by Tran Thi Hong Ngoc and Vo Khac Tri
Original Research
This paper presents the result of suspended and deposited sediment measurements on the floodplain of Long Xuyen Quadrangle-An Giang (LXQ-AG) along the Cambodia - Vietnam border during a flood event in 2018. GIS and Remote sensing techniques were used to build maps for the flooded areas. Water level and discharge were also measured on main channels and on the floodplain. The two correlation equations between deposition sediment, Suspended Sediment concentration (SSC) and discharge were build. The results of Landsat interpretting showed that inundation area of the floodplain was 35,765 ha. SSC and deposited sediment decreased with distance from the main channels. The results showed thattotal deposited sediment mass brought to the floodplain during a single flood event in 2018 was 5.023 million tons (14.04 kg/m2).
American Journal of Water Resources. 2020, 8(2), 92-103. DOI: 10.12691/ajwr-8-2-5
Pub. Date: April 22, 2020
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by Abdoul Aziz Gning, Mansour Gueye, Mapathé Ndiaye, Fatou Ngom Diop and Raymond Malou
Original Research
The Senegal River delta is located in a semi-arid sahelian zone of West Africa. Due to low pluviometry in the delta, this river is an exceptionally important water resource for the region. The importance of surface water from the Senegal River is elevated more by the fact that much of the groundwater accessible by shallow wells is saline. Salinization in the Senegal River delta originates from marine water invasion, both past and present, into the continent. Marine invasion and even full transgressions have been known to what is now the delta throughout geological history. Evidence of cyclical marine transgressions and regressions go back to the Jurassic, and multiple transgressions have occured in the Quaternary period alone. The main interest of this work is on the hydrogeological aspect of salinization of shallow aquifers in the the Senegal River delta. The objective is to be able to characterize salinization dynamics and the related surface water-groundwater interactions. Identifying mechanisms of groundwater freshening, and to understand the role of surface river water to this end, will be investigated in depth. Irrigated agriculture is not a primary object of study, although it’s presence and impact on groundwater is closely linked and evaluated. To approach the problematic, a combination of multiple monitoring methods was used in the interest of characterizing groundwater salinizationand/River water intrusion in the Senegal river delta. Collection of data for this study was founded on field work. This included hydrochemical monitoring as well as geophysical profiling over multiple selected sites. Field work was performed during the months of February and March 2016, in the middle of the dry season. Analysis of geochemical and geophysical data collected during the course of this study has brought together strong evidence of river water recharge into the shallow aquifer from the Senegal River delta, and to have dimensioned the sub-surface hydraulic intrusion. The magnitude of intrusion seems to be a function at least of the relative difference in head and of the debit of the surface water that is in closest proximity. In other words, even the most simple hydrodynamic parameters play an important role in the phenomenon. Other factors - geologic, climactic, chemical - have their part. Comparing the data of this study with historical context and data that has been collected over at least the past century has aided in constructing such additional factors controlling water dynamics.
American Journal of Water Resources. 2020, 8(2), 78-91. DOI: 10.12691/ajwr-8-2-4
Pub. Date: March 25, 2020
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by Kouassi Kouadio Dobi-Brice, Ekou Lynda, Yacouba Zoungranan and Ekou Tchirioua
Original Research
Among the methods of wastewater treatment, adsorption is the one that remains accessible because it is easy to implement. It uses less expensive, abundant and available adsorbent supports. Adsorption can be implemented through two types of processes: continuous adsorption and discontinuous adsorption. Continuous adsorption allows the treatment of large volumes of water compared to discontinuous adsorption, which is suitable for the treatment of small quantities of water [1]. This study is part of an approach to the removal of toxic dyes using the continuous mode adsorption method. Two dyes were used: crystal violet and methyl red. The adsorbent fixed bed of the column consists of biomass of previously deactivated lichens. The influence of some physico-chemical parameters on the column such as flow rate, lichen grain size, adsorbent bed mass and initial dye concentration were evaluated. The application of Bohart-Adams, Thomas and Yonn-Nelson models to the experimental data made it possible to predict the theoretical characteristics of the column. For a given dye, under the influence of a given physico-chemical parameter, the application of the Bohart-Adams model determined the saturation concentration of the adsorbent bed (N0). The application of the Thomas model allowed to determine the theoretical adsorption capacity of the column (Qthe), and the Yonn-Nelson model allowed to predict the time (τ) necessary for the 50% breakthrough of the adsorbent bed.
American Journal of Water Resources. 2020, 8(2), 69-77. DOI: 10.12691/ajwr-8-2-3
Pub. Date: March 24, 2020
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by Yosef Abebe Yimer and Abraha Geberkidan
Original Research
The aim of this study is to assess the current status of the Awash River. The study was desighned using 12 sampling stations for three consecutive months from December-2016 to February-2017. Samples were taken for physicochemical analysis from the main river and tributaries. All parameters have been analyzed using standard methods. High level of EC, TDS, NO3-, NH3, Cl-, SO42-, Cr+6, DO, COD and BOD were recorded in station S04. Accordingly, EC in station S04, S07 and S09; nitrate in S02 and S04; chloride in S04 and S09; Na and alkalinity in S07, S09, S10, S11 and S12 exceeded the standard guideline limit of WHO and FAO. Some irrigation water quality parameters such as EC, %Na, SAR, RSC, HCO3-, and Cl- concentration showed a progressive increase from station S10 to S12. Based on this investigation, it is concluded that the discharge of industrial, domestic, and agricultural effluents together with the expansion of Lake Beseka has strongly degraded the quality of Awash River at the study area. Untreated industrial wastes and unregulated lake water have caused significant pollution in the Awash River system and mitigation measures are required to restore good water quality.
American Journal of Water Resources. 2020, 8(2), 56-68. DOI: 10.12691/ajwr-8-2-2
Pub. Date: March 14, 2020
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by Ochungo Akech Elisha
Original Research
A lot of studies have been done to decongest urban road networks especially at major intersections mainly to improve flow efficiency and capacity. Both simulation and computer aided geometric modeling techniques have facilitated these investigations, but little has been done to document the steps leading to the selection of the most optimized architectural configuration of the interchange for implementation. This paper presents the explanation of the steps followed during the decongestion design process of the “GSU” interchange located at the intersection of Nairobi-Thika Super Highway and the newly improved Outer Ring Road (ORR); two key arterial road corridors in Nairobi city, Kenya. The new “GSU” interchange design deployed both micro-simulation modeling using Parallel Microscopic Simulation Software (PARAMICS) and AutoCAD Civil 3D geometric modeling techniques. Using excerpts from the traffic engineering expert’s micro-simulation work together with the design report prepared by the ORR improvement supervision consultant’s team, this paper outlines the workflow steps that led to the final choice of the interchange configuration’s shape and form. The finding of this paper demonstrates the efficacy of the use of micro-simulation models in supporting CAD geometric remodeling of existing intersections for enhanced capacity and flow. The process involving the integration of simulation and geometric modeling is rather complex in nature as it requires team members to exercise patience with each other. This paper recommends that urban road authorities should have a dedicated traffic flow simulation team to work closely with road design engineers in city road network decongestion plans.
American Journal of Water Resources. 2020, 8(2), 48-55. DOI: 10.12691/ajwr-8-2-1
Pub. Date: February 20, 2020
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