Water Conveyance Research Articles

Remote Sensing of Aerated Flows at Large Dams: Proof of Concept

Dams are important for flood mitigation, water supply, and hydroelectricity. Every dam has a water conveyance structure, such as a spillway, to safely release extreme floods when needed. The flows down spillways are often self-aerated and spillway design has typically been investigated in laboratory experiments, which is due to limitations in suitable full scale flow measurement instrumentation and safety considerations. Prototype measurements of aerated flows are urgently needed to quantify potential scale effects and to provide missing validation data for design guidelines and numerical simulations. Herein, an image-based analysis of free-surface flows on a stepped spillway was conducted from a top-view perspective at laboratory scale (fixed camera installation) and prototype scale (drone footage). The drone videos were obtained from citizen science data. Analyses allowed to remotely estimate the location of the inception point of free-surface aeration, air–water surface velocities, and their fluctuations, as well as the residual energy at the downstream end of the chute. The laboratory results were successfully validated against intrusive phase-detection probe data, while the prototype observations provided proof of concept at full scale. This study highlights the feasibility of image-based measurements at prototype spillways. It demonstrates how citizen science data can be used to advance our understanding of real world air–water flow processes and lays the foundations for the remote collection of long-missing prototype data.

Towards design of compound channels with minimum overall cost through grey wolf optimization algorithm

Abstract The significant role of open channels in agriculture include supplying drinking water, industry, irrigation and flood control, making these hydraulic structures an integral part of the water conveyance system. Determination of optimum dimensions with minimum construction costs is considered as the primary concern when designing artificial open channels. To achieve this, the compound channels were evaluated with the following constraints, viz. composite roughness, velocity, Froude number and channel stability. Grey wolf optimization (GWO) was used to determine the optimal geometry of the channel. Optimization results clearly showed that the variation of roughness coefficient and the increase of factor of safety increased costs by 60 and 20% respectively. The optimum suitable cross-section for the compound channels was obtained by conducting various model scenarios.

Identifying tree characteristics to determine the blocking effects of water conveyance for natural flood management in urban rivers

AbstractPlants, especially trees, provide ecological functions but may harm the flood conveyance efficiency of rivers. Understanding the impacts of tree heights, tree areas, and tree locations on flood levels is crucial for floodplain management. This study aims to present a methodology to improve the performance of hydrodynamic modeling by considering plant resistance with the goal of analyzing flood risk reduction strategies that support ecological conservation enhancement. An unmanned aerial vehicle was used to collect floodplain topography, landcover, and tree characteristic data. A modified maximum likelihood classification scheme was developed by incorporating the tree height information to improve the landcover classification. The water‐blocking effect of trees, which represents the reduced flood conveyance area, was investigated by establishing tree obstructions in hydrodynamic models. Two hydrodynamic models were established with different tree obstruction setups and Manning's n values, including blocked obstructions (BOs) and conventional high n‐values (Adj‐n). Among the model setups, the Manning's n values of the trees remained the same as that of the soil in the BO model, in which trees were modeled as blocking obstructions. The n‐values of trees were determined to be 0.022 in the BO model and refined to 0.055 in the Adj‐n model after the model calibration and verification processes. The results indicated that the simulated flood levels of the BO model were very similar to those of the Adj‐n model. The NSE values were 0.98 and 0.97 in the simulations of two historical typhoon events, indicating that the BO model could obtain reliable predictions without altering the n‐values. The verified BO model was used to evaluate the degrees of influence of tree heights, tree coverage areas, and tree locations on flood levels. Several nature‐based solutions were proposed to analyze the tradeoffs between reducing flood prevention and enhancing wetland restoration using the verified BO model, suggesting a win–win strategy for natural river management.

Velocity bias in intrusive gas-liquid flow measurements

Gas–liquid flows occur in many natural environments such as breaking waves, river rapids and human-made systems, including nuclear reactors and water treatment or conveyance infrastructure. Such two-phase flows are commonly investigated using phase-detection intrusive probes, yielding velocities that are considered to be directly representative of bubble velocities. Using different state-of-the-art instruments and analysis algorithms, we show that bubble–probe interactions lead to an underestimation of the real bubble velocity due to surface tension. To overcome this velocity bias, a correction method is formulated based on a force balance on the bubble. The proposed methodology allows to assess the bubble–probe interaction bias for various types of gas-liquid flows and to recover the undisturbed real bubble velocity. We show that the velocity bias is strong in laboratory scale investigations and therefore may affect the extrapolation of results to full scale. The correction method increases the accuracy of bubble velocity estimations, thereby enabling a deeper understanding of fundamental gas-liquid flow processes.

