Proceedings of the 4th International Conference on Advances in Civil and Ecological Engineering Research

Due to environmental erosion and loading effects, reinforced concrete structures inevitably have various macro- or micro-cracks. The existence of cracks would aggravate chloride ingress and reinforcement corrosion, especially for offshore engineering structures, thereby further weakening the structural performance and reducing their service life. The research on the chloride-induced corrosion of steel bars in pre-cracked concrete is fundamental. On this basis, this paper mainly reviews the studies from three perspectives: corrosion model of steel reinforcement in concrete, chloride ion transport in pre-cracked concrete under loading effects, and interaction between rebar corrosion and the concrete cover layer and tries to put forward the deficiencies and look forward to the research prospects.

The objective of the study is to review the theoretical and practical methods for determining the reliability of buildings that have been in operation for more than 50–70 years. The necessity to survey the technical state of the operating buildings to monitor the required parameters of their reliability and safety has recently become one of the most important activity areas for research, design, and construction organizations because of cases of collapse of buildings over the world all have become frequent. The work is based on analysis of existing approaches, experimental and theoretical studies in the area of reliability of buildings and structures. The results of surveying the partially ruinous 4-story residential building are considered and analyzed. The technical condition of certain structures is defined as a result of a general analysis of defects and damages determined by the results of the preliminary inspection. The analysis of the stress–strain state of the collapsed building was performed on the basis of verification calculations by using modern program complex “Lira”. The verification calculations have been performed for two conditions of soil base of foundations: the natural condition of soil base and soaked condition of soil base. The procedure of revealing the causes of building collapse and recommendations of its possible restoration is discussed also.

China proposes to achieve the goal of carbon neutralization by 2060, and in this background, the buildings with steel structures are regarded as “green buildings” in the twenty-first century. Compared with the traditional concrete structure, a steel structure building offers low weight, low production cost, good anti-seismic performance, and is easy to repair after disaster. Also, the materials for construction are recyclable and renewable, thereby saving resources like energy, land, and water. Considering these advantages, steel structure is widely used in substations. To quantitatively evaluate the benefits of energy saving and emission reduction of steel substations, the 100 kV substation in Jiangsu Province was selected as a case study. Based on the full life-cycle theory and the calculation method of building life-cycle carbon emission, we calculated the emission volume of greenhouse gases generated by the steel and concrete substation. The results indicated that there was a 29% reduction of carbon emission reduction from the steel substation compared with concrete ones.

Owing to the traditional offshore floating foundation built of steel cannot break through the constraints of high material costs, easy corrosion, and post-maintenance difficulties. Reinforced concrete has the characteristics of low cost and good corrosion resistance, and the application of reinforced concrete in floating foundations is less studied. Therefore, a new type of foundation for offshore wind power construction with prestressed reinforced concrete is proposed in this study. The floating reinforced concrete foundation model for offshore wind turbines is established by applying finite element software. Considering buoyancy, wind, wave, and other loads, the safety and stability of the structure are discussed by analyzing the working case and survival case. The results show that most areas of prestressed concrete foundations are compressed in different circumstances. Little tensile stress occurs in small areas at corners and junctions. The tilting angle of the structure satisfies the tilting safety angle, which indicates the stability of the prestressed concrete floating foundation performance. The calculation results of the floating foundation with prestressed concrete can provide a reference value for the corresponding engineering design.

Big data (BD) in structural health monitoring for civil engineers has become possible because of recent advances in sensor networks, computing, information, and data acquisition systems technologies (SHM). The time-frequency analysis-based data-driven method provides good opportunities for implementing a strategy of long-term SHM for the bridge by using measured vibration signals. But there are limitations associated with complex and time-consuming feature extraction and decision-making procedures due to high-dimensional big data. Therefore, this paper proposes an innovative strategy that integrates the empirical mode decomposition (EMD) and Hilbert transform (HT) for informative feature extraction for bridge condition assessment. The efficiency of the suggested method is evaluated using data pertinent to a cable-stayed bridge. The findings demonstrate that the proposed technique is effective and robust in extracting informative features for bridge assessments in cases highly characterized by big data without any concerns regarding the information loss about the structural state. It is concluded that the proposed technique can address the issues of identifying data anomalies that are reliable early warning signs for future bridge failure and produce interpretable signal analyses that can handle BD with numerous periodic components, nonlinear functions, and periodic mode amplitudes as well as the problems of identifying data anomalies that are trustworthy early warning indications for upcoming bridge failure.

