Sensitivity analysis of optimal operation of irrigation supply systems with water quality considerations

A model for optimal operation of water supply/irrigation systems of various water quality sources, with treatment plants, multiple water quality conservative factors, and dilution junctions is presented. The objective function includes water cost at the sources, water conveyance costs which account for the hydraulics of the network indirectly, water treatment cost, and yield reduction costs of irrigated crops due to irrigation with poor quality water. The model can be used for systems with supply by canals as well as pipes, which serve both drinking water demands of urban/rural consumers and field irrigation requirements. The general nonlinear optimization problem has been simplified by decomposing it to a problem with linear constraints and nonlinear objective function. This problem is solved using the projected gradient method. The method is demonstrated for a regional water supply system in southern Israel that contains 39 pipes, 37 nodes, 11 sources, 10 agricultural consumers, and 4 domestic consumers. The optimal operation solution is described by discharge and salinity values for all pipes of the network. Sensitivity of the optimal solution to changes in the parameters is examined. The solution was found to be sensitive to the upper limit on drinking water quality, with total cost being reduced by 5% as the upper limit increases from 260 to 600 mg Cl l^–1. The effect of income from unit crop yield is more pronounced. An increase of income by a factor of 20 results in an increase of the total cost by a factor of 3, thus encouraging more use of fresh water as long as the marginal cost of water supply is smaller than the marginal decrease in yield loss. The effect of conveyance cost becomes more pronounced as its cost increases. An increase by a factor of 100 results in an increase of the total cost by about 14%. The network studied has a long pipe that connects two distinct parts of the network and permits the supply of fresh water from one part to the other. Increasing the maximum permitted discharge in this pipe from 0 to 200 m³ h^–1 reduces the total cost by 11%. Increasing the maximum discharge at one of the sources from 90 to 300 m³ h^–1 reduces the total cost by about 8%.     

Salinity control in multi-quality irrigation networks — Kibbutz Hamadia feasibility study

A farm-scale water supply system of Kibbutz Hamadia in Israel has been analyzed to demonstrate the feasibility of controlling water quality by using a multi-quality network so as to meet the various water quality requirements at the consumer outlets. The irrigation network has been analyzed in steady-state and transient conditions. The results show the importance of the setting of the degree of opening of the control valves to prevent a shift in the dilution point. The quality of water supplied to the consumers was found to change significantly during the transition period and the consequences of this lag time have been shown.This method offers an alternative to a dual or even multiple water distribution system.     

Three-year growth studies of Leucaena leucocephala (1094) and L. pulverulenta (1001) at two spacings in Texas

The productivity of Leucaena leucocephala and a superior L. pulverulenta family were examined over a 3-year period at spacings (1.5 m×1.5 m and 1.5×3.0 m) chosen to compare two mechanical weeding operations. Leucaena pulverulenta was examined since faster-growing families of this cold-hardy, low-mimosine leucaena species were recently identified. There was no significant difference in yields between the species (P = 0.9060) but there was a significant difference between spacings (P = 0.0491). There was no significant spacing×species, species×year or spacing×year interaction. The annual growth rates for the first, second, and third seasons' growth for L. leucocephala were 3.73, 10.11 and 6.00 t ha⁻¹ at the close spacing and 3.03, 7.14 and 5.04 for the wider spacing. The annual growth-rates for the first, second and third seasons' growth for L. pulverulenta were 2.03, 8.35 and 8.31 t ha⁻¹ at the close spacing and 1.25, 9.38 and 5.29 at the wider spacing. Despite the fact that L. leucocephala froze to the ground in the first and second winter when L. pulverulenta was nearly undamaged, the L. leucocephala coppice resprout was greater than the second year's growth for L. pulverulenta.     

Shifting the natural spring–summer breeding season of the Australian freshwater crayfish Cherax quadricarinatus into the winter by environmental manipulations

Ninety sexually mature Cherax quadricarinatus females were exposed to various combinations of photoperiod and temperature for 2 months during the summer. Females were randomly assigned to either “winter” “semi-winter” or “summer” simulation treatments. In the “winter” treatment, crayfish were exposed to a simulated winter photoperiod (gradual decrease from 14L:10D to 10L:14D, 4 weeks at short day length followed by gradual increase to 14L:10D) and temperature (gradual decrease from 27 to 15 °C, held for 4 weeks, and then gradual increase to 27 °C). In the “semi-winter” treatment, crayfish were exposed to a simulated winter photoperiod and a summer temperature (27–29 °C). In the “summer” treatment, the crayfish were exposed to summer water temperatures and a photoperiod of 14L:10D. Following the 2 months of conditioning, the females were stocked for 7 months in small groups with males under environmental conditions similar to those of the “summer” treatment. All females were individually tagged and molting and spawning events were monitored. Females exposed to “semi-winter” conditioning in the summer, demonstrated a threefold increase in the rate of first spawning during the winter (December–February) compared with the other females. Crayfish breeders can easily implement these findings since shifting the breeding season into the winter only requires shortening of the photoperiod in the summer. The stocking of ponds in the spring with large nursed juveniles that hatched from eggs spawned in the winter, would allow the attainment of market size at the end of the limited growout season in temperate zones.     