One- and three-dimensional coupling flow simulations of pumped-storage power stations with complex long-distance water conveyance pipeline system

This study developed a one-dimensional and three-dimensional (1D–3D) coupling transient flow simulation method to investigate the effect of nonlinear fluctuations of pressures and hydraulic thrusts on the impeller and reveal their underlying flow mechanism during a combined operation mode, comprising two parallel pump-turbines, in a complex water conveyance pipeline system at an actual pumped-storage power station. Experimental verification suggested that the 1D–3D coupling method could accurately simulate the pressure fluctuations and rotational speed of the impeller. Additionally, three combined operation modes consisting of two parallel pump-turbines in a complex hydraulic pipeline system at an actual pumped-storage power station were simulated to test the performances of the developed 1D–3D coupling method. Test results suggested that the proposed method can successfully capture the nonlinear fluctuations of pressures and hydraulic thrusts on the impeller and water hammer phenomena. Additionally, it can reproduce the local and global backflow in the impeller, which induce fluctuations in the pressures and hydraulic thrusts. This study demonstrated that the 1D–3D coupling flow simulation method can provide more transient flow in a pumped-storage power station, possessing a complex long-distance hydraulic pipeline system, using lower computational cost than the conventional pure 1D and full 3D simulation method.

Estimation and Canal Conveyance Losses in Pune District

Water is a very precious natural resource. When this precious resource moves through the canals certain part of the water is lost by seepage, evaporation etc. This loss is known as conveyance loss. In present paper, study of Nira Left Bank Canal (NLBC) is done which is situated in Pune district. Total length of canal is 162 Km out of which 30 Km is our study area. Discharge calculations at the head of canal and at 30th Km is done, two standing wave flumes are present at these two locations. Since last few decades, the extensive underutilization has been found in canal irrigation. This issue constitutes the serious lacuna in irrigational planning which often depicts the major problem about optimal water use. As per FAO Aquastat 2015 records for India, out of 91% of water utilized for agriculture purpose, 45% is getting lost under different types of conveyance losses from dam headworks till farms. The conveyance losses constitute the seepage and evaporation losses. Out of these, seepage is a quite significant loss in most of the water conveyance systems. Estimating conveyance losses using physical methods is quite difficult and involves lots of field work and calculations, whereas empirical and analytical methods will not accommodate site condition of respective study area. This study attempted to assess the conveyance loss of Nira Left Bank Bank Main canal with the help of a hydraulic model built on a spatial platform and verified with flow-monitoring events. The hydrospatial model was simulated to understand the canal behaviour and evaluate the conveyance losses. The results show Nira Left Bank Main canal has average 39.96% water conveyance loss.

Impact of underground storm drain systems on larval ecology of Culex and Aedes species in urban environments of Southern California

An extensive network of storm water conveyance systems in urban areas, often referred to as the “underground storm drain system” (USDS), serves as significant production habitats for mosquitoes. Knowledge of whether USDS habitats are suitable for newly introduced dengue vectors Aedes aegypti and Ae. albopictus will help guide surveillance and control efforts. To determine whether the USDS functions as a suitable larval habitat for Culex, Ae. aegypti and Ae. albopictus in southern California, we examined mosquito habitat utilization and larval survivorship using laboratory microcosm studies. The data showed that USDS constituted 4.1% of sampled larval habitats for Ae. aegypti and Ae. albopictus, and 22.0% for Cx. quinquefasciatus. Furthermore, USDS water collected in the summer completely inhibited Aedes larval development, but yielded a 15.0% pupation rate for Cx. quinquefasciatus. Food supplementation in the microcosms suggests that nutrient deficiency, toxins and other factors in the USDS water led to low success or complete failure of larval development. These results suggest that USDS habitats are currently not major productive larval habitats for Aedes mosquitoes in southern California. Our findings prompt inclusion of assessments of pupal productivity in USDS habitats and adult mosquito resting sites in the mosquito surveillance program.

