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Assessing Flood Vulnerability Index for Policy Implications Towards Flood Risk Management Along the Atlantic Coast of Limbe, Cameroon
Usongo Patience Ajonina,
Tepoule Nguéke Joseph,
Chang Linda Meh
Issue:
Volume 7, Issue 2, June 2021
Pages:
24-38
Received:
9 March 2021
Accepted:
22 March 2021
Published:
7 April 2021
Abstract: Floods along the Atlantic coast of Limbe are the most predominant natural disaster posing serious threats to man and the environment. Without adequate information about the risk levels and why the implementation of locally appropriate adaptation measures are less effective, flood disasters will continue to become more rampant and disastrous. The ability to accurately identify, measure and evaluate the various vulnerabilities of affected people and communities is a right step towards reducing disaster risk. This article focuses on developing a Flood Vulnerability Index (FVI) based on exposure, susceptibility and resilience factors that will guide putting in place specific adaptation plans targeted at reducing the impacts of floods. The study made use of the mixed research design method. Reponses were gathered from 183 respondents using questionnaires and focus group discussions (FGD) from household heads to construct an integrated vulnerability index made up of 22 indicators grouped into susceptibility indicators (15), resilience (5) and exposure (2). A handheld Global Positioning System (GPS) was used in the measurement of distance and elevation. Data collected was subjected to analysis of variance to test if significant differences in vulnerability exist within the neighborhoods and the level of success of adaptation strategies was also investigated. Findings show that Motowo and Church Street have very small vulnerability to floods, Cassava Farm and Clerks Quarters have high vulnerability to floods and Down Beach with an index of 0.84 has a very high vulnerable to floods. From the results coastal communities are significantly different (p < 0.01) in terms of vulnerability to flood hazards. A total of 19.39% of the population highlighted that the adaptation strategies put in place to help combat floods in their neighborhoods are effective while 80.61% of the respondents decried that the measures were not effective. Coping strategies need to take into consideration the myriad of factors involved in the determination of vulnerability so as to help putting in place a comprehensive multi-risk adaptation strategy. Policies implications of the results warrant a conscious effort by the council to clear chocked gutters, culverts and major drains to ease water flow especially during the rainy seasons and local authorities and ministries must make sure proper land use plans are in place and are enforced without any fear or favor so as to ensure resilience to flood risks.
Abstract: Floods along the Atlantic coast of Limbe are the most predominant natural disaster posing serious threats to man and the environment. Without adequate information about the risk levels and why the implementation of locally appropriate adaptation measures are less effective, flood disasters will continue to become more rampant and disastrous. The ab...
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Effects of Plow-Tillage on Preventing and Controlling the Black Water Events in Shallow Lakes
Issue:
Volume 7, Issue 2, June 2021
Pages:
39-47
Received:
20 April 2021
Accepted:
7 May 2021
Published:
14 May 2021
Abstract: The high organic loading sediment in the areas of algal accumulation are the primary cause of frequent occurrence of black water in the western Chao Lake. Through an algal accumulation experiment, plow-tillage based on resuspension characteristics and its effect on lake sediment was assessed using a large device capable of simulating lake-winds and sediment resuspension. The dynamics of overlying water coloration, ρ(Fe2+), ρ(S2-) in the process of black water induction, the key physicochemical characteristics of newly formed water–sediment interface, and iron and sulfur variations in interstitial-water and their response to plow-tillage were examined. The results showed that plow-tillage depth