Construction Of Drainage System Research Articles

Assessment of stream order and drainage pattern of flood prone areas of Ebonyi state, Southeastern Nigeria

This study evaluates stream order and drainage pattern of flood in Ebonyi state, Southeastern Nigeria. The drainage network within Ebonyi State was identified using the Shuttle Rader Topographic Mission (SRTM), the stream order and flood drainage pattern with the aid of the Digital Elevation Model (DEM), and the Topographic analysis of Spatial Analyst on Hydrology. The data was acquired using Geometric Positioning and the LANDSAT downloaded from the United States Geological Survey (USGS) Earth Explorer 2019 and Thematic Mapper (TM) 2009. The result shows that the map of the eastern part of Ebonyi State houses the Cross River basin as a main consequent river draining to the Atlantic Ocean. The drainage gets darker down the slope as more volumes of water move into the traversing drainage channels in their corresponding orders. As flood magnitude increases, the velocity decreases because more water from different river orders or tributaries has been added to the adjusting river channels. It proves that consequent rivers like the Enyim River of Izzi, Iyiokwu River of Abakaliki, Alcor River of Ikwo, Iyere River of Afikpo South, and Esu Umuchimaewuze River of Ohaozara Local Government areas slope down through the adjourning tributaries when the basin is saturated. The map legend shows a thick blue outcome indicating that the flood originates from the Enyim River of Izzi, Iyiokwu River of Abakaliki, Alchor River of Ikwo, Iyere River of Afikpo South, and Esu Umuchimaewueze River of Ohaozara. Therefore, urgent adjustments and construction of drainage systems are needed to accommodate more water volumes.

Конструкции дренажа и метод расчета для подвалов глубокого заложения

For the considered hydrogeological conditions of the Kulikovo Pole museum complex, located in the Kimovsky district of the Tula region, there is no necessary design of the drainage system, the method of its construction and the calculation method to ensure the drainage of groundwater from the basement. A vertical drainage design and calculation method necessary for the normal operation of the Kulikovo Pole museum complex were proposed. The purpose of the work is to develop a drainage design and substantiate a method for calculating the drainage of deep basements using the example of the Kulikovo Pole museum complex. The proposed design of vertical drainage makes it possible to increase the reliability of the drainage system due to the installation of a filter bed and a geotextile winding. The calculation of the proposed vertical drainage design consists of determining the following positions: the radius of the depression curve (the influence of drainage away from the basement of the building); drainage flow rate; water inflow into the drain; reducing the pressure in the middle between the row drains, selecting vertical drainage pumps. The proposed drainage design, the method of its construction (a patent for the invention was received) and the calculation method were tested when draining the deep basements of the Kulikovo Pole museum complex. The created system drains excess groundwater and eliminates the “barrage” effect. It is noted that the construction of drainage systems currently underway requires careful consideration of the experience of design and operation of drainage systems of the previous period and the use of new promising, cost-effective solutions.

Framework structure design based on porous permeable concrete material in expressway tunnel drainage system

