Optimal Water Allocation from Subsurface Dams: A Risk-Based Optimization Approach

Subsurface dams, strongly advocated in the 1992 United Nations Agenda-21, have been widely studied to increase groundwater storage capacity. However, an optimal allocation of augmented water with the construction of the subsurface dams to compensate for the water shortage during dry periods has not so far been investigated. This study, therefore, presents a risk-based simulation–optimization framework to determine optimal water allocation with subsurface dams, which minimizes the risk of water shortage in different climatic conditions. The developed framework was evaluated in Al-Aswad falaj, an ancient water supply system in which a gently sloping underground channel was dug to convey water from an aquifer via the gravity force to the surface for irrigation of downstream agricultural zones. The groundwater dynamics were modeled using MODFLOW UnStructured-Grid. The data of boreholes were used to generate a three-dimensional stratigraphic model, which was used to define materials and elevations of five-layer grid cells. The validated groundwater model was employed to assess the effects of the subsurface dam on the discharge of the falaj. A Conditional Value-at-Risk optimization model was also developed to minimize the risk of water shortage for the augmented discharge on downstream agricultural zones. Results show that discharge of the falaj is significantly augmented with a long-term average increase of 46.51%. Moreover, it was found that the developed framework decreases the water shortage percentage in 5% of the worst cases from 87%, 75%, and 32% to 53%, 32%, and 0% under the current and augmented discharge in dry, normal, and wet periods, respectively.

     

A Flexible Approach for the Reinforcement of Water Networks Using Multi-Criteria Decision Analysis

Water Resources Management - This work proposes a multi-criteria decision analysis (MCDA) as a useful tool for supporting interventions to overcome problems faced by water utilities due to...     

Integrated Approach for Identifying Suitable Sites for Rainwater Harvesting Structures for Groundwater Augmentation in Basaltic Terrain

Integrated hydrological, geophysical and groundwater modeling studies has been carried out for identification of suitable sites for rainwater harvesting structures for groundwater augmentation in RRCAT Campus, Indore, M.P. Based on these studies ten check dams, two contour bunds and one earthen bund were recommended on the existing stream channels and in valley fills respectively. Likely water impoundment on these structures was calculated keeping in view the length and width of stream channels. Based on these study a groundwater flow model using MODFLOW were carried out keeping in view the geologic and hydrologic conditions of the area. The net rechargeable impounded rain water from these structures to groundwater regime was calculated for monsoon seasons which varied from 20 % to 48 % and net enhancement of groundwater recharge from all structures would be around 0.11 mcm/year and the water level in the existing well would rise by 2–3 m above its present level for future Groundwater augmentation.     

A GIS-Based Spatial Multi-Criteria Approach for Flood Risk Assessment in the Dongting Lake Region,Hunan, Central China

Floods, the most common natural hazard in the world, cause serious loss in terms of lives, buildings, and infrastructures. As a consequence, the need for flood risk assessment has become critical. Using a semi-quantitative model and fuzzy analytic hierarchy process (FAHP) weighting approach, this paper assessed flood risk in the Dongting Lake region, Hunan Province, Central China, an area where flood hazards frequently occur. The model was designed using spatial multi-criteria analysis (SMCA) techniques in a Geographic Information System (GIS). A GIS database of indicators for the evaluation of hazard and vulnerability was created. Each indicator was analyzed, standardized, and weighted; after which, the weights of the indicators were combined to obtain the final flood risk index map. Using the flood risk index, the study area was classified into five categories of flood risk: very low, low, medium, high, and very high. The high and very high risk zones are mainly concentrated in the northern and central plains. The results obtained can provide useful information for decision makers and insurance companies.     

