The Covid-19 Pandemic: Limited Water Access and the Precarity of Women Fishers at Lake Kariba, Zimbabwe

Man-made reservoirs are constructed to meet certain purposes and Lake Kariba, Zimbabwe, was designed for hydroelectric power generation. However, it has developed other multiple uses, and the growth of fisheries on the lake has had a significant impact on the livelihoods of local communities. The declaration of Covid-19 as a pandemic in Zimbabwe in March 2020 was quickly followed by the imposition of national lockdowns with varying levels of severity up to the present day. This was done to curtail the spread of the disease, meanwhile enhancing the nation’s capacity in terms of acquiring testing kits, constructing more admission and quarantine centres as well as educating the people about ways to keep safe. In response to the calls by the government to monitor the movement of people and compliance of the lockdown rules, the Zimbabwe National Parks and Wildlife Management Authority (ZNPWMA), the governing body of the Lake Kariba fisheries, imposed rules that have significantly impacted the fishing communities at Lake Kariba. Both gillnet fishers and rod and line fishers have been impacted, but our focus here is on women rod and line fishers. Using the precarious livelihoods conceptual frameworks, we show how the changes in water management during the Covid-19 pandemic lockdowns has generated high levels of precariousness on the livelihoods of women at Kariba. We define precariousness as the condition of uncertainties brought to the women fishers by changes in water restrictions. The precarity of women was induced by several factors. For instance, the women fishers reported that restrictions to accessing fish in areas with high catches impacted them. They are also now obliged to pay exorbitant fishing fees in a way to discourage them to fish; they were frequently chased away from the Lake by ZNPWMA officers; they had limited amount of time to fish due to curfews; and failure to comply results in heavy fines imposed on them among other challenges. We show how these challenges interact with the current Zimbabwe socio-economic crisis to worsen the precariousness and vulnerability of women fishers at Lake Kariba. Data presented in this manuscript are based on participant observation and interviews with women fishers at Lake Kariba.

Breaking the symmetry to suppress the Plateau–Rayleigh instability and optimize hydropower utilization

Droplet impact on solid surfaces is essential for natural and industrial processes. Particularly, controlling the instability after droplet impact, and avoiding the satellite drops generation, have aroused great interest for its significance in inkjet printing, pesticide spraying, and hydroelectric power collection. Herein, we found that breaking the symmetry of the droplet impact dynamics using patterned-wettability surfaces can suppress the Plateau–Rayleigh instability during the droplet rebounding and improve the energy collection efficiency. Systematic experimental investigation, together with mechanical modeling and numerical simulation, revealed that the asymmetric wettability patterns can regulate the internal liquid flow and reduce the vertical velocity gradient inside the droplet, thus suppressing the instability during droplet rebounding and eliminating the satellite drops. Accordingly, the droplet energy utilization was promoted, as demonstrated by the improved hydroelectric power generation efficiency by 36.5%. These findings deepen the understanding of the wettability-induced asymmetrical droplet dynamics during the liquid–solid interactions, and facilitate related applications such as hydroelectric power generation and materials transportation.

Dynamics Water Quality in Koto Panjang Reservoir, Indonesia

Riau Province has the Koto Panjang reservoir which is generated from the damming of the Kampar River flow for hydroelectric power generation and other utilization activities. The increase in community activities in reservoir waters and on land causes water quality dynamics that can affect fish farming activities. The purpose of this study was to determine the dynamics of reservoir water quality. The survey was conducted in March – August 2021 at seven sampling points, where water samples at each sampling point were taken at a depth of 1 m as much as 1 liter using a van dorn water sampler and preserved and analyzed according to standard methods. Data from measurement and analysis were tabulated and analyzed descriptively including temperature, pH, turbidity, TSS, TDS, DO, nitrate, ammonia, total nitrogen, BOD5, COD, and total phosphate. The results obtained indicate that the values of temperature, turbidity, TDS, TSS, pH, DO, ammonia, nitrate, and phosphate are still below the quality standard, except in the range of BOD values of 4.30 – 5.75 mg/L and COD of 17.90. – 23.73 mg/L is an indication of organic matter originating from other activities on the reservoir land, such as plantations, agriculture, settlements, tourism, apart from floating net cage cultivation activities.