As an important construction material for drainage system construction, permeable concrete has the characteristics of porous and breathable, but the existing mix preparation technology makes it difficult to prepare high-strength porous permeable concrete material. The study introduces a permeable concrete skeleton structure that considers compressive strength and permeability coefficient. Moreover, the proportion design method is adjusted based on the spherical characteristics of the aggregates, which are analyzed using Image Pro-Plus image processing technology. The parameters of the permeable concrete skeleton structure, such as the number of contact points, width of the contact zone, and thickness of the inter-aggregate slurry, are quantified. Additionally, the proportion design method is refined by incorporating the target mechanical properties and water permeability performance of the permeable concrete, aiming to enhance its mechanical properties and water permeability. To enhance the mechanical properties and water permeability of pervious concrete, modifications are made to the proportion design method based on target mechanical properties and water permeability. This includes balancing the mechanical properties and water permeability through the design of the concrete's skeleton structure, the composition of the cement slurry, and the adjustment of additive mixing amounts. The use of a single-graded pyrophyllite aggregate enables the preparation of high-strength and high-permeability concrete. The experiment showed that the minimum deviation of compressive strength of group A was 15.29%, the average was 18.17%, and the minimum deviation of compressive strength of group B was 42.59%, the average was 45.27%. The minimum deviation of the water permeability coefficient in group A was 10.60%, with an average of 16.50%, and the minimum deviation of the water permeability coefficient in group B was 11.35%, with an average of 19.18%. In addition, the correction coefficient relationship between aggregate sphericity and the number of contact points, contact zone width and paste thickness between aggregates was established. Through the correction of the coefficient, the high strength, and high permeability concrete with permeability coefficient, compressive strength, and effective porosity of 1.15, 23.6mpa, and 18.5% can be obtained. The mix proportion design of permeable concrete using a skeleton structure in this study has economic and social benefits for construction engineering, "sponge city" construction, and urban sustainable development. In terms of economic benefits, permeable concrete, as an ecological and environmentally friendly concrete, has low production costs and good bearing capacity and permeability, reducing construction costs. In terms of social benefits, the application of permeable concrete can make urban floors more breathable and permeable, alleviate the pressure on urban drainage systems, and improve the ecological balance and environmental quality of the city. The application of permeable concrete can reduce reliance on traditional drainage materials and reduce negative impacts on the environment. Materials can also be recycled and reused, which helps to enhance the sustainable development capacity of cities.

FLOOD RISK ASSESSMENT, CLIMATE CHANGE ADAPTATIONS AND MITIGATION STRATEGIES OF COMMUNITIES IN EDO STATE, NIGERIA

Despite flooding being one of the most common and destructive natural hazards, the risk it poses is systematically underestimated and still increasing due to climate change and growing concentrations of people and assets in flood-prone areas. The study carried out a flood risk assessment, climate adaptation and mitigation strategies of communities in Edo State, Nigeria. With the aid of questionnaires and GIS techniques, the flood risk level of communities within Edo states were analysed by capturing all the components of flood risk which include exposure and vulnerability. All analysis was carried out using descriptive statistics and Analytical Hierarchy Process (AHP) to determine the extent of the communities’ flood. The extent of risk showed that 778 communities were captured in risk analysis, 503 (64.65%) of the communities were found within low flood risk level while 150 (19.28%) communities and 125 (16.07%) communities were found to be within medium and high flood risk level respectively. The climate variables showed some level of fluctuation while the adopted adaptation measures such as expansion of floodplain and wetlands was based on political will of administrators, and the measure was perceived less effective. There was high level of awareness about government mitigation measures in the area and the main mitigation measure by government is construction of drainage system which was perceived to be effective. It was therefore concluded that all the adopted attributes contributed to the establishment of flood risk of Edo State and was categories into high, medium and low flood risk level. Hence, there is need to intensify the planning and execution of disaster management programs with the support of the produced flood risk map.

Dosadašnji značaj i uloga Poljoprivrednog fakulteta u Beogradu na razvoj i primenu melioracija u Republici Srbiji

The development of agriculture in Serbia would not have been possible without the implementation of ameliorative measures. Measures to improve the soil water regime in our country have existed throughout modern era, but very significant ameliorative practices have been implemented in the last 100 years, coinciding with the establishment of the Faculty of Agriculture at the University of Belgrade. In Serbia, after the First World War, extensive work was carried out in the field of drainage, which underwent a real expansion after the Second World War. In the period from 1950 to 1970, drainage systems were built on about 1.5 million hectares, and by 1990 the total drained area exceeded 2.01 million hectares. Alongside the construction of drainage systems, dams were built on the major rivers to protect coastal areas from flooding. A significant achievement is the construction of the Danube-Tisza-Danube water system (1947-1977), which involved complex and versatile water management in Vojvodina. The introduction of irrigation in agriculture progressed much more slowly than drainage. The total irrigated area in 1990 was about 120,000 hectares, and today, after the crisis-ridden 1990s, it amounts to about 100,000 hectares. Nowadays, it is necessary to design additional drainage systems where problems of this kind arise, whereas the potential areas for irrigation are considerably larger. Until the beginning of the 21st century, various ameliorative activities were the focus of technical and research activity: soil surveys, investigation of the soil physical and water characteristics, soil chemical amelioration , the application of horizontal pipe drainage, soil recultivation, soil conservation, introduction of large machines for pressurised irrigation and application of drip irrigation methods. More recently, modern technologies and contemporary global trends such as the use of GIS, remote sensing, soil water balance monitoring, crop cover monitoring, micrometeorological measurements, automation of irrigation systems and crop growth modelling have been introduced alongside the application of traditional methods. The last decade has been marked by researches focused on the effects of climate change on agricultural production. The importance of the Soil and Water Management department is reflected in the training of professionals who are able to keep pace with technological changes and apply them to the management of soil and water resources, from the planning and implementation of new hydromeliorative systems to the maintenance of old systems and the management of crop production.

