Elevated Water Levels Research Articles

Extending multi-criteria coastal vulnerability assessment to low-lying inland areas: examples from Estonia, eastern Baltic Sea

The assessment of vulnerability to coastal hazards is a significant coastal management problem in regions with complicated shoreline, such as Estonia. This study implements the vulnerability assessment based on the multi-criteria decision analysis using fuzzy logic, analytical hierarchy process, and weighted linear combination (including input from experts) integrated with a geographical information system, to map the coastal vulnerability index (CVI) of the Estonian coasts at high resolution based on 16 parameters. The novelty of our approach is that we expand this assessment to a 2 km wide inland area that is an intrinsic but often overlooked part of coastal vulnerability estimates. The Estonian shores have mostly low and moderate vulnerability. Short segments with high vulnerability are impacted by severe waves and highly elevated water levels. The CVI also characterizes low-lying areas, such as large river valleys, reasonably well. Estimates of coastal vulnerability based on the three most important parameters according to experts’ judgements provide a reasonable approximation of the 16-parameter CVI in mostly homogeneous coastal regions, but less so elsewhere where its value is questioned. The results show that the application of the developed integrated decision support system, applied to a 2 km wide coastal strip, provides more information than single tools to assist coastal managers and stakeholders in planning, preparing for and responding to hazards.

Assessment of Overflow Risk in Agricultural Reservoir Based on Water Balance Theory

The unexpected climate changes are causing rainfalls to exceed the design frequency, which complicates the management and operation of agricultural reservoirs and increases the risk of overflow. According to the “Planning and Design Standards for Agricultural Prediction Infrastructure Maintenance Project (Fill Dam Section),” agricultural reservoirs were originally designed without flood control functions, with the standard being to directly discharge incoming flood. Based on this foundation, this study assesses the overflow risk of agricultural reservoirs using the concepts of inflow and outflow theories as well as storage capacity. The balance when inflow and outflow are at their maximum was analyzed for prioritized areas, focusing on the flood management area (the area between the full water level and crest elevation) relative to the basin area, to examine the feasibility of balance through flood routing. The proposed method is easily accessible to facility managers, enabling them to assess the risk of reservoirs for efficient management and operation during floods.

The Coupled Application of the DB-IWHR Model and the MIKE 21 Model for the Assessment of Dam Failure Risk

The phenomenon of global climate change has led to an increase in the frequency of extreme precipitation events, an acceleration in the melting of glaciers and snow cover, and an elevation of the risk of flooding. In this study, the DB-IWHR model was employed in conjunction with the MIKE 21 hydrodynamic model to develop a simulation system for the dam failure flow process of an earth and rock dam. The study concentrated on the KET reservoir, and 12 dam failure scenarios were devised based on varying design flood criteria. The impact of reservoir failures on flood-risk areas was subjected to detailed analysis, with consideration given to a range of potential failure scenarios and flood sizes. It was determined that under identical inflow frequency conditions, the higher the water level, the more rapid the breakout process and the corresponding increase in flood peak discharge. Conversely, for a given frequency of incoming water, an elevated water level results in a transient breach process, accompanied by a reduction in flood peak flow. Moreover, for a given water level, an increase in water frequency results in a reduction in breaching time, an extension of flood duration, and an increase in flood peak flow. The observed trend of flood spreading is generally north-south, and this process is highly compatible with the topographic and geomorphological features, demonstrating good adaptability.

Hydrological-driven changes in the phytoplankton community structure under nutrient stress in island river ecosystems

While the spatiotemporal dynamics of phytoplankton community structures in river ecosystems have been extensively studied, their primary driving factors remain elusive, particularly at the watershed scale. This research examined the phytoplankton community structure across three watersheds of an island and concurrently analyzed its response to water level fluctuations (WLFs). The phytoplankton density was notably higher at elevated water levels, registering an increase of 1.29 times in Nandu River, 1.34 times in Changhua River, and 1.28 times in Wanquan River. Notably, the middle reaches of the Changhua River recorded the highest phytoplankton density (4.46 × 108 cells/L). Broadly speaking, Cyanophyta, Chlorophyta, and Bacillariophyta remained the predominant phytoplankton across varied water levels. Dominant phytoplankton species varied with water levels; however, the most prevalent species consistently belonged to the Cyanophyta group, primarily Microcystis or Merismopedia, with dominance ranging between 0.17 to 0.38 (low water level) and 0.18 to 0.32 (high water level). Enhanced phytoplankton diversity and richness were observed at higher water levels, correlating with increased concentrations of NH4+-N, NO3−-N, and PO43− in the river water. Consequently, nutrient fluctuations driven by hydrodynamics significantly influence the phytoplankton community structure in island river ecosystems.

