3 research outputs found
Remote sensing and GIS
Presented at the fifth international conference on irrigation and drainage, Irrigation and drainage for food, energy and the environment on November 3-6, 2009 in Salt Lake City, Utah.Includes bibliographical references.Managing water resources in western US has been a challenge for decision makers. In the last few decades, the rapid growth rates of population along with the alarming rates of global warming have added to the complexity of this issue. In this study, remote sensing techniques have been applied to evaluate the performance of agricultural irrigation, the largest consumptive user of water. The study area, "Palo Verde irrigation District" which is located in Riverside and Imperial counties, California, is an old irrigation district with a fairly heterogeneous cropping pattern. Landsat Thematic Mapper satellite images were used to estimate the actual ET using the SEBAL energy balance model. These estimates were integrated to obtain crop water demand for different periods throughout the growing season. The amount of diverted water was also estimated for the same periods, using flow measurements within the Palo Verde irrigation district. The results were analyzed within the ArcGIS environment in conjunction with water conveyance and field boundary layers to evaluate different performance indicators such as relative water supply, overall consumed ratio, depleted fraction, crop water deficit, and relative evapotranspiration. The results of these indicators can help irrigation managers to get a general idea of how the system performs and to identify possible ways of improving it
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Allometric Equations for Predicting Above-ground Biomass of Tamarix in the Lower Colorado River Basin
Allometric equations are essential for quantitative study of aboveground biomass. The paper presents an effort in acquisition and validation of allometric equation for salt cedar (Tamarix spp.), a species that has been criticized for its invasion and negative impacts on the riparian ecosystem in the western United States. In the summers of 2009 and 2011, biomass destructive samplings were conducted to harvest and collect salt cedar samples at Cibola National Wildlife Refuge, Arizona. The allometric equations were developed by establishing the relationship between aboveground biomass with average basal diameter, tree height, and total basal area. The validity and the strength of the allometric models were examined with the adjusted coefficient of determination (r²), standard error of estimate (SSE), and Akaike Information Criterion (AIC). Total basal area was identified as the best predictor for salt cedar biomass, followed by tree height. Average basal diameter was a poor predictor. In linear equations, total basal area accounted for 78.4 percent of the total variation in aboveground biomass. In logarithmic equations, tree height and total basal area together explained 87.7 percent and yielded the small AIC and SSE. These equations will advance the quantitative estimation of salt cedar biomass and provide useful information for studying evapotranspiration, water consumption, and carbon storage.Desert Plants is published by The University of Arizona for the Boyce Thompson Southwestern Arboretum. For more information about this unique botanical journal, please email the College of Agriculture and Life Sciences Publications Office at [email protected]