PRACTICAL IMPLICATIONS IN THE USE OF STOCHASTIC DYNAMIC PROGRAMMING FOR RESERVOIR OPERATION1

ABSTRACT: A stochastic dynamic programming model is applied to a small hydroelectric system. The variation in number of stage iterations and the computer time required to reach steady state conditions with changes in the number of storage states is investigated. The increase in computer time required to develop the storage probability distributions with increase in the number of storage states is reviewed. It is found that for an average of seven inflow states, the largest number of storage states for which it is computationally feasible to develop the storage probability distributions is nine. It is shown that use of the dynamic program results based on a small number of storage states results in unrealistically skewed storage probability distributions. These skewed distributions are attributed to “trapping” states at the low end of the storage range.     

涔天河水库灌区土壤资源特点及其合理利用

对涔天河水库灌区土壤资源现状，特点进行了调查研究，对土壤资源利用中存在的问题进行了剖析，并提出了合理利用土地资源，提高土壤生产力的措施。     

Longitudinal‐Vertical Hydrodynamic and Turbidity Simulations for Prediction of Dam Reconstruction Effects in Asian Monsoon Area1

Abstract: This research investigates possible impacts of enlarged water body according to dam reconstruction on the hydrodynamics and water quality of the reservoir using a laterally averaged, two‐dimensional hydrodynamic and transport model, CE‐QUAL‐W2. The lake was formed by the artificial dam in 1983 for agricultural water supply and is currently under consideration of reconstruction so as to expand the volume of reservoir for flood control as well as water supply in downstream areas. To calibrate and validate the model, field‐collected data were compared with model predictions for water level fluctuations and water temperature during the years of 2001 (from January to December) and 2003 (from March to November). The model results showed a good agreement with field measurements both in calibration and verification. Utilizing the model, impacts of dam reconstruction on the thermal hydrodynamics and turbid current were predicted. From the model results, dam reconstruction limited the depth of thermal stratification below 10 meter and formed steep temperature gradient between epilimnion and hypolimnion. The restricted thermal stratification persisted up to the end of September. This result indicated that thermal stratification would become stronger during summer and stay longer after dam reconstruction. In addition, the restricted thermal stratification caused vertical circulation of water mixing lower than 10 meter and isolated the upper water layer from the lower water layer which increased the volume of hypolimnetic water with low temperature. The vertical circulation near the surface also mitigated propagation of density plume within the depth of 10 m which would remain the hypolimnetic water clean.     

AN ASSESSMENT OF USES MADE OF A MULTIPURPOSE RESERVOIR'

ABSTRACT: Data were collected from residents of a rural community at two time periods to assess attitudes toward uses made of a reservoir which had been recently constructed in the area. The findings revealed that attitudes became significantly more favorable for flood control, water supply, and recreation uses of the reservoir. Attitudes toward fish and wildlife conservation use were not significantly different over time but these uses were perceived positively at both time periods. The data were also analyzed in the context of a vested interest perspective using cross-sectional design. The findings demonstrated that the theoretical model used to guide the investigation was quite useful in predicting attitudes toward the four uses examined.     

A COMPARISON OF SOME DYNAMIC,LINEAR AND POLICY ITERATION METHODS FOR RESERVOIR OPERATION1

Within the past few years, a number of papers have been published in which stochastic mathematical programming models, incorporating first order Markov chains, have been used to derive alternative sequential operating policies for a multiple purpose reservoir. This paper attempts to review and compare three such mathematical modeling and solution techniques, namely dynamic programming, policy iteration, and linear programming. It is assumed that the flows into the reservoir are serially correlated stochastic quantities. The design parameters are assumed fixed, i.e., the reservoir capacity and the storage and release targets, if any, are predetermined. The models are discrete since the continuous variables of time, volume, and flow are approximated by discrete units. The problem is to derive an optimal operating policy. Such a policy defines the reservoir release as a function of the current storage volume and inflow. The form of the solution and some of the advantages, limitations and computational efficiencies of each of the models and their algorithms are compared using a simplified numerical example.     

RESERVOIR WATER QUALITY SAMPLING DESIGN1

ABSTRACT: The design of monitoring programs often serves as one of the major sources of error or uncertainty in water quality data. Properly designed programs should minimize uncertainty or at least provide a means by which variability can be partitioned into recognizable components. While the design of sampling programs has received recent attention, commonly employed strategies for limnological sampling of lakes may not be completely appropriate for many reservoirs. Based on NES data, reservoirs are generally larger, deeper, and morphologically more complex than natural lakes. Reservoirs also receive a majority of their inflow from a single tributary located a considerable distance from the point of outflow. The result is the establishment of marked physical, biological, and chemical gradients from headwater to dam. The existence of horizontal as well as vertical gradients, and their importance in water quality sampling design were the subject of intensive transect sampling efforts at DeGray Lake, a U.S. Army Corps of Engineers reservoir in southern Arkansas. Data collected were used to partition Variance, identify areas of similarity, and demonstrate how an equitable sampling program might be designed.     

