Response of Hydrodynamics and Water-quality Conditions to Climate Change in a Shallow Lake

Lake water resources operation and water quality management come up with higher challenges due to climate change. The frequency and intensity of extreme hydrological events are increasing under global warming, which may directly lead to more uncertainty and complexity for hydrodynamic and water-quality conditions in large shallow lake. However, studies about effects of climate change on lake hydrodynamic and water-quality conditions are not enough. Thus, a coupled model is es-tablished to investigate the potential responses of lake water level, flow field and pollutant migra-tion to the changing climatic factors. The results imply that water flow capacity and self-purification in the Hongze Lake can be improved by west, northwest, north, south and southeast winds indi-cating wind filed change has a great effect on the hydrodynamic and water-quality conditions in large shallow lake. It is further observed that both hydrodynamics and water quality are more sensitive to rainfall change than to temperature change; compared to the effect from temperature and rainfall, the effect from wind field appear to be more pronounced. Moreover, the results verify the feasibility of coupling basin hydrological model with lake hydrodynamic and water quality model. To the best of knowledge, the coupled model should not be used until independent calibra-tions and verifications for hydrodynamics and water quality modeling, the hydrological model and the coupled model.

     

Cloud-Based Multidimensional Parallel Dynamic Programming Algorithm for a Cascade Hydropower System

The joint optimal operation of cascade reservoir system can greatly improve the utilization of water resources. However, the complex high-dimensional and non-linear features and calculated costs often hinder the refined operation and management of reservoirs. Recently, the local parallel computing has become an effective way to alleviate the "curse of dimensionality". Current local parallel computing has hardware limitations, which is difficult to adapt to large-scale computing. This study proposes a novel parallel dynamic programming algorithm based on Spark (PDPoS) via cloud computing. The simulation experiments are carried out for a comparative analysis of the solution efficiency, influence factors and stability of cloud computing. The results are as follows: (1) The efficiency of the cloud-based PDPoS is related to some factors; the number of CPU cores is the main influencing factor, followed by the operator, and the architecture has the least influence. (2) The runtime variance of cloud computing is 2.03, indicating cloud computing has high stability. (3) Under the same configuration (i.e., CPU and memory), the runtime of cloud computing is 41.5%?~?110.3% longer than that of physical machines. However, cloud computing has rich resources, good scalability, and good portability of online operations, which is an attractive alternative for optimal operation of large-scale reservoir system.

     

Reduction of the Criteria System for Identifying Effective Reservoirs in the Joint Operation of a Flood Control System

Water Resources Management - The accurate and efficient identification of effective reservoirs plays an important role in the real-time flood control operation of multireservoir systems. The...     

浅析山区小型农村饮水安全工程问题与解决途径

结合"十三五"期间全面解决山区贫困人口饮水安全目标,以安徽省岳西县为例,针对高、偏、远山区小型农村饮水安全工程建设存在的难题,提出低海拔提水、建设集雨工程或者借水等解决方式,并分析了其适用性。针对一般山区小型农村饮水安全工程运行管理存在的问题,提出实施农村饮水安全巩固提升工程,加强宣传、技术培训和行业监管等对策建议。     

河流系统实时洪水预报误差多点联合校正方法研究

实时校正是改善洪水实时预报精度的重要手段。河流系统中多个站点之间具有高度的水力联系,各个站点之间的误差也具有空间关联性。依据河道水流演进的基本方程和动态自适应的自回归方法,建立了考虑误差空间演化的河流系统实时洪水预报误差多点联合校正方法。利用洪峰段洪量误差、洪峰流量误差、纳什效率系数(NSE)和峰滞时间等指标分别对多点联合校正和不考虑误差空间关联性的单点校正开展校正效果评估。以淮河王家坝断面以上为背景开展实证研究,结果表明:考虑河流系统误差空间关联性的多点联合校正效果优于单点校正,洪峰段效果更为显著,能够更有效地提高河流系统洪水预报的精度。     

Water Resources Allocation in Transboundary River Basins Based on a Game Model Considering Inflow Forecasting Errors

Dynamic transboundary water resources allocation based on inflow prediction results is an important task for water resources management in river basins. This paper takes the watershed management agency as the leader and the associated area as the follower, and proposes a two-level asymmetric Nash-Harsanyi Leader-Follower game model considering inflow forecasting errors. In the proposed model, the Monte Carlo method is used to analyze the uncertainty of various stakeholder allocation results and the response regularity to the total water resource uncertainty. The quantitative relationship between the allocation results of stakeholders and the mean and standard deviation of total water resource uncertainty is subsequently established. The Huaihe River basin in China is selected as a case study. The results show the following: (1) the water allocated to the watershed management agency and three provinces has a normal distribution when the inflow forecasting error obeys the normal distribution; (2) the sum of the mean of the water allocated to stakeholders equals the mean of the forecast water resource and the sum of the standard deviations of the water allocated to stakeholders equals the standard deviation of the forecast water resource; (3) the mean and standard deviation of the allocation results have a good linear relationship with the mean and standard deviation of forecast water resource; (4) the distribution parameters of the stakeholder allocation results can be directly derived from the distribution parameters of the forecast information, thus aiding the stakeholders in making decisions and improving the practical value of the method.

