficient supply of water and will give insight on the most important dimensions and facts about the international challenges to meet the shortage. The trans-boundary water issue between China and India have also been studied to try to explore new options and find the solution of a much pressing problem. The study might thus contribute to understand the issue, study the role of international community, and give useful and practical suggestions to solve the most pressing problem.

scholarly journals Quantifying the Role of Large Floods in Riverine Nutrient Loadings Using Linear Regression and Analysis of Covariance

2018 ◽  
Vol 10 (8) ◽  
pp. 2876 ◽  
Author(s):  
Siddhartha Verma ◽  
Alena Bartosova ◽  
Momcilo Markus ◽  
Richard Cooke ◽  
Myoung-Jin Um ◽  
...  
Keyword(s):  
River Flow ◽  
Spatial Scales ◽  
Dominant Role ◽  
Large River ◽  
Analysis Of Covariance ◽  
Ohio River ◽  
Prediction Errors ◽  
Nutrient Loadings ◽  
Daily Data

This study analyzes the role of large river flow events in annual loads, for three constituents and for up to 32 years of daily data at multiple watersheds with different land-uses. Prior studies were mainly based on simple descriptive statistics, such as the percentage of nutrient loadings transported during several of the largest river flows, while this study uses log-regression and analysis of covariance (ANCOVA) to describe and quantify the relationships between large flow events and nutrient loadings. Regression relationships were developed to predict total annual loads based on loads exported by the largest events in a year for nitrate plus nitrite nitrogen (NO3-N + NO2-N, indicated as total oxidized nitrogen; TON), total phosphorus (TP), and suspended solids (SS) for eight watersheds in the Lake Erie and Ohio River basins. The median prediction errors for annual TON, TP, and SS loads from the top five load events for spatially aggregated watersheds were 13.2%, 18.6%, and 13.4%, respectively, which improve further on refining the spatial scales. ANCOVA suggests that the relationships between annual loads and large load events are regionally consistent. The findings outline the dominant role of large hydroclimatic events, and can help to improve the design of pollutant monitoring and agricultural conservation programs.

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