Hasil untuk "River, lake, and water-supply engineering (General)"

JIANG Yubo, MO Shuhong, JIANG Kaixin et al.

In order to reveal the characteristics of the runoff and sediment yield patterns of different vegetation types under erosive rainfall in purple soil, based on the daily measured data from 2017 to 2021 at the Soil and Water Conservation Experimental Station in Hengdong County, Hunan Province, four runoff plots were selected, namely bare land, forest land, agricultural land, and grassland. By using the cluster analysis method, 132 erosive rainfall events were classified into three different rainfall types: A (with large rainfall amount, large rainfall intensity, and long duration), B (with large rainfall amount, small rainfall intensity, and long duration), and C (with small rainfall amount, large rainfall intensity, and short duration). According to the analysis, among the three types of erosive rainfall, the type with the lowest occurrence frequency was type B. The rainfall amount of the three types of rainfall had a greater impact on runoff volume than on slope erosion-induced sediment yield. The rainfall type with the largest cumulative runoff and sediment yield was type B. The cumulative runoff and sediment yield of the four land types in ascending order was bare land > agricultural land > grassland > forest land. Compared with that by bare land, the runoff and sediment reduction by forest land was higher, being 20.4% and 70.4%, respectively. Moreover, the runoff and sediment reduction by various vegetation types was the highest under type B rainfall. Overall, the sediment reduction was greater than the runoff reduction.

CHENG Bei, HU Yuying

Calculating the water surface profile of river channels is an indispensable part of projects such as river channel management in mountainous areas. While the application of the HEC-RAS software developed in the United States in the calculation of river water surface profiles has been extensively studied, little attention has been paid to the impact of software cross-section interpolation on the calculation results when the distance between cross-sections in mountainous river channels is large and the number of cross-sections is limited. In this study, using HEC-RAS software and DEM elevation data of the mountainous river, Caishi River in Huairou District, Beijing, water surface profiles of the river for recurrence intervals of 10, 20, and 50 years are established under three scenarios including base cross-sections, interpolated cross-sections, and dense cross-sections. The results indicate that for mountainous river channels with relatively straight courses and little variation in cross-sectional forms and bed elevations, interpolation calculations can enhance accuracy. However, for mountainous river channels with irregular courses and significant variations in cross-sectional forms and bed elevations, interpolation calculations result in larger errors, and the uncertainty of recurrence intervals has an impact on water levels.

