Assessment of spatial-temporal changes in water bodies and its influencing factors using remote sensing and GIS - a model study in the southeast coast of India.

Concerns have been raised about the threat of ecological imbalance due to the loss of water bodies in densely populated areas. The present study explored the changes in water bodies in terms of area, number, and size in northern districts of Tamil Nadu, India, between 1978 and 2018 using satellite data, geographic information system, spatial analysis, ground truth verification, and field validation. The analysis indicated that the water bodies' area has reduced by 3027 ha and 4363 ha in the Kancheepuram and Tiruvallur Districts, respectively. Almost 179 water bodies have entirely disappeared, and 628 water bodies have been partly converted for other purposes. Of the disappeared water bodies, small, medium, and large water bodies account for 53, 93, and 33, respectively. The main reason for the changes in water bodies was the conversion to agriculture and buildings. Overall, the water bodies' area and number have been reduced by 9% and 12%, respectively, while the population has grown by 37%. The water bodies lost due to anthropogenic activities demand the scientific inventory of water bodies and integrated water resources management at a state or national level with strict monitoring regulations to protect them.

Multi-criteria coastal environmental vulnerability assessment using analytic hierarchy process based uncertainty analysis integrated into GIS.

Changes in environmental conditions influence vulnerability due to interacting stresses and pressures across the nations and regions. Coastal resources are under severe stress due to climate change, growing trade and commerce, and the human population depends on them. The coastal vulnerability to changing climatic variables has created a major concern at regional, national and global scales. The present model study assessed the coastal vulnerability of the densely populated districts in South India, which are prone to extreme climatic events at a higher frequency. The seven crucial influencing variables that have been selected for the study were sea-level rise, coastal elevation, coastal slope, extreme rainy days, historical shoreline change, tidal range, and geomorphology. The identified variables were ranked by relative importance and linked by weightage using analytical hierarchy process-based uncertainty analysis. Mapped and reclassified variables have been integrated to derive the overall vulnerability using geospatial techniques. The study shows that the coast has experienced high vulnerability to SLR impact, extreme rainfall, geomorphology, and elevation; medium vulnerability to the shoreline change and least vulnerable to coastal slope and tidal range. Of the coastal regions studied, 29% and 14.3% had high vulnerability; 70.5% and 85.7% had medium vulnerability in the two selected densely populated districts (Kancheepuram and Tiruvallur District). Applying geospatial techniques to assess the environmental vulnerability resulted in reliable and informative maps which will serve as a model to determine the critical coastal regions to plan for the conservation and adaptation measures.

Conventional aortic valve replacement for high-risk aortic stenosis patients not suitable for trans-catheter aortic valve implantation: feasibility and outcome.

OBJECTIVE: High-risk patients with aortic stenosis are increasingly referred to specialist multidisciplinary teams (MDTs) for consideration of trans-catheter aortic valve implantation (TAVI). A subgroup of these cases is unsuitable for TAVI, and high-risk conventional aortic valve replacement (AVR) is undertaken. We have studied our outcomes in this cohort. METHODS: Data prospectively collected between March 2008 and November 2009 for patients (n = 28, nine male) undergoing high-risk AVR were analysed. The mean age was 78.4 ± 9.2 years. The mean additive EuroSCORE (European System for Cardiac Operative Risk Evaluation) was 10.0 ± 3.6 and mean logistic EuroSCORE was 19.9 ± 18.8. Three patients had undergone previous coronary artery bypass grafting (CABG). RESULTS: The mean ejection fraction was 51 ± 16%, mean valve area 0.56 ± 0.19 cm², and mean peak gradient 91 ± 27 mm Hg. Ascending aortic, right axillary artery and femoral artery cannulation was used in 64%, 29% and 7% of cases, respectively. Median cross-clamp and cardiopulmonary bypass times were 84 (68-143) min and 111 (94-223) min. The median (range) inserted valve size was 21 (19-25) mm. Median intensive care and overall hospital stay were 5 (2-37) and 11 (5-44) days, respectively. In-hospital mortality was 4% (one patient). Postoperative complications included re-operation for bleeding (7%), renal failure (21%), tracheostomy (14%), sternal wound infection (7%), atrial fibrillation (25%) and permanent pacemaker implantation (7%). Kaplan-Meier survival at median follow-up of 359 (148-744) days was 81% (one further death of non-cardiac aetiology). Quality-of-life assessment at follow-up also yielded satisfactory results. CONCLUSIONS: MDT assessment of high-risk aortic stenosis in the era of TAVI has increased the number of referrals. Conventional open surgery remains a valid option for these patients, with acceptable in-hospital mortality and early/midterm outcomes but high in-hospital morbidity.