Investigating the impacts of different degrees of deficit irrigation and nitrogen interactions on assimilate translocation, yield, and resource use efficiencies in winter wheat

Water and nitrogen (N) are recognized as the primary determinants influencing the development and output of winter wheat. They affect the growth of winter wheat not only through their own changes, but also through their interaction. The translocation and accumulation of pre- and post-anthesis assimilates (including dry matter and N) are important physiological processes in winter wheat, which are closely related to the resource use efficiency and yield. However, a dearth of research exists that examines the complex interplay between varying water levels, especially severe water deficit, and N deficiency levels on the growth dynamics of winter wheat. The purpose of this study was to quantify and compare the effects of different degrees of water deficit and N interaction on assimilate translocation, water and N use efficiency and yield of winter wheat. A four-year long-term field experiment conducted under the rain-out shelter including four irrigation and two N levels was launched during 2019–2023. This method avoided the impact of precipitation on water treatment and helped to achieve serious water deficit treatment. The findings indicated that the higher N application improved the wheat's ability by 49.6 % - 362.3 % to utilize the available soil water. The pre- and post-anthesis translocation and accumulation of assimilates (including dry matter and N) in winter wheat increase alongside elevated levels of water and N application, except under severe water deficit treatment. Plants under mild to moderate water deficit were better able to translocate the pre-anthesis assimilates. However, the severe water deficit hindered the re-translocation of assimilates before anthesis. Providing additional N during periods of severe water scarcity leads to a 13.4 % - 44.7 % reduction in water use efficiency (WUE). Furthermore, both the irrigation water use efficiency and WUE diminished by 10.3 % - 60.5 % and 4.5 % - 41.4 % with higher levels of irrigation, while improved by 24.4 % - 48.2 % and 12.6 % - 39.4 % with higher N application rates. Conversely, N partial factor productivity and N use efficiency followed the opposite trend. Similar to WUE, increasing N application under severe water deficit would result in a yield reduction of 38.7 %. The reduction in crop yield resulting from severe water stress was primarily ascribed to the decline in the kernels number per spike (up to 74.9 %), with the reduction in spike number per unit area following closely behind (up to 29.1 %). This integrated approach, combining resource use efficiency with a detailed assessment of assimilate dynamics, provides a holistic view of how water and N management strategies impact winter wheat performance. The findings will offer precise insights for developing targeted irrigation and N scheduling strategies for sustaining both winter wheat production and environmental sustainability.

Effects of water level gradients on the physiological ecology of Potamogeton crispus

Water level is crucial to the growth and development of wetland plants, in order to study the physiological and ecological responses of Pomatogeton crispus under different water levels, in the study, P. crispus were placed under 50 cm (control) and 60–135 cm water levels following a 15 cm gap gradient for 60 days in a simulation experiment. The results showed that: (1) As the water level gradient increased, the plant height, leaf number and biomass of P. crispus showed a trend of increasing and then decreasing. (2) The concentrations of chlorophyll a (Chl-a), chlorophyll b (Chl-b), chlorophyll a + b (Chl a + b) and carotenoids (Car) showed a multi-peak increasing trend with increasing water level, with the maximum values occurring in the 135 cm water level group. (3) The antioxidant enzymes of P. crispus showed a fluctuating upward trend with increasing water level, and the higher the water level the greater the difference within the group, and rooting activity of P. crispus was significantly increased under elevated water level conditions. (4) The P. crispus grows best in the water level range of 105 ∼ 120 cm, and the growth indexes such as the number of leaves and biomass all reach higher values in the water level of 105 ∼ 120 cm, If the water level is too high or too low, it has an effect on the growth and development of P. crispus.

