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Irrigation systems involve both physical works and human activity. There is little need to discuss the physical works or the fact that human activity, such as management and the knowledge and effort to irrigate, are essential. High tension systems require extensive physical works and diligent management to stretch and hold the water membrane in place. Except for fully automated mechanical systems, irrigation is essentially a "happening." There are three potential management levels: the main system, the middle system, and the farmer system. The objective of the farmers who are the beneficiaries of public irrigation systems is to maximize their net benefits from irrigation by maximizing the productivity per unit of land, which is usually their scarce resource. In most irrigation projects or systems, infrastructure and/or management are such that the water is not equitably distributed to all the land. The lack of equity can occur at the main system level between unit command areas (UCAs) or within the UCAs.

In this paper, we introduce the Lehigh Ocean Research Craft Autonomous (LORCA) — a high performance USV with applications to surveillance and monitoring tasks. Compact (1.2 m), lightweight (5 kg) and robust (one-piece carbon fiber design), LORCA is capable of speeds of 80 kph (50 mph). It was also designed to be capable of operations in ocean waves, with self-righting ability in all sea states. We first review the LORCA design and technical specifications. We then discuss our initial work in trajectory following where an EKF-based approach is employed for localization and a sample based planner for control. Using only the sensing and computational resources available on a 3DR Pixhawk, we demonstrate effective trajectory following in a riverine environment at peak speeds of 48 kph (30 mph). We conclude with discussions on the limitations of the current approach and planned future work.

Despite the impressive gains in global food production over the last half century, an estimated 790 million people remain hungry. Many of the chronically hungry are poor farm families, who have neither the means to produce the food they need nor sufficient income to purchase it. For them, access to irrigation water, or the means to use the water they have more productively, is a key to increasing their crop production, their incomes, and their household food security. Ironically, a technology typically associated with wealthy farmers, drip irrigation, may hold the key to alleviating a significant share of rural hunger and poverty. A new spectrum of drip systems keyed to different income levels and farm sizes (beginning with a US$5 bucket kit for home gardens) now exists and can from the backbone of a second green revolution, this one aimed specifically at poor farmers in sub-Saharan Africa, Asia, and Latin America. We describe the experience with affordable drip irrigation to date, including its ...

Irrigation application using a low-cost microtube-type drip irrigation system tends to be relatively non-uniform especially under steep slopes and low operating pressure heads. This study was conducted to evaluate the effect of using a simple and inexpensive adjustable valve (AV) pressure regulator on water distribution uniformity of the low-cost microtube-type drip system under sloping conditions at various operating pressure heads. A 100 m 2 microtube-type drip kit developed by the International Development Enterprises (IDE) was tested for water distribution uniformity with and without AVs under average operating pressure heads of 0.5, 1.0, and 1.5 m, submain slopes of 10%, 20%, and 30%, and lateral slope of 0%. Based on volumetric measurement of emitter discharge, the average Christiansen’s coefficient of uniformity (CU) and Merriam and Keller’s distribution uniformity (DU) values improved to a range of 76% to 94% and 64% to 91%, respectively, with AV adjustment. For all pressure heads and submain slope of 30%, CU and DU were increased by an average of 25% and 82%, respectively, with AV adjustment. Pair-wise t-test comparison (I±=5%) of average CU and DU values for each setting showed significant improvement of water distribution uniformity except for a combination of a high pressure head of 1.5 m and steep slopes of 20% and 30%. These exceptional results suggest that at relatively steep slopes, the microtube-type drip system may be operated at relatively low pressure heads with proper AV adjustment to increase the water distribution uniformity. Results indicated that the use of AVs can significantly improve water distribution uniformity of the low-cost microtube-type drip irrigation system at low pressure heads even at slopes as steep as 30%, and offers the potential for maximizing crop yield in steep upland areas.

To profit from growing high value commodity, vegetable, and horticultural crops smallholder farmers need affordable irrigation products to get the most “crop per drop” and net income from small-plot (0.1 to 1 ha) irrigation systems. In view of this we have developed a generic Small-plot Irrigation Product (SIP) line that includes three types of drip, two types of sprinkle, and a piped surface irrigation application system. Simple to manufacture polyethylene layflat tubing of diameters between 16 mm and 75 mm and with thicknesses ranging from 125 to 900 microns is used for the pipe networks.

This paper demonstrates the potential productive and economic advantages of designing for deficit (or under-) irrigation of selected crops in water short areas. The example presented is for the supplemental irrigation of rainfed coconut trees in the state of Kerala, India. In particular, the productive and economic advantages of designing drip systems for deficit irrigation as compared to standard drip systems designed for full irrigation to meet potential evapotranspiration is demonstrated.

Several water technologies that have been designed specifically for and are being marketed to resource poor farmers (smallholders) with small land holdings are presented. Both the market creation approach to development and the appropriate technologies are described. The water technologies include: treadle pumps and storage tanks to supply water for crop irrigation; and low-cost drip and mini-sprinkle irrigation systems to apply water to high value crops. The development of these efficient and affordable water technologies provides smallholders with an essential tool for intensifying their farming practices. This allows them to grow high value crops and significantly boost their farming income while also increasing crop production per unit of water used and consumed.