The wide development in deep learning (DL) application in different fields such as speech recognition, computer vision, and natural language processing has been done by different architectures of networks, such as the most applied network named convolutional neural networks (CNN). This work discusses the framework for monitoring the structural surface cracks based on DL. The proposed model is combined with unmanned aerial vehicles (UAVs) to collect the surface cracks images automatically to detect the cracks in real-time. Equipped with a comparatively heterogeneous dataset, the use of DL allows the crack detection development system. In this proposed work, the results dataset has a high accuracy rate (P%), regression rate (R%), and F-score (F%), and the overall performance is $$95.5{\text{\% }},{ }93.78{\text{\% }}$$ , and $$91.55{\text{\% }}$$ , respectively.

This paper deals with the numerical study of the postbuckling behavior of the symmetrical and asymmetrical sigmoid functionally graded materials (S-FGM) circular plates subjected to thermal load, and the numerical results obtained from the present paper are used to analyze the differences of the mechanics behavior between the two types of S-FGM circular plates and between S-FGM circular plates and ordinary functionally graded ones. Assuming that the distribution of material components satisfies the sigmoid law, the temperature change in the direction of the thickness of the circular plate is described by a one-dimensional heat conduction equation and satisfies the sigmoid law. First, the nonlinear equilibrium equations with static problem of the S-FGM circular plate and boundary conditions using the energy method, and then solved numerically by applying the shooting method. The influence of factors such as the distribution form of component materials, external loads and boundary states to the mechanical behavior of S-FGM circular plate is discussed in detail.

About 40% of global energy consumption is attributed to the construction sector which, in view of the European Green Deal, needs a profound renewal in structural, energy, and environmental performance. Exoskeletons offer structural retrofit solutions that allow an overall architectural and performance upgrade to the building but must be supported by energy analyzes of each technological component involved to be considered really efficient. The adoption of exoskeletons can determine thermal criticalities on the envelope and in particular, at a local level, thermal bridges in the connections between pre-existing and new structures. This paper deals with this topic by referring to a real explanatory case and reports some early results of an assessment based on a 2D thermal bridge finite element model under steady-state conditions. The results point out the likelihood of vapor condensation inside components of the building envelope and an increase of the linear transmittance Ψ through thermal bridges.

The tower foundation in the Power Transmission and Transformation Project is critical for the power supply across China. The stability of the tower foundation slope ensures a continuous power supply. However, the stability of the tower foundation slope is influenced by many factors, including internal and external factors, especially in the areas under a strong typhoon environment. In this study, we conduct a case study at Fujian to analyze the stability of the tower foundation slope under a strong typhoon environment by considering the electric tower's weight, strong wind, and heavy precipitation, and test which factor contributes the most to affect the stability of tower foundation slope. The results showed that with the increase of influencing factors, the slope stability gradually decreases, and the safety factor of the tower foundation slope is different. Precipitation is the main factor affecting the stability of the tower foundation slope. This analysis will guide the construction and protection of electrical towers and avoid potential losses caused by the instability of the tower foundation slope.

In order to study the problem of slope ecosystem restoration, the slope restoration of power transmission and transformation projects is the research object. Based on the principles of slope ecological restoration, combined with the connotation and principles of ecological restoration. On the basis of the existing slope restoration technology, analysis is carried out through the water and soil monitoring, water and soil conservation measures, and comparison before and after restoration of the power transmission and transformation project. The research results show that: engineering measures, plant measures, and temporary measures have been taken during the construction of the power transmission and transformation project; the water and soil erosion in the station area is well controlled, and the impact on the surrounding environment is small; 99.42%, soil loss control ratio reached 1.03, slag blocking rate was 98%, forest and grass vegetation restoration rate was 99.16%, and forest and grass coverage rate was 40.40%. The target value of comprehensive prevention and control of soil erosion meets the requirements, and the overall implementation effect is good.