Numerical study and field performance of rockbolt support schemes in TBM-excavated coal mine roadways: A case study

There is an increasing number of TBMs applied in coal mine roadway excavation projects due to the higher safety, faster tunnelling speed and fewer labor works. Nevertheless, the experiences gained from TBM tunnelling projects of transportation or water conveyance tunnels are not well applicable in underground coal mines because of their special engineering and geological conditions. This paper proposed a case study of the excavation disturbance behaviors and support design of TBM-excavated roadway in Zhangji coal mine in Anhui Province, China. Mechanical properties of roadway surrounding rocks were obtained based on parameters of intact rocks and Rock Quality Designation (RQD) values of rock masses. The Universal Discrete Element Code (UDEC) software was used to establish numerical model of the roadway and micro-parameters are also calibrated. The excavation disturbance behaviors of unsupported roadway were firstly simulated. Moreover, the excavation disturbance behaviors and rockbolts loading characters under two different support schemes were studied and compared based on simulation and monitoring results. In this case, simulation results are in good agreement with monitoring results. Research results and experiences obtained from the working site suggest that installing rockbolts perpendicularly to rock surface can better satisfy the requirements of TBM tunnelling in weak grounds of coal mine roadways.

Improving seawater desalination efficiency by solar driven interfacial evaporation based on biochar evaporator of Nannochloropsis oculata residue

Solar driven interfacial evaporation technologies have significant potential in seawater desalination, sewage purification and steam power generation applications. The interfacial evaporator is primarily composed of a solar absorption layer and a substrate for thermal insulation and water conveyance. However, the materials used in the solar absorption layer and substrate are typically expensive and difficult to produce, which is not conducive to large-scale application. Herein, a novel porous microalgae biochar solar interfacial evaporator (MBSIE) was developed for high-performance solar-driven water vapor generation. The solar absorption layer was synthesized with the residue of the microalgae species Nannochloropsis oculata, which was generated from the process of biodiesel production. The substrate was composed of polystyrene foam and absorbent cotton sticks with an optimized water channel design. The light absorptivity of porous Nannochloropsis oculata biochar reached 94.1%, and the material contains hydrophilic groups such as C–O and N–H, which was conducive to water delivery. MBSIE attains a maximum seawater evaporation rate of 1.165 kg m−2 h−1 under one Sun irradiation intensity. The total dissolved solids and salinity of the produced fresh water was 265 mg L−1 and 0.06‰, respectively. This quality of freshwater could meet domestic water standards.

Evaluating the Efficiency of a\xa0New Cutterhead Design to Counteract the Drawbacks of Excavation through Very Hard Rocks

The application of appropriate excavation equipment in difficult grounds is of crucial importance and consequently improves the performance of hard rock Tunnel Boring Machines (TBMs). The cutterhead is one of the main components of TBMs which is directly involved in the excavation process, and its design can highly affect the cutting efficiency, the overall balance of the head, the performance of main bearing in long term, and the wear of the whole cutting face and muck buckets. This paper mainly focuses on the significant role of a proper design on the cutting efficiency with reference to a TBM tunneling project. Due to existence of very hard and abrasive rocks on the path of Kerman water conveyance tunnel, a new cutterhead was designed to be applied on a second hand TBM. The new cutterhead contains larger 19-inch disc cutters with a new disc cutter layout. Since the new cutterhead was launched following the excavation of the old one in a specific chainage of the tunnel, the performance of the two cutterheads in pyroclastic rocks could be compared with respect to the cutting efficiency, and lower specific energy values were observed for the new cutterhead which is the indicator of a better cutting efficiency in this geological condition.

