1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
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Item Land use pattern and regional water balance in relation to climate change - a case study of Kanthallor panchayath, Idukki, Kerala(Academy of Climate Change Education and Research Vellanikkara, 2018) Vishnumaya, A P; Jalaja S MenonItem Impact of projected climate change on cropping pattern of different agro ecological units of Central Kerala(Academy of Climate Change Education and Research Vellanikkara, 2017) Divya Sunil; Sunil, K MAgriculture faces hastily growing challenges because it must supply food to an increasing population under shifting climate conditions. To stabilize the negative effects of climate change, researchers have generally emphasized incremental adaptation to existing cropping systems, such as the adjustment of planting window, suitable variety and improved agronomic practices. Characterization of the ecosystems using the AEZ concept is a good decision making approach for variety of farming activities performed by the farmers and is a useful tool for the studying the impact of climate change. The objectives of this study are (1) To study rainfall variability and to determine water availability periods of Agro ecological units of Central Kerala under different climate change scenarios. (2) To study the impact of projected climate change on cropping pattern, crop calendar and the possible changes in the water requirements of major cropping systems prevailed in the various Agro ecological Units of central Kerala. Daily rainfall data for the period 1991-2014 were collected from the India Meteorological Department, Thiruvananthapurm. The weather data from General Circulation Models based on RCP 4.5 and 8.5 were analyzed. Weather cock v.1.5 was used for converting the daily weather data into standard week, month and seasonal formats. The rainfall parameters or indices like seasonal and monthly rainfall, rainy days, high rainfall events, length of growing period were calculated. It is also used to compute PET and Thornthwaite water balances. CROPWAT model was used for the calculations of crop evapotranspiration, crop water requirements and irrigation requirements for the development of irrigation schedules under various management conditions and scheme water supply. A decline in rainfall can be observed during the months January, February, September and December in projected climate as per RCP 4.5 and 8.5 whereas an increased rainfall during the months June, July and August. In nut shell the wet months will be wetter and dry periods will be drier. The south west monsoon and summer season shows an increasing trend in the number of rainy days and amount of rainfall in projected climate. The projected climate indicates that there will be a decreasing trend in the number of rainfall events below 50 mm per day whereas the heavy rainfall events show an increasing trend. Most of the agro ecological units in central Kerala indicate a decreasing pattern in the length of growing period in projected climate as per RCP 4.5 and 8.5. In projected climate the maximum amount of potential evapotranspiration can be observed during the months May, July and September whereas the minimum will be in January, November and December. The number of periods were deficit will happen indicate an increasing trend and also the annual amount of deficit show an increasing pattern in projected climate. A shift in the water surplus periods can be observed during projected climate. Most of the AEUs in central Kerala indicate a reduced number of surplus periods in projected climate. The crop evapotranspiration indicate an increasing trend in the rice based cropping system during the projected climate whereas in perennial crops it shows a decreasing trend. The water requirement indicates an increasing trend in most of the major cropping systems whereas in Rice-Fallow-Fallow cropping the irrigation requirement remains unchanged. As a general trend, the length of growing period in the major rice growing areas of different AEUs are getting shorter with slight differences among various agro-ecological units, implying a higher risk of operating under projected climate as per RCP 4.5. The crop calendar of rice based cropping system indicates a delay in sowing date due to delay in summer showers and the crops will have to suffer water stress during the grain filling stage and will be under heavy rains at the time of harvest in projected climate as per RCP 4.5.Item Inter-annual variability of thermal and chlorophyll fronts in selected parts of Eastern Arabian sea and their relation to marine fishery(Academy of Climate Change Education and Research Vellanikkara, 2017) Ananth C Babu; Grinson GeorgeIn the marine ecosystem, distribution of fish, as well as abundance, is determined by the presence