APPLICATION OF THE HEC-4 MONTHLY STREAM FLOW SIMULATION MODEL1

ABSTRACT: The HEC-4 monthly stream flow simulation model, developed by the Hydrologic Engineering Center, Davis, California, is used to extend the available historical stream flow records in the Central Ohio area. The principal objective of this paper is to examine the effectiveness of the HEC-4 model in generating synthetic monthly flows. Important statistical parameters are evaluated in order to relate the statistical properties of the historical and generated flows. In doing so, it is observed that the mean, standard deviation, and skewness of the generated flows are consistently larger than the corresponding estimates based on historical flows. However, results show that these statistics, as well as the lag-1 serial correlation, are generally well maintained by the generated sequences. The degree to which any statistical dissimilarities would be critical, from an engineering design point of view, is demonstrated by utilizing their low flow characteristics. Estimates of reservoir safe-yields, based on a nonsequential mass-curve analysis of the historical and generated low flows, indicate a nominal difference in this particular study.     

RESERVOIR SEDIMENTATION AND ITS CAUSES IN ILLINOIS1

ABSTRACT: During the years 1930 to 1978 a research program has been carried out in Illinois dealing with reservoir sedimentation. Detailed surveys have been made on 107 lakes. A generalized graph allows annual reservoir capacity loss in percent to be estimated based on size of watershed, lake capacity, and watershed ratio. For the 258 square miles of land on the watershed of Lake Springfield, complete soil maps were measured using a graphic digitizer. A computer readable map was produced. The Universal Soil Loss Equation was solved to provide upland soil losses for each acre of the watershed. Average watershed soil loss was 3.96 tons per acre per year, and 24 percent of this was delivered to the lake.     

A QUASI-LINEAR SPATIALLY DISTRIBUTED CELL MODEL FOR THE SURFACE RUNOFF SYSTEM1

ABSTRACT: The paper presents a spatially distributed model consisting of cells that are interconnected in a pattern similar to the major drainage network of the watershed. Each cell receives as input the rainfall excess for the area represented by the cell as well as inflows from cells located upstream. Outflow from the cell is derived by routing the total input through the cell assuming it to be a linear reservoir during the storm. The time constant of the cells is however allowed to vary from storm to storm so that the model may be described as a quasi-linear model. The model was tested with rainfall excess and direct surface runoff data available for a medium size watershed with satisfactory results. The time constant was found to be related to the rainfall excess of the storms studied, its value decreasing with the increase in the total rainfall excess.     

IMPLEMENTATION OF AN OPTIMIZATION MODEL FOR OPERATION OF A METROPOLITAN RESERVOIR SYSTEM1

ABSTRACT: A deterministic dynamic programming optimization model with a refining sectioning search procedure is developed and implemented to find least cost withdrawal and release patterns for water supple from a multiple reservoir system serving a metropolitan area. Applications are made to teh four reservoir system operated by the city of Dallas, Texas. A realistic cost structure, including nonlinear power consumption, block rate unit power costs, and flow dependent power consumption for intracity water distribution, is utilized. Applications are made to find least cost operating patterns and, as well, by inclusion of a water loss penalty function, supply patterns which will reduce evaporation water losses for the Dallas system.     

LEAF LITTER BREAKDOWN IN A RECENTLY IMPOUNDED RESERVOIR1

ABSTRACT: The impoundment of Richard B. Russell Lake resulted in the inundation of 3490 ha of forested area or 33 percent of the total area of the lake. Estimates of the total inundated leaf litter biomass were combined with a leaf litter decomposition study to determine the nutrient load and dissolved oxygen demand to the reservoir. Hickory leaf bags broke down most rapidly at the 3-m and 28-rn depths, followed by short-needle pine, white oak, a hardwood litter mixture, beech, and red oak. Leaf bags incubated at the 3-m depth exhibited significantly higher breakdown rates than those at the 28-m depth for most leaf types, due to differences in dissolved oxygen and temperature. Respiration rates of litter were also higher at the 3-m depth. Most leaf types accumulated nitrogen and phosphorus and lost organic carbon after an initial leaching period. Richard B. Russell Lake exhibited extensive anoxia and the buildup of total organic carbon, nitrogen, and phosphorus during summer stratification. Leaf litter breakdown accounted for 64 percent of the organic carbon increase but acted as a sink for nitrogen and phosphorus. The dissolved oxygen demand of the litter accounted for over 50 percent of the demand incurred in the lake.     

RESERVOIR WATER LEVEL IMPACTS ON RECREATION,PROPERTY, AND NONUSER VALUES1

ABSTRACT: Wise interbasin management of Southeastern U.S. water resources is important for future development. Alabama‐Coosa‐Tallapoosa and Apalachicola‐Flint‐Chattahoochee River basins' water usage has evolved from power generation to multiple uses. Recreation and housing have become increasingly valuable components. Changing use patterns imply changing resource values. This study focused on six Alabama reservoirs, using contingent valuation questions in on‐site, telephone, and mail surveys to estimate impacts on lakefront property values, recreational expenditures, and preservation values for scenarios of permanent changes to reservoir water quantity. As summer full‐pool duration decreased, lakefront property value decreased, and as duration increased, property values increased, but at a lesser rate. Similar findings occurred for winter draw down alternatives. Permanent one‐foot reductions in summer full‐pool water levels resulted in a 4 to 15 percent decrease in lakefront property values. Recreational expenditures decreased 4 to 30 percent for each one‐foot lowering of reservoir water levels. Current nonusers of the six reservoirs showed strong preferences for protecting study reservoirs with willingness to pay values of 47 per household or approximately 29 million for the entire six‐reservoir watershed basin area. Resource management based on historic use patterns may be inappropriate and more frequent and comprehensive valuation of reservoir resources is needed.     

暴雨后水库中铁、锰超标成因分析

以福建省某水库为例,对南方地区暴雨后水库中铁锰超标现象从外污染源、地下水、土壤、底质多方面进行了分析,找出了该类型水库中铁、锰超标的原因,并提出建议。     

天津市地热资源开发及可持续利用研究

根据天津市地热资源勘探，开发和科研资料。对天津市地热资源的形成条件。热储类型和资源潜力分析评价。采用压力场和温度场藕合的三维有限元模拟方法，对热储动态进行预测，以此确定每眼井的年开采量，并逐步实行对井回灌开采。实现地热资源的可持续利用。     

铁岭柴河水库水源涵养区环境问题及控制对策

简述了柴河水库水源涵养对保护水源水质、改善水质的作用；针对柴河水库水源涵养区氮磷污染、面源污染和生态破坏等存在的主要环境问题，提出了可操作性较强的保护措施。     

以科学发展观加强磨盘山饮用水源地的水质保护

磨盘山水库饮用水工程将有艰巨的水源地水质保护任务.磨盘山饮用水源地存在的潜在环境问题,包括旅游开发对饮用水源地将构成威胁;面源污染将影响水库水质;保护区内开荒种田破环水质和森林植被仍在减少等.建议在加强磨盘山水库饮用水源保护方面进一步加强科学研究工作,尽快制定和完善相关法规体系,尽快出台水源地保护区划分.