CFD simulation of the pump trip runaway transient process of a pumped-storage power plant with head 700 m

Simulating transient processes of pumped-storage power plants is essential for the design and optimization of pump-turbine and water conveyance system. Because pressure pulsations and runner forces cannot be obtained from the traditional 1D transient simulation methods, 3D CFD simulations are necessary. In this study, the fast runaway transient process, occurring after the pump trip of a pumped-storage plant with a head of 700m, was simulated by using the CFD method that couples the 1D water conveyance system and 3D turbine. The phenomena, composed of water hammer fluctuations, pressure pulsation transitions, and flow pattern evolutions, were described and analyzed. We found that the flow patterns and pressure pulsations change violently as the working point goes through different regions. Especially, the pressure pulsations and unbalanced radial runner forces are the most severe in the S-shaped characteristic region. The strong impact on blades, large scale recirculating vortices in blade passages, obvious rotating stalls in vane and blade regions, transitional backflows at runner inlet and outlet, and strong circumferential velocity in vaneless space are the main sources. The dynamic working trajectory does not follow the measured static characteristic curve and demonstrates an undamped loop in the S-shaped region. This paper provides some evidence on the relations between flow structure and pressure pulsation features, although the mechanism of dynamic characteristics needs further investigations.

Numerical simulation of hydraulic transients in hydropower station with complicated water conveyance system

With the construction of Jinping II hydropower station with extra-large diversion tunnel, Baihetan hydropower station with complicated tailwater system, Yangfanggou hydropower station with complicated surge chamber, High requirements are put forward for the calculation and analysis of hydraulic transient process. In the water transmission and power generation system design of these projects, the following technical problems was solved by Power China Huadong Engineering Corporation Limited: simulation of variable impedance coefficient of differential surge chamber, interface tracking analysis of free-surface-pressure flow system, narrow upper chamber open channel effect and simulation of trigeminy surge chamber. The solutions to those technical problems and were summarized, and the hydraulic transients simulation and calculation software of complex waterway system - Hysim was developed. Based on the field test of Jinping II Hydropower Station, Baihetan hydropower station and Yangfanggou hydropower station, the simulation calculations were carried out. The accuracy of the hydraulic transients simulation software is verified by comparing the inversion results with the test values.

Improvement of Irrigation Efficiency by Developing on Farm Irrigation System

The experiments were Carried out in Biahmu Village at Al-Fayoum Governorate, Egypt during the two winter seasons of 2018/2019 and 2019/2020, on wheat crop to (cv. Gemmiza 11) evaluate the traditional surface irrigation system TSIS and the improved surface irrigation system ISIS(terrace), under laser leveling with two slops (S1≈ zero% and S2 ≈ 3%). The evaluation parameters included; reduction in land loss LL, the roughness coefficient of marwa-walls, water efficiencies (i.e., water conveyance efficiencies WCE, water application efficiencies WAE and water storage efficiencies WSE), yield productivity Yp, total applied water and water required, irrigation water productivity IWP and times of water advance, recession and opportunity. The results concluded that improving traditional marwa, led to reduction in land loss by 49.46% from the area of marwa, and WCE increased by 83.17% in improved Marwa IM the compare to Traditional Marwa It was observed that on the efficiency of water added to the field irrigated by TM. The highest level of water productivity (1.79kg wheat/m3 water) was achieved in IM at a level of 3%. Advanced time T.Adv (min) decreased at 50, 50.77, 27.6, 20.75, and 17.17% and 30.9, 40.51, 22.8, 10.89 and7.05% for TL and IL by sloping to S2.

Determination of the optimal ecological water conveyance volume for vegetation restoration in an arid inland river basin, northwestern China

Overexploitation of water resources has led to severe ecological degradation and even desertification in some arid inland river basins, northwestern China. To alleviate or restore the degraded vegetation ecosystem, ecological water conveyance (EWC) has become an important and effective measure. Scientific assessment of the impact of EWC on vegetation restoration and determination of the corresponding optimal EWC volume (EWCV) are important to formulate rational ecological water management. In this study, long time series normalized difference vegetation index (NDVI) was used to extract the restored vegetation area in Qingtu Lake area, a terminal lake in inland Shiyang River basin, northwestern China. The relationship between restored vegetation coverage and EWC was explored to determine the optimal EWCV. The restored vegetation area (RVA) increased dramatically in the first five years and became stable from 2016. The time lag of the response of RVA increase to EWC was about 2 years. A bell-shaped function between RVA and groundwater depth was obtained based on the results from Unmanned Aerial Vehicle (UAV) and micro terrain of the lake area. Based on the fitted function, five groundwater depth thresholds were obtained. The optimal groundwater depth in the hydrometric station was 2.91 ± 0.09 m for the maximal RVA (17.08 ± 3.25 km2). A polynomial function between the yearly EWCV and groundwater depth was developed and the EWCV thresholds corresponding to the groundwater depth thresholds were estimated. The optimal EWCV into Qingtu Lake was 2224.4 × 104 m3 for the maximal RVA. The correspondingly optimal EWCV from Hongyashan Reservoir was 3271.4 × 104 m3. The spatial distribution patterns of remotely sensed water surface and NDVI suggested that expanding the water-receiving area of conveyed water was useful to improve the vegetation growth. This study provides a reference for assessing the impact of EWC on vegetation restoration and determining the correspondingly optimal EWCV in arid inland river basins.

