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

DU Peng, LIU Xiao-ling, ZHOU De-quan, LI Guang-fan

[Objective] Traditional piles with uniform cross-sections have inadequate properties of the bearing stratum at pile tip or difficulties in penetrating into rock when used in soft soil areas or karst regions. Based on the concept of transforming end-bearing piles into mid-bearing piles, this study proposes a novel discontinuous variable cross-section thorn pile, aiming to systematically reveal the mechanisms by which thorn length and the number of thorn layers affect the compressive bearing properties of thorn piles through indoor model tests, thereby providing a theoretical basis for establishing a performance-based optimized design method. [Methods] Using a self-developed loading device, a geometric similarity ratio of 1∶75 was adopted, and PVC hollow circular pipes and 304 stainless steel cylindrical pins were used as the model piles and pile thorns, respectively. Using the controlled variable method, a total of 21 test groups were designed, and indoor model tests with different thorn lengths and number of thorn layers were conducted to investigate the compressive bearing properties of thorn piles in sand. [Results] (1) compared with smooth piles, thorn piles exhibited superior compressive bearing and settlement resistance. Under sand conditions, the ultimate bearing capacity of the 17-layer Type-38 thorn pile increased by 278% compared with that of the smooth pile. (2) Both thorn length and the number of thorn layers showed positive correlations with the bearing capacity of the pile foundation; compared with thorn length, the number of thorn layers was more sensitive to the ultimate bearing capacity of a single pile and the pile shaft resistance. (3) From an engineering economic perspective, when the thorn spacing was approximately one-eighth of the pile length and the thorn length was about equal to the pile diameter, the thorn pile exhibited optimal compressive bearing properties. [Conclusion] (1) The presence of thorn structures increases the interlocking effect between thorns and soil as well as the effective stress of the surrounding soil, delays the softening of pile shaft resistance, expands the influence range of the surrounding soil, and effectively redistributes the applied load, thereby significantly enhancing the overall bearing capacity of the pile foundation. (2) The concept of mid-bearing degree is introduced to quantify the mid-bearing contribution of pile thorns, and a calculation method for the ultimate bearing capacity of a single thorn pile is proposed, laying a foundation for subsequent theoretical studies. (3) Future research may consider the effects of layered foundations, soil squeezing during thorn formation, and thorn geometry on the compressive bearing properties of thorn piles, so as to further improve the comprehensiveness of bearing mechanisms and the applicability of theoretical models. The findings of this study have important theoretical and practical value in promoting the transformation of modern pile foundation engineering toward green and intelligent development, and their application will profoundly influence future modes of underground space development.

GUO Binbin, DAI Zhong

To explore the accuracy and applicability of near real-time (IMERG-Early, IMERG-Late and GSMaP-NRT) and post-real-time (IMERG-Final, GSMaP-Gauge and GSMaP-MVK) remote sensing precipitation products from the global precipitation measurement (GPM) program in complex terrain basins, this study conducted a comprehensive assessment on the accuracy evaluation indexes (CC, RMSE and BIAS) and precipitation capacity detection indexes (POD, FAR and CSI) of remote sensing precipitation based on rain gauge data in the Weihe River Basin across various spatial and temporal scales. Additionally, the IHACRES hydrological model was employed to assess the applicability of satellite precipitation data in runoff simulation. The results show that both GSMaP-Gauge (CC = 0.55, RMSE = 5.09 and Bias = 0.3%) and IMERG-Final (CC = 0.458, RMSE = 5.92 and Bias = 8%) precipitation products accurately reflect the spatiotemporal distribution characteristics of precipitation but generally tend to overestimate the precipitation. The data of precipitation products in GSMaP and IMERG series exhibits significantly obviously lower precipitation detection capabilities in winter (POD < 0.4) than in other seasons. The satellite precipitation data is significantly affected by altitude, and its quality declines with increasing altitude. The IHACRES model driven by IMERG-Final performs the best (NSE = 0.856), with monthly Nash efficiency coefficients greater than 0.8 for hydrological models driven by GSMaP-Gauge and IMERG-Final, suggesting that these data can be used as precipitation inputs for regional hydrological process simulation.