It is difficult to anti-gas-migration in the Shunnan well regions due to the deep well, higher of the static formation temperature, lost circulation, and the active gas zone, conventional cementing operations cannot meet the requirements of such operations. Here, liquid silicon and latex are introduced into the cement slurry to mutually improve the gas migration resistance of the cement slurry. Silica with different particle sizes and fibers with different lengths are optimized, and their dosage can significantly improve the strength and toughness of the cement under high-temperature conditions, so as to reduce the risk of lost circulation. In cementing technology, centralizer spacing is optimized to improve casing centrality and displacement efficiency; In order to remove drilling fluid and improve interfacial cementing strength, the dosage and performance of cement slurry and spacer were optimized. At the same time, flow restriction and back pressure are used to reduce the risk of gas channeling. The field application shows that the integration and application of a whole set of technologies provide an effective method for solving the cementing problem of liner in ultra-deep wells.

In order to better control the diffusion of coal dust at the belt conveyor transfer point, it is explored that the air flow and dust movement laws in the coal mine roadway. A mathematical model on coal dust diffusion is established based on Euler–Lagrange model, and the physical model of the transfer point is established with SOLIDWORKS. With these models, simulations about the dust diffusion center on belt conveyor transfer point are carried out with Ansys Fluent. The results show that, with the influence of the two kinds of airflow, the coal dust is concentrated near the outlet of the windward side of the transfer point in the form of vortex, and there is a tendency to bypass the transfer point and spread to the side of the sidewalk. It is no longer evenly distributed along the roadway. Where the dust concentrated is the important position to fix dust removal equipment. The dust particle size and diffusion laws at the concentrate position are analyzed, with the increase of diffusion distance, the mass proportion of the particle size less than 10 μm increases. This means that the dust within the particle size range is not easy to settle, and appropriate measures should be taken to reduce its concentration.

To improve the separation performance, the effects of feed rate on the hydrocyclone flow field and the classification performance were researched by numerical simulation. It is found that the pressure at the hydrocyclone wall increases with increasing feed rate, as the feed rate increases from 3 to 5 m/s, the pressure at the hydrocyclone wall increases by 193%; the tangential velocity increases with higher feed rate, and with the feed rate increases from 3 to 5 m/s, the maximum value of tangential velocity in the separation area increases by 4.28 m/s; the separation size decreases with increasing feed rate, when the feed rate increases from 3 to 5 m/s, the separation size d50 decreases. When the feed rate increases from 3 to 5 m/s, separation size d50 decreases by 2.14 μm. The findings reveal that enlargement in feed rate can increase the processing capacity, strengthen the centrifugal strength, and improve the classification efficiency. However, excessive feed rates can also shorten the particle retention time in the hydrocyclone, resulting in insufficient separation and thus reducing the classification accuracy of the hydrocyclone.

With the rapid development of lithium battery industry, the production of lithium slag is also increasing. Lithium slag contains rare elements of considerable grade, but the high content of fine mud increases the cost of subsequent extraction of elements, so it is necessary to remove the mud in order to improve the production efficiency. Therefore, this paper proposed the use of water-injection cyclone to desliming pretreatment. The results show that with the increase of water-injection flow, the overflow concentration increases by 1.46 percentage points from 6.87 to 8.33%, and the underflow concentration decreases by 2.83 percentage points from 52.58 to 50.25%. For the −20 μm particle content in the underflow products, when the water-injection flow is 80 L/h, the removal effect is the best, and the comprehensive classification efficiency is the highest, up to 69.37%. The research results can provide some reference for industrial practice.

The length of overflow tube insertion was a vital parameter that affects the classification performance of the hydrocyclone. In this paper, the effect of the insertion length of the overflow tube on classification performance and flow field distribution of the hydrocyclone with a diameter of 50 mm was studied by numerical simulation. It was found that the tangential and axial velocity in the inner swirl increase as the increase of the insertion length of the overflow tube. When the insertion length of the overflow tube increases from 8 to 40 mm, the tangential velocity of the internal swirl increases from 5.13 to 5.50 m/s, an increase of 7.2%; The axial velocity increases from 2.37 to 3.44 m/s, an increase of 45.15%. At the same time, it was found that the classification performance of the hydrocyclone increased first and then decreased with the insertion length increase of the overflow tube, and the best value was obtained when the insertion length was 16 mm. The research showed that choosing the appropriate insertion length of overflow tube was very important to the classification performance of hydrocyclone. This study has important reference value for the optimal design of hydrocyclone.