A Spatially Explicit Multi-Criteria Analysis Method on Solving Spatial Heterogeneity Problems for Flood Hazard Assessment

Flood hazard assessment and mapping of flood prone area are of great importance for flood management, as well as the reduction of potential losses of life and property caused by flooding. In this study, a spatially explicit multi-criteria analysis approach which emphasizes on spatial heterogeneity in decision-making process is developed for flood hazard assessment, and it has been applied to the area including Hanyang, Caidian and Hannan of Wuhan, China, where flood events occur frequently. Factors associated with flood mechanism and characteristics of the watershed itself were selected, and primary analysis was implemented to make the factors concise and essential. This paper emphasized the spatial heterogeneity problem in flood hazard assessment by incorporating spatial ordered weighted averaging (OWA) method into windows-based local spatial multi-criteria analysis (MCA). On one hand, the local normalization was applied to normalize the criteria, and entropy-based local criteria weights were calculated to adjust the criteria weight at local level. On the other hand, spatial OWA method with spatially variable risk preference was applied to assign different order weights at different locations. The results indicate that the proposed approach focused on the flood hazard at local level, and the flood hazard map presented more dispersive distribution of the high and very high hazard area than that derived by global MCA. Furthermore, flood hazard in important and unimportant area was distinguished by paying more attention to the former one. And the distribution of high hazard area tends to be mainly located in populated and developed areas.     

Cost Analysis of Water Quality Assessment Using Multi-Criteria Decision-Making Approach

In modern competitive markets, cost and quality parameters are the two main factors. So, it is essential to study their relationship, especially in leading industries such as urban public service companies. Consequently, manufacturers always try to reduce production costs and improve product quality and services to consumer expectations. Also, the concerns of the new century in the field of fresh water and the reduction of its resources related to global warming have increased the costs of quality and supply of freshwater. Therefore, in this research, in order to estimate the quality costs in the field of water resources and wastewater management and identify the option that creates the most cost, in the first step, the “Prevention, Assessment, and Failure (PAF)” model was used to select cost-imposing options in organizational quality analysis. After determining the main options, appropriate criteria and sub-criteria were selected under the main study area (water and wastewater resources management). In the next step, a “Multiple-Criteria Decision-Making (MCDM) “ method based on the “Fuzzy Analytical Hierarchy Process (FAHP)” and “Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS)” method was used to identify the option that creates the most cost. The results show that The highest cost of quality in the water and wastewater industry and its management are related to “Assessment Costs” and account for 36.55% of total costs. Also, The lowest cost of quality in the water and wastewater industry is related to “Preventive Costs” and accounts for only 12.18% of the total cost. In addition, the expert’s opinion shows that the effect of increasing credit with 34.01% has the greatest weight, and this criterion is the most essential in water and wastewater resources management.

     

Modelling Optimum Sites for Locating Reservoirs in Tropical Environments

A team of specialists normally carries out the task of locating reservoir sites based on general guidelines, technical knowledge and experience. Consequently, the procedures used are not based on a defined criteria in addition to being time consuming and expensive. Furthermore, the failure of a number of dams and the increase in environmental awareness will require the inclusion ofenvironmental and social factors in the processes besides economy. In this study, a criteria was developed and implementedto locate potential sites for reservoirs in the Langkawi Island, Malaysia based on all relevant factors including: topography, geology, hydrology, land use/cover types and settlements. A satellite imagery and digitized geological and elevation maps were utilized to generate the necessary data layers for the developed criteria. Then IDRISI, a raster based GIS was employed to implement the criteria using the Boolean and the Weighted Linear Combination (WLC) methods. The Boolean method produced five reservoir sites with the 70 Mld water capacity, two of which corresponded well with a field-based study. Whilst theproposed site with the 90 Mld water capacity did not correspond with the field based study. The WLC method produced five sites with the 70 Mld water capacity, three of which matched those of the field study. Whilst for the 90 Mld water requirement, two potential sites were produced and both have matched those of thefield study. The outcomes indicated that the developed criteria were sensitive to physical, environmental and economical settingson the Langkawi Island. Furthermore, GIS and remote sensing can be useful tools for generating, manipulating and handling relevant data layers and ultimately providing management optionsfor decision makers.     

