More than 80% of agricultural land in Ireland is grassland, providing a major feed source for the pasture based dairy farming and livestock industry. Intensive grass based systems demand high levels of intervention by the farmer, with estimation of pasture cover (biomass) being the most important variable in land use management decisions, as well as playing a vital role in paddock and herd management. Many studies have been undertaken to estimate grassland biomass using satellite remote sensing data, but rarely in systems like Irelands intensively managed, small scale pastures, where grass is grazed as well as harvested for winter fodder. The objective of this study is to estimate grassland yield (kgDM/ha) from MODIS derived vegetation indices on a near weekly basis across the entire 300+ day growing season using three different methods (Multiple Linear Regression (MLR), Artificial Neural Networks (ANN) and Adaptive Neuro-Fuzzy Inference Systems (ANFIS)). The results show that ANFIS model produced best result (R 2 = 0.86) as compare to the ANN (R 2 = 0.57) and MLR (R 2 = 0.31).
Abstract:Soil moisture estimation studies using Synthetic Aperture Radar (SAR) routinely utilise only the amplitude part of the received echo. In this study, repeat-pass C-and L-band interferometric SAR coherence from 2007 -2009 was evaluated for the detection of surface soil moisture changes in the presence of vegetation using two different approaches. In the first analysis, the association between low coherence and large in situ soil moisture changes was investigated using 24 interferometric pairs and the decorrelation effects due to vegetation and weather were also assessed. Results reveal that, in very few cases soil moisture differences between acquisitions contributed to the signal decorrelation. For the majority of cases, particularly in C-band, the change in vegetation tended to be the predominant source of decorrelation, suppressing the influence of any soil moisture changes. The second analysis applied thresholds to both coherence and intensity data to determine if a coalesced coherence ( ) and intensity change ( 0 ) approach could improve detection of changes in measured soil moisture content. The aim was to test the usefulness of a > 0.3 and 0 > 1.5 dB thresholding approach to separate the effects of a vegetation change and a soil moisture change on the SAR signal. Results suggest that the approach improves the reliability of the soil moisture change detection although clearly limits the use of available image pairs. These analyses demonstrate the increased information the coherence adds to SAR studies over agricultural areas.
Coastal mapping plays an important role in informing decision makers on issues such as national sovereignty, resource management, maritime safety and hazard assessment. A key aspect of this trend has been the development of coastal web atlases (CWAs), based on web enabled geographic information systems (GIS). CWAs contain spatial data and thematic information on environmental, social and economic aspects of the coast and provide an integrated visualisation, download and sometimes analysis environment.An important element of CWA development is to ensure that the needs of the target audience are being addressed. Sometimes there can be a break in developer-user communication after the initial atlas design phase is completed. Identifying how to maintain effective engagement by CWA providers with end users is a key task for development teams. A key initial task is to profile the target end users. Workshops and surveys can be effective at this stage. Launch events and media exposure is used effectively to build user communities, however usage drops when such publicity events are discontinued. During the atlas operations phase baseline web statistics are often gathered, but these give a somewhat limited idea of the end user community and their use of the atlases.Additional means of remaining in touch with users and incorporating their requirements in CWAs need to be used. Web 2.0 applications such as "like/dislike" buttons and content comment boxes are used with success in social networking and some news media sites and their utility should be considered for CWAs. Focus groups have also been used with success to complete semi-structured surveys when trying to gather answers to specific questions. It is important to demonstrate to users that the survey has a goal such as atlas improvements in order to motivate them to provide information.Enhancing users' sense of ownership achieved by web applications that allow more direct user input has been accomplished by some CWAs. The strengths and weaknesses of such an approach should be further explored by individual CWAs, as this could enhance the understanding of user needs and improve the relationship of the atlas developer to the user community. Atlas developers within the International Coastal Atlas Network (ICAN) who have worked on the Marine Irish Digital Atlas, the Belgian Coastal Atlas, Chesapeake Bay Atlases, the Washington Coastal Atlas and the Wisconsin Coastal Atlas have significant experience in gathering and analysing user feedback and are investigating means of enhancing their interaction with the end-user community.
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