Soheyla Maleyeri, Mohammad Bashirgonbad

Extended Abstract Background: Depending on rainfall systems and conditions influenced by unprincipled human activities, floods cause a lot of damage to natural resources, settlements, and projects every year. Hydrometric stations are often destroyed during floods or small watersheds lack hydrometric stations, which means that the estimation of runoff and maximum flood discharges requires a suitable method to calculate runoff and flood values in these basins. Prevention of this damage is doubly important when the study area overlooks places with a high density of settlements and urban facilities that can threaten the lives of many residents. The amount of runoff in each sub-basin of the watershed overlooking Malayer City was estimated in this study. Methods: The watershed overlooking the city of Malayer with an area of 14,700 hectares is stretched from the north to the northeast of the city. The processing of digital elevation models identified five sub-basins overlooking the city and field visits. The curve number method was used to estimate runoff height and flood volume in each sub-basin. The most intense rainfall event (88 mm per day) with a return period of 30 years was designed as rainfall, considering the amount of previous rainfall 5 days before this event with a cumulative value of 45.2 mm. To calculate the physical parameters of the watershed in this study, topography, geology, vegetation, soil, and land use maps were digitized using a geographic information system. Simultaneous maps of land use and rainfall were provided using Sentinel-2 images, containing 13 spectral bands and a spatial resolution of 10 meters. Utilizing the SCS method, the layers of land use, vegetation, and soil hydrological groups were combined to produce a curve number map. The value of the curve number was corrected for the wet condition based on the rainfall 5 days before and the location of the basin in the previous wet conditions. A weighted curve number approach for each sub-basin was compared with another approach based on the arithmetic mean of the curve number for each sub-basin, as well as a weighted runoff height approach for each curve number. Kirpich's method was used to calculate the concentration time of each sub-basin. In the next step, using the maximum daily rainfall data from the Malayer synoptic station in the statistical period from 1991 to 2021, the rainfall height values were converted to runoff height using the SCS relationship, and then the peak flood discharge was calculated for each sub-basin. Results: The lack of permanent vegetation and the presence of annual grasses are among the reasons for the high potential of the sub-basins in runoff production. As a result, the average curve numbers of arithmetic and weighted average methods are 79.09 and 81.46, respectively, which shows the high capacity of the basin in producing runoff. Converting curve number values to peak flood height and flow using two commonly used methods of curve number calculation and comparing it with the results of the weighted runoff height calculation approach for each curve number in the working units of the study area showed no significant difference. Finally, the runoff height maps and the peak discharge of each sub-basin were drawn. The northern sub-basin of the basin with an average runoff height of 44.32 mm and a peak discharge of 168 m3/s has the highest participation in flood discharge toward the city of Malayer, and sub-basin 4 in the south-eastern part of the basin has the least participation in flood generation. The results of the relationship between the area and runoff height showed that the basins with a larger area did not necessarily contribute the most to the occurrence of floods in all three calculation methods of the curve number and runoff height. Other factors also play a role in these results, such as the extent of rocky outcrops and reduction time of concentration due to the high slope as one of the reasons for this problem. The formation of the longest watercourse in the basin with a length of 16314 meters under Sub-basin 3, which has the highest peak flood flow after Sub-basin 2, is one of the discussed technical points that can handle the rapid discharge of the peak flow of about 100 m3/s. However, the study of its longitudinal slope of about 2% indicates the high risk of flooding caused by the lack of evacuation in rains with a high return period, which in turn is a serious risk for the threats caused by floods in the southeastern part of the city. The intersection of the end part of the main waterway with the exit of other sub-basins and the collection of runoff under the upstream basins are other problems that increase the risk of flooding in the downstream areas. Conclusion: It is suitable to use the curve number method to estimate the amount of runoff produced in the basins overlooking the settlements that do not usually have hydrometric stations. Because of its low-density pastures and rain-fed agriculture, the watershed overlooking Malayer has a high potential for runoff production.

Kolbjørn Engeland, Maris Klavins, Harri Koivusalo et al.

Rong Ji, Shu-Qing Yang, Muttucumaru Sivakumar et al.

Abstract Australia is the driest inhabited continent on earth, and most of its population is concentrated along the coastal line. In recent years, extreme climate events such as floods and droughts have occurred more frequently. Sydney, as the largest city in Australia, requires a reliable water supply. Many solutions have been conducted to secure its water supply. This paper is focused on future water supply for the Greater Sydney area. The analysis supports the concept that in runoff-rich regions like Greater Sydney, there is no water shortage but a lack of water storage. The novel technology, coastal reservoirs, can increase the storage capacity of freshwater in the sea. The average annual discharge at Shoalhaven River mouth is estimated as 1,334 gigalitres. By comparison, the average annual inflow to the Warragamba Dam, which supplies 80% of Sydney's drinking water, is 1,069 gigalitres. This paper discusses how to apply a Coastal Reservoir at the Shoalhaven River mouth to secure additional water supply for ever-growing Greater Sydney. The proposed reservoir with a capacity of 500 gigalitres could supply 1,000 gigalitres of water per year with a reliability of 90%. A preliminary design of the reservoir is demonstrated.

Yan Nie, Chen Yin, Pu Wang et al.