Using the Relative Elevation Models to delimit the floodplain level development: The case of the braided-wandering Belá River, Slovakia

Abstract The Belá River is a specific submountain river running through the Liptov Basin in the Slovak Carpathians. Its transformation from a braided to a braided-wandering system and degradation including incision of the river system has been observed since the middle of the 20th century. These processes have created a complex system of floodplains with development stages. For their identification, the Relative Elevation Model normalizing absolute floodplain elevation to the river channel changes has been established. Three models have been prepared, from the channel bottom and water level elevation gauge by GPS, and the water level elevation by LiDAR. Based on the resulting models, the floodplain was identified and delineated to an active or potentially active floodplain, to an inaccessible floodplain spread behind artificial structures, and to a perched floodplain beyond the reach of the river. Spatial statistics, including “Hot spot analysis” and “Cluster and outlier analysis” have been used to identify recent river floodplain formation from 1949 to 2018, caused by simplification and incision of the Belá River. The unique aspect and contribution of the research lies in implementing and comparing the Relative Elevation Models and linking them to floodplain age.

Seismic Vulnerability Assessment of Non-Overflow Concrete Gravity Dam Section

Abstract As the economy advances, there is a growing need for energy. Harnessing hydroelectric energy has emerged as a crucial strategy for addressing the energy crisis. To promote hydropower development, numerous tall concrete dams are either under construction or in the planning stages. These dams are frequently situated in areas with elevated water levels and face the challenge of being located in regions with high seismic intensity. An accident resulting from the failure of concrete dams can pose significant threats to both economic development and public safety. Therefore, it is of crucial importance to investigate the stability of such dams, particularly under conditions of high water levels and seismic activity. The finite element program Geostudio is being undertaken to evaluate a complete numerical analysis of the dam. In this paper, Longtan Dam has been selected as the case study for the research. This study is applied in two cases: seismic and static conditions. A two-dimensional seismic numerical analysis was carried out using the Koyna earthquake acceleration time records in 1976. The results of the FEM model concluded that the dam is unsafe under sesmic conditions. The concrete-rock interface, particularly susceptible to sliding, was identified as the most critical part of the dam, presenting the most likely failure mode. The study highlights the significance of its methodology in investigating earthquake effects on dams, prioritizing it over the achieved results. The aim is for the conclusions and recommendations to provide valuable guidance for future studies and initiatives focused on enhancing safety at hydropower dams.

Skill assessment of a total water level and coastal change forecast during the landfall of a hurricane

The Total Water Level and Coastal Change Forecast (TWL&CC Forecast) provides coastal communities with 6-day notice of potential elevated water levels and coastal change (i.e., dune erosion, overwash, or inundation) on sandy beaches that threatens safety, infrastructure, or resources. This continuously operating model provides hourly information for select regions along U.S. Gulf of Mexico and Atlantic Ocean coastlines. The objective of this work is to assess the skill of forecasts during a period of elevated water levels along the coasts of North Carolina (NC) and South Carolina, USA caused by Hurricane Isaias in August 2020, using a combination of observations and model hindcasts. Water levels and waves were observed throughout the storm at three locations near Wrightsville Beach, NC, which provided information to assess forecast skill; a wave buoy offshore, a tide gage at a local pier, and a pressure sensor deployed at the pier. In addition to observations, the non-hydrostatic phase-resolving model SWASH (Simulating WAves till SHore) was forced with hourly wave energy spectra derived from a coupled Delft3D-SWAN simulation during the peak of Isaias, to complement observations by computing nearshore wave height and wave-induced setup and runup at the shoreline. During the storm peak, SWASH-simulated water levels at the sensor position were comparable to those at the maximum landward extent (bias = −0.05 m; gain = 0.26; r2 = 0.99), suggesting that observations at the USGS sensor location were a useful proxy for total water level (TWL; sum of tide, surge and wave runup) at the shoreline that are predicted by the TWL&CC Forecast. The TWL forecast at Wrightsville Beach was consistent with observations from the USGS sensor (bias = −0.38 m and −0.74 m, scatter index = 0.22 and 0.28 for the two forecast model grids considered, respectively; weighted regression considering model uncertainty explained 95 percent of variability in observed TWL). Observed TWL was within the confidence interval of the TWL&CC Forecast for the 5 h at the storm peak. Forecast mean water levels (MWL; sum of tide, surge and wave setup) and tide gage observations were also consistent (bias = 0.07 m and 0.02 m for the forecast model grids; scatter index = 0.46; r2 = 0.80). Forecast MWL at the storm peak was within 0.06 m of the observed MWL from the tide gage for both sites. In the region where Isaias made landfall, eight additional pressure sensors were compared to the peak TWL forecast (bias = 0.14 m; scatter index = 0.18). Forecast TWL explained 90 percent of observed variability in TWL when considering uncertainty of the forecast with a weighted regression. The results demonstrate that wave-driven water levels contributed a significant portion of the forecast TWL during Isaias (52 percent during the three peak hours of the storm), and that TWL were represented using the forecast model. Mean absolute error of the coastal change forecast and observed overwash is 0.4 and 0.14 for the two forecast model grids considered. The skill demonstrated by this computationally efficient method indicates that the forecasting system can provide fast and reliable predictions of TWL across hundreds of km of coastline at sub-km resolution, days to hours in advance of when storms threaten coastal regions.

