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...     

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.     

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 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.     

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。     

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.     

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。     

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。     

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.     

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.     

Multi-Criteria Decision Analysis for the Purposes of Groundwater Control System Design

The best way for an engineer or scientist to express their knowledge, experience and opinions is day-to-day verbal communication. When a decision needs to be made about an optimal groundwater control system, the decision-making criteria need not always be numerical values. If fuzzy logic is used in multi-criteria decision-making, the criteria are described by linguistic variables that can be represented through fuzzy membership and expert judgment is used to describe such a system. Prior hydrodynamic modeling of the aquifer regime defines the management scenarios for groundwater control and provides an indication of their effectiveness. In this paper, the fuzzy analytic hierarchy process is applied to deal with a trending decision problem such as the selection of the optimal groundwater management system. Linguistic variables are used to evaluate all the criteria and sub-criteria that influence the final decision and the numerical weights of each alternative are determined by mathematical calculations. The paper presents a part of the algorithm – fuzzy optimization in hydrodynamic analysis, which leads to the selection of the optimal groundwater control system. The proposed method is applied in a real case study of an open-cast mine.     

高坝风险分析的事件树法

新世纪一批高坝将要在我国开工建设,这对我国的水电能源及国民经济的发展有着不可估量的作用,而高坝建设中,安全性是需要首先保证的。目前对高坝的风险分析方法有主观概率法、客观概率法等。从系统工程的角度出发,采用事件树方法对高坝的风险进行了探索研究,并给出了算例以说明该方法的有效性和实用性。     

An Integrating Approach for Conjunctive-Use Planning of Surface and Subsurface Water System

This study proposes an integrated approach to assess the performance of a conjunctive-use surface and subsurface water system. System dynamics serves as the main framework of the proposed conjunctive-use model, simulating the interaction between surface and subsurface water and the impact of various conjunctive-use alternatives on the system as a whole. This study assumes natural groundwater recharge as a water source to the system, and estimates its volume using geographic information system (GIS) tools, a groundwater simulation model (MODFLOW), and a parameter identification model (UCODE). This study assesses various conjunctive-use alternatives and analyzes the frequency of water shortage to illustrate how the recharge rate affects water supply reliability under the conjunctive-use framework. Simulation results indicate that conjunctive-use with artificial recharge indeed reduces the frequency of extreme water shortages. Results also reveal that artificial recharge is necessary to maintain groundwater conservation without overusing river flow. Although this study focuses on southern Taiwan, the proposed concepts and procedure are applicable to other areas with a similar conjunctive-use framework.