ANALYSIS OF FIRM WATER SUPPLY UNDER COMPLEX INSTITUTIONAL CONSTRAINTS1

River basin computer simulation studies often do not properly include the complex legal and institutional factors governing water allocation. These factors include formal water rights and informal borrowing agreements among the basin water users. An attempt has been made in this study to show that such factors can be included. We also show that an optimal, integrated approach to reservoir operations in a river basin can do much to alleviate the burden of new demands placed on available water resources. The procurement of a firm water supply for a proposed coal fired power plant is analyzed as a case study. An efficient river basin simulation model is used to determine the viability of a scheme for providing an annual firm water supply to the plant, with consideration of the existing water storage and demands within the basin. Given the hydrologic sequence considered, the model results show that the proposed strategy is viable in that the required firm water supply can be realized without causing harm to decreed water users in the basin. However, integrated diversion and reservoir operations are required to assure a desirable uniform rate of delivery of reusable effluent to the power plant.     

硝酸盐抑制油田采出水中硫酸盐还原菌活性研究

硫酸盐还原菌(SRB)的生长代谢可导致油藏酸化,进而引发一系列环境和腐蚀等问题.硝酸盐(NO-3)补加及对硝酸盐还原菌(NRB)的调控是抑制SRB活性进而控制油藏酸化的重要策略.本研究从大庆油田水驱采出液中分离筛选出了1株兼性自养的NRB菌株DNB-8,并分析了在有机碳源充足的条件下不同浓度的NO-3结合使用该菌株抑制SRB富集培养物SO2-4还原活性的作用效果与机制.结果表明,浓度≤1.0 mmol·L-1的NO-3无法抑制SRB的SO2-4还原活性;NO-3浓度>1.0mmol·L-1或NO-2浓度>0.45 mmol·L-1均可有效抑制SRB的SO2-4还原活性.此时,NRB对有机碳源的竞争以及在利用NO-3的同时产生的NO-2是抑制SRB活性的主要机制.另外,大庆油田采出水中SRB富集培养物的细胞内存在异化NO-3还原生成NH+4的代谢途径(NO-2为中间产物).当NO-3浓度较高时,SRB可能通过该代谢途径减轻NO-2引起的抑制效应.     

油藏封存CO_2后扩散逃逸数学模型及实例应用

利用油藏封存CO_2是缓解温室效应的重要途径,CO_2扩散逃逸在整个封存体内广泛存在,因此有必要研究扩散逃逸对封存效果的破坏强度。通过理论分析,建立了能够描述油藏封存CO_2后扩散逃逸行为的物理模型和数学模型。结果表明:示范区在1万年累计逃逸量为0.178×104t,1万年累计逃逸量和封存量比值为0.067%,需要1470万年CO_2才能全部逃逸,扩散逃逸对封存破坏甚微。研究结果为CO_2封存效果评价提供了新指标,也为盆地级封存体扩散逃逸量计算提供了方法。     

水位变化对消落带氨氧化微生物丰度和多样性的影响

南水北调来水进入密云水库将直接引起水库水位上涨,这必将影响消落带土壤中氨氧化微生物的丰度和多样性,从而影响消落带中氮循环过程.采用分子生物学方法,探讨了水位变化对消落带氨氧化细菌(AOB)和古菌(AOA)的生物多样性和丰度的影响.Real-time PCR结果显示,2015年9月消落带岸上/水陆界面土壤和沉积物中AOA和AOB的丰度范围分别为1.00×10~7~3.91×10~7copies·g~(-1)和5.49×10~6~9.77×10~6copies·g~(-1).2015年11月水位比9月上升3 m,淹没区土壤/沉积物中AOA和AOB的丰度范围分别为5.80×106~1.56×10~7copies·g~(-1)和2.14×10~6~4.40×106copies·g~(-1),比被淹没前有所下降,但AOA的丰度始终高于AOB,说明AOA比AOB更适合在低氨氮的消落带环境中生长,并且更能适应低氧环境.水位上升3 m后,水陆交界面土壤中AOA和AOB的多样性均有所增加,而在沉积物中多样性减少.水位上涨之前,AOA大多数OTU属于Nitrososphaera、Nitrosopumilus,而水位上涨之后,大多数OTU归属于土壤簇Nitrososphaera,即在低氧消落带环境中土壤簇Nitrososphaera为优势AOA菌.对于AOB,水陆交界面土壤和沉积物中Nitrosopira和Nitrosomonas分别在氨氧化过程中发挥作用.