     

大体积混凝土早期裂缝的施工控制

神华准能哈尔乌素露天矿产品槽仓工程,仓下暗道混凝土顶板3.5m厚,为典型的大体积混凝土。为杜绝大体积混凝土产生早期裂缝带来质量隐患,通过粉煤灰掺加技术,对混凝土配合比进行优化,降低混凝土中心温度,并采取各种施工措施控制了大体积混凝土早期裂缝的产生。     

岱海湖水位对气候要素与土地利用的响应

利用Mann-Kendall检验、Hurst系数法、基于有序聚类法的t检验等方法分析湖区水位演变趋势;利用Partial Mantel检验法,并通过构建缺失资料地区的湖区水文模型,探究了典型半干旱区湖泊岱海湖水位对气候要素与土地利用变化的响应。结果表明：岱海湖水位1959—2018年呈现显著下降趋势,于1982年和2005年发生突变,未来水位将呈现持续降低趋势;岱海湖春季受融雪影响导致水位较高,秋季受用水影响导致水位较低,且秋季水位降低在四季中最为明显;气候变化与水土资源开发利用是影响半干旱区湖泊水位变化的主要因素,在气候变化条件下,岱海湖水位对气温变化最为敏感,对日照变化的响应次之;由于岱海湖流域降水-产流-下渗机制较为复杂,岱海湖水位对降水变化的响应具有滞后性,流域林草面积增加可能是引发岱海湖水位降低的重要因素。     

Multidimensional Parallel Dynamic Programming Algorithm Based on Spark for Large-Scale Hydropower Systems

The “curse of dimensionality” is a major problem in dynamic programming (DP) algorithms for large-scale hydropower systems. This study proposes a parallel DP algorithm based on Spark (PDPoS) to alleviate the “curse of dimensionality”. Parallel computing experiments are formulated by varying the number of reservoirs, the number of discrete water levels and the number of CPU cores to analyze the quality and efficiency of PDPoS. The methodologies were applied to a cascade reservoir system made up of eight reservoirs in the Yuanshui River Basin in China. The results are as follows. (1) The number of discrete water levels is the dominant factor in the solution quality, while the number of reservoirs is the dominant factor in the solving efficiency. (2) The runtime of PDPoS is markedly affected by the calculational scale (determined by the number of reservoirs and discrete water levels), and the relationship between the number of CPU cores and the runtime is triphasic with increasing calculational scale. (3) The larger the calculational scale is, the better the parallel performance (i.e., the parallel speedup and parallel efficiency). The proposed PDPoS method has strong generality, high parallel performance, and high practical value.

     

Bargaining Model of Synergistic Revenue Allocation for the Joint Operations of a Multi-Stakeholder Cascade Reservoir System

Given the institutional limitations of multi-stakeholders, exploring the synergistic revenue from the joint reservoir operations of a multi-stakeholder multi-reservoir system requires a synergistic revenue allocation mechanism to ensure a beneficial solution for multi stakeholders. This study established a synergistic revenue allocation model using bargaining game theory under the principles of equity, rationality, and efficiency. For the maximization the Nash product of gains in the utility of stakeholders and constraints on the feasibility of allocation plans considering all the possible formations of sub-coalitions, the analytic optimal solution of the bargaining model was derived using the first-order optimality condition. The optimal revenue allocation plan meets the conditions of the equal quasi-marginal utility function among stakeholders. The methodologies were applied to a hypothetical cascade reservoir system operated by multiple stakeholders. Compared with the revenue allocation plans obtained by a proportional rule method and the Shapley value method, the results corroborate that (1) the allocation plan of the bargaining model is jointly determined by the interval of the revenue range of each reservoir and the effectiveness of the sub-coalition constraints, indicating that the allocated synergistic revenue is positively correlated with the singleton contribution and team contribution on the total revenue of the grand coalition; (2) the difference in the plans obtained by the three methods is generally determined by the difference in equity definition; and (3) the synergistic revenue allocation plan obtained from the bargaining model is the highest homogenized among all reservoirs (stakeholders), which demonstrates that the revenue of those dominated stakeholders can be improved compared with other plans. The proposed methodologies provide new insights to guide benefit share decisions in multi-stakeholder reservoirs system.