DESALTING SALINE WATER FOR IRRIGATION A CASE STUDY,COACHELLA AREA,CALIFORNIA1

ABSTRACT .A case study was performed to evaluate potential applications of desalted saline water for agriculture using 2 distillation type processes and 2 membrane type processes. The investigation determined the costs and benefits associated with desalting saline water at concentrations of 1,500, 900, 400, 200, and 50 ppm. Benefits from desalting are generated by shifts to more profitable crops, reduced costs for drainage, and reduction in fertilizer and labor requirements with better quality water. Costs are based on the project features such as desalting plants, raw water diversion facilities, storage reservoirs, conveyance and distribution systems, brine disposal, blending facilities, and gypsum addition systems. Hydrologic studies determined the crop irrigation requirements, water demand schedules, desalted water storage requirements, brine disposal requirements, and size of facilities required. Reconnaissance design layouts were made for producing desalted water using a combination of 14 schemes. The study also included a review of irrigation practices. The benefit-cost ratios range from 0.4 to 1.0 for 1,500 ppm irrigation water to 0.8 to 1.0 for 50 and 200 ppm water. Investment costs per acre are high, ranging from $12,900 to $20,900. Irrigation benefits are based on the increase in production from a desert condition with no water supply to the irrigation conditions studied.     

FLOW DURATION CURVES II: A REVIEW OF APPLICATIONS IN WATER RESOURCES PLANNING1

ABSTRACT: A streamflow duration curve illustrates the relationship between the frequency and magnitude of streamflow. Flow duration curves have a long history in the field of water-resource engineering and have been used to solve problems in water-quality management, hydropower, instream flow methodologies, water-use planning, flood control, and river and reservoir sedimentation, and for scientific comparisons of streamflow characteristics across watersheds. This paper reviews traditional applications and provides extensions to some new applications, including water allocation, wasteload allocation, river and wetland inundation mapping, and the economic selection of a water-resource project.     

A STOCHASTIC DYNAMIC PROGRAMMING BASED APPROACH TO THE OPERATION OF A MULTI-RESERVOIR SYSTEM1

ABSTRACT: An heuristic iterative technique based upon stochastic dynamic programming is presented for the analysis of the operation of a three reservoir ‘Y’ shaped hydroelectric system. The technique is initiated using historical inflow data for the downstream reservoir. At each iteration the optimal policies for the downstream hydroelectric generating unit are used to provide relative weightings or targets for operation of upstream reservoirs. New input inflows to the downstream reservoir are then obtained by running the historical streamflow record through the optimal policies for the upstream reservoirs. These flows are then used to develop a new operating policy for the downstream reservoir and hence new targets for the upstream reservoirs. The process is continued until the operating policies for each reservoir provide the same overall system benefit for two successive iterations. Results obtained from the procedure are compared to the results obtained by historical operation of the system. The procedure is shown to develop operating policies which give benefits which are as close to the historical benefits as can be expected given the choice of the number of storage state variables.     

3池交替运行活性污泥法生物除磷脱氮的探讨

介绍了 3池交替运行活性污泥法进行生物除磷脱氮的运行模式 ,从理论上探讨了溶解氧、污泥龄等运行参数的确定与控制及碳源、硝酸盐对工艺生物除磷脱氮的影响。     

重症胰腺炎手术治疗的护理

本文对我院2001年以来收治的54例重症胰腺炎患者手术治疗的护理进行总结，以求对重症胰腺炎患者手术治疗中的护理工作提供参考．     

地震电磁辐射前兆判据探讨

本文对DPJ和ULF型地震电磁辐射观测仪观测场量的主要特征进行简单的理论分析,并综合国内各地观测资料,初步探讨了电磁辐射方法在短临预报应用中有关时、空、强的前兆判据问题:1.电磁辐射异常信号的弱-强-弱-平静-发震的变化过程中,多点位异常时间趋于集中之后的信号减弱甚至平静,可能是数十小时内发震的一种标志。2.目前所观测到的地震电磁辐射信号主要来自震源(或震中)方向。3.利用lgT-M关系曲线能在一定程度上定量估算未来地震的强度。     