Impacts of Urbanization on Drainage System Health and Sustainable Drainage Recommendations for Future Scenarios—A Small City Case in China

China is urbanizing at an unprecedented rate, but also accelerating the use of water resources and overloading of urban drainage systems. To analyze the impact of urbanization on the drainage-system health in Jinxi, a typical small case area in China, this study proposed an innovative methodological framework for evaluation and prediction based on statistical and modeling methods, which provides a demonstration and reference for urban development and drainage-system construction in developing countries. The result shows that the comprehensive urbanization index (CUI) of Jinxi shows an overall upward trend between 2009 and 2020. The drainage-system health index (DHI) shows a U-shaped trend of decreasing and then increasing, with the threshold in 2016. The years when the DHI and CUI are in balanced development occurred in 2014 and 2018. The impact of urbanization on the drainage-system health is divided into positive and negative aspects, depending on the drainage demands of the urban development. According to the predicted results, it is suggested that the next drainage upgrading measures will be favorable for sustainable urban development when the urbanization rate reaches 60%, the gross industrial output increases by 10%, or the total retail sales of consumer goods increase by 40%.

Land-Use Changes on Ob River Floodplain (Western Siberia, Russia) in Context of Natural and Social Changes over Past 200 Years

Over the past century, substantial changes in land use have taken place in the boreal zone of northern Eurasia. The consequences of these large-scale changes for the ecosystems of Europe have been well studied; however, they have not been addressed for the large expanses of Russia. We conducted a retrospective analysis of the landscape dynamics of the middle reaches of the Ob floodplain (Western Siberia) using multitemporal maps of the vegetation cover and land use for five time points (1830, 1910, 1950, 1976, and 2019). By the 1830s, all the land that was suitable for haymaking and plowing (rarely flooded and not swamped) had been put to agricultural use. The meadows of the Ob floodplain are human-controlled and were mainly formed before the 1830s. From the 1830s to the 1990s, the meadows were used in agriculture and their areas increased. The maximum development of the floodplain occurred in the 1970s and 1980s, when previous wetlands were put into operation through the construction of drainage systems. A massive abandonment of pastures and reclaimed land occurred in the late 20th century. According to the data over the last 30 years, abandoned meadows are resistant to overgrowth with trees and shrubs. The spatial configurations of the floodplain landscapes have also been quite stable. The main spatial changes are confined to the near-channel floodplain, with the formation of new near-channel shallows. The floodplain landscapes of the Ob River demonstrate substantial spatial and temporal stabilities, and long-standing agricultural development.

Effect of Changing the Shape and Size of Inlet Area of Grates on the Hydraulic Efficiency of Urban Rainstorm Drainage Systems

Urban rainstorm drainage systems are used to collect the surface runoff from streets and other land surfaces through grate or curb openings that convey it to the drains. The quantity of surface runoff that is not discharged to the urban rainstorm drainage systems due to inadequate grate size or because the grate capacity is exceeded can cause flooding, immoderate hazards to drivers and pedestrians, and disrupt urban activities. This study aims to carry out experimental work to investigate the hydraulic efficiency of urban rainstorm drainage systems using different types of grates (shape and size of inlet area) for harvesting excess rainwater. Different grate shapes (five) with different inlet areas were investigated, as well as using three relative grate inlet areas (26%, 51%, and 64%). The results of the experimental work indicated that the best grate shape is the grate type 4 which provided the smallest reduction in discharge efficiency within 8.7%. The results specified that changing the size of the inlet area of grates from (26%) to (64%) has a significant impact on urban rainstorm drainage systems efficiency which decreased by 4%. In addition, the dimensional analysis principle with multi regression analysis were used to develop an empirical equation to compute the efficiency of urban rainstorm drainage systems. The relation between grate shapes and the relative inlet area with the efficiency of grate capture provides an indication to the decisionmakers to increase the time period for maintenance which will save the cost for further maintenance. The presented empirical equation can help decisionmakers for monitoring the current situation of grate blockage (relative grate inlet areas) and the corresponding efficiency. This study is beneficial for future road drainage system construction to avoid problems by assessing the performances of the current drainage systems and proposing mitigation measures to avoid improper functioning. Finally, this methodology can help to improve the efficiency of urban rainstorm drainage systems that can reduce the risks of urban floods.