Aiming at the soil heat imbalance caused by the GSHP system with uneven cooling and heating loads, a solar-assisted ground source heat pump system (SAGSHP) was designed for an office building in Beijing. In this paper, the cooling and heating loads of the office building were calculated in detail and the equipment’s parameters were strictly selected. The TRNSYS software was used to conduct numerical simulation research and feasibility analysis for the SAGSHP system. The advantages of the SAGSHP system over a single energy supply system and soil thermal balance after long-term operation are explored. The results show that the collector efficiency of the SAGSHP system is increased by 13.36% compared with the single solar heat collection system, and the soil thermal imbalance can be greatly reduced compared with the single GSHP system. The average soil temperature in the SAGSHP system and the GSHP system decreased by 0.04 °C and 0.31 °C after one year and 0.06 °C and 1.97 °C after ten years, respectively. The SAGSHP system also has a more stable unit performance coefficient than the GSHP system. The SAGSHP system can improve the efficiency of solar energy, make the system power supply stable and maintain the soil thermal balance, which is worth promoting in engineering applications.

With the increase in the number of oils transported by sea, the risk of oil spills from ships has increased year by year. Ship oil spills often incur huge costs of surroundings cleanup and environmental remediation. The Civil Code of the People’s Republic of China has come into effect on January 1, 2021. Chapter 7 in Part VII Tort Liability of the Civil Code, Liability for Environmental Pollution and Ecological Damage (Articles 1229 to 1235), is called “Green Clauses,” foreseeably to play a significant regulatory and guiding role in the compensation-related work of China’s ship oil spill pollution accidents. The Green Clause in the Civil Code is consistent with the principles of the three international conventions in the field of compensation for oil pollution damage from ships to which China is a party. The characteristic provisions such as ecological environment damage repair and compensation are in line with China's ecological environment protection system. The inversion of the burden of proof and other provisions can more effectively protect the victims of ship oil spill pollution accidents.

The influence of C/P change on the occurrence form and content of phosphorus in the municipal wastewater treatment system by MBBR was studied, and the dynamic equilibrium process of phosphorus in the reactor was analyzed, in order to reveal the biological treatment mechanism of phosphorus in MBBR. The results show that when C/P changes from 36 to 109, the removal effect of chemical oxygen demand (COD) is small, and the removal rates of ammonia nitrogen (NH4±N) and total phosphorus (TP) show an increasing trend. The highest removal rates of COD, NH4±N, and TP are 93.1%, 51.1%, and 72.4%, respectively. The content of phosphorus in the biofilm was higher than that in the suspended sludge, and the content of phosphorus in the attached biofilm and exfoliated biofilm was higher under higher C/P conditions. In the biofilm, the content of inorganic phosphorus was significantly higher than that of organic phosphorus, which accounted for 75.43%–92.67% of TP, and non-apatite inorganic phosphorus accounted for 44.93%–65.69% of TP. The content of phosphorus in the attached biofilm was significantly higher than that in the exfoliated biofilm, and the phosphorus in the system was in a state of dynamic balance, and the amount of phosphorus treated was equal to the content of phosphorus in the discharged biofilm. These results can provide a theoretical basis for efficient phosphorus treatment and stable phosphorus removal.

The study area (Imphal-West district, a region in the north-eastern state of India) chosen is frequently prone to flooding due to its low-lying landscape. However, in the year 2019, there was an elevated scarcity of available surface water, which led to a drought-like situation. Thus, in this study, drought-affected areas are identified and simulated (for the year 2019) using the combined approach of analytic hierarchy process (AHP) tools and the weighted overlay method in the geographical information system (GIS) platform. For the study, seven key parameters were considered (rainfall, temperature, slope, drainage density, soil, land use/land cover, and groundwater yield). On a scale of one to nine, these parameters were assigned based on their degree of influence on drought. Then, using a pairwise comparison matrix and normalized weights from the AHP method, an overlay analysis (a weighted method on the scale of one to five) was performed. There were four drought classes (mild, moderate, severe, and extreme), and the percentage of drought-affected area in the region was 22.82% as mild, 60.10% as moderate, 16.16% as severe, and 0.92% as extreme. The simulated drought-affected regions were validated using collected ground data (State Government Department) and found that 43.71% of the area was mild drought and 51.32% was moderate drought, which shows that moderate drought regions are effectively modeled (error 8.78%) by the AHP method.

