Analysis of Livelihood Asset Pentagon to Assess the Performance of Irrigation Systems

Abstract

There has been a growing consciousness for the need for a framework that is holistic and comprehensive in the assessment of irrigation system performance. This paper presents the results of statistical tests conducted on the analytical framework developed in Part 1 of the paper to examine whether or not it addresses the important issues of system performance. Information collected from two farmer-managed irrigation systems of Nepal was used to test the validity of the framework. The empirical evidence shows that the framework is valid in identifying and fitting conventionally-overlooked livelihood assets and that it demonstrates differences in farm households' access to these assets resulting in varying performance of irrigation systems.     

Simple Method for the Design of Microirrigation Paired Laterals on Sloped Fields

In this study, a method for designing paired laterals that meet with required water application uniformity on sloped fields was developed using the energy gradient line approach based on the definition of the best submain position locations in which the same minimum pressure exists in uphill and downhill laterals. The best equation form of best submain position was determined. Also, the solution procedure was introduced to get the final solution to avoid the phenomena of no convergence or slow convergence. In this method, the required water application uniformity was used directly as a computational parameter in designing. When the designed emitter discharge, required water application uniformity and one parameter (either length or diameter) of a paired lateral are provided; the system developed here enables another parameter and the best submain position to be determined for any field slope conditions. Taken together, the results of this study show that final solutions can be obtained quickly and reasonably.     

红旗陂农民用水协会的组建及灌区管理实践

本文介绍了江西省于都县红旗陂农民用水户协会组建的主要做法和成效，供同行参考。     

Hydraulic Analysis and Optimum Design of Multidiameter Irrigation Laterals

A new analytical continuous-uniform outflow approach that takes into account the effect of the number of outlets on the multidiameter lateral hydraulics is presented. The pressure head profile along the multidiameter pipeline is described by a simple analytical function providing direct calculation of the outlet pressure head along the pipeline. The method is significantly improved by introducing an adjusted spatially variable outflow equation—of power function form—for the errors caused by the assumption of equal outlet discharge. The effect of ground slope on hydraulic computation is also considered. Simple equations are derived for the direct calculation of the maximum, minimum, and inlet pressure head along the multidiameter pipeline. The optimum design problem for two-diameter laterals is also solved analytically. For specified total length of a two-diameter pipeline, a simple algebraic equation is derived to calculate directly the appropriate lengths of the reaches of different diameters in such a way that the total cost of the pipeline is minimized. Comparison tests with an accurate numerical stepwise method indicate that the proposed analytical approach is sufficiently accurate.     

北京钟鼓楼地区更新前期研究：现状成因.历史脉络.更新动力

分析了钟鼓楼地区现状的基本问题与矛盾，其形成原因，历史发展演变过程以及此地区更新的内在动力，在此基础上提出更新设计目标及原则建议，为下一步进行详细设计提供依据。     

Analysis of Residential Irrigation Distribution Uniformity

Irrigation has become commonplace for residential homeowners desiring high quality landscapes in Florida. The goal of this project was to document irrigation system uniformity in Central Florida and to quantify distribution uniformity of residential sprinkler equipment under controlled conditions. The catch-can testing procedure used was a modified version of both the American Society of Agricultural Engineers standard and Florida Mobile Irrigation Laboratory (MIL) procedures. The modified version included a larger sample size to ensure complete sample collection over the entire irrigated area. The standard MIL procedure may overestimate the uniformity for residential systems. From the tests on residential irrigation systems, the average low quarter distribution uniformity (DUlq) value was calculated as 0.45. Rotary sprinklers resulted in significantly higher DUlq compared to fixed pattern spray heads with 0.49 compared to 0.41, respectively. From uniformity tests performed on rotor and spray heads under ideal conditions, rotor heads had more uniform distributions than the spray heads of 0.55 compared to 0.49, respectively. Spray heads had better uniformity when fixed quarter circle nozzles were used as opposed to adjustable nozzles. Both residential irrigation system and controlled tests resulted in (DUlq) at the low end of industry guidelines. Residential irrigation system uniformity can be improved by minimizing the occurrence of low pressure in the irrigation system and by ensuring proper spacing is used in design and installation.     