Analysis of Spatial and Temporal Rainfall Variation in Gandaki Province, Nepal

Daily, seasonable and annual variation on precipitation should be carried out properly to enhance the better relaxation caused by damaging drain structure, hydraulic parameters and even climatic disorder. In order to incorporate all these needs and to enhance the existing research theories and even on developing new theories, this study will surely provide basic framework. The problems for the researcher as well as meteorological department for the further study of climatic change action and to provide basic knowledge to the farmer and agricultural department to yield seasonal wise crops without consideration of hydrological analysis (i.e. precipitation data) associates problems like flood risk and drought causing loss of lives and property. For the hydrological study, daily and monthly rainfall data was obtained from meteorological station from the year 1991-2020. The monthly and daily precipitation concentration were determined using Time series analysis, single mass curve analysis, coefficient of variation and spatial analysis and were represented using Histogram chart, Spreadsheet and GIS tool. With this, daily, monthly, seasonal wise variation on precipitation with respect to location wise (Spatial) as well as Time wise (Temporal) was obtained. The temporal characteristic shows that peak month of rainfall were July and August for all the regions. Considering Total Annual, the maximum value is at Beni Bazar i.e. more than 200000mm and least in the Ranipauwa i.e less than 10000mm. The mean annual rainfall of 30 years indicating that the Beni Bazar, Myagdi region has the highest rainfall and Ranipauwa, Mustang the least. Similarly, trend analysis shows that there are increasing (+ve), decreasing (-ve) and somewhat constant trends for the different stations. Furthermore, results from variability and reliability data shows that that Ranipauwa has the highest annual variability (138.86%) and Lumle has the least annual variability (15%) in which in turn implies that the rainfall at Lumle is more reliable than other areas. The computed Spatial and Temporal variation on rainfall has been developed as a basic tool for further research. It will also help farmers to know seasonal wise crops production as well as analysis of storm water for the construction of drainage system. These findings can be considered for monitoring extreme weather events like; erosion and floods. This would therefore contribute significantly to the effective management and sustainable development of the Gandaki Province and region having similar topographical features, which are rain dependent.

Towards the long term implementation of real time control of combined sewer systems: a review of performance and influencing factors.

Real Time Control (RTC) is widely accepted as a cost-effective way to operate urban drainage systems (UDS) effectively. However, what factors influence RTC efficacy and how this might change in the long term remains largely unknown. This paper reviews the literature to understand what these factors likely are, and how they can be assessed in the future. Despite decades of research, inconsistent definitions of the performance of RTC are used, hindering an objective and quantitative examination of the benefits and drawbacks of different control strategies with regard to their performance and robustness. Furthermore, a discussion on the changes occurring and projected to occur to UDS reveals that the potential impact of these changes on the functioning of RTC systems can be significant and should be considered in the design stage of the RTC strategy. Understanding this 'best-before' characteristic of an RTC strategy is the key step to ensure long term optimal functioning of the UDS. Additionally, unexplored potential for RTC systems might exist in the transitions, rehabilitation and construction of drainage systems. The research gaps highlighted here could guide the way for further development of RTC strategies, and enabling more optimal, long term implementation of RTC for urban drainage systems.

