Broad-Crested Weir Application on 15,000-Acre Farm

Growers in California have been subjected to increasing pressure to account for water used on the farm due to limited water supplies and increasing energy costs. Water measurement capability provides for equitable distribution of assigned costs and enables effective water management to be accomplished. Broad-crested weirs are proven water measurement devices, especially when applied to on-farm applications. The broad-crested weirs and published data were developed by the USDA Agricultural Research Service in Phoenix, Arizona. This paper is a discussion of an application of these weirs

ITRC Weir Stick

The Irrigation Training and Research Center, working under a technical service agreement with the United States Bureau of Reclamation (USBR) Mid-Pacific Region, has developed a new weir rule for open-channel flow rate measurement

Telog PR-31 Water Level Tracker

The Irrigation Training and Research Center, working under a technical service agreement with the United States Bureau of Reclamation (USBR) Mid-Pacific Region, has undertaken a performance review of advanced electronic water level measurement technologies in irrigation applications. An example is the Telog PR-31 Level Tracker

USCID 14th technical conference

Presented at Contemporary challenges for irrigation and drainage: proceedings from the USCID 14th technical conference on irrigation, drainage and flood control held on June 3-6, 1998 in Phoenix, Arizona.Includes bibliographical references.Water properties, such as the viscosity and surface tension, can be affected by temperature and surfactants to increase infiltration rates into soils. Specifically, they will change the hydraulic conductivity of the soil. A simple soap solution and the new material PAM (inexpensive polymer chemical) were evaluated as surfactants. Laboratory experiments and field tests on a site in Davis, California were done to quantify the effects of changing the water properties. Additional effects, like the improved soil structure during infiltration and less soil particles in tailwater (reduced erosion due to runoff) were observed and are described in this paper. The conclusions of this study are translated into suggestions for improved on-farm water use in furrows, sprinklers, and drip irrigation

Evaluation of Subsurface Drip Irrigation on Peppers

This paper is a summary of two farms that utilized the California Energy Commission\u27s low-interest loan program to facilitate their entry into drip irrigation. One farm is located near Oxnard, California, USA and the other is located near Gilroy, California, USA. Both of these growers farm about 162 hectares (400 acres) in their overall operations and used the loans to purchase subsurface drip irrigation systems for Peppers. Over $4 million in low-interest loans have been made available to California growers from the California Energy Commission (CEC) since 1986. The CEC initiated the loan program for growers to help implement energy conservation practices. The primary findings ofthis paper include: I) The growers needed a two to three year learning curve to solve basic problems. They continually adapt to new challenges by trying different approaches to management and hardware. 2) The nature of problems will change from year to year. 3) Peppers have an excellent yield response to drip irrigation. The energy used (per unit yield) decreased and the volume of water required (per unit yield) decreased. Fertilizer application accounts for a significant amount of the total input energy for peppers (over 30%) due to the energy required to manufacture N-based fertilizers. Fertilizer application rates remained relatively constant. This is the area for greatest future reduction in energy use, by gradually using less fertilizers. 4) Both growers are expanding the amount of drip irrigation systems on their farms

Use of personalised risk-based screening schedules to optimise workload and sojourn time in screening programmes for diabetic retinopathy:A retrospective cohort study

Background: National guidelines in most countries set screening intervals for diabetic retinopathy (DR) that are insufficiently informed by contemporary incidence rates. This has unspecified implications for interval disease risks (IDs) of referable DR, disparities in ID between groups or individuals, time spent in referable state before screening (sojourn time), and workload. We explored the effect of various screening schedules on these outcomes and developed an open-access interactive policy tool informed by contemporary DR incidence rates. Methods and findings: Scottish Diabetic Retinopathy Screening Programme data from 1 January 2007 to 31 December 2016 were linked to diabetes registry data. This yielded 128,606 screening examinations in people with type 1 diabetes (T1D) and 1,384,360 examinations in people with type 2 diabetes (T2D). Among those with T1D, 47% of those without and 44% of those with referable DR were female, mean diabetes duration was 21 and 23 years, respectively, and mean age was 26 and 24 years, respectively. Among those with T2D, 44% of those without and 42% of those with referable DR were female, mean diabetes duration was 9 and 14 years, respectively, and mean age was 58 and 52 years, respectively. Individual probability of developing referable DR was estimated using a generalised linear model and was used to calculate the intervals needed to achieve various IDs across prior grade strata, or at the individual level, and the resultant workload and sojourn time. The current policy in Scotland—screening people with no or mild disease annually and moderate disease every 6 months—yielded large differences in ID by prior grade (13.2%, 3.6%, and 0.6% annually for moderate, mild, and no prior DR strata, respectively, in T1D) and diabetes type (2.4% in T1D and 0.6% in T2D overall). Maintaining these overall risks but equalising risk across prior grade strata would require extremely short intervals in those with moderate DR (1–2 months) and very long intervals in those with no prior DR (35–47 months), with little change in workload or average sojourn time. Changing to intervals of 12, 9, and 3 months in T1D and to 24, 9, and 3 months in T2D for no, mild, and moderate DR strata, respectively, would substantially reduce disparity in ID across strata and between diabetes types whilst reducing workload by 26% and increasing sojourn time by 2.3 months. Including clinical risk factor data gave a small but significant increment in prediction of referable DR beyond grade (increase in C-statistic of 0.013 in T1D and 0.016 in T2D, both p < 0.001). However, using this model to derive personalised intervals did not have substantial workload or sojourn time benefits over stratum-specific intervals. The main limitation is that the results are pertinent only to countries that share broadly similar rates of retinal disease and risk factor distributions to Scotland. Conclusions: Changing current policies could reduce disparities in ID and achieve substantial reductions in workload within the range of IDs likely to be deemed acceptable. Our tool s

Hydrous upwelling across the mantle transition zone beneath the Afar Triple Junction

The mechanisms that drive the upwelling of chemical heterogeneity from the lower to upper mantle (e.g., thermal versus compositional buoyancy) are key to our understanding of whole mantle con- vective processes. We address these issues through a receiver function study on new seismic data from recent deployments located on the Afar Triple Junction, a location associated with deep mantle upwelling. The detailed images of upper mantle and mantle transition zone structure illuminate features that give insights into the nature of upwelling from the deep Earth. A seismic low-velocity layer directly above the mantle transition zone, interpreted as a stable melt layer, along with a prominent 520 km discontinuity sug- gest the presence of a hydrous upwelling. A relatively uniform transition zone thickness across the region suggests a weak thermal anomaly (<100 K) may be present and that upwelling must be at least partly driven by compositional buoyancy. The results suggest that the lower mantle is a source of volatile rich, chemically distinct upwellings that influence the structure of the upper mantle, and potentially the chemis- try of surface lavas