The genetics of hard seed coat in the genus Lens

Summary Seeds of the cultivated lentil are capable of germinating shortly after maturation. The seed dormancy of wild lentil species is due to a hard seed coat. In crosses between the cultivated species L. culinaris and its wild progenitor L. orientalis the hard seed coat of the wild species was controlled by a single recessive gene in homozygous condition. In a cross between the wild species L. ervoides and L. culinaris the hard seed coat of L. ervoides was controlled by a single dominant gene. The significance of the genetics of seed coat hardness in the domestication of lentil is briefly discussed.     

Notes on species delimination,species relationships and polyploidy in Avena L.

Summary On the combined evidence from morphology, ecology, and cytogenetics, seven species are recognized in the genus Avena L. 1. A. clauda Dur., 2. A. ventricosa Bal. 3. A. longiglumis Dur, 4. A. strigosa Schreb., 5. A. magna Murphy et Terr., 6. A. murphyi Ladiz. and 7. A. sativa L. The first three species are wild diploids. The fourth is a diploid-tetraploid complex of wild forms, weeds and cultivars. The fifth and sixth are wild tetraploids and the seventh constitutes a hexaploid aggregate of wild forms, weeds and cultivated forms. A short morphological and ecological characterization is given to each species.The cytogenetic, ecological and morphological evidence available on the evolutionary divergence and on the genetic affinities between the seven species is reviewed and discussed. The conclusion in drawn that in Avena there are two independent developments of polyploidy: 1. strigosa tetraploids, where the diploid background is well known; 2. the tetraploid-hexaploid of A. magna, A. murphyi and A. sativa (series Denticulatae). Here the first two species apparently represent the general tetraploid background from which hexaploid A. sativa evolved. It is also argued that it is impossible to explain the morphology, ecology and cytology of series Denticulatae in terms of the known diploid species of Avena, and a yet missing hypothetical diploid ancestor was extrapolated.     

Genetics of allozyme variants and linkage groups in lentil

Summary The genetics of 8 electrophoretically detectable enzymes in lentil was examined. The enzyme systems glutamic-oxaloacetic transaminase, malic enzyme, phosphoglucomutase, alcohol dehydrogenase, 6-phosphogluconate dehydrogenase, shikimic dehydrogenase and isocitrate dehydrogenase were assayed. The allozymes at each of the studied loci behaved in a codominant manner and segregated in the expected Mendelian fashion. Linkage tests between these loci and an additional morphological trait revealed two linkage groups that involved 5 loci, the rest were independent of each other.     

Could early gene flow have created similar allozyme-gene frequencies in cultivated and wild barley?

The possible role of early gene flow between wild and cultivated barley in their similar esterase gene frequencies was tested in a simulation study. The hypothetical population consisted of 99.9% wild forms possessing three alleles of an esterase gene and 0.01% domesticated forms possessing one of these esterase alleles. Various rates of inbreeding, selection coefficients against the wild form and shifting cultivation methods were tested for their effect on the establishment of the domesticated form and the esterase gene flow between the two barley types. Of these factors, inbreeding rates, in the range of 90–99%, had the smallest effect on the establishment of the domesticated form under primitive cultivation. Via gene flow, the esterase allelic frequency in the domesticated form could be similar to that of the wild form under 90% outcrossing in the domesticated form for 115–230 years, an unrealistic situation for barley which normally exhibits about 1% outcrossing. It seems, therefore, that the similar esterase allelic frequencies in wild and cultivated barley is only partly due to gene flow, and it is more plausibly accounted for by multiple domestications.     

Layout structure of multi-quality irrigation networks: I��introduction and layout types

The affect of network structure on the performance of water supply systems of diverse water quality sources was assessed, using analytic methods. The analysis is presented in a series of 3 papers in which this paper is the first of the series. Five types of network structures were analyzed: i) single networks; ii) separate sub-networks; iii) multiple networks; iv) dilution networks; and v) combined dilution-separate networks. The properties of each network type were evaluated using the Q-C ??Feasibility domain?? (QCFD) concept, where discharge (Q) and concentration (C) are the major design parameters. The dilution network type was found most flexible and the single and separate network types were most rigid. The multiple network type provides certain flexibility, however it was exceptionally expensive. The improved network, which combined the advantages of the separate sub-networks with the dilution network was proposed and as an optimal design. The planning of such systems commenced with an initial analysis at the sources-consumers?? level without network facilities. The second stage required analysis of the various structures of the network layout. Ultimately, a layout was assumed and the effect of flow directions in that network was assessed for installation of back flow preventing devices, and improving the control of water quality. A rural region in southern Israel of 6 sources, 5 villages, and 8 fields was chosen. The 5 types of networks were planned for this region. The effect of network structure on the performance of these networks was analyzed and discussed.     

Climatic control of riverine and seawater uranium-isotope ratios

The large variation in the ratio of uranium-234 to uranium-238 (234U/238U) in rivers is not well understood, but may provide information about past weathering and rainfall and is important because it controls seawater (234U/238U). Here, we demonstrate the importance of physical weathering and rainfall for (234U/238U), using rivers from South Island, New Zealand. These data allow interpretation of an existing speleothem (234U/238U) record and suggest that New Zealand glacier advance 13,000 years ago was influenced by increased rainfall rather than by Younger Dryas-like cooling. A model of seawater (234U/238U) during glacial cycles indicates that rejection of corals based on modern (234U/238U) +/- <0.01 is not merited and may reject the highest quality ages.