Aquatic plants are common in rivers and other waterways. Their presence affects both the structure and hydraulic characteristics of water flow. In this study, we examined effects of aquatic plants on a river network and present a numerical model that represents the flow characteristics through an aquatic plant zone. Resistance characteristics, velocity distribution, and water level differences are all simulated and analyzed for different flow conditions. Various types of submerged aquatic plants are reconstructed in our numerical model and a differential equation is summarized. Simulated results confirm the significance of resistance increasing with height of submerged aquatic plants. Future research should focus on effects of both submerged and unsubmerged aquatic plants on river networks.

China clearly pointed out in the “14th Five-Year Plan” that “accelerating the energy revolution, building a clean, low-carbon, safe and efficient energy system, and enhance the capability of ensure energy supply. Promote the concentration of coal production in resource-rich areas, rationally control the scale and pace of coal power construction, and promote the replacement of coal with electricity.” Combining the “carbon peaking and carbon neutrality goals” with the existing energy Internet architecture. Firstly, the essential concept and main features of the energy Internet are expounded. Secondly, according to the basic framework of the Energy Internet and the key technologies of the Energy Internet, briefly analyze it and summarize the problem. Finally, the research status and key points of the energy Internet at home and abroad are briefly sorted out, and look forward to the Internet of energy, in order to offer to reference for the research on the energy Internet in my country.

Most of China, the development rate of water resources exceeds the warning line. Water shortage has become an important condition that hinders the development of our country's socialist economy. The precipitation in Jiangsu Province is showing an uneven distribution from north to south, the water resources between regions are disparate, and the available water resources appear slightly inadequate. How to protect the ecological balance has become a major problem in Jiangsu Province. Our research results indicate the fluctuation characteristics of the affordability of water resources from 2010 to 2015. The total water ecological footprint decreased from 91.2 million hm2 in 2010 to 76.1 million hm2 in 2015. From 2010 to 2014, there were ecological deficits of varying degrees, and in 2015, there was a surplus. The continuous update and change may be explained by the close relationship with rainfall.

The API and AQI values of Huaian city for the period from 2014 to 2018 were calculated based on daily and hourly air pollution monitoring data. According to those values, the air pollution characteristics of Huaian city were analyzed. The results showed that from 2014 to 2018 the major pollutant was PM2.5, while the secondary pollutants were PM10 and O3. The annual changes in API and AQI values in Huaian city showed a downward trend. The inter-month changes in API and AQI in Huaian in 2018 were related to temperature, air pressure, wind speed, and relative humidity. The average wind speed was significantly negatively correlated with API and AQI. The relationship between relative humidity and API and AQI was related to seasons. The climatic conditions of high temperature and low pressure were conducive to the reduction of API and AQI values.

Water distribution systems are considered vital arteries of urban communities. The purpose of a water supply distribution system or network is to provide water to consumer with adequate pressure and quality. The quality must be healthy and standards in terms of chemical and biological standards. Chlorine is used as the most common disinfectant in municipal drinking water supply networks due to its high efficiency and economy. The aim of this study was to assess the effect of environmental temperature on residual chlorine, turbidity, TOC and HPC in Abadan, Iran, WDN, during summer and winter seasons. In this cross-sectional study, according to the water supply maps, the 232 samples from different point of WDN were analyzed to measurement of free residual chlorine, total organic carbon (TOC), Turbidity (NTU), and heterotrophic plate count (HPC) (cfu/100 ml), based on the standard methods for examination of water and wastewater (APHA). Samples were collected from effluent of water treatment plant to distribution system according to the Cluster sampling model. Regression analysis was used to investigate the relationship between variables. Results show that temperatures in Abadan typically range from 29 to 46 °C at summer and 12 to 27 °C in winter. Statistical analyzes show that as the ambient temperature increased, the free residual chlorine in the distribution network from the water treatment plant decreased to the end of the distribution network and reached zero at some end points (R2 = 0.97). Also TOC, Turbidity (NTU), and HPC (cfu/100 ml) showed a significant increase with increasing environmental temperature in distribution network (P < 0.05). According to the results of this study, in cities with high seasonal air temperatures, due to changes in the water quality of the distribution network, it is necessary to take re-chlorination, change the coagulation and flocculation process of surface water treatment plants in, and continuous monitoring of WDN in hot seasons.

