OCR Text |
Show Meteorological and hydrological data are particularly necessary during the construction phase of projects to efficient utilization of construction facilities and to protect the contractor's equipment, coffer dams, and other tem- porary works. Further these data lay the groundwork for operation and maintenance of the project. Operation and Maintenance After a project is completed, there is a continuing need for the collection of meteorological and hydrologic data essential to the efficient operation of the project. This is particularly true in the case of multiple-purpose proj- ects and in the case of projects which are a part of a system which has unified or integrated operation. The operation of an integrated system of reservoirs inrolves dispatching water through the system for efficient utili- zation, and conservation of water and protection of life and property from floods. This is a complex task and re- quires an adequate amount of data of high accuracy to satisfactorily control and dispatch the water. By categories, the following data should be obtained for operation of a project or a system of projects. Precipitation.-There is needed an adequate network of stations covering the watershed of a project so located that they provide in advance essential information from which runoff may be estimated.- Such stations must be located so that regular reports, daily or oftener, can be sent from the station to some central point for use in forecasting river flow and water-control operations. In remote areas, where ordinary means of communication are not available, then automatic transmitting radio precipi- tation gages are needed. A certain number of these radio gages are also desirable to provide insurance in the case of storms which disrupt line communications. In addition to the regular network of reporting stations, other stations are required to refine forecasting of runoff stages for each watershed. Evaporation and Other Meteorological Data.-Records should be collected for appropriately located stations so that reservoir losses may be estimated. Surface Water.-There is needed an adequate network of stream gaging stations so located as to provide essential data regarding the current flow of water in all important streams throughout the watershed. The stations must be located with respect to the stream pattern. If communi- cation facilities are available for quick transmission of stream stages, then ordinary recording gages installations are satisfactory. If such facilities for communication are not available, then automatic radio transmitting gages must be used. These radio gages, as in the case of pre- cipitation gages, provide excellent insurance against wire transmission failing during storm periods. For a system of multiple-purpose reservoirs, greater accuracy of stream flow determination is required for operating purposes through a series of reservoirs. Without a high degree of accuracy, the water-dispatching operations are greatly handicapped due to apparent flow discrepancies. Water temperature data throughout a reservoir are needed in order to determine the flow pattern of water through the reservoir. Water temperature data are also important in other operating situations such as water cooling. Ground water.-Data on the quantity of water in the ground at any time are very important in operation. Such water is actually in storage and will be discharged over a period of time varying with the watershed. In a mul- tiple-purpose system, it is important to know what this quantity of water is in order to plan for the most efficient use of water over perhaps 1 or 2 months in the future. Ground water and amount of soil moisture in a watershed also give the water-control engineers a basis for estimating runoff from rain storms since storm runoff is influenced greatly by the moisture condition of the watershed at the time of the storm. Soil moisture meters and ground water well installations are necessary to pro- vide data on ground water and soil moisture. Quality of water.-Additional data may be needed in connection with domestic water supply, industrial diffi- culty in the use of polluted water (either bacterial or chemical pollution), or reservoir operation for irrigation. Sedimentation.-Data are needed with regard to reser- voir sedimentation in order to determine when the project operation may be affected by deposition in a reservoir. Likewise, the planning of current corrective measures that may improve operating conditions or prolong project life require that accurate sedimentation data be secured on a regularly planned schedule. Topography.-Maps prepared for purposes of project report and design should be adequate. Maps should be available covering the watershed of the operating projects so that the engineers will have information as to the char- acter of the topography which is an important factor in estimating stream flow. Geology.-Information previously obtained is usually sufficient. Fish and wildlife.-Biological investigations are con- ducted and various types of operational data collected in connection with the management of Federal and State fish and wildlife. Various types of data may be collected in connection with biological investigations in the project area during its operational life. Socio-economic data.-After a project is built, basic socio-economic data are needed to evaluate costs of opera- tion and maintenance as shown in table 1. 335 |