福建砌石拱坝施工技术与经济分析

福建省的砌石拱坝设计体型日趋多样化 ,并向新颖、轻、高和薄的方向发展 .对石料的强度要求从严 ,形状要求从宽 ;混凝土普遍采用“双掺”技术 .施工机械有国产的 ,也有进口的 .大坝面石砌筑 ,多数采用粗料石丁砌 ,砂浆深勾缝防渗 ;腹石砌筑 ,从卧砌发展为竖砌 ,不求单块自稳 ,石料之间允许点接触 ,层高为 0 .8～ 1.0m ,强调砌体密实性及埋石率 ,大坝每升高 3～ 5m进行一次压水试验检查砌体透水率 ,并进行补强灌浆 ,大大提高了坝体自身的防渗能力 .实践证明 ,随着砌石拱坝施工工艺水平的提高 ,近百米级的高、薄砌石拱坝 ,不设混凝土防渗面板或心墙 ,只靠坝体自身防渗是可行的 ,是一种比较经济的坝型 .     

空间相关非平稳地震荷载作用下的大坝风险分析

坝体风险性研究具有十分重要的意义。文章提出了在空间相关非平稳地震荷载作用下,不同破坏模式下的大坝风险分析系统分析方法。首先采用人工生成空间相关非平稳地震动时程和Mazars混凝土损伤模型,通过对混凝土重力坝的坝头、上游折坡面以及建基面等处的损伤值及其抗滑稳定系数的研究,然后推导了大坝溃口宽度以及相应的溃口流量随时间的变化规律,根据溃口时间和流量变化推出了溃坝后的生命损失以及财产损失,最后进行了算例分析。通过计算结果可以看出,所提出的模型能够考虑大坝的风险发生的各个过程,并能够较全面的描述大坝的风险。更多还原     

面板堆石坝变形计算的一种新型数值方法

针对高面板堆石坝对变形控制要求高的问题，利用中井本构关系模型及其稳定、快速收敛的欧拉向后应力积分算法，在局部误差和整体误差都得到精确控制的情况下，用弹塑性有限元方法对面板堆石坝进行有限元分析计算。同时，提出了按设计阶段和施工阶段分别采用不同的方法确定模型参数，从而使得选取的模型参数尽可能反映工程实际，提高数值计算精度。     

混凝土坝仿真应力分析方法

混凝土坝是逐层浇筑的，施工过程对坝体温度场和应力场有重要影响。模拟施工过程进行仿真计算是困难的。为了真实地模拟施工过程并保证较高的计算精度，需要庞大的存储量和很长的机时，限于目前的计算机上即可完成混凝土高坝的仿真计算。     

考虑材料参数空间变异的重力坝地震损伤分析

由于施工质量不均匀和混凝土自身的非均质性,因此重力坝坝体混凝土材料强度具有空间变异性。利用对数正态分布随机场模拟混凝土参数的空间变异性,采用中心点法将参数随机场离散为一组相关随机变量,通过结构空间位置和相关距离构建了自相关函数、得到相关系数矩阵。采用Cholesky方法分解相关系数矩阵并线性变换,通过n维独立标准正态分布样本矩阵生成n维相关对数正态分布样本矩阵,实现了混凝土材料参数空间变异性的抽样模拟。对印度Koyna重力坝的地震损伤分析表明,考虑混凝土参数(特别是抗拉强度)的空间变异性后,坝体损伤程度加重,坝顶位移振幅减小,坝顶垂直残余位移增大,因此在重力坝抗震设计中应考虑材料参数空间变异性的影响。     

Design and Construction of Earthquake-Proof Soil Dams with Asphalt Concrete Cores in the Northern Constructional-Climatic Zone

The advantages of soil dams with asphalt concrete cores over other types of dams in the Northern construction climatic zone are considered.__________Translated from Gidrotekhnicheskoe Stroitel’stvo, No. 3, March 2005, pp.2 – 8.     

About the Safety of Dams in the Northern Constructional-Climatic Zone

Measures for raising the safety of operation of earthfill dams on the Far North are suggested.     