A Fresh Take: Seasonal Changes in Terrestrial Freshwater Inputs Impact Salt Marsh Hydrology and Vegetation Dynamics

Salt marshes exist at the terrestrial-marine interface, providing important ecosystem services such as nutrient cycling and carbon sequestration. Tidal inputs play a dominant role in salt marsh porewater mixing, and terrestrially derived freshwater inputs are increasingly recognized as important sources of water and solutes to intertidal wetlands. However, there remains a critical gap in understanding the role of freshwater inputs on salt marsh hydrology, and how this may impact marsh subsurface salinity and plant productivity. Here, we address this knowledge gap by examining the hydrologic behavior, porewater salinity, and pickleweed (Sarcocornia pacifica also known as Salicornia pacifica) plant productivity along a salt marsh transect in an estuary along the central coast of California. Through the installation of a suite of hydrometric sensors and routine porewater sampling and vegetation surveys, we sought to understand how seasonal changes in terrestrial freshwater inputs impact salt marsh ecohydrologic processes. We found that salt marsh porewater salinity, shallow subsurface saturation, and pickleweed productivity are closely coupled with elevated upland water level during the winter and spring, and more influenced by tidal inputs during the summer and fall. This seasonal response indicates a switch in salt marsh hydrologic connectivity with the terrestrial upland that impacts ecosystem functioning. Through elucidating the interannual impacts of drought on salt marsh hydrology, we found that the severity of drought and historical precipitation can impact contemporary hydrologic behavior and the duration and timing of the upland-marsh hydrologic connectivity. This implies that the sensitivity of salt marshes to climate change involves a complex interaction between sea level rise and freshwater inputs that vary at seasonal to interannual timescales.

SUBSIDENCE ANALYSIS OF HYDROELECTRIC DAM USING THE KALMAN FILTER – A CASE STUDY IN HOA BINH HYDROPOWER PLANT, VIETNAM

Hydroelectric dams have a great influence on the safety of the downstream area. Therefore, deformation monitoring for assessing the safety of dam should be carried out regularly. In order to improve efficiency of the dam management, it is necessary to analyse the displacement values in space, over time to assess overally the displacement of dam. In this purpose, an attempt was conducted to analyse the subsidence of hydroelectric dams located in Hoa Binh, Vietnam using one of the most useful method – Kalman filter. Kalman filter is the unique method that can determine influence of external factors (particularly, elevation of water level in the reservoir) on dams, simultaneously forecast the displacement values of dam in the future. Moreover, Kalman filter allows to predict subsidence accurately in about 6 months that is longer prediction time than other static models. These are clearly presented and discussed in the article. The obtained results demonstrate the high applicability of Kalman filter method in analysing and forecasting the subsidence of the Hoa Binh hydroelectric dam.

