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Wave energy is a renewable resource with high energy potential. This research work proposes a low power piezoelectric energy harvesting system based on the heave motion of ocean buoys. This Piezoelectric Energy Harvester (PEH) is composed of piezoelectric diaphragms coupled with superballs to enhance the output of the piezoelectric sensor. The PEH setup is designed within a floating buoy and tested in a wave flume by varying the frequency of regular waves. The heaving of the buoy causes the superball to oscillate and impact upon the piezo diaphragms thereby producing power. This output is then processed using appropriate AC to DC converter and booster circuits. The single-axis sensor-diaphragm responses under regular wave conditions with varying wave heights were analyzed. A rms voltage of about 2.56 V was generated for a wave height of 0.21 m and wave period of 1.2 s. The wave flume experimental results show that the maximum harvested power was about 80 mW by the entire piezo sensor diaphragm setup for the wave height range of 0.06 m to 0.21 m and wave period of 1.22 s to 2.13 s. Using the same technique in the ocean buoys of diameter 0.9 m in the swell wave conditions between 0.5 to 3.5 m significant wave height, the system can generate maximum voltage of up to 16 V using 28 numbers of superballs with sensors arranged in parallel/series combinational power circuits. This harvesting technique will be very much useful for coastal & offshore buoys to harvest power in a hybrid approach during the failure in solar battery charging during monsoon and unfavorable weathers. [ABSTRACT FROM AUTHOR]

Research on the effect of climate variability/climate change on runoff is limited in humid tropical regions. Climate change has implications beyond the water resources sector, such as effects on agriculture and fisheries. Hence, such studies are becoming increasingly important. This study uses both historical field data and future climate forecasts from General Circulation Model Hadley Centre Coupled Model, version 3 GCM HadCM3. These data are further downscaled using third generation of the Hadley Centre's regional climate model (HadRM3), with Providing REgional Climates for Impacts Studies (PRECIS) software under the three Quantifying Uncertainties in Model Projections (QUMPs) with a horizontal resolution of 25 km X 25 km by the Centre for Climate Change and Adaptation Research, Anna University Chennai, for the state of Tamil Nadu. These downscaled data are used to study runoff changes due to climate change for the Kosasthaliyar sub-basin in South India. A trend analysis of the hydro-meteorological data for the sub-basin indicates that future rainfall is expected to decrease by approximately 10%, while the mean temperatures will increase by the year 2100. The runoff changes from 2011 to 2040 are not perceptible when compared to the historical period of 1971 to 2000. This study attempts to provide information on climate variability and its impacts on runoff in the Kosasthaliyar sub-basin. [ABSTRACT FROM AUTHOR]

This paper applies Soft Systems Methodology ( SSM) within the context of action research and Integrated Flood Management ( IFM). A case study from the Adayar watershed, Chennai, is provided as an example of how SSM can be used to understand complex situations and as a problem-solving strategy for flood management. Flat topography, uncontrolled urban development, population growth, sand bar formation at the river mouth and low tidal action render complexity to flood management in Chennai. For effective flood management, a participatory and integrated approach, which includes stakeholders in the decision-making process and an enabling institutional set-up, is essential. As part of an integrated approach, the relationship between various organizations and the public is identified. SSM is an approach for addressing fuzzy problematic situations involving human activity. In this paper, SSM techniques like 'Rich Picture Diagrams' and ' CATWOE analysis' and participatory action research tools like 'pairwise ranking' and 'force field analysis' were investigated. Two workshops were conducted to define and explore the problematic situation, the role of various actors involved in the problem, to develop the conceptual model, to rank decision-making criteria, and to analyse the forces for and against to solve the problem. The flood management approach provided in this paper can be used by government agencies and policy makers to manage floods. [ABSTRACT FROM AUTHOR]