Classification of Vegetation and Analysis of its Recent Trends at Camp Williams, Utah Using Remote Sensing and Geographic Information System Techniques

Current vegetation classes were generated from remotely sensed data to provide coarse-level information for an ecosystem management plan developed at Camp Williams, Utah. Vegetation trend from 1973 - 1993 was also examined via satellite imagery. The data set consisted of Landsat Multispectral Scanner (MSS) and Thematic Mapper (TM) images from July or August of 1973, 1975, 1980, 1988, and 1993. Two approaches were used to detect vegetation change. The first approach determined overall and cover type trend from standard digital image differencing of soil-adjusted vegetation index (SAVI) images. The second approach used an unsupervised classification of a composite SAVI image of all dates. The first approach defined areas of increase, decrease, and no significant change in SAVI and differences in trend for tree versus shrub cover types. The second approach resulted in an ecological classification that defined new environmental patterns based on vegetation trend

Caractérisation des sous-produits d'oxydation des boues en conditions sous-critiques et supercritiques

L'élimination de la matière organique et la réduction de volume des boues peuvent être obtenues par incinération, par oxydation sous pression en milieu humide ("wet air oxidation") ou par combustion en eau supercritique ("supercritical water oxidation"). Une étude en autoclave agité a permis de comparer sur une même boue d'épuration les performances des deux techniques d'oxydation voie humide et d'oxydation supercritique, en mettant l'accent sur les sous-produits résiduels en phase liquide et la composition de la phase gaz. Les résultats obtenus montrent que l'élimination de la DCO dépend fortement de la température: l'abattement de la DCO passe de 70 % à 235 °C à 94 % à 430 °C. L'azote organique de la boue est transformé en NH4+ mais seule une élimination limitée de l'azote totale est obtenue à 430 °C. Les sous-produits résiduels dans la phase liquide sont constitués en majorité d'acides gras, d'aldéhydes et de cétones, l'acide acétique étant prédominant. Hormis le CO2, les sous-produits gazeux majeurs formés par des réactions complexes comme la pyrolyse, le réformage et la méthanation sont CO, H2 et CH4. Dans les conditions supercritiques, tous les sous-produits gazeux sont fortement oxydés. L'augmentation de la température de traitement permet d'obtenir un résidu solide de plus en plus inerte, les cendres obtenues en conditions supercritiques contenant moins de 1 % de matière organique. Les performances des deux procédés étudiés laissent envisager leur développement à moyen terme comme voies alternatives d'élimination des boues.ContextAs the number of wastewater treatment plants increases, and the efficiency of treatment improves, the problem of how to dispose of the ever increasing amounts of generated sludge has intensified. For the beginning of the next century 1 million tons of sludge will be produced annually in France; disposal in landfills will be impossible and agricultural use could be limited by tight quality standards. Therefore, the development of effective and acceptable sludge processes is urgently needed.Destruction of organic matter in sludge and large reductions in sludge volume are achieved either by incineration or by wet air oxidation (WAO), which needs no fuel and generates no smoke, fly ash or emissions of NOx and SO2. Supercritical water oxidation (SCWO) offers an attractive alternative. Water, above its vapor-liquid critical point of 374°C and 221 bar, is an excellent solvent for organic compounds and becomes completely miscible with oxygen. Reported results of sewage sludge SCWO demonstrate rapid and effective treatment. The objective of this study was to compare sub- and supercritical water oxidation of sludge in terms of organic matter destruction and formation of by-products in both gas and liquid phases. MethodologyOxidation of sludge was studied in a 0.5 L batch reactor rated for 450°C-300 bar. The raw material was a biological sludge containing 4% solids with a chemical oxygen demand (COD) value of 52 g/L. In the standard experimental procedure, 100 mL sludge were heated up to reaction temperature and oxygen was then introduced in 50% excess with respect to COD. Heating was maintained during 1 hour before slow cooling to room temperature. The overall organic destruction was quantified in terms of total organic carbon (TOC) and COD. Gas and liquid phases sampled at room temperature after reaction were analyzed by gas chromatography (GC). Sulfur and nitrogen species were also analyzed.ResultsWhen the temperature increased from 210 to 383°C, COD destruction increased significantly (Table 1). At 383°C, a COD destruction efficiency of 94.3% was obtained. However, at 430°C, organic matter oxidation was only marginally improved. In WAO tests, considerable acetic acid was produced and remained in the substrate. The produced acetic acid was oxidized rapidly under SCWO conditions. Surprisingly, the concentrations of the other volatile fatty acids (VFA) remained approximately constant between 310 and 430°C (Table 2). In addition to VFA, which represent ca. 50% of the residual COD, oxygenated organic compounds such as aldehydes, ketones and alcohols were produced (Table 3). The data in Table 4 show that decomposition of organic nitrogen compounds into ammonia was completed at 383°C, while nitrates were reduced to N2 by reaction with organic matter and ammonia. NOx were not detected in the gas phase. The low reactivity of ammonia in supercritical water had been previously demonstrated. At 430°C, ammonia removal from sludge was limited to 15%. On the other hand, even in WAO conditions all sulfur species were totally converted to sulfate. Under subcritical conditions, the gas phase contained significant concentrations of hydrogen and carbon monoxide in addition to water, residual oxygen and carbon dioxide. Traces of methane and C2-C3 hydrocarbons were also detected (Figs. 1 and 2). These gases result from a complex chemistry including pyrolysis, steam reforming and water-gas shift. Under supercritical conditions, all these compounds were extensively eliminated by oxidation. Under supercritical conditions the residual solids contained less than 1% organic matter. By X-ray diffraction hydroxyapatite, quartz and kaliophilite were identified in the residual solids.These results confirm that supercritical water oxidation is a new sludge treatment concept of great interest. The degree of conversion of organic carbon is high, while liquid and especially gaseous by- products are produced in minor amounts compared to subcritical conditions. Temperatures higher than 430°C would be needed for substantial nitrogen removal