DNA metabarcoding illustrates biological pollution threats of Red Sea - Dead Sea water conveyance to Dead Sea biodiversity

The Dead Sea has a hypersaline environment where only extremophile species like Archaea, Bacteria, and fungi can survive. The Red Sea-Dead Sea Water Conveyance (RDSC) is constructing a pipeline of 180 km to import water from the Red Sea in the shrinking Dead Sea. Both seas exhibit highly different hydrographic features that determine their biodiversity. Using environmental DNA (eDNA) metabarcoding and amplifying a fragment of the cytochrome oxidase subunit I gene (COI) from water samples, we compared the communities of the Red Sea and the Dead Sea to understand the potential impact of the water conveyance project on biodiversity, following by an identification of potential biopollutants able to enter the Dead Sea for their small size. The results suggest a high likelihood of acquiring harmful algae into the Dead Sea. This study alerts about the real risk of losing the unique Dead Sea biota when the conveyance is actually undertaken.

Study on hydraulic transient process of K hydropower station with low head, large flow and complex long tail water system

K hydropower station is a hydraulic engineering with the main task of power generation, which is also a typical hydropower station with low head, large discharge and long tail water conveyance system. The hydraulic characteristics of these-type hydropower stations are of high water inertia, large amplitude of surge chamber water level fluctuation and poor stability of units. Therefore, due to the control requirements of the stability, the area of the horizontal section of the surge chamber is usually large, which leads to the long period of water level fluctuation of the surge chamber and the relatively long time of unit output oscillation in the transition process, and the regulating quality of the unit is often difficult to meet the control requirements due to the large inertia time constant of the water flow in the water conveyance system and the unique characteristic curve of unit. It is important to design appropriately to ensure the safe and stable operation of the hydropower station. In this paper, it is shown the process of hydraulic design of these-type stations. According to the design of K hydropower station, the simple surge chamber and restricted orifice surge chamber are compared in terms of hydraulic characteristics including the head loss of steady operation, the water level fluctuation of transition process and the stability of operation. Based on the optimized restricted orifice surge chamber, the overall calculation and analysis of the hydraulic transition process and the stability analysis of K hydropower station are carried out, it is concluded that the unit stability quality of the K power station is fine and the maximum pressure of pipe is in control, which provide strong support for the safe and stable operation of K station. The comprehensive and thorough analysis in this paper can provide reference for the design of the similar projects.

Relationship between Water Surface Area of Qingtu Lake and Ecological Water Delivery: A Case Study in Northwest China

Qingtu Lake is located between Tengger Desert and Badain Jilin Desert, Gansu Province, Northwest China. It is the terminal lake of Shiyang River. In recent years, Qingtu lake has maintained a certain area of water surface and vegetation by artificial water conveyance. It is of great significance in preventing the convergence of the two deserts and restraining the trend of ecological deterioration of Shiyang River Basin. The relationship between the water surface area and the ecological water conveyance have not been thoroughly investigated. This study analyzed the spatial and temporal distribution of water surface area of Qingtu Lake and surrounding reeds by interpreting remote sensing data; the change of water surface area under the influence of meteorological factors and water conveyance by linear regression; the water conveyance to maintain current water surface area by water balance method, as well as the reasonable ecological water delivery in high flow year, normal flow year and low flow year by the means of analyzing the upstream inflow and water consumption in Minqin Basin. The results showed that there is a significant correlation between the water surface area of Qingtu Lake, evaporation and ecological water conveyance, and the minimum and maximum water surface areas generally appear before and after water delivery, indicating that the ecological water delivery and evaporation are the two main factors affecting the water surface area change of Qingtu Lake. The result calculated by linear regression indicated that the ecological water delivery volume to maintain current water surface area of Qingtu Lake is 3.146 × 107 m3/yr, while the value was 3.136 × 107 m3/yr calculated by water balance method. These two results are similar and can be verified with each other. Reasonable ecological water conveyance of Qingtu Lake in high flow year, normal flow year and low flow years were 4 × 107 m3/yr, 3.2 × 107 m3/yr and 2.3 × 107 m3/yr, respectively.