significantly influenced black-water formation; a 15 cm plow-tillage depth helped in controlling black-water. When black water occurred in other plow-tillage controls, i.e., (2, 5, and 10 cm), along with blank-treatments during day 8 to 14, typical overlying water characteristics [ρ(Fe2+) and ρ(S2-)] of the plow-tillage 15 cm treatments were 68.6%, 79.5%, 48.1%, 46.7%, and 51.3%; and 75.2%, 65.7%, 57.1%, 74.5%, and 75.0%, respectively, in comparison to that of the other plow-tillage controls and blank-treatments. Further analysis of the bottom-water and bottom-sediments revealed that the 15 cm plow-tillage depth treatment significantly enhanced the tolerance of the fresh water–sediment interface to algal accumulation and anoxic environments. Through the black water induction simulation, the dissolved oxygen concentration, redox potential, and pH of the bottom-water and at the interface were observably much higher than those in the black-water groups. However, ρ(ΣH2S) was significantly lower than that of other treatments. The ρ(Fe2+) in the surface-sediment water was 0.54 mg/L, which corresponds only 25.3–33.7% that of the black-water groups. Fe2+ accounted for 25.2% of the total iron, being considerably lower than ~40.0% of the black-water groups. The concentration of acid-volatile sulfides was 0.51 µg/g, which corresponds only 14.6–17.2% that of the black-water groups. Overall, plow-tillage helped to physically improve sediment in areas of algal accumulation. Plow-tillage could help turn surface-sediment overloaded with organic pollutants to the lower-layer, blocking material migration and supply of contaminated surface-sediment, and controlling anaerobic microbial activity. It could prevent the formation of black water-generating substances in the water column where algae accumulate and die, effectively preventing the occurrence of black water.
Abstract: The high organic loading sediment in the areas of algal accumulation are the primary cause of frequent occurrence of black water in the western Chao Lake. Through an algal accumulation experiment, plow-tillage based on resuspension characteristics and its effect on lake sediment was assessed using a large device capable of simulating lake-winds and...
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Analysis of Riverbed Evolution of the Waigaoqiao Branch Channel of the Yangtze Estuary in Flood Period Under New Water and Sediment Conditions
Issue:
Volume 7, Issue 2, June 2021
Pages:
48-56
Received:
27 April 2021
Accepted:
8 May 2021
Published:
21 May 2021
Abstract: With the change of sediment conditions in the Yangtze River Estuary, the river regime evolution pattern has entered a new stage. The overall trend has changed from siltation to erosion, and the impact of the evolution trend of overall river regime on local river regime needs to be further studied. Based on the hydrological and topographic data of flood season in 2020, this paper analyzes the riverbed change of Waigaoqiao branch channel during flood period under new water and sediment conditions. The river bed evolution law and causes of scouring and silting are analyzed statistically. Result shows that the water depth of branch channel decreases with the influence of channel dredging and river regime change in South Harbour under new water and sediment condition. During the flood period of 2020, the Waigaoqiao branch channel generally presents a continuous silting situation, mainly located in the front of Waigaoqiao Wharf (phase IV). The increase of sediment concentration caused by the flood and the scouring of shoal along the upstream of the branch channel are the main reasons for the silting of the branch channel. Based on the actual needs of waterway operation and maintenance, this paper puts forward relevant countermeasures and suggestions according to the analysis results.
Abstract: With the change of sediment conditions in the Yangtze River Estuary, the river regime evolution pattern has entered a new stage. The overall trend has changed from siltation to erosion, and the impact of the evolution trend of overall river regime on local river regime needs to be further studied. Based on the hydrological and topographic data of f...