Cover collapse sinkhole formation is delayed in time and uncorrelated to distance from quarry in a long-term study of a karst basin

Collapse sinkholes are problematic for the hazards they bring to property, infrastructure, and human life but the prediction of their formation in time and space remains elusive. We make use of long-term data gathered in a small, highly monitored, hydrologically constrained basin; Primrose Creek, Bucks County, Pennsylvania, USA, to examine the relation between groundwater extraction, precipitation, terrain position, and cover collapse sinkhole development. The selected site is unique as a natural laboratory to explore induced sinkhole processes in that it is a clearly demarcated topographic basin with geological structural and lithologic boundaries; the stressor is extreme, has been plainly identified, and effectively captures all upstream runoff and groundwater; the groundwater withdrawals and water-level elevations have been closely monitored over a period of 20 years; and the general record of land conditions goes back more than a century. We evaluated the history of a carbonate-rock quarry, its development and expansion over many decades, as well as associated precipitation and ground-water level data, and cover collapse sinkhole occurrence within the basin. Interception of discrete high conductivity zones in the Paleozoic carbonate rocks by quarry expansion was an important factor in propagating collapse occurrence. Collapses occurred mainly, though not exclusively, along drainageways and at lithologic boundaries. They formed in time-based clusters with delay of up to several years. Surprisingly, distance of collapse formation from the pumping area was not directly correlated with time elapsed; i.e., collapses did not begin to form close to the quarry, and then later form farther away. Monitoring wells were unsuccessful in delineating the pumping zone of influence although some documented water table decline and response to weather and anthropogenic events. This comprehensive study shows that in order to successfully monitor and control impacts from quarry dewatering in Paleozoic carbonate rocks it is critical to 1) develop a detailed conceptual model of groundwater pathways, 2) try to avoid excavating into high permeability zones, 3) clearly document karst features when exposed, and 4) carefully site a suitable number of monitoring wells and collect data at short intervals.

The effect of emergent vegetation on flow, bedload transport, and bed morphology in a diffluence-confluence unit on a meandering channel

A diffluence-confluence unit on a meandering channel, coupled with the broadening of the divergence zone and meander circulation, promotes sediment deposition on the convex bank, forming shoals to stimulate vegetation growth, which results in water level elevation, velocity reduction, and bank stabilization. Despite these significant impacts, current research on the influence of this channel remains limited. This study conducts a series of flume experiments to quantify the influence of vegetation in a such channel on flow hydraulics, bedload transport, and bed morphology, and their inter-links. The results reveal that increased vegetation cover density subtly influences the flow depth in straight inlet reaches, triggers higher flow depth and fluctuations in the left anabranch, and induces uneven velocity distribution, especially below the crest of the curved channel. Centrifugal forces and vegetation-induced water levels shape the transverse water surface slope, resulting in a downward concave trend and unique slopes within each anabranch. The bedload transport capacity rapidly increases until an armoring layer forms, a process expedited by vegetation, particularly in high discharge conditions. This vegetation effect, amplified with higher density, enhances bedload transport rate and size but is lessened by increased discharge, which also reduces fluctuations during armoring layer formation. The statistical parameters of bed morphology at the grain-scale and structure-form-scale indicate that denser vegetation reshapes erosion dynamics across anabranches, intensifying downstream scouring and propelling the sediment deposition zone, especially under high discharge. Furthermore, the flow bifurcation ratio intensifies with escalating vegetation cover density and is assessed by a modified model consider vegetation effects with heightened precision. The apex scour depth downstream of the unit, induced by the confluence of water from both anabranches, can be characterized as a function of the dimensionless discharge and vegetation density. Concurrently, a refined model for bedload transport rate, influenced by the turbulent kinetic energy arising from emergent vegetation in this intricate reach, is proposed with high accuracy.

Investigation of the microfracture and damage characteristics of dam during impoundment at Sanhekou hydropower station

Dam stability is one of the most important issues in hydraulic engineering. Microfractures and damage commonly occur during impoundment, which might lead to serious dam problems. In this study, based on the engineering background of the Sanhekou hydropower station, microseismic monitoring and numerical simulation were employed to systematically investigate the microfracture and damage characteristics of the dam body. First, the microseismic monitoring system was established to capture the microfractures inside the dam. The results indicated that the rise in water level elevation has a significant effect on the microfracture and damage characteristics of the dam body, especially during the early stage of impoundment. This can be reflected by the variation in the derived source parameters, i.e., the b value, daily energy release, daily apparent stress and daily apparent volume. In addition, the failure mode of the microfractures could be determined by using the ES/EP value of microseismic events and the moment tensor inversion method. The cracking orientation of the failure surfaces could also be determined by the moment tensor inversion method. Subsequently, numerical simulation was conducted where the initial damage of the dam was considered by integrating the microseismic monitoring data. The simulation results suggested that dam deformation under impoundment considering microseismic feedback agrees well with the real field measured results. The stress level of the dam toe was larger than that of the dam heel, and both the dam toe and dam heel were under compression before impoundment. However, with increasing water level elevation, the stress status of the dam heel area changes from compression to tension. The findings in this study will provide a better understanding of the damage and failure mechanism of dams during impoundment, which might be helpful for the design and support of dams in hydropower stations.

