Discharge Capacity of Labyrinth Side Weir Located on a Straight Channel

Side weirs, also known as lateral weirs, are flow diversion devices widely used in irrigation as a head regulator of distributaries and escapes, land drainage, and urban sewage systems. The studies on the subject have been generally focused on rectangular and triangular side weirs located on a straight channel. However, the same is not true for labyrinth side weirs. The current studies deal with sediment transport and scour problems around side weirs and lateral structures. The investigation of the hydraulic effects of labyrinth side weirs to increase discharge capacity of them has been studied in this particular work. In the study, 2,830 laboratory tests were conducted for determining discharge coefficient of labyrinth side weirs, and results were analyzed to find the influence of the dimensionless weir length L/b, the dimensionless effective length L/?, the dimensionless weir height p/h1, triangular labyrinth side weir included angle θ, and upstream Froude number F1 on the discharge coefficient, water surface profile and velocities in the channel along the side weir. It has been found that discharge coefficient of labyrinth side weirs gives pretty higher coefficient value compare to that of classical side weirs and a reliable equation for discharge coefficient of labyrinth weirs is presented. Discharge coefficient of the labyrinth side weir is 1.5–4.5 times higher than rectangular side weir.     

River Hydrograph Retransmission Functions of Irrigated Valley Surface Water–Groundwater Interactions

Storage and release functions of western U.S. traditional river valley irrigation systems may counteract early and rapid spring river runoff associated with climate variation. Along the Rio Grande in northern New Mexico, we instrumented a 20-km-long irrigated valley to measure water balance components from 2005 to 2007. Hydrologic processes of the system were incorporated into a system dynamics model to test scenarios of changed water use. Of river water diverted into an earthen irrigation canal system, some was consumed by crop evapotranspiration (7.4%), the rest returned to the river as surface return flow (59.3%) and shallow groundwater return flow that originated as seepage from canals (12.1%) and fields (21.2%). The modeled simulations showed that the coupled surface water irrigation system and shallow aquifer act together to store water underground and then release it to the river, effectively retransmitting river flow until later in the year. Water use conversion to nonirrigation purposes and reduced seepage from canals and fields will likely result in higher spring runoff and lower fall and winter river flow.     

农业大棚的温湿度控制系统

为了适应作物生长过程中所需参数值不是精准值的实际并且尽可能取得较理想的控制效果 ,系统采用了模糊控制技术。实现对棚内的空气湿度、土壤湿度及温度三项主要灌溉参数的自动检测及显示。由键盘输入三项灌溉参数的参考值 ,系统的模糊逻辑自动控制相应炉、泵通断 ,调节棚内温湿度 ,使其趋于参考值。器件选择留有余地 ,便于扩展。     

大型灌区闸系分布式监控系统设计

本文介绍了一种灌区闸系分布式监控系统的设计方法。简单介绍了DCS系统的发展和结构形式,对该分布式控制系统的设备选型和软件设计作了详细说明,该控制系统的使用是实现大型灌区综合信息化的重要前提。     

橡胶止水带在禹门口提水工程U型渡槽上的应用

U型渡槽槽身止水是渡槽设计中比较难处理的问题，往往因处理不当，造成槽身漏水，情况严重时甚至可能引起基础产生不均匀沉陷。禹门口提水灌区工程渡槽设计曾采用过多种止水方案，经运行检验证明，橡胶止水带方案效果较好，投资较省，是一种较好的止水型式，可供类似工程借鉴。     

节水灌溉器材设备开发与应用

我国的节水灌溉设备需求量大，是广阔的大市场。目前我国已初步形成了门类比较齐全的节水灌溉器材设备生产制造体系，但与发达国家比，还有很大差距。为促进我国节水灌溉事业的发展，国产器材设备必须在产品科技含量、技术性能、使用可靠性、稳定性、耐久性上下工夫。     

Pan Evaporation to Reference Evapotranspiration Conversion Methods

Reference evapotranspiration (ET0) is often estimated from evaporation pan data as they are widely available and of longer duration than more recently available micrometeorologically based ET0 estimates. Evaporation pan estimation of ET0 ( = KpEpan) relies on determination of the pan coefficient (Kp), which depends on upwind fetch distance, wind run, and relative humidity at the pan site. The Kp estimation equations have been developed using regression techniques applied either to the table presented in FAO-24 or to the original data upon which this table was based (from lysimeter studies in Davis, Calif.). Here, the relative performances of the FAO-24 table and six different Kp equations are evaluated with respect to reproducing the original data table using the FAO-24 table as a standard. Evaporation pan- and CIMIS-based estimates of ET0 are also compared for stations having ranges of mean humidities (48–66%) and mean wind runs (156–193 km/day) located in the Sacramento and San Joaquin valleys, and for a coastal station (Point Heuneme) near Ventura, Calif., having a greater mean humidity (71%). In comparing the means, standard deviations, root-mean-square errors, and linear regression coefficients, five of the six equations reproduced the original data table with approximately the same accuracy as the FAO-24 table. Use of either Kp table slightly underestimated measured ET0 at the coastal site, while the Cuenca, Allen-Pruitt, and Snyder Kp equations most closely approximated the average measured ET0 at all seven sites.     

Irrigation water requirement models of some major crops

A case study of the Mahanadi-Kathjori-Devi delta of Orissa, India was undertaken for the formulation of irrigation water requirement models of some major crops. Principal crops such as paddy (both during the Kharif and Rabi Seasons), sugarcane, jute, chilly, mustard, groundnuts, etc., which are mostly grown in the delta, were taken into account for the present study. Effective rainfall and irrigation water requirements are the two basic parameters of the developed models. The models help in predicting irrigation water requirements for different crops once the values of effective rainfalls are ascertained. This irrigation water requirement, estimated by models so developed, includes water requirements for consumptive use only and when any other water used for special requirements such as leaching, seed bed preparation, etc., is added to it, the total irrigation water requirement is determined. The models so developed can be used for the same crops grown in other areas having the same hydrometeorological characteristics.     

Irrigation Scheduling. II: Heuristics Approach

A sequential irrigation schedule that honors user demands of duration and minimizes earliness and tardiness is interpreted as a single-machine schedule with earliness and tardiness costs and a common deadline (or fixed interval). A heuristic solution is presented for this irrigation scheduling problem. Four models are presented to reflect the different methods in which an irrigation system at the tertiary unit level may be operated, the first model permits jobs to be noncontiguous, i.e., idle time between jobs is permitted, whereas the others permit contiguous jobs only. The heuristic is tested extensively and the solution quality is compared with either an optimum solution from an integer program or the best available solution obtained from an integer program within allocated computation time. The heuristic is computationally efficient for all models presented, however for schedules with noncontiguous jobs, or where idle time is inserted before and after a contiguous set of jobs, solution quality deteriorates. The work brings the science of single scheduling from operations research into irrigation scheduling and suggests areas for further development.     

A case study of the Rajasthan canal

The study deals with the policy issues relevant to agriculture development in arid regions where water has a very high economic value. The experience gained in irrigation planning under such conditions in different parts of the world is described. The issues relevant for such a study are the level of technology, the cropping pattern, the area under cultivation and the size of the holdings. For the study of these issues a linear programming model maximizing returns, subject to land and water constraints, has been developed and is applied in the Rajasthan canal command area. The study concludes that agriculture and irrigation technology of a high level should be used to maximize benefits and production, which would also generate more employment.