Main Threats in Mediterranean Coastal Wetlands. The Ebro Delta Case

Coastal wetlands are dynamic ecosystems that exist at the interface between land and sea. They represent environments with a great diversity of habitats and communities, high carbon sequestration capacity and a wide range of ecosystem services. In the Mediterranean, the largest coastal wetlands are found in deltaic areas like that of the Ebro River (Spain), which has a coastline length of approximately 50 km, occupying a total area of 325 km2. The Ebro Delta is included in different national and international frameworks for environmental conservation, despite which there are several risks that threaten it. The lack of sedimentary contributions due to the regulation of the Ebro riverbed (irrigation, reservoirs, and hydroelectric power generation) has caused erosion and the retreat of certain sections of its coastline. To this situation of sediment deficit must be added the threat posed by the effects of global change, such as the rise in sea level, the increase in temperature and in the frequency and intensity of storms. This study analyses the particularities of the coastal wetland of the Ebro Delta, identifying the main threats it faces, as well as possible adaptation and mitigation strategies to these changes.

Breaking the symmetry: Suppressing Plateau-Rayleigh instability and optimizing hydropower utilization

Droplet impact on solid surfaces is essential for natural and industrial processes. Particularly, controlling the instability after droplet impact, and avoiding the satellite drops generation, have aroused great interest for its significance in inkjet printing, pesticide spraying, and hydroelectric power collection. Herein, we found that breaking the symmetry of the droplet impact dynamics using patterned-wettability surfaces can suppress the Plateau-Rayleigh instability during the droplet rebounding and improve the energy collection efficiency. Systematic experimental investigation, together with mechanical modeling and numerical simulation, revealed that the asymmetric wettability patterns can regulate the internal liquid flow and reduce the vertical velocity gradient inside the droplet, thus suppressing the instability during droplet rebounding and eliminating the satellite drops. Accordingly, the droplet energy utilization was promoted, as demonstrated by the improved hydroelectric power generation efficiency by 36.5%. These findings deepen the understanding of the wettability-induced asymmetrical droplet dynamics during the liquid-solid interactions, and facilitate related applications such as hydroelectric power generation and materials transportation.

Forecasting the hydroelectric power generation of GCMs using machine learning techniques and deep learning (Almus Dam, Turkey)

Renewable energy is one of the most important factors for developed and sustainable societies. However, its utilization in electrical power grid systems can be very challenging regarding rates predictably. Renewable energy depends mainly on environmental conditions such as rainfall-runoff ratios and temperature. Because of that, the expected power production heavily fluctuates, which makes the prediction and calculation of feed-in into the power grid very challenging. The accurate forecasting of energy production is a very crucial issue for power management process. This paper presents the results of deploying Machine Learning Techniques in short-term forecasting of the amount of energy produced of General Circulation Models (GCMs) Data by Almus Dam and Hydroelectric Power Plant in Tokat, Turkey. The study demonstrates the use of modeling techniques in hydropower forecasting process using the predicted monthly hydroelectric power generation data of GCMs from 2018 to 2080. Decision Tree, Deep Learning, Generalized Linear, Gradient Boosted Trees and Random Forest models are utilized to forecast the hydropower production. The results show that the correlation value of the gradient boosted trees model equals 0.717, which means that the gradient boosted trees model is the most successful model for the present data. The gradient boosted trees model used in the prediction process for each GCM in each scenario is 4.5 and 8.5. The results show that there are small differences between the models, which means that the predictions are going in similar directions for all these models.

Did the Construction of the Bhumibol Dam Cause a Dramatic Reduction in Sediment Supply to the Chao Phraya River?

The Bhumibol Dam on Ping River, Thailand, was constructed in 1964 to provide water for irrigation, hydroelectric power generation, flood mitigation, fisheries, and saltwater intrusion control to the Great Chao Phraya River basin. Many studies, carried out near the basin outlet, have suggested that the dam impounds significant sediment, resulting in shoreline retreat of the Chao Phraya Delta. In this study, the impact of damming on the sediment regime is analyzed through the sediment variation along the Ping River. The results show that the Ping River drains a mountainous region, with sediment mainly transported in suspension in the upper and middle reaches. By contrast, sediment is mostly transported as bedload in the lower basin. Variation of long-term total sediment flux data suggests that, while the Bhumibol Dam does effectively trap sediment, there was only a 5% reduction in sediment supply to the Chao Phraya River system because of sediment additions downstream.

Evaluating Irrigation Efficiency: Toward a Sustainable Water Future for Montana

Water is our most valuable natural resource, and is used to support the demands of industry, agriculture, hydroelectric power generation, and municipalities. Water also sustains Montana’s booming recreation and tourism economy and maintains the diverse freshwater ecosystems that provide natural goods and services and promote human well-being. As our population continues to grow, and the collective demand for water increases, it is imperative that we carefully assess how our water is used, as well as how changes in water distribution, management, and governance are likely to influence its availability in the future. This is especially important in the context of a changing climate.