Analysis of Multiple Scattering Characteristics of Cable-Stayed Bridges with Multi-band SAR

Abstract. Accurate localization of multi-scattering features of cable-stayed bridges in multi-band Synthetic Aperture Radar (SAR) imagery is crucial for intelligent recognition of bridge targets within images, as well as for precise water level extraction. This study focuses on the Badong Yangtze River Bridge, utilizing Unmanned Aerial Vehicle (UAV) LiDAR data of the bridge, and analyzes the multi-scattering characteristics of different bridge structural targets based on Geometric Optics (GO) methods and the Range-Doppler principle. Furthermore, the study integrates LiDAR data of the bridge's cable-stays to examine their multi-scattering phenomena, finding that the undulations of the Yangtze River's surface waves significantly contribute to the pronounced double scattering features of the bridge's cable-stays. Additionally, statistical analysis of multi-source SAR data indicates that this phenomenon is not directly correlated with radar wavelength, implying no direct connection to surface roughness. Utilizing LiDAR point cloud data from the bridge's street lamps, this paper proposes a novel method for estimating water level elevation by identifying the center position of spots formed by double scattering from lamp posts. The results show that using TerraSAR ascending and descending orbit images, this method achieves a water level elevation accuracy of approximately 0.2 meters.

Effects of Water Level Fluctuations and Vegetation Restoration on Soil Prokaryotic Microbial Community Structure in the Riparian Zone of the Three Gorges Reservoir

Riparian zones are typical fragile and sensitive ecological areas. Fluctuations in water level are the main factor affecting the soil environment in these zones, and vegetation restoration is considered an important means of soil conservation there. However, the interactive effects of water level fluctuations and vegetation restoration on the soil microbial community structure in the reservoir riparian zone remain unclear. Therefore, we selected abandoned grassland and artificial forestland at different water level elevations as research objects in the riparian zone of the Three Gorges Reservoir. We used 16S rRNA high-throughput sequencing technology to explore the composition and diversity of soil prokaryotic microbial communities and investigated the main environmental factors driving the soil microbial community structure. The results showed that the α diversity of soil prokaryotes was the highest at the low water level of the riparian zone. The Pielou_e index, Shannon index, and Simpson index at the 163 m elevation were significantly higher than those at the 168 m elevation, and the Chao1 index and Shannon index were significantly higher than those at the 173 m elevation. However, no significant difference was found in the soil microbial community α diversity between abandoned grassland and artificial forestland. At the same time, water level fluctuations and vegetation restoration had significant effects on the community composition of soil prokaryotic microorganisms, and there were significant differences in biomarker categories in different study sites. Notably, the effects of vegetation restoration types on the soil prokaryotic microbial community structure were stronger than that of water level fluctuations. In addition, the results of hierarchical segmentation showed that soil pH was the main driving factor for the change in soil prokaryotic microbial community structure in the Three Gorges Reservoir. These results deepen our understanding of the variations in microbial community structure in the reservoir riparian zone and provide scientific reference for the restoration and reconstruction of the riparian zone ecosystem.

Wonorejo dam operation and storage analysis against climate change

Climate change affecting rain intensity within catchment and increase the potential hydrometeorology disasters. Wonorejo Reservoir as a multipurpose dam requires an operational plan and water allocation to fulfill downstream needs, such as irrigation, hydropower, microhydropower, domestic industry uses and flood control. Wonorejo Dam is a backfill type dam with High Water Level (HWL) elevation is +183.00 mSHVP and Low Water Level (LWL) elevation is +141.00 mSHVP, Total storage capacity Wonorejo Reservoir is 109.118 million m3 (2021) or 89.4% from initial total storage capacity (2000), in 2050 predicted sediment volume increase to 17.73 million m3 or 17.6% reservoir capacity and 2050 capacity volume is 100,585 million m3 or 82.4% from initial total storage capacity. Annual Reservoir Operation Plan and Annual Water Allocation Plan for Wonorejo Reservoir in 2022/2023 as water services December 2022 to November 2023 periode, Wonorejo Reservoir elevation at the end of May 2023 reaches HWL and lowest water elevation is +162.64 mSHVP in the first week of November 2023.