TAN Hanze, ZHANG Zezhong, FENG Kai et al.

In order to realize the high quality and sustainable development of the Inner-Mongolia Reaches of Yellow River, this paper took Dalad Banner and its townships as research objects and constructed a water-energy-food-ecology (W-E-F-E) coupling coordination evaluation index system. The coupling coordination degree model was used to carry out system coordination research based on the W-E-F-E system coupling from the temporal and spatial perspectives, and the gray correlation model and the geographic detector were used to explore the driving mechanisms. The results show that: ① The comprehensive evaluation index of the W-E-F-E system in the Dalad Banner region generally shows a slow upward trend, from 0.356 in 2000 to 0.575 in 2022. ② The coupling degree of the W-E-F-E system in Dalad Banner and its townships is high, and it is in the stage of high-level coupling (The mean value is 0.967). However, the coupling coordination degree is low and maintains at the primary coordination stage (The mean value is 0.668). Unbalanced and uncoordinated spatial development exists in the Dalad Banner region, mainly in the eastern part of Dalad Banner, and areas with a higher coordination degree gradually change from the west to the center. ③ The coordination of the W-E-F-E system of Dalad Banner and its townships shows a good trend on the whole, and the whole region is gradually developing into a good coordination stage. The townships have basically entered the intermediate coordination stage. ④ In general, the influence degree of driving factors on the system coupling coordination degree is as follows: ecology > water > energy > food. In terms of spatial differences, energy has the greatest impact, while water has the least explanatory power. The interaction among water, food, and ecology yields the greatest explanatory power. The results can provide a basis for decision-making on the efficient utilization of resources and habitat protection in the Inner-Mongolia Reaches of Yellow River.

Karamat Akhavan Giglou, Milad Kheiry, Hedieh Ahmadpari et al.

Introduction Agriculture has played a vital role in the economy, life, and culture in the civil history of Iranians. In recent years, this sector is the largest consumer of freshwater resources in this country. One of the adaptive ways to deal with the water shortage is the optimal use of water. In the production process of a commodity, different sources of water may be used, and the type of water supply source can play a significant role in the analysis of virtual water trade. In the period of 2016-2018, previous research covered by the Moghan irrigation network has been conducted in the field of physical and economic water productivity indicators estimation of crops. Moreover, in previous studies, only benefit per drop (BPD) and net benefit per drop (NBPD) indices have been used to estimate the economic productivity of agricultural water. Therefore, in this research, the agricultural year 2020-2021 was studied in order to investigate the physical and economical water productivity indicators of crops covered by the Moghan irrigation network.   Materials and Methods The Moghan Plain is located in the northwestern part of Iran, on the west side of the Caspian Sea, and north of Ardabil province, on the border between Iran and the Republic of Azerbaijan. The total area of the Moghan watershed is more than 5545 km2. The altitude of the region is 50 to 600 m above sea level and its climate is semi-arid and moderate. Most of the agricultural farm covered by Moghan's irrigation and drainage network is devoted to cultivating crops such as wheat, barley, seed corn, fodder corn, soybean, rapeseed, rice, tomato, cotton, sugar beet, and peanut. In this research, these products' virtual water content and physical and economic water productivity are investigated. In this research, to complete the previous studies in the aforementioned field, the virtual water content of the studied products has also been investigated. In addition to the BPD and NBPD, the unit virtual water value (UWV) has been studied to further investigate the Moghan irrigation network economic efficiency of water crops.   Results and Discussion The content of gray, blue, green, and white virtual water of the studied crops, sugar beet, tomato, and fodder corn, have the lowest content of gray virtual water among crops. Among the studied crops, fodder corn, tomato, and sugar beet products, respectively, have the highest physical water productivity, and rice, soybean, cotton, and peanut respectively have the lowest physical water productivity. Regarding gross value index per unit of irrigation volume among the studied crops tomatoes, peanuts, fodder corn, barley, and wheat, respectively have the; highest, moreover peanut, tomato, cotton, fodder corn, and sugar beet products, respectively, have the highest net value index per unit of irrigation volume among the studied crops, however, barley, wheat, rice, and grain corn, respectively, have the lowest net value index per unit of irrigation volume among the studied crops. In addition, tomatoes, peanuts, fodder corn, wheat, and barley have the highest index of value per virtual water unit among the studied crops, respectively, while rice has the lowest value index per virtual water unit among the studied crops. According to the BPD index, tomatoes, peanuts, fodder corn, barley, and wheat are the first to fifth priorities for cultivation in the Moghan Plain. The first to fifth priorities for cultivation in the Moghan plain according to the NBPD index are peanuts, tomatoes, cotton, fodder corn, and sugar beet, and based on the UWV index, tomatoes, peanuts, fodder corn, wheat, and barley are the first to fifth priorities.   Conclusion In the current research, the content of virtual water and the amount of physical and economic water productivity of crops covered by the Moghan irrigation network were calculated. The crop per drop (CPD) index of rice shows the last level in the crop year 2020-2021 due to the amount of water consumed and the significant cost. Also, in the analysis of the BPD and NBPD index, this product has the lowest and ninth priority, respectively, and in the current water shortage conditions in the Moghan Plain, there is a need to review the cultivation of this product. Tomatoes and fodder corn have good productivity in all three indices of CPD, BPD, and NBPD in the crop year 2020-2021. In fact, while tomato does not have a low water requirement, measuring the performance of this product shows the high net and gross profit obtained according to the cost of planting and harvesting. The amount of UWV index of wheat, rapeseed, soybean, rice, fodder corn, seed corn, tomato, barley, sugar beet, cotton, and peanut products is 24269, 15644, 18894, 9956, 36279, 17362, 50073, 23010, 21748, 19403, and 45718 rials per m3, respectively. The proposed approaches and models of this research are different depending on whether the index of physical productivity or economic productivity of water is considered in planning and policy-making.

