Small inner marsh area delimitation using remote sensing spectral indexes and decision tree method in southern Brazil

<p>Vast small inner marsh (SIM) areas have been lost in the past few decades through the conversion to agricultural, urban and industrial lands. The remaining marshes face several threats such as drainage for agriculture, construction of roads and port facilities, waste disposal, among others. This study integrates 17 remote sensing spectral indexes and decision tree (DT) method to map SIM areas using Sentinel 2A images from Summer and Winter seasons. Our results showed that remote sensing indexes, although not developed specifically for wetland delimitation, presented satisfactory results in order to classify these ecosystems. The indexes that showed to be more useful for marshes classification by DT techniques in the study area were NDTI, BI, NDPI and BI_2, with 25.9%, 17.7%, 11.1% and 0.8%, respectively. In general, the Proportion Correct (PC) found was 95.9% and 77.9% for the Summer and Winter images respectively. We hypothetize that this significant PC variation is related to the rice-planting period in the Summer and/or to the water level oscillation period in the Winter. For future studies, we recommend the use of active remote sensors (e.g., radar) and soil maps in addition to the remote sensing spectral indexes in order to obtain better results in the delimitation of small inner marsh areas.</p>

Block Monitoring Method of SG Tube Support Plate With Intelligent ECT for Maintenance Work

Intelligent ECT (Eddy Current Testing) probe (I-Probe) has a capability to inspect tubes more productively and more accurately than conventional probes for Steam Generators (SG) as shown in Fig. 1. And I-Probe provides effective “One-Pass” solution by combination with MHI (Mitsubishi Heavy Industries, Ltd.) Intelligent Data Analysis System (MIDAS) [1]. It has been applied to full length tube inspection in Japan since 2003 and there is much field experience to date. On the other hand, a phenomenon in SG secondary side is known that scale deposits clog holes of quatrefoil type tube support plate (TSP). Water level oscillation of secondary side caused by excessive blockage of scale deposits may decrease operation efficiency and it can be a cause of unintended troubles. Therefore, periodical monitoring of blockage condition and applying countermeasures like secondary side cleaning are very important. A new method has been developed to evaluate blockage condition of every TSP around all tubes automatically using I-Probe data. Also, a new software has been developed to visualize the evaluation results as color maps. This new method may contribute to increase the reliability of SG maintenance like cleaning, because the new method makes it possible to monitor a whole SG condition more precisely.

A post-Lake Minong transgressive event on the north shore of Lake Superior, Ontario: possible evidence of Lake Agassiz inflow

Modification of an ice-contact delta built on the margin of Lake Minong (9500 BP) is ascribed to a transgressive event. Reworking of fluvial sediments by wave action and the infilling of the lower end of a distributary valley demonstrate a post-Minong transgression and reoccupation of the lower portion of the delta. Estimated to be in the order of 18 m, this water-level oscillation may represent evidence of one of several catastrophic discharges of Lake Agassiz into the Superior basin, proposed to have occurred between 9.5 and 8.0 ka BP.