Водопонижение и водоотлив как способ предварительного осушения территории парка академика Сахарова г. Санкт-Петербурга

The purpose of our work is to determine the causes of overwetting of the territory, to design a temporary pre-drainage system that ensures the effective removal of excess water during the construction of a permanent drainage system in the conditions of the Academician Sakharov Park. The main causes for excessive moisture withinthe object are: humid climate(precipitation exceeds evaporation by 2.8 times), shallow occurrence of the aquifer confi ning layer, high ground water position, which leads to the formation of headwater lenses during the year. According to climatic and hydrogeological studies, prior drainage should be carried out before starting work on the construction of a drainage system. The article considers in detail the design features of the water drawdown and dewatering, as well as the stages of construction. According to calculations on dewatering in the conditions of the Academician Sakharov Park with the capacity of the drained aquifer1.0…1.4 m, the average depth of the confining layer 2.0 …2.3 m and trench lengths from 110 …225 m, the time for drainage is 5…6 days, and the estimated infl ow of water to the mouth of the trench is within 3.29…3.85 m³ / day. To ensure effective work on dewatering from a trench with lengths of up to 225 m and with a drained aquifer capacity of up to 1.4 in the hydrogeological conditions of the territory of the Sakharov Park, it is recommended to use domestic pumping and power equipment of the «Vihr» type DN-400 with a flow rate of 11.5 m³ / h.

Drainage system construction influence on the groundwater level of reclaimed soils

The influence of the drainage system construction on the formation of the regime of groundwater levels has been studied. The results of statistical processing of the data from parallel observations of meteorological parameters and groundwater levels over a 32-year period have demonstrated that groundwater levels are most closely correlated with the hydrothermic coefficient (HTC) of the previous period. With an increase in the degree of moisture, the groundwater level rises most rapidly in the first decade of May and is less subject to variations in the third decade of May. The highest groundwater level in the 1st decade of May with the long-time annual average HTC equal to 2 was observed in the shallow drainage option–35 cm, the lowest–in the two-tiered drainage option–70 cm. In an excessively humid year (HTC = 3.5), groundwater in the options of shallow drainage and collectors with filling the drainage trench with sand-gravel mixture (SGM) rise into the plough layer; and, when the HTC exceeds 4.5, in the options of shallow drainage and collectors with SGM, they reach the soil surface. In a wet year, the rate of groundwater decline is from 1.25 cm/day–in the option of two-tiered drainage to 2.00 cm/day–in the option of collectors with wood chip. In modern conditions of climate change, the most advanced drainage systems are the structures of two-tiered drainage and collectors with wood chip, which ensure timely drainage of groundwater. In a high-water year, the use of wood chip instead of a sand-gravel mixture in the collector structure will increase the rate of lowering of the groundwater level by 5%.

Technology for Draining Heavy, Poorly Water-Permeable Soils with Two-Tier Drainage

The described technology refers to the hydro-technical construction of drainage systems. The design purpose is to drain surface and groundwater from waterlogged heavy, poorly water-permeable farmland soils. The method includes making two-tier drainage with lower tier consisting of dehumidifiers, which are a drainage tube with a protective filter filled to a height of 10 cm with a sand and gravel mixture, and the upper tier made of non-cavity drains. The plan location of the upper tier drains is perpendicular to the lower tier drains. A column of sand and gravel mixture is arranged at the intersection of the upper and lower tiers. The technology allows reducing the volume of the filter drainage backfill by 1.5–2.0 times while maintaining a high drainage rate and reliable hydraulic connection of the arable horizon with the drainage pipe while reducing the material consumption of the proposed structure by reducing the volume of the drainage backfill made of sand and gravel mixture.

RETRACTED ARTICLE: Plant planning and urban construction of sponge city based on GIS system

In the process of development in recent years, my country’s urban construction has achieved very good results, but the acceleration of the urbanization process has also brought a lot of pressure and problems to the city itself. In the process of urban construction, the construction of drainage systems in many cities was not perfect, which resulted in the infiltration of surface water in the city. Many places in the city were flooded by rain, which seriously affected people’s daily life. The construction of cities has led to changes in many resources and the environment, and the normal structural network of rivers has also been destroyed. Surface water in cities is more difficult to drain, and urban waterlogging often occurs. To solve the problem of urban waterlogging, it is necessary to use knowledge of multiple disciplines. This article comprehensively considers various factors affecting urban waterlogging, summarizes the advantages and methods of sponge city construction, and introduces the sponge city based on the geographic information system. The construction is simulated and simulated. Through research and analysis, we can know that the use of geographic information system can provide good help for plant planning and architectural planning in the process of sponge city construction. The use of the system can evaluate actual construction work and prevent work mistakes.