Yongping Chen, Ebenezer Otoo, Yuhang Chen et al.

Abstract Wastewater disposal through the dumping of spoil and sludge into the river, lake, or ocean is typically in the form of a sediment‐laden jet. The inorganic and organic solids from the effluent settling close to the source often result in the formation of sludge banks which can have a damaging effect on the marine ecosystem. Therefore, predicting the transport and deposition of sediment‐laden wastewater jet flows has been a focus of intense research for decades. In this paper, we discussed the fundamental understanding of sediment‐laden jets and the progress made in their predictions. We also highlighted some of the pertinent research challenges revealed by the previous studies and identified some key research issues that need to be addressed to achieve sustainable marine wastewater disposal in the face of increasing river, lake, and marine pollution.

XIAO Xiwen, ZHANG Yunlu, LIU Chunhong et al.

Regional climate analysis can optimize and supplement global climate research,and it is of vital significance for predicting regional climate changes and extreme weather.Based on the daily temperature and precipitation data from 1961 to 2016 in Xichang city,this paper systematically reveals the characteristics of temperature,precipitation,and dry and wet climate changes at annual and inter-annual scales by using the cumulative anomaly method,nonparametric trend analysis of time series (innovative trend analysis (ITA) method and ITA-change boxes (ITA-CB) method) and standardized precipitation evaporation index (SPEI).The results show that:① The distribution characteristics of annual temperature and precipitation in Xichang are similar,with the maximum value of both appearing in July.Moreover,the minimum temperature and precipitation appear in January and February,respectively.The average inter-annual and inter-decadal temperatures increase obviously,and the average inter-decadal precipitation improves slowly.② For the past 56 years,Xichang has witnessed apparent dry and wet climate changes.SPEI has dropped in a fluctuating tendency.In addition,it is negatively correlated with temperature (p<0.05) but positively correlated with precipitation (p<0.01).As temperature increases significantly,the drought degree has become more and more serious since 2003,and the negative value of SPEI accounts for 78.6%.The proportion of drought to extreme drought has increased to 28.6% in 2010.③ The average annual precipitation increases in low-value regions but decreases in high-value regions.The average annual temperature rises both in low-value regions and high-value regions and basically maintains an increasing tendency in median regions.SPEI increases in low-value regions but decreases in median and high-value regions.The research results can provide a reference for Xichang in dealing with climate change and formulating disaster prevention and mitigation plans.