The result of NaOH/Fe(III) modified natural clinoptilolite on removal of Cr3+ in water was studied. The results of batch experiments indicated that that Cr3+ adsorption on NaOH/Fe(NO3)3 modified clinoptilolite was in good accordance with Langmuir adsorption isotherm formula. The Langmuir adsorption isotherms of Cr3+ adsorption indicated the highest adsorption capacities of 31.47 mg/g for Cr3+. In comparison with raw natural clinoptilolite, the adsorption capacity of Cr3+ of NaOH/Fe(III) modified clinoptilolite is 57.41% higher than that of the original natural clinoptilolite. Hence, the advantage of modified natural clinoptilolite for the treatment of trivalent chromium ion in sewage in contrast to other materials is that it realizes a good Cr3+ adsorption property and relatively low cost.

Optimizing and raising flood limited water levels can significantly improve the flood resources utilization and increase the comprehensive benefit. For those multipurpose reservoirs in sediment-laden river, flood limited water level optimization process is a multi-objective and complex system task, where the considering of characteristic by stages enhances the complexity. In this research, to solve the optimization problem of flood limited water levels of reservoirs by stages in sediment-laden river, the recognition methods of multiple points were integrated and modified; the optimal model and its solving method were developed. Taking the Xiaolangdi Reservoir during the normal period as case study, the flood control operation schemes for the Xiaolangdi reservoir were built, the multiple points of the middle reaches and lower reaches of Yellow River were recognized, the developing and solving schemes for the optimal models for seasonal flood limited water levels of reservoirs in sediment-laden rivers were shown, which can technically support for reservoirs operation in flood seasons.

An accurate simulation of the three-dimensional (3D) flow structure of a fishway is performed. The simulation is based on an in-depth study of the advantages and disadvantages of the hydrodynamic characteristics of the fishway using a 3D mathematical flow and turbulence model. Triangular and quadrilateral hybrid grids are used to discretize the plane calculation domain and improve the adaptability of the mathematical model for complex boundaries. The vertical adaptive capture method is introduced to ensure that the zero-pressure boundary condition of the free surface can be accurately applied to the model. By solving the Navier–Stokes and turbulence closure equations, a high-resolution numerical solution format for the hydraulic factor of the fishway is developed. Thus, a fully refined 3D non-hydrostatic mathematical model for the hydraulic factor of a fishway in an inland river hub is established. The model can simulate 3D flow problems with high accuracy and efficiency. It has good adaptability to incorporate complex boundaries and can accurately simulate the 3D hydraulic characteristics of fishways with a free surface.

In order to discuss the effect of diversion system transformation after combined system, taking some areas of Jinfeng District of Yinchuan city as an example. The simulation analysis of separate system transformation was carried out from the aspects of treatment capacity, overflow and pollutant reduction rate of sewage treatment plant under the conditions of 1a, 3a, 5a, 10a, 20a, 50a and 100a, respectively. The results show that the treatment capacity of the sewage treatment plant is only 3a, and the reduction rates of overflows, TSS, NH4+–N, COD, TP and BOD5 can reach 13.56%, 11.56%, 18.62%, 10.86% and 17.08%, respectively. The average reduction rate of overflows is about 10%. This paper provides some reference and basis for the effect after the transformation of combined and separate system.