Research and application of L-shaped ground well gas drainage technology in mining area

By law mining fracture morphology analysis, based on coal face gas flow characteristics, obtain the L-shaped surface well layout area in the mining area under the influence of mining. Analysis of overlying strata "three zones" distribution, the calculation method of the height of overburden rock "three zones" designed in mining area ground well structure proposed safety drainage system construction plan. In Sihe Mine was L-shaped ground mining area well engineering practice, the average gas production at a concentration of 80%, with an average drainage net amount 22 000 m3 / d, a total of more than 300 days running, drainaging 6.5 million CBM m3. After the implementation of drainage work surface corner gas content fell 46.5%, to effectively improve production efficiency, for the surface treatment gas play a key role. Successfully removed Mining Face Gas for safe production constraints, to protect the mining of coal mine safety, and achieved good social and economic results, with good promotional value.

The role of artificial ditches and their buffer zones in intensively utilized agricultural landscape.

The extensive construction of drainage systems in the lowlands and flood plains of Slovakia has significantly changed the landscape and runoff ratios of rivers. Our study focuses on the assessment of the benefits provided by the ecosystems of water ditches and their catchment areas. Ditches and their buffer zone, similarly to other artificial anthropogenic elements in the country, fulfil various landscape-ecological functions and provide different ecosystem services (ESs) to human populations and society. As study areas, we chose ditches and their 1-km buffer zones in the Podunajská nížina (P) lowland and Východoslovenská nížina (V) lowland (Slovakia). There are notable differences between these two selected lowlands. Hence, there are also differences in their potential to provide various ESs. Based on a re-evaluation of the present state of the ditches, we evaluated nine ESs related to three main groups of ESs, using the Common International Classification of Ecosystem Services (CICES). We assessed the ESs and benefits provided by ditches and their buffer zone in two ways: (1) ES assessment by experts and (2) biophysical assessment of ESs and their benefits based on an integrated assessment framework (relations between pressures, ecological status, and delivery of ESs). Finally, we compared the potentials for provisioning of the study areas. The study area in the V lowland has the highest potential to provide "Lifecycle maintenance, habitat and gene pool protection" benefits, and the study area in the P lowland has the highest potential to provide "Surface water for non-drinking purposes."

Experimental investigation on the potentials of Sisal Fibres as Reinforcements for Drainage Concrete Cover Plates

With the development of infrastructures in Rwanda, the roads construction has been one of busiest area, and as the country counts thousands hills the design and construction of drainage systems required a great attention. Most of road drainage channels are covered with concrete plates that are reinforced with ordinary steel bars, while others are not covered due to the high cost of reinforced concrete plates. As the majority of these plates are only subjected to light pedestrian loads, they should be reinforced accordingly. This study was intended to check the potentials of sisal fibres from Agave Sisalana’ cactus plant which has shown good results in flexural members, as plates reinforcements. At first the quality of ordinary concrete components was checked. Then some of sisal fibres were prepared, manufactured into ropes of 10 mm diameter and then used as replacements of main steel bars in concrete plates before their tensile capacity was checked. Other pieces of sisal fibres of 5 cm length were mixed in concrete mass with different percentages of 0.5%, 1% and 1.5% of concrete volume. Test results showed that the compressive, tensile and flexural strengths for concrete with 1% of sisal fibres were more adequate for M30 concrete and therefore able of sustaining the real loads applied to the drainage concrete cover plates. As the performance of natural sisal fibres depends on fibres treatment methods, length, and type of required concrete, further studies on the use of sisal fibres should consider those factors.
 Keywords: Agave sisalana, drainage channel, Reinforced Concrete, Sisal Fibres, Sisal ropes.