Timely understanding and quantitative analysis of the changing trend in natural ecosystems in arid and semi-arid areas and their response to the ecological water supply process are of great significance for maintaining the health of oasis ecosystems. Taking the Eichmann Lake wetland of the Aksu River Basin in Xinjiang as the research area, the temporal-spatial distribution characteristics of the lake and the response of ecological water in recent years were studied based on remote sensing images and monitoring data. The results show that: (1) The water surface area of Eichmann Lake is shrinking, from 61.57 km2 in 1996 to 27.76 km2 in 2020. The changes in water surface area have experienced three stages: rapid decline, slow decline, and slow recovery. After the ecological water supply, the water surface area has obvious seasonal changes with hysteresis; (2) In areas with a low average water level, the ecological water supply has a significant impact on the groundwater level. The higher the water supply is, the higher the groundwater level will be. There is a significant lag effect between the change in the groundwater level and the response of the ecological water supply, which is 1–2 months; (3) The response characteristics of different natural vegetation to the ecological water supply were different in interannual, seasonal, and spatial contexts. The response of Populus euphratica to the ecological water supply is obvious, and its growth is the best within the range of 100–500 m from the water supply outlet. This research can provide the basis for the rational allocation of the Aksu River Basin’s water resources, and also act as a valuable reference for the restoration and reconstruction of surrounding vegetation in the Aksu River irrigation area.

CHEN Ci, ZHU Kunpeng, LIU Yue et al.

The Liuxi River is the most important river system in Guangzhou,and systematic monitoring and assessment provide basic information for the health management of the Liuxi River ecosystem.Field in-situ sampling of zoobenthos in the Liuxi River was conducted during the dry (March) and wet (September) seasons in 2019 to explore the spatio-temporal distribution characteristics of functional feeding groups (FFGs) of zoobenthos,and the habitat conditions of the Liuxi River were assessed by the composition of the zoobenthos FFGs.The results show that the main group of zoobenthos in the Liuxi River Basin is collectors,followed by scrapers and predators,whereas filterers and shredders are rarely observed.The dominant groups at the sampling sites in the upper and middle reaches are moderate pollution tolerant collectors (Baetidae and Corbiculidae) and pollution tolerant collectors (Chironomidae),while the sampling sites in the lower reaches are overwhelmingly dominated by pollution tolerant collectors (Chironomidae).Environmental factors significantly affect the distribution of zoobenthos FFGs.Specifically,the key environmental factors in the dry season are velocity and NO₃,while those in the wet season are SiO₂ and velocity.The attributes of the Liuxi River ecosystem were analyzed on the basis of the composition of the zoobenthos FFGs.The results indicate that the ecosystems at most of the sampling sites in the Liuxi River are heterotrophic ones,and the riparian zone of this basin is not healthy.The longitudinal transport ability of the river is mostly in an unhealthy state.Predators' control effect is normal except at some sampling sites in the upper reaches.The basin maintains favorable habitat stability except at the sampling sites affected by sand dredging.

ZHOU Jiaqi, LIN Kairong, XIE Xue et al.

Under the background of global climate change,the frequency of extreme rainfall events increases,and the urban water-logging disaster occurs frequently.The risk assessment of water-logging disaster can effectively reduce the loss.Taking Haojiang District of Shantou City as case study,this paper improves the weights of the analytic hierarchy process (AHP) by neural network,expands the traditional nine-point scaling,and constructs the water-logging disaster risk evaluation model.The results show that the water-logging disaster risk in Haojiang District is generally high in the south-central region and low in the northwest region.Especially,Yuxin Street,Binhai Street,Majiao Street and Dahao Street have higher risk values,which need to take preventive measures.After verification of evaluation results with historical data,it is shown that about 80% of historical flood disaster points are distributed in high-risk areas,which is consistent with the verification results of historical disaster points.The weight determination method of AHP is improved by neural network,the intermediate variables of the traditional nine-point method is expanded to three decimal places,and the weight is determined by the computer to reduce subjectivity to a certain extent.The results of risk assessment can provide technical support for flood warning and flood control scheduling within a certain time limit.