Reservoir for drinking water supply is an important engineering measure to ensure water supply. However, with the frequent occurrence of water pollution in recent years, reservoirs for drinking water supply are faced with increasingly serious water quality risks. In this paper, taking the Songbaishan Reservoir in China as a typical reservoir with drinking water supply function, the water quality model of the Songbaishan Reservoir was constructed, the leakage scenario of sudden water pollution accident was simulated, the transfer and transformation process of the leakage pollutant Chemical Oxygen Demand, (COD), in the reservoir was simulated, and the impact of COD leakage on the water quality at the water intake was analyzed. The results showed that: (1) after sudden water pollution accident, COD will form pollutant clusters in the reservoir; (2) the peak concentration of pollutant clusters declines along the reservoir from upstream to downstream, but the sphere of influence gradually expands; (3) the peak COD concentration of the cross-section at water intake of the reservoir reaches 22.7 mg/L, and the water quality exceeds the standard for 4.8 days, indicating that sudden water pollution accident can have a significant adverse impact on reservoir water supply. In this study, possible impacts of sudden water pollution accidents on the water source reservoir are analyzed, and the results are of great significance for preventing and controlling reservoir water quality risks.

We used the in-situ monitoring method to study the space and time dynamics of soil moisture (SM) of grassland and fixed dunes in Horqin Sandy Land at different yearly rainfall patterns, and the dynamic of SM, the impact of precipitation characteristics to SM were analyzed. Results showed that: (1) the seasonal dynamic of SM in the fixed dunes was significantly lower than that in the grassland. In a normal year, the seasonal dynamic of SM in two sandy lands was basically the same. Barring the months with big rainfall, the difference in SM between the months was small. SM in dry year continued to decrease before the rainy occurring, and after rainy, SM at fixed dunes increased significantly. In a wet year, the soil moisture of these two sandy lands showed an increasing trend with the months. (2) Under different precipitation years, the variation range of SM compared to the soil depth in the grassland was much more obvious than that in fixed dunes. Higher SM content generally occurred in the 30–60 cm soil layer; the SM of below 60 cm changed small, and below 90 cm, it tended to be stable.

In order to discuss the evaluation of the peak clipping delay efficiency of the rainwater garden outside the embankment of Qiantang River in Hangzhou City, through the establishment of the SWMM numerical model of the rainwater garden, the analysis of the runoff efficiency under different working conditions is obtained, and the following conclusions are obtained. Under the condition of low rainfall return period, the application of rainwater garden has a good effect. Under the condition of the return period of once in 2 years, the export peak clipping rate is 43.6%. Under the condition of the return period of once in 5 years, the peak rate was 36.2%. As the return period increases, the effect of peak clipping and stagnation decreases. Among them, the rainwater garden has a peak clipping rate of about 40% with the rainfall of once in 10 years, and the effect of peak clipping and stagnation (a peak clipping rate of about 10%) decreases rapidly with the rainfall of once in 20 years.

With the rapid population growth and economic expansion in the current society, water shortages, water ecological imbalance, water environmental damage, and other issues have become important constraints on sustainable development. To explore the influencing factors of water resources carrying capacity (WRCC), the principal component analysis (PCA) was used to evaluate the spatio-temporal change of WRCC. Results show that WRCC of Henan Province has been demonstrating stable increasing trend annually. The influencing factors mainly include social economy and population development level, social water use efficiency, water supply and demand relations, and urban sewage treatment capacity. The main factors affecting the WRCC level of each province-administered city include the relationship between water supply and demand, level of urban sewage treatment, water supply facilities and capacity, and the amount of natural river runoff in the region. The spatial distribution of WRCC in each province-administered city is uneven, and cities located in the Yellow River basin have significantly higher WRCC levels than other cities. The reasonable exploitation of water resources, improving the purification efficiency of urban sewage, rational distribution, and dispatch of water resources within the province are favorable measures to improve the WRCC level. The research conclusions provide a reference for government departments in formulating water resources management policies.

The results of water quality and sediment monitoring of the sea areas adjacent to the sewage outlet of the Xiamen Qianpu sewage treatment plant in 2019 were used to assess and evaluate the environmental quality of the sea area using the single factor pollution index evaluation method. Trends in the variation of the sediment environment were analyzed. The results indicated that the content of pollutants in the area close to the discharge outlet was not significantly higher than the peripheral reference points and that the tailwater discharge had no significant impact on the water quality and sediment quality of the sea area around the discharge outlet. The primary aim of this paper was to analyze and evaluate the quality of the Shiweitou sewage outlet of the Qianpu sewage treatment plant and its adjacent sea areas, with the goal of providing data to support the future environmental quality management of the eastern sea area of Xiamen Island.