Formation of pit lake and slope stability following mine closure: a case study of Fushun West Open-pit Mine

The Fushun West Open-pit Mine, recognized as Asia’s largest open-pit coal mine, transitioned to a closure management phase following the cessation of operations in 2019. This study presents a quantitative analysis of the water inflow sources by meticulously reviewing historical data on the mine’s drainage system and the hydrogeological conditions of the mining area. A numerical model representing the unsaturated-saturated groundwater dynamics was constructed to illustrate the spatial distribution of the groundwater flow. Employing the water storage analysis module within the WebGIS system, projections were made regarding the natural water accumulation process at varying water levels. The results indicate that, under natural conditions, an estimated 48 years would be required to reach a water level elevation of 50 m. However, this timeframe could be drastically reduced to approximately 3.3 years by implementing an accelerated filling strategy that channels water from the Hun River. Numerical simulations elucidate the failure mechanism of the water-sensitive slope on the northern bank during the water storage process, as well as the potential impact on the slopes above the water level. This comprehensive approach provides critical insights for managing decommissioned open-pit mines and optimizing water storage schemes.

Pipe Flow Simulation Model on Shrimp Hatching Infrastructure (Hatchery) Through Recirculating Aquaculture System (RAS) Approach

The shrimp nursery infrastructure consists of nursery tanks, mechanical filters, biological filters, and ultraviolet (UV) filters. This study aimed to simulate the water level elevation (head) of shrimp nursery infrastructure, especially nursery tanks. The placement of the nursery greatly affects the elevation of the water table owing to the loss of energy (headloss) that occurs in the flow. The nursery tub used in this study was round and consisted of four tubs made of fiber resin measuring 250 cm in diameter and 120 cm in height. The bottom of the tub was placed at an elevation of +40 cm above the ground. The simulation was conducted for 24 hours. The results of the EPANET 2.2 simulation showed head fluctuations in each nursery with the highest elevation (1.38 m and the lowest (1.20 m, from the data. The head fluctuated constantly after 6 h of the flow. The optimal pipe diameters were 3" (80 mm) PVC and 4" (110 mm) PVC.

Effects of Water-Level Fluctuation on Soil Aggregates and Aggregate-Associated Organic Carbon in the Water-Level Fluctuation Zone of the Three Gorges Reservoir, China

Water-level fluctuation (WLF) can destroy soil aggregates and induce soil organic carbon (SOC) loss, potentially triggering impacts on the concentration of atmospheric carbon dioxide. However, responses of soil aggregate content and aggregate-associated organic carbon to WLF have not been well studied, especially in the water-level fluctuation zone (WLFZ) of the Three Gorges Reservoir (TGR). Therefore, samples from different elevations (145 m, 155 m and 165 m) in the WLFZ of the TGR were collected for experiments. The wet sieving method was used to divide soil into silt and clay (<0.053 mm), micro-aggregate (0.053–0.25 mm) and macro-aggregate (>0.25 mm). The K2Cr2O7-H2SO4 oxidation method was used to measure total SOC content in different soil aggregates. A modified Walkley and Black method was used to measure labile carbon in different soil aggregates. Results showed that macro-aggregate content substantially decreased, while micro-aggregate content remained stable and silt and clay fraction accumulated with a decrease in water-level elevations. Moreover, total SOC content and labile carbon in macro-aggregate were obviously higher than those in the micro-aggregate and the silt and clay fraction. Macro-aggregate contributed the most to SOC sequestration, while micro-aggregate contributed the least, and the contribution of macro-aggregate increased with a decrease in water-level elevations. We concluded that the macro-aggregate was the most active participant in the SOC sequestration process, and preferentially increasing the macro-aggregate content of the lowest water-level elevation was conducive to an improvement in soil carbon sequestration potential and would mitigate climate change.