邻避型PPP项目的运营模式与居民环境行为研究

运营模式的科学设计以及居民环境行为的有效管理是邻避型PPP项目能否成功的关键。针对邻避项目存在的低收益和居民环境行为转变难两大问题,本文基于计算实验理论与方法构建邻避型PPP项目的运营模式与居民环境行为模型。通过对利益相关主体的社会属性与行为变化规律分析,进而设计运营商、政府、居民和从业人员等主体的计算实验交互规则。模型与计算实验研究了邻避型PPP项目的运营状态和居民环境行为在自负盈亏与统一价格、最小收益保证与统一价格、固定收益率与统一价格、自负盈亏与阶梯价格、最小收益保证与阶梯价格、最小收益保证与阶梯价格以及固定收益率与阶梯价格等六种情景下的演变规律。研究发现:(1)阶梯价格能在短期内改善邻避型PPP项目的运营状况,统一价格机制更有利于项目长远发展。(2)自负盈亏并不是邻避型PPP项目的一个理想方案,收益担保是一个相对稳妥可行的选择,而固定收益率是一个对政府财政有高要求的优化模式,可优化居民环境行为并降低PPP项目的邻避效应。(3)自负盈亏模式下运营商无心开展环境教育和提高从业人员待遇,固定收益率模式有利于推行环境教育并提高从业人员待遇。(4)邻避型PPP项目的环境投入-环境意愿-环境行为之间存在时滞效应。这意味着,较难通过收益模式与价格机制的调整实现系统的最优化,市场的力量无法协调邻避型PPP项目目前存在的矛盾与冲突,需要政府统一管理价格并保证社会资本的回报。同时,改善居民环境行为和管理邻避项目是一个复杂系统工程,需要有系统的筹划与长期时间的积累。     

负荷历时曲线法在梁子湖流域污染容量总量控制中的应用

采用负荷历时曲线法(LDC),基于水质保护目标,研究水体纳污能力,确定最大日负荷总量(TMDL)是当前流域污染总量控制的主要方法之一。根据梁子湖高桥河流域控制断面2008~2011年的水文、水质数据,以主要污染物COD为指标,将负荷历史曲线法运用到梁子湖高桥河等子流域污染容量总量控制中,对该流域的最大日负荷(TMDL)变化规律进行分析,提出流域不同水文条件下的污染负荷消减量。研究结果表明:梁子湖水环境受面源污染影响较大。高桥河、徐家港、张家桥港、山坡港、宁港流域,在高流量期实际负荷值均已超出了允许负荷,其削减量分别为61.36、4.33、12.98、3.84、7.13 t/d;徐家港和宁港流域在丰水期实际负荷值也超出了允许负荷,削减量分别为0.16、0.17 t/d。该研究为流域相关管理部门对湖泊水环境的污染控制提供可靠的决策依据。     

REGIONAL RAINFALL INTENSITY-DURATION-FREQUENCY CURVES FOR PENNSYLVANIA1

ABSTRACT: A statistical analysis of all available continuous hourly and 15-minute duration rainfall records for Pennsylvania was performed to develop an updated procedure to estimate design storms. As a resuit of this study, Pennsylvania was divided into five homogeneous rainfall regions and a set of rainfall intensity-duration curves developed for each region, for return periods of 1 to 100 years and durations ranging from 5 minutes to 24 hours. The PDT-IDF curves were judged to be a better representation of Pennsylvania rainfall than the nationwide TP-40 maps, particularly for storm events of 10-years and lower return periods. The average time distribution of 24-hour storms in Pennsylvania was found to be well represented by the SCS Type II distribution. The Corps of Engineers SPS 24-hour distribution was found to differ appreciably from both the SCS Type H and the Pennsylvania 24-hour storm distribution. For storm durations between 15 and 90 minutes the standard Yarnell intensity-duration curves closely resemble Pennsylvania storm distributions.