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A Contraction Based Solution for the Improvement of Fish Ladder Attraction Flow
Kristian Angele,
Patrik Andreasson,
Ake Forssen,
David Aldven,
Gustav Hellstrom,
Kjell Leonardsson
Issue:
Volume 7, Issue 2, June 2021
Pages:
57-71
Received:
22 April 2021
Accepted:
24 May 2021
Published:
4 June 2021
Abstract: A new, potentially cost efficient, concept for improving the attraction flow to a fish ladder has been investigated in a case study. For the upstream migrating Atlantic salmon to reach the fish ladder and by-pass the case study hydropower plant, it must be able to localize the attraction flow where it enters the main flow from the tailrace of the hydropower plant in the so-called confluence area. Here the comparatively small and limited attraction flow from the old river channel must be improved in order to be able compete with the substantially larger main flow. The objective of the present study is to investigate the feasibility of a new concept for further improvement of the attraction flow using guiding walls forming a contraction channel. Field measurements were performed tracing tagged fish in the confluence area downstream of the case study hydropower plant in order to understand the movement pattern of the fish. Based on the results, and results from bathymetry measurements in the same area, a physical scale model was constructed where it was experimentally demonstrated that it is hydraulically feasible to construct guiding walls, forming a contraction, which accelerate the attraction flow and generate a concentrated turbulent jet with a higher velocity, while keeping the flow rate unchanged. The attraction flow penetrates about half-way (70 m) into the main flow and reaches the position where most fish are positioned according to fish position measurements and therefore potentially has a good ability to attract upstream migrating fish. There is no negative impact on the water level in the confluence area and thereby not on electricity production. It was shown that the results can be scaled up to prototype conditions and the strategy can presumably be generalized to similar flow situations, existing at other hydropower plants, allowing for improved upstream fish migration in coexistence with a sound hydropower production.
Abstract: A new, potentially cost efficient, concept for improving the attraction flow to a fish ladder has been investigated in a case study. For the upstream migrating Atlantic salmon to reach the fish ladder and by-pass the case study hydropower plant, it must be able to localize the attraction flow where it enters the main flow from the tailrace of the h...
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Our Water Mains Contaminate Us with E. Coli, Lead and Copper – Preventable Illness and Death Follow
Issue:
Volume 7, Issue 2, June 2021
Pages:
72-96
Received:
12 April 2021
Accepted:
24 April 2021
Published:
28 June 2021
Abstract: The title of this article may seem abrasive, but the stakes are human lives that are affected by E. coli infections and drinking water contaminations by lead and copper. First of all, this research targets a new and urgent understanding of a common cause for E. coli outbreaks, which results in many illnesses and deaths every year. As part of a world-wide problem, E. coli infects more than 73,000 people and kills more than 60 people every year in the U.S. alone. Also a connection exists between urinary tract infections and water main break transmissions of E. coli, where five to seven million cases strike each year in the U.S. Methods are confined to an extensive literature review and detailed studies of pertinent topics. Research concludes that a phenomenon referred to as water hammer breaks underground water mains, and underground E. coli enters water mains during power outages or pressure losses to distribute E. Coli to our homes, businesses and irrigation systems to drive E. coli outbreaks. People die from E. coli, and illnesses and deaths are preventable. New theory proves that water systems are infected during normal operations that crack water mains to permit E. coli ingress into pipes to infect homes, businesses and irrigation. E. Coli infection outbreaks can be stopped. Essentially, water hammer breaks water mains, E. coli enters piping during power outages and other system shutdowns, infected water is pushed to customers ahead of any disinfectants that are added prior to return to service, and infections spread to water consumers. The most important research conclusion is that E. coli infections will stop by controlling water main break destruction and controlling water operations after power outages and water pressure losses. A parallel health concern relates lead and copper contaminations of water supplies to water hammer induced water main breaks. Another important finding proves that lead and copper contamination of drinking water systems can be minimized. If water hammers are reduced, water main breaks will be reduced, and infections and contaminations will be reduced. Although facts explain observations of lethal E. coli outbreaks, experimental validation of theory following a future outbreak is required. There is more work required, but if people are unaware of this pandemic health hazard, no work will be done, and the hazard will continue. The learning curve to safe drinking water should not climb slowly, but should sharply leap to save lives and ensure water safety.
Abstract: The title of this article may seem abrasive, but the stakes are human lives that are affected by E. coli infections and drinking water contaminations by lead and copper. First of all, this research targets a new and urgent understanding of a common cause for E. coli outbreaks, which results in many illnesses and deaths every year. As part of a worl...
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