Views from the Sluice Gate: Water Insecurity, Conflict and Cooperation in Peri-Urban Khulna, Bangladesh

This chapter explores conflict and cooperation around water infrastructure in relation to contestations over water and land in peri-urban Khulna, Bangladesh. It analyses how these contestations, together with the effects of climate change and urbanization, contribute to water insecurity. These dynamics are explored by viewing the peri-urban space as a hydro-social system where physical infrastructure (a sluice gate), hydrological processes and various actors interact. Through participatory appraisal, stakeholder analysis and social power mapping, we analyse the emergence, manifestations and implications of conflicts, and how power relations influence the conflict dynamics. The chapter further presents the process and outcome of participatory actions for capacity-building of communities to facilitate their empowerment by elevating their knowledge level and negotiating capabilities toward securing water and resolving conflicts. We argue that conflicts and water insecurities of peri-urban communities largely emerge from the absence of their participation in the planning and management of water infrastructure, and their limited capacity to resist changes in the control of water and agricultural land. The chapter concludes that peri-urban communities lack the power and agency to mitigate the impacts of urbanization and climate change, while neither urban nor rural planning processes formally recognize the peri-urban and its specific water security problems and needs. This policy gap leads to increasingly complex conflicts and water insecurities. Success and sustainability of alternative livelihood choices and collective action by marginalized communities depend much on continued advocacy, cooperation among and between communities and government agencies, commitment of a trusted neutral actor, and mutual understanding and respect for each other’s positions.

Model of discharge coefficient of crest gate rubber weir at fully closed condition

Crest Gate Rubber Weir is a modification of rubber weir with adding a metal plate or crest gate on the upstream side. The rubber in this weir functioning as a support while the crest gate serves on elevating water. Although many have been implemented, this weir’s discharge coefficient needs be researched considering its unique shape. This study looks for discharge coefficient to determine the discharge that passes through weirs at fully closed conditions. The research was conducted with a hydraulic model resembling part of Tirtonadi Weir in Surakarta with a hydraulic model. The model is made in an angle 53°, which represents the prototype at fully closed condition. Laboratory experiment shows that the discharge coefficient of this weir is greater than the Ogee Weir and Sluice Gate for the same height because of less flow resistance from this weir structural form.

Sluice Gate Discharge From Momentum Balance

Discharge from sluice gate flows is commonly calculated using the Torricelli outflow velocity, which is inaccurate and must be corrected by a discharge coefficient. Moreover, this approach commonly only considers the relative gate opening, without including the impact of 3D effects, scaling effects, different velocity profiles and friction forces. Aiming for a theoretical approach that can address all flow effects for sluice gate discharge calculations, the authors applied the momentum balance theory to this problem. First the control volume was introduced and parameterization equations for the pressure distributions and momentum coefficients at the control volume borders for both the standard and the inclined sluice gates were determined using CFD simulations. The results show good agreements with the discharge measurement results of frequently quoted experimental studies from other authors, demonstrating the potential of this approach. Also, one example of the impact of the 3D effect of various channels widths was investigated with the momentum balance theory.

Using side flow jets as a scour countermeasure downstream of a sluice gate

Background Local scour is one of the main problems affecting the stability and operation of control hydraulic structures. Many techniques were used to control the resulting scour. In the recent study, a new technique was used to control local scour downstream single-gate hydraulic regulator by using side flow jets. This study aimed to demonstrate the effect of side jets at different angles on the local scour parameters (depth, length, and volume) and energy dissipation in the downstream hydraulic regulator. Results A physical model was used to represent the open channel, regulator, and the side jets with different angles. Five flow discharges, four jet angles, and three gate openings were applied through the experiment. The experiment results showed that the presence of side jets had a remarkable effect on the parameters of the local scour hole and energy dissipation. They dissipated more energy of hydraulic jump than in the absence of jets, and consequently, scour hole dimensions were significantly reduced. Regression analysis was used to deduce equations that can predict the development of local scour downstream sluice gate considering the inclination angle of side flow jets under different flow conditions. Conclusions Side flow jets can be used as scour reducer techniques with the advantages of eliminating the jet clog produced from sediments and suspended solids.

Effect of Cross-section Geometry on Air-Demand Ratio in High-head Conduits With Sluice Gate

When the researches on the gated conduits were examined, it was determined that the air-demand ratio changed according to the hydraulic and geometric parameters. However, no study investigated the effect of the cross-section geometry of gated conduits on the air-demand ratio. In this study, the effect of conduit cross-section geometry on the air-demand ratio was examined. Results showed that conduit cross-section geometry was an important effect on the air-demand ratio especially at 10% and 15% gate opening rates. It was seen that the effect of the conduit geometry on the air-demand ratio decreased at 20%, and greater gate opening rates. In addition, a design formula related to the gate opening rate, Froude number, hydraulic radius, and conduit length was presented for estimating the air-demand ratio.

Study on the Contribution of Normalization to Reducing Flood Risk in the Ciliwung River, Tebet District, Jakarta

Jakarta is the capital city of the State of Indonesia and fast economy and population growth rate. With these, urbanization continues to increase every year. In this study, we analyse the effect of river normalization on reducing flood risk on the MT. Haryono - Manggarai section based on the Hec-RAS hydraulic model. Boundary Condition applied in upstream river is flow hydrograph with a peak discharge of 561.48 m3/s. In the upstream part, a rating curve is applied from the water level measurement data for the Manggarai Sluice Gate. While in the middle, the lateral flow from the urban drainage channels is inserted. The simulation results show that normalizing the channel can increase the drainage capacity as implied by the decrease in the flood water level. However, downstream there is backwater due to the lack of capacity of the Manggarai floodgate.

Principal Component Analysis and Support Vector Machine on Ice Entrainment Through a Sluice Gate

The entrainment and accumulation of ice floes in front of the sluice gates are closely related to the water transport efficiency and safe operation of the channel during an ice period. A flume study is carried out for a sluice gate with free outflow. A framework of stacking ensemble models is used to analyze the data, which consists of a two-level structure including the principal component analysis (PCA) and the support vector machine (SVM) algorithms. Based on the mechanism of ice floe accumulation, ten input characteristics of the machine learning (ML) model are selected. The PCA method is used to eliminate redundant information. The first principal component, with a contribution rate of 71.76%, and the second principal component, with a contribution of rate 15.64%, are extracted as the inputs of the SVM model, and the state of the floating ice in front of the gate is used to determine the classification labels. The 5-fold cross-validation method is used to train the model. The training results showed that the Gaussian radial basis functions (RBF) were the optimal kernel function. The performance of the developed model is measured using area under curve (AUC), accuracy (Acc) and F1-score (F1) values as statistical indicators. The results showed that the established PCA-SVM model improves the Bernoulli naive Bayes (Bernoulli NB) classifier and K-nearest neighbors’ algorithm (KNN) models. It increasing the AUC value by 11% and 5%, the Acc value by 16% and 17%, and the F1 value by 17% and 2%, respectively.

Impact of Flow Characteristics on the Pressure Distribution on Sluice Gates

The pressure distribution on sluice gate walls was investigated in this paper, based on CFD simulations. The flow characteristics impacting the pressure distribution were analyzed. Based on this analyzation, a new parametrization approach for the gate pressure distribution is derived for both, standard sluice gates and inclined sluice gates. Based on these investigations the impact of 3D flow characteristics on the pressure profile at the sluice gate wall is presented and discussed in detail.