River-groundwater interaction affected species composition and diversity perpendicular to a regulated river in an arid riparian zone

In regulated rivers, many studies have found that ecological water conveyance was conducive to protection and restoration of riparian plants. However, most of the studies about the influence of water conveyance on plants did not consider river-groundwater relationship in regional scale. In this study, field investigation, dynamic observation, Canonical Correspondence Analysis and ANOSIM analysis were mainly used to explore the lateral zonation of plant composition and diversity among different river-groundwater relationship types and reveal its reasons. The obtained results showed that: Spatio-temporal change of river-groundwater relationship controlled the difference of lateral zonation of species composition and diversity. Within the groundwater fluctuation zone, the water-table depth and salinity decreased during flood season. The proportion of hygrophyte herb and mesophyte shrub species is large with the highest diversity. If the river was gaining river during dry season, the riparian water table depth was less than 4–5 m, the strong evaporation-crystallization process lead to Cl-, Na+, and SO42- enriched. The total dissolved solids (TDS) was more than 6–10 g/L and the plants degenerated to halophyte herbs and shrubs with low diversity outside the groundwater fluctuation zone. If the river dry out during dry season, the riparian water table depth was more than 6–10 m. Plants were under water stress and degenerated to xerophyte herbs and mesophyte and xerophyte shrubs with low diversity outside the groundwater fluctuation zone. The study can enrich the understanding of riparian plant distribution pattern and provide guidance for making appropriate water conveyance scheme.

Impact of the Pumping Regime on Electricity Cost Savings in Urban Water Supply System

The main purpose of the presented research is to raise the efficiency of pumping stations’ operational work by developing a model for reducing energy costs in urban water supply systems. Pumping systems are responsible for a significant portion of the total electrical energy use. Significant opportunities exist to reduce the pumping energy through smart design, retrofitting, and operating practices. Today, considering the increase in pumping energy prices in water conveyance systems, the problem of optimal operation of pumping stations is very actual. The optimal operation of pumping stations was determined using a Genetic Algorithm Optimization (GAO) to achieve the minimum energy cost. The paper presents a novel management model for the optimal design and operation of water pumping systems on a real case study for the town of Gonabad in Iran. To achieve this goal, three days in a year were selected randomly. The results indicate that the proposed mode in conjunction with a GAO is a versatile management model for the design and operation of the real pumping station. Modeling results show that optimization with a GAO reduces power consumption by about 15–20%.

TBM performance analysis in very strong and massive rocks; case study: Kerman water conveyance tunnel project, Iran

ABSTRACT When TBMs are applied for tunnel excavation in very strong and massive rocks, the cutting mechanism happening under the disc cutters is converted from chipping to grinding. On the other hand, the most common TBM performance prediction models that have been developed assuming the occurrence of the chipping phenomenon would not be sufficiently accurate in grinding conditions. Therefore, this study aimed to develop a new empirical equation for estimation of the TBM performance in grinding conditions. In this regard, the database composed of actual measured TBM parameters (i.e. penetration rate and cutter load) and engineering rock properties (i.e. UCS, RQD in rock mass) was established using the data collected from a mechanised tunnelling project (the southern lot of Kerman water conveyance tunnel project, Iran) constructed in very strong rocks. Based on the established database, the statistical analyses were performed in order to develop a new TBM performance prediction model for grinding conditions. The proposed model provides a relationship between TBM penetration and cutter load for strong (UCS = 150–300 MPa) and massive rocks (RQD > 90) under grinding conditions.