Changjiang Water Resources Commission of Ministry of Water Resources of the People’s Republic of China

CHEN Jian, CHEN Chen

Based on the construction of Capusilang hot spring reservoir and the characteristics ofmany water conservancy projects at thelower reach of hot spring reservoir and the transition frommountain river to plain river, this paper studies the influence of hot spring reservoirconstruction on the hydrological regime of the downstream river by combining one-dimensionalhydrodynamic calculation model with two-dimensional calculation hydrodynamic model. The resultsshow that the combination of the one-dimensional and two-dimensional hydrodynamic calculationmodel can objectively reflect the hydrodynamic changes in the transition area from the narrow anddeep mountain river channels at the upper reach to the broad, shallow and many-branch plain riverchannels at the lower reach, which is suitable for the study on the changes of hydrological regimein this area.Due to the storage and operation of the hot spring reservoir, in August of the floodseason,the flow of river channel at the lower reach of reservoir reduces significantly, with waterdepth, water width, and flow rate of river section decreasing obviously. In the main period ofagricultural irrigation(from March to June),the flow of river channel at the lower reach ofreservoir rises generally, with water depth, water width, and flow rate of river section increasingcorrespondingly. However, the construction of hot spring reservoir exerts little impact on thehydrological regime in the remaining months.

Ialy Rayane de Aguiar Costa, Artur Paiva Coutinho, Suzana Maria Gico Lima Montenegro et al.

ABSTRACT The high urbanization process has caused profound changes in the components of the hydrological cycle, causing various problems such as flooding, rainwater degradation, among others. Low Impact Development (LID) techniques have proven to be a viable and effective alternative to stormwater management, reducing runoff, and increasing the infiltration and evapotranspiration capacity of urban areas. The operation prediction of a compensatory technique, such as permeable pavement, depends on the hydrodynamic properties of the permeable pavement layers and the subsoil properties. The numerical solutions based on the solution of Richards’ equation have been the most used to estimate water transfer processes. The objective of this work was to investigate the influence of hydrodynamic parameters on the hydraulic behavior of a permeable pavement installed in Recife-PE. The effect of 5 hydrodynamical parameters was analyzed for a highly heterogeneous permeable pavement. The Hydrus 1-D model was used to simulate water transfer processes on the permeable pavement. Initially, a sensitivity analysis of the mesh refinement degree was performed to simulate the transfer processes in the permeable pavement. The response surface method was applied to the hydrodynamic parameters to perform the sensitivity analysis. The calculations were carried out for hourly and daily time scales. As a result, it was observed that the spatial discretization had no influence on the scenarios of the flow variable. The use of a daily time resolution reduced the influence of events with higher precipitation intensity, underestimating the generation of runoff. The surface runoff showed higher sensitivity to the parameters of the superficial layer, especially to the saturated hydraulic conductivity. The cumulative infiltration and groundwater recharge showed low sensitivity when the hydrodynamic parameters of the retention curve and the saturated hydraulic conductivity varied. The volume of water stored in the profile showed higher sensitivity to the ‘θs’ and ‘n’ parameter of the subbase layer. The use of meteorological input data with different temporal resolutions for the simulation of the water transfer processes in the permeable pavement section demonstrated that the hydrodynamic parameters have a higher influence than the climatic variables in the daily resolution. The use of meteorological data with hourly temporal resolution demonstrated that runoff was hypothetically controlled by meteorological variables. The mesh and parameter sensitivity analysis can influence researches that seek to understand water transfer processes in a structure as a permeable pavement through the Richards’ equation, generating a lower operating cost and speeding up simulations.