THE selection of irrigation systems and management of irrigation water to maximize profit from crop pro-duction implies an optimization process of some sort. Such an optimization of irrigation system design is a complicated task and most often it is done by intuition. It involves the physical system, crop growth patterns, crop response to water and fertility and on-farm manage-ment practices. This paper presents a methodology for relating the selection of irrigation system design parameters to the crop production profitability. Irrigation system unifor-mity along with the scheduling of applied water has an important effect on crop yield and thus net farm income. A computerized technique is used which related system uniformity and scheduling practices to crop growth and production. For a given irrigation system design, furrow, sprinkle, or trickle, and a particular scheduling scheme, the seasonal water application which will maximize the net profit from a specified crop can be estimated. The computerized mathemathical model requires data relating system costs and design parameters to water ap-plication uniformity, crop-water production functions (from field data or crop growth models), production costs, and system capital costs. This systematized design process allows the designer to evaluate relative trade-offs between water, system and crop production costs, and returns with relative ease. Without this capability many irrigation systems, as a result of minimal effort expended in their design, are less than adequate for the field condi-tions in which they must operate. The inclusion of more relevant variables into a workable design process should prove helpful in increasing the designers' awareness of the interaction of crop production with irrigation systems. It is not our purpose to present an exhaustive array of design examples. However, field based crop pro-duction and economic data for sugar cane are used to il-lustrate the technique.

Expressions are developed and presented for the pressure head available at any point within a trickle irrigation subunit. Histograms are drawn showing the distributions of pressure within typical subunits. Distributions of emitter flow rates within typical subunits are derived from considerations of the effects of pressure differentials and manufacturing variations in emitter characteristics. The coefficient of emitter manufacturing variation is shown to be a significant design consideration. The equations and distributions developed are used to complete tables giving the emission uniformity and efficiency of systems for various combinations of design and equipment characteristics.

Energy inputs to irrigation are dramatically increasing as irrigated agriculture expands to meet world food demands and more sophisticated technologies are developed to increase water use efficiency. In this study nine irrigation systems, designed for a specific land area, are analyzed and the total energy inputs computed for each system. The analysis includes energy inputs to manufactured components and installation as well as operation and maintenance. The expected life of each system and the energy value of salvable materials are also taken into account. It is concluded that a practical balance must be established between maximizing water use efficiency and minimizing water use efficiency and minimizing energy inputs to the irrigation system.

During 1962 apholate-sterilized male boll weevils, Anthonomus grandis Boheman, normal males, and virgin untreated females were released in 2 experimental 1-acre plots of cotton in Virginia and Tennessee in the ratio of 20:1:1 in each of 5 uniformly distributed points. In 7 additional weekly releases, about 20 sterile males were placed at each distribution point. Release of the sterile male failed to achieve eradication, possibly because of low competitiveness of the males subjected to this sterilant. In a third experimental plot in Louisiana, 10 gravid females were released and permitted to oviposit for 6 days before the initiation of a sterile-male release program designed to provide an overwhelming number of sterile males at the height of the F1 emergence. A total of 8850 sterile males, released over an 8-week period, prevented or nullified matings between the ensuing F1 males and females. Dissection of ovipsition-punctured squares, collected from the 4th to 11th week after release of sterile males began, failed to yield a larva, pupa, or adult. Proof that eradication was achieved was obtained on the 17th week of the experiment when no egg or feeding punctures were found in 2 examinations of all the squares and bolls on plants in the field. A high ratio of sterile insects was required to achieve eradication, but the experiment established that the sterility principle could be applied for the elimination of a boll weevil population, even when the sterile males used were low in mating competitiveness.

Results of large scale model study on design of interceptor drains; previously developed analytical relationships for determining shape of resultant water table drawdown curve are analyzed; new relationships are developed for estimating flow from drains; examples given.

Water use efficiency and economic factors as a basis for the selection of irrigation methods for farm systems and projects are examined. A brief review of comparative studies of water application and operational efficiencies is presented. This review indicates that farmers obtain approximately the same application efficiency with sprinkler irrigation as do research workers. The researchers, however, obtain considerably higher efficiencies than farmers when using surface irrigation methods. A review of comparative irrigation costs demonstrates the relative cost between methods and facilities when the limiting resource is land or water. The effect of methods on the management of both farms and projects is considered.

Career Development Programs (CDPs) are a rather recent area of study in organizational and industrial psychology. The present study investigated the status and evaluation of such programs in Fortune 500 firms. Data were obtained by a questionnaire completed by each firm's human resources director. Of the 500 companies surveyed, only those that had programs in place ( N = 50) were analyzed. The programs were targeted at middle-to-upper level managers and the programs were evaluated as being quite helpful. These programs were usually of short duration (workshops lasting several days) and conducted by professionals from within the organization. The findings were discussed in light of some recent literature in the field.