Peigui Liu, Xingyuan Yi, Yuan Feng et al.

Abstract Based on grey water footprint theory and the characteristics of the water resources system, this paper constructs the evaluation index of the water environment carrying capacity of the Yangtze River Economic Belt, and calculates the point-source grey water footprint, non point-source grey water footprint, and water environment carrying capacity of the study area from 2012 to 2017. The results show that the non point-source grey water footprint is much larger than the point-source grey water footprint. The non point-source grey water footprint decreased from 1,089.75 billion m3 in 2014 to 1,038.7 billion m3 in 2017, indicating that the pollutants discharged into the water were decreasing in those four years. In addition, the water environment carrying capacity of the western and middle sections of the Yangtze River Economic Belt are in a good state, but the eastern section is overloaded.

YAN Yulin

To understand the physical properties and pollution degree of the sediment in the North Canal,this paper collects the sediment in sections of North Canal with a columnar sampling device,and determines the physical properties,nutrient salt and heavy metal content of sediment.The results indicate that the average value of organic matter,TN and TP were 30.39 g/kg,0.161% and 0.174%,respectively,and were primary section, tertiary section and quaternary section according to the evaluation criterion.The average value of Cd,Cr,Ni,Zn,Cu,Pb and As were 0.39、86.55、29.09、199.82、52.27、33.86 and 8.26 mg/kg,respectively,which exceeded the background values for soil in Beijing.The evaluation results of geo-accumulation index show that the upper reach was partial moderate pollution,among which Cd and Zn were moderate pollution,and the middle and lower reaches were mild pollution.The average content of heavy metals was below the light pollution,so the pollution is not serious.Besides,the sediment can be reused to agricultural land and used as levee material,which exploit the way of resource utilization.

WANG Hanye, HUANG Shengzhi, WANG Lu et al.

Flood is characterized by flood peak, flood volume and duration. The impact of theproject's reasonable service life was ignored in previous flood risk assessment. And the riskindex considering reasonable service life of the project can better describe the flood riskundertaken by the projects. Based on this, this paper adopts the daily flow data of typicalhydrological stations in the Pearl River Basin from 1997 to 2017, and selects floods by the peaksover threshold method to enrich the flood samples, builds the joint distribution function of floodpeak and volume by Copula function, calculates the joint return period, and builds the flood riskindex with consideration of the joint return period and the reasonable service life of project.The results show that: ① Under the combination of flood peak and flood volume in the same returnperiod, compared with other stations, the risk of flood with high peak or large volume is thehighest in Yujiang River, while risk of flood with high peak and large volume is the highest inLiujiang River (except 10-year return period); ② When the reasonable service life of Type I largewater conservancy project (dam, n=50~100 years) is considered, the risk of flood with high peakor large volume is the highest in Xijiang River; and ③ The risk of flood with high peak and largevolume exceeding the design value is the highest in Liujiang River.