Farda Ali ogly Imanov, Irada Sabir kyzy Aliyeva

The article applies a water resources use coefficient and a map of its distribution to assess comprehensively the anthropogenic factors’ impact upon annual runoff of the rivers of Azerbaijan. We used the observation data for 27 rivers. By comparison we have assessed changes of many-year average annual water flows up to 1972 and for the 1973 - 2011/2016 period. We found that anthropogenic decrease of transboundary and national Azerbaijan rivers annual runoff resulted in different degree water stress. At that the number of rivers with high level of water stress (Кисп= 20–40 %) is significantly greater. The annual runoff decrease of many local rivers caused by water withdrawal for irrigation purposes is accompanied with the water content decrease during the summer/fall low water periods up to the rivers’ drying up. We noted that the volume of the permissible water abstraction should be normalized to secure permissible values of ecological river runoff in order to provide rational use of national river water.

Luis Eduardo de Oliveira Muraro, Sueli Yoshinaga Pereira, Paulo Ricardo Brum Pereira

Os aquíferos aluvionares geralmente são apresentados como áreas de pouca significância pela sua pequena extensão e descontinuidade. No entanto, decorrente de seu posicionamento topográfico e proximidades de rios, geralmente áreas de descarga de água subterrânea (rios efluentes), podem ser reservatórios de água estratégicos e relevantes. No presente estudo considerações foram feitas sobre a capacidade de reservação da planície aluvionar do rio Atibaia, na região limítrofe entre os municípios de Campinas, Jaguariúna e Paulínia. A área da planície apresenta cerca de 20 km2 e espessura média de 50 metros. As reservas ativa (0,031 m3 /s), permanente (3,09 m3 /s), total (12,4 m3 /s) e reserva disponível (3,103 m3 /s) foram estimadas. Os valores resultantes são extremamente altos e indicam uma elevada potencialidade de explotação para abastecimento público. Há relatos de problemas da qualidade destas águas, muitas vezes são ferruginosas e relativamente ácidas, sendo necessárias a remoção de ferro e neutralização para deixá-las potáveis. Assim esta disponibilidade merece maiores estudos para sua real quantificação.

Geying Lai, Peng Wang, Lin Li

Flow regime change is the leading driving force in the evolution of lacustrine ecological systems. According to the planned water level regulation scheme of the Poyang Lake hydraulic project (PLHP), this research discusses the possible impacts of PLHP on the hydrology and hydrodynamics of Poyang Lake (China) using the method of scenario simulation. The results show that a controlled water level of 11 m would effectively raise the average water level during the low-flow period of the lake in a typical dry year, normal year, and wet year, leading to the decrease of flow velocity in the lake. Those changes were more obvious in regions to the north of Tangyin, especially in the waterway of Poyang Lake into the Yangtze River. The flow field to the north of Tangyin under the scenario with the PLHP was apparently different from that under the scenario without PLHP. Furthermore, the PLHP had a significant impact on the water exchange period of the lake due to the increase in the water storage capacity and the reduction of flow velocity. These results can provide support for further quantitative analysis of water quality and the evolution of ecological systems in the lake affected by the PLHP.

Bartnik Adam, Moniewski Piotr

The paper presents the results of the monitoring of the selected physicochemical properties of the Jasień River waters (in Łódź, the third biggest city of Poland) and their changes under the influence of drainage of a railway station Łódź Fabryczna construction site. Even 25 years ago the Jasień River was a receiver for the sewage from the Łódź textile factories. The drainage of the excavations and disposal of the water into the Jasień River was started on January 2014 and changed stable hydrological, physical and chemical regime of the river once again. In a consequence, average monthly flows exceeded the Jasień River flow in its upper section by six times, and at the beginning by even ten times. Chloride concentration was systematically growing over the study period. This growth and higher water pH were probably associated with increasing level of contaminants in the discharged water and its gradually decreasing uptake. Average annual water temperature increased and a decrease in its amplitude was observed. The annual conductivity and pH patterns became more uniform and the changes in pH followed a clear trend of monthly changes. Water turbidity increased by two times and during summer floods this parameter was often even a few times higher than before the drainage commenced. Chlorides improved water conductance and sodium and potassium increased basicity.

David Stevenson

S. F. Emmons