Staged optimization of urban drainage systems considering climate change and hydrological model uncertainty

Flood risk increases with climate change and rapid urbanization, which urgently needs to improve the capacity of urban drainage systems. In the study, a staged optimization model considering climate change and hydrological model uncertainty (SOCU) was proposed for urban drainage system design. The SOCU model refers to the construction of drainage system by stages instead of traditional implement-once plans, which was established based on an integration of staged optimization policy, urban hydrological model, generalized likelihood uncertainty estimation (GLUE) method and chance-constrained programming (CCP) model. The staged optimization policy was employed to deal with the uncertainty of climate change. The GLUE method was adopted to analyze the uncertainty of urban hydrological model established by PCSWMM. Considering the uncertainty from urban hydrological simulation, the CCP model (one of the main methods of stochastic mathematical programming) was used to deal with the uncertainty of the optimization model. Subsequently, a case study of the Haidian Island of Hainan Province in China was used to demonstrate the proposed model. The result shows that the optimal investment is 183 million Yuan with a pumping capacity of 28.3 m3/s for the first stage and 38.4 m3/s for the next stage. The SOCU model is not only more flexible to adapt to climate change, but also is economically efficient (10% lower than implement-once plans). The urban drainage system design obtained from the SOCU model is more reliable and robust than traditional implement-once plans since the climate change and hydrological model uncertainty are simultaneously taken into account. Furthermore, the investment increases from 166 million Yuan to 195 million Yuan when the flood constraint satisfaction probability increases from 0.75 to 0.95. Therefore, the model could provide richer decision-making information than traditional implement-once plans and help decision makers seek a trade-off between system investment and acceptable flood damage. The study outcomes provide a reliable optimization model for urban drainage design and may have profound implications and contributions for urban flood management.

New insights into the occurrence of the Baige landslide along the Jinsha River in Tibet

The catastrophic Baige landslide occurred on October 10, 2018 in the Tibet Autonomous Region, China, and formed a barrier lake with a direct economic loss of 6.8 billion RMB (~ 963.5 million USD). After the landslide, field investigations were conducted both to support emergency operations and to understand the failure mechanism immediately after the landslide. Detailed field surveys, borehole exploration, discharge measurements, laboratory experiments, and meteorological analyses were employed in this study to explore the mechanisms underlying the Baige landslide. A key influence from the water source in Bogong Gully on the Baige landslide formation was newly found. The results show that the underground of the slope comprises extremely weathered serpentinite, and fresh rock has not yet been revealed in boreholes. The seepage outlets are 450–550 m higher than the Jinsha River and ~ 118 m lower than the bed of Bogong Gully. Water flow in the channel of Bogong Gully is strongly infiltrated, with a flow loss of 62.6%. Seepage into the Bogong Gully, along with the landslide, caused by the local geological structure and lithology, accelerated the extreme weathering of rock masses and promoted landslide formation. Furthermore, extreme annual rainfall also contributed to the occurrence of the Baige landslide by increasing the discharge of the Bogong Gully. Further risk management measures in this area should include increasing the depth of geological explorations and the construction of drainage systems.

Risk evaluation of urban rainwater system waterlogging based on neural network and dynamic hydraulic model

With the rapid development of urban construction and the further improvement of the degree of urbanization, despite the intensification of the drainage system construction, the problem of urban waterlogging is still showing an increasingly significant trend. In this paper, the authors analyze the risk evaluation of urban rainwater system waterlogging based on neural network and dynamic hydraulic model. This article introduces the concept of risk into the study of urban waterlogging problems, combines advanced computer simulation methods to simulate different conditions of rainwater systems, and conducts urban waterlogging risk assessment. Because the phenomenon of urban waterlogging is vague, it is affected by a variety of factors and requires comprehensive evaluation. Therefore, the fuzzy comprehensive evaluation method is very suitable for solving the risk evaluation problem of urban waterlogging. In order to improve the scientificity of drainage and waterlogging prevention planning, sponge cities should gradually establish rainwater impact assessment and waterlogging risk evaluation systems, comprehensively evaluate the current capacity of urban drainage and waterlogging prevention facilities and waterlogging risks, draw a map of urban rainwater and waterlogging risks, and determine the risk level. At the same time, delineate drainage and waterlogging prevention zones and risk management zones to provide effective technical support for the formulation of drainage and storm waterlogging prevention plans and emergency management.