混凝土高坝全过程仿真分析

施工过程对混凝土坝的温度场和应力场有重要影响，但混凝土高坝分层很多，施工期长达数年，要模拟施工全过程进行大坝仿真应力分析难度很大，经过多年的研究，笔提出了混凝土高坝仿真计算的一整套计算方法，并编制了程序，较好地解决了这个难题。     

Application of Spatial Analysis Techniques to Select the Most Suitable Areas for Flood Spreading

This study addressed potential areas for flood spreading by evaluating the Boolean Logic, Overlay Index and Fuzzy Clustering techniques for spatial analysis. We applied these techniques on the artificial recharge criteria of slope, infiltration rate, alluvium thickness, land use and alluvial quality. The above criteria were prepared, classified, weighted and integrated in a GIS environment. The resultant maps were organized into two classes of potentiality, suitable and unsuitable, which expressed two different levels of favorability for site selection of flood spreading in the study area. We used 32 controlling areas to compare the performance of these spatial analysis techniques. By validation of the produced maps, the most suitable areas of flood spreading for each technique were determined: Fuzzy Clustering (14.4 %) Overlay Index (10.84 %) and Boolean Logic (10 %). After land use filtering, 72 %, 70 % and 65 % of the most suitable areas were eliminated in the, Overlay Index, Boolean model and Fuzzy Clustering, respectively. According to our results, the spatial analysis techniques can be powerful tools for selecting the most suitable areas for flood spreading.     

Multi-Criteria Decision Analysis and GIS Approach for Prioritization of Drinking Water Utilities Protection Based on their Vulnerability to Contamination

This work presents the use of multi-criteria decision analysis (MCDA) as a decision tool to facilitate the process of prioritization of drinking wells that would need more protection before contamination risk. In this study, three aspects of the protection of the groundwater quality were taken into account: natural, anthropic and technical. From these aspects, elements more representative were selected, which can be quantified with available and easily accessible information. Considering those elements, selection criteria were defined which have been represented by: population distribution indicator, human development index, land use, index for aquifer vulnerability to contamination, well age and well yearly pumping rate. The developed method has been applied to drinking supply wells located in the Toluca Valley aquifer (Mexico), and implied the generation of the thematic maps of the defined selection criteria. For the MCDA, the values of each map were converted to the same scale, each criterion was weighted in function of its importance according to the objective and there were aggregated by the way of a lineal combination. The obtained result is a map that shows the level of protection priority of the supply wells. This map can offer information to the stakeholder in a relative short time and contribute to accelerate the actions aimed to protect the quality of the vital underground liquid.     

一种适宜枢纽工程建设的新型道路及其施工方法

面对水利枢纽建设工地场内衍生的大量施工沙石弃料,结合枢纽临时性道路的复杂性、多样性的特点,采用高新技术材料(高强高耐水土体固结剂HEC)作为道路建筑中的胶凝材料,在稳定平整的路床上运用二次摊铺一次找平一次碾压的施工技术及工艺,成功地建造了无论是在技术质量还是在经济投入上都极其适合于水利枢纽工程建设需要的新型道路HEC-RCC,其道路路型、设计思想、材料选取和施工技术及工艺都具有特色。     

Regional Flood Frequency Analysis of the Seven Sites of Punjab, Pakistan, Using L-Moments

L-moments based regional flood frequency analysis has been carried out on the seven sites of Punjab, Pakistan. Discordancy measure in terms of L-moments has been used to screen the data on each of the seven sites. Homogeneity of the region has been tested using the L-moments based heterogeneity measure (H). H has been calculated using four parameter Kappa distribution with 500 simulations. In order to find the most suitable distribution for quantile estimates, a number of L-moments based frequency distributions, such as, generalized logistic (GLO), generalized extreme-value (GEV), generalized normal (GNO), Pearson type III (PE3), generalized Pareto (GPA) and five parameter Wakeby (WAK) distribution, have been used. Based on the L-moment ratio diagram and Z ^DIST statistic, three distributions; GNO, GPA and GEV have been identified as the suitable candidates for regional distribution. Accuracy measures for the estimated regional growth curves and quantiles have been calculated for the three candidate distributions, using Monte Carlo simulations. Simulations study showed that GNO distribution is the robust distribution with GPA as suitable alternative but GEV is not an appropriate distribution for the study area.