Remote Sensing Of Rice-Based Irrigated Agriculture: A Review

The ‘Green Revolution’ in rice farming of the late 1960’s denotes the beginning of the extensive breeding programs that have led to the many improved rice varieties that are now planted on more than 60% of the world’s riceland (Khush, 1987). This revolution led to increases in yield potential of 2 to 3 times that of traditional varieties (Khush, 1987). Similar trends have also been seen in the Irrigation Areas and Districts of southern New South Wales (NSW) as the local breeding program has produced many improved varieties of rice adapted to local growing conditions since the 1960’s (Brennan et al., 1994). Increases in area of rice planted, rice quality, and paddy yield resulted (Brennan et al., 1994). Increased rice area, however, has led to the development of high water tables and risk of large tracts of land becoming salt-affected in southern NSW (Humphreys et al., 1994b). These concerns have led to various environmental regulations on rice in the region, culminating in 1994 when restrictions on rice area, soil suitability, and water consumption were fully enacted (Humphreys et al., 1994b). Strict environmental restrictions in combination with large areas of land make the management of this region a difficult task. Land managers require, among other things, a way of regulating water use, assessing or predicting crop area and productivity, and making management decisions in support of environmentally and economically sustainable agriculture. In the search for more time and cost effective methods for attaining these goals, while monitoring complex management situations, many have turned to remote sensing and Geographic Information System (GIS) technologies for assistance. The spectral information and spatial density of remote sensing data lends itself well to the measurement of large areas. Since the launch of LANDSAT-1 in 1972, this technology has been used extensively in agricultural systems for crop identification and area estimation, crop yield estimation and prediction, and crop damage assessment. The incorporation of remote sensing and GIS can also help integrate management practices and develop effective management plans. However, in order to take advantage of these tools, users must have an understanding of both what remote sensing is and what sensors are now available, and how the technology is being used in applied agricultural research. Accordingly, a description of both follows: first a description of the technology, and then how it is currently being applied. The applications of remote sensing relevant to this discussion can be separated into crop type identification; crop area measurement; crop yield; crop damage; water use/ moisture availability (ma) mapping; and water use efficiency monitoring/mapping. This report focuses on satellite remote sensing for broad-scale rice-based irrigation agricultural applications. It also discusses related regional GIS analyses that may or may not include remote sensing data, and briefly addresses other sources of finer-scale remote sensing and geospatial data as they relate to agriculture. Since a complete review of the remote sensing research was not provided in the rice literature alone, some generic agricultural issues have been learned from applications not specifically dealing with rice. Remote sensing specialists may wish to skip to section 2

Assessing and Improving Positional Accuracy and its Effects on Areal Estimation at Coleambally Irrigation Area