The Bad Blumau geothermal project: a low temperature, sustainable and environmentally benign power plant

The 250 kW geothermal project at Bad Blumau is the first geothermal project developed in Austria by the private sector following the deregulation of the electricity industry in this country. What makes the project unique besides its private ownership structure is its ability to generate electrical power and district heating for the Rogner Bad Blumau Hotel & Spa by using a low temperature geothermal resource. Installed in the record time of less than a week, the air-cooled ORMAT ® Energy Converter (OEC) CHP module has been in commercial operation since July 2001. With an annual availability exceeding 99%, between October 2001 and December 2002 the plant delivered 1,560,000 kWh to the local grid. The geothermal CHP module utilizes brine at 110 °C, available from a 3000 m deep production well. Exiting the OEC unit at a temperature of 85 °C, the brine is then fed into the district heating system, providing heat for the Rogner Bad Blumau Hotel & Spa. The geothermal brine is returned from the district heating system and injected into a 3000 m depth reinjection well. The system is a pollution-free, unattended operating power generation module, which has avoided more than 1100 kg of CO₂ emissions over its first operating year.     

Discharge Relation for Cutthroat Flume under Free-Flow Condition

A cutthroat flume is commonly used as flow measuring device for open-channel flow due to ease of fabrication and installation. In most of the cases it is difficult to calibrate the flume in the field. Therefore, accurate relation between discharge and upstream head applicable for all sizes of cutthroat flume is needed. Seven different sizes of cutthroat flumes, having different length to throat width ratios, are fabricated and tested in the laboratory under free-flow condition. Selecting groups of different variables describing flow through a cutthroat flume number of dimensionless parameters are formed. Regression analysis of experimental data is carried out between all possible combinations of pairs of dimensionless parameters and the pair giving the best correlation is selected. Using the selected pair, relation between dimensionless parameters of discharge and head is developed. The relation is simple and convenient to use and, at the same time, more accurate compared to methods available in literature for prediction of discharge.     

Demand Forecasting for Irrigation Water Distribution Systems

One of the main problems in the management of large water supply and distribution systems is the forecasting of daily demand in order to schedule pumping effort and minimize costs. This paper examines methodologies for consumer demand modeling and prediction in a real-time environment for an on-demand irrigation water distribution system. Approaches based on linear multiple regression, univariate time series models (exponential smoothing and ARIMA models), and computational neural networks (CNNs) are developed to predict the total daily volume demand. A set of templates is then applied to the daily demand to produce the diurnal demand profile. The models are established using actual data from an irrigation water distribution system in southern Spain. The input variables used in various CNN and multiple regression models are (1) water demands from previous days; (2) climatic data from previous days (maximum temperature, minimum temperature, average temperature, precipitation, relative humidity, wind speed, and sunshine duration); (3) crop data (surfaces and crop coefficients); and (4) water demands and climatic and crop data. In CNN models, the training method used is a standard back-propagation variation known as extended-delta-bar-delta. Different neural architectures are compared whose learning is carried out by controlling several threshold determination coefficients. The nonlinear CNN model approach is shown to provide a better prediction of daily water demand than linear multiple regression and univariate time series analysis. The best results were obtained when water demand and maximum temperature variables from the two previous days were used as input data.     

潇河灌区渠系改造节水效益评析

潇河灌区经过近 5 0年的运行 ,渠系建筑物老化破损严重 ,灌溉水利用率极低。通过实施渠系改造工程 ,渠系水利用率由 0 .485提高到 0 .6 3,年节水量 70 4万m3,增加灌溉面积 8.6万亩次 ,节水效果明显 ,经济效益显著 ,保障了灌区的可持续发展