Weihua Wang, Yaning Chen, Wanrui Wang

Groundwater is an important source for maintaining desert ecological processes in arid areas. With the increasing intensity of climate change and human activities, the rivers in Tarim Basin are severely dried-up. Aiming at the dried-up river, vegetation degradation and oasis maintenance in the middle and lower reaches of dried-up river basin, groundwater recharge and groundwater-surface water interaction have become hotspots, but are not well known. We examined spatial distributions and controlling factors of groundwater stable isotopes and recharge at oasis scale using data from 247 samples surveyed in the four headwaters in the northern Tarim Basin. Stable isotopes of surface water and groundwater were different from each other, and varied among sampling sites. Surface water and groundwater isotopes generally became enriched towards the east throughout the study area, while surface water isotopes showed enrichment towards the upstream direction within each catchment, mainly due to cultivated area expansion. Surface water mainly originated from precipitation, groundwater, and meltwater, while shallow groundwater derived from lateral groundwater flow, river and irrigated water infiltration, and little precipitation. The mainstream water was directly recharged by the headwaters. The results could provide a new insight into groundwater cycling in oases of dried-up river basins, which is helpful for regional groundwater management. HIGHLIGHTS Groundwater recharge in the oasis-desert areas of northern Tarim Basin was examined.; Shallow groundwater mainly originated from lateral groundwater flow and infiltrating river and irrigation water.; Human activities greatly impact the groundwater recharge.;

Warwade Pratibha, Tiwari Shalini, Ranjan Sunil et al.

This study detected, for the first time, the long term annual and seasonal rainfall trends over Bihar state, India, between 1901 and 2002. The shift change point was identified with the cumulative deviation test (cumulative sum – CUSUM), and linear regression. After the shift change point was detected, the time series was subdivided into two groups: before and after the change point. Arc-Map 10.3 was used to evaluate the spatial distribution of the trends. It was found that annual and monsoon rainfall trends decreased significantly; no significant trends were observed in pre-monsoon, monsoon, post-monsoon and winter rainfall. The average decline in rainfall rate was –2.17 mm·year−1 and –2.13 mm·year−1 for the annual and monsoon periods. The probable change point was 1956. The number of negative extreme events were higher in the later period (1957–2002) than the earlier period (1901–1956).

Xiaoliu Yang, Huili Chen, Yueling Wang et al.

Land use/cover change (LUCC) is one of the crucial factors influencing the hydrological process, thus the flood characteristics in time and space. Therefore the evaluation of the change of flood characteristics implies an integrated analysis of LUCC and hydraulic simulation. In this study, the effect of LUCC on flood is examined based on an approach composed of three parts: (1) reproduction of spatially explicit LUCC; (2) application of a 2D hydraulic modelling for flood simulation; (3) demonstration of results for Beijing. The approach is applied to a flood-prone area in Beijing. The results show that 8% and 21% of the study area experienced LUCC during 1991–2001 and 2001–2011, respectively, and these changes greatly influenced the characteristics of the 20-year flood, i.e.: (1) the flood zone is doubled during 1991–2001 and about four-fold during 2001–2011; (2) the water depth is increased for most of the study area; and (3) the flow velocity becomes faster. It indicates that flooding still exists within Beijing and is even more dangerous than 40 years ago and suggests that actual land use pattern and existing flood protection works should be re-evaluated regarding the flood characteristics change due to LUCC.

Paulo Cesar Negrão, Sueli Yoshinaga Pereira, Felipe Gasparini et al.

In determining the hydraulic gradients of groundwater aquifers in estuarine environment, it is essential to consider the pressure waves resulting from tidal fluctuations and water bodies. The fluctuations of the water level of the Cubatão River and hydraulic head of the shallow aquifer (in 3 levels of depth) in Cubatão, SP, were monitored for 45 days in an adjacent industrial area to the river in order to determine the mean hydraulic head and mean hydraulic gradients by the method proposed by Serfes (1991). The monitoring was continuous and performed in two scenarios: with the remediation system ("Air sparging" technology) activated and deactivated. The results showed the interference of the remediation system and the variations of the tide in hydraulic heads of the nearby wells, and only the variation of the tide in the more distant wells. However, in the upper aquifer the influent condition of the Cubatão river was present in both scenarios. Effluent and influent conditions in the intermediate portion, and predominant effluent of the river in the deep portion were observed. In the intermediate and deep portions of the aquifer, the hydraulic gradients have low values (-0.0027 to 0.0030) so that the analysis of the flow direction have to be careful.

Hiroumi Yoshikawa, F. Nanayama, K. Shigeno

P. Malaterre, Philippe Lamour

A. E. Palmer

Sugai Toshihiko, Hachinohe Shoichi

P. Zheng, B. Hobbs