If management decisions are made with geospatial data that have not been assessed for positional accuracy, then debate about both methodologies of measurement and management decisions can occur. This debate, in part, can be avoided by assessing the positional accuracy of geospatial data, leading to increased confidence (decreased uncertainty) in both the data and the decisions made from the data. In this study, we assessed the positional accuracy of two Geographic Information System (GIS) baseline datasets at the Coleambally Irrigation Area (CIA); high-resolution digital aerial photography acquired in January 2000, and the Digital Topographic Data Base (DTDB) roads data. We also assessed areal error of paddock measurements from an improved accuracy version of the high-resolution digital aerial photography. Positional accuracies were assessed by comparing well-defined features from both baseline datasets (original aerial photography and DTDB roads) to high-level accuracy Differential Global Positioning System (DGPS) data for the same features. This assessment showed that neither baseline dataset met the National Mapping Council of Australia’s standards of map accuracy. Consequently, we processed the original digital photography to create an improved dataset, which was over 2.5 times more accurate than the original photography, and over 4 times more accurate than the DTDB data. The improved dataset also met the map accuracy standard for Australia. We also assessed areal error by comparing paddock boundaries delineated from the improved dataset to those delineated from a DGPS associated with paddock soil surveys. The 90% confidence interval measured from the improved data for any individual paddock is approximately at the ± 5% target error set by Coleambally Irrigation Limited (CIL). The 95% confidence interval is roughly ± 6%. Overall areal error of multiple paddocks is much lower than the individual case with the 95% confidence interval for 2 paddocks being from about ± 4% error reducing to less than ± 2% for 8 or more paddocks. Knowledge of both positional and areal accuracies of the improved high-resolution digital aerial photography provides a means to more effectively manage environmental compliance of rice farmers at CIA and gives the CIL justification for making management decisions from this spatial data

Persistent time intervals between features in solar flare hard X-ray emission

Several solar hard X-ray events (greater than 100 keV) were observed simultaneously with identical instruments on the Venera 11, 12, 13, 14, and Prognoz spacecraft. High time resolution (= 2 ms) data were stored in memory when a trigger occurred. The observations of modulation are presented with a period of 1.6 s for the event on December 3, 1978. Evidence is also presented for fast time fluctuations from an event on November 6, 1979, observed from Venera 12 and another on September 6, 1981, observed from the Solar Maximum Mission. Power spectrum analysis, epoch folding, and Monte Carlo simulation were used to evaluate the statistical significance of persistent time delays between features. The results are discussed in light of the MHD model proposed by Zaitsev and Stepanov

Pneumatic valves for automation of irrigation systems

CER65HRH46.July 1965.Includes bibliographical references

Detection of a fast, intense and unusual gamma ray transient

An unusual transient pulse of approximately 50 keV was detected by the gamma-ray burst sensor network using nine space probes and satellites. Its characteristics are unlike those of the known variety of gamma-ray bursts and therefore suggest that it was formed either by a completely different origin species or in a very different manner. It is identified with the LMC supernova remnant N49

Three precise gamma-ray burst source locations

The precise source regions of three moderately intense gamma ray bursts are derived. These events were observed with the first interplanetary burst sensor network. The optimum locations of the detectors, widely separated throughout the inner solar system, allowed for high accuracy, over-determined source fields of size 0.7 to 7.0 arc-min(2). All three locations are at fairly high galactic latitude in regions of low source confusion; none can be identified with a steady source object. Archived photographs were searched for optical transients that are able to be associated with these source fields; one such association was made

A second catalog of gamma ray bursts: 1978 - 1980 localizations from the interplanetary network

Eighty-two gamma ray bursts were detected between 1978 September 14 and 1980 February 13 by the experiments of the interplanetary network (Prognoz 7, Venera 11 and 12 SIGNE experiments, Pioneer Venus Orbiter, International Sun-Earth Explorer 3, Helios 2, and Vela). Sixty-five of these events have been localized to annuli or error boxes by the method of arrival time analysis. The distribution of sources is consistent with isotropy, and there is no statistically convincing evidence for the detection of more than one burst from any source position. The localizations are compared with those of two previous catalogs

In flight performance and first results of FREGATE

The gamma-ray detector of HETE-2, called FREGATE, has been designed to detect gamma-ray bursts in the energy range [6-400] keV. Its main task is to alert the other instruments of the occurrence of a gamma-ray burst (GRB) and to provide the spectral coverage of the GRB prompt emission in hard X-rays and soft gamma-rays. FREGATE was switched on on October 16, 2000, one week after the successful launch of HETE-2, and has been continuously working since then. We describe here the main characteristics of the instrument, its in-flight performance and we briefly discuss the first GRB observations.Comment: Invited lecture at the Woods Hole 2001 GRB Conference, 8 pages, 15 figure