of conditions favourable for their existence. Among various oceanic features, frontal zones are important sites promoting fish aggregation and these zones are found to be ideal habitats for fish. Therefore, areas with higher incidence of fronts are likely to be associated with higher fish production, than those with lower frontal incidence. An evaluation of this concept based on total thermal/chlorophyll frontal area of the eastern Arabian Sea (50- 80oE; 0 to 30oN), was performed for the period July 2002 to December 2016. This work utilized 8-day averaged satellite Sea Surface Temperature observations (SST) from MODIS/AQUA sensor as well as 8-day averaged satellite chlorophyll a concentration (Chl-a) from the Ocean Colour Climate Change Initiative (OC- CCI) project. Frontal identification was based on Cayula-Cornillon (1992) single- image edge detection algorithm on the satellite SST/Chl-a image in ArcGIS platform. Seasonal variation of thermal fronts showed maximum frontal coverage (0.5 – 0.6 million km2) during the winter period.Thermal fronts have their lowest incidence (0.2 – 0.3 million km2) during post and pre-monsoon period, and moderate existence during the summer monsoon (0.3 – 0.4 million km2). Chlorophyll fronts showed a slightly different pattern with highest frontal coverage (0.5- 0.6 million km2) during winter period followed by pre and post monsoon period (0.4 – 0.5 million km2). Chlorophyll fronts had their lowest incidence (0.2 – 0.3 million km2) during summer monsoon period.Possible physical reasons for the seasonal variation in thermal and chlorophyll front incidence are discussed. Analysis of inter-annual variability of thermal fronts indicated an increasing trend during 2015 and 2016 whereas chlorophyll frontal area showed a sudden drop in values from mid-2012 onwards. During this period, the usual seasonal variation in frontal zones is not observed. The mechanism responsible for this unusual behaviour was also analysed. Spatial variability of frontal zones in the Arabian Sea indicated that the pattern of variability in the west is different from that of the eastern Arabian Sea. The impact of thermal as well as chlorophyll frontal areaon fisheries during the inter-annual cycle is also discussed.Item Assessment of the impact of sand minig on the morphology of the severely affected reach of Bharathapuzha river between Pattambi and Kuttippuram using remote sensing and GIS(Department of Irrigation and Drainage Engineering , Kellappaji College of Agricultural Engineering and Technology, Tavanur, 2017) Ardra Wilson; Vishnu, BRivers have been a subject of study by engineers and scientists who have been fascinated by their self-formed geometric shapes and their responses to changes in nature and human interference. Among various types of human interventions, indiscriminate extraction of sand and gravel is the most disastrous one, as it threatens the very existence of the riverine ecosystem. Bharatapuzha River in Kerala is a great victim of illegal sand mining. The effect of over exploitation of instream sand on the river morphology is very important for quantifying its effect and for exploring alternatives. The mining activity is particularly very high in the stretch between Pattambi and Kuttippuram of Bharathapuzha river. Use of remote sensing technology coupled with Geographical information system (GIS) is a quick means of gathering latest accurate information, economically. The study was undertaken to assess the morphological changes as well as the spatial and temporal variations along the reach due to sand mining The study utilized DEM imageries to evaluate the effect of sand mining. The study utilized DEM imageries to evaluate the effect of sand mining on the morphology of the river reach by analysing the cross-sectional details. LANDSAT imageries were used to analyse the spatial and temporal variations of channel in the reach. The analysis and assessment of satellite imageries were carried out using the ArcGIS 10.5 software. The Elevation profile add- in toolbar was utilised to create profile graphs by taking sections across the river course in ArcGIS and the morphological changes of the river were calculated by comparing the cross- section profiles. The spatial and temporal variations in river morphology were analysed by extracting the bank lines using Normalized difference Water Index (NDWI) and overlaying the extracted bank lines. The study revealed that the impact of sand mining was high at areas closer to Kuttippuram. Channel enlargement in the reach was found to be varying from 0.52-8.43 m/year. The reach experienced an average rate of change in width of 028m/ year. The shift in bank lines indicated the drifting of the river direction towards the north. From the study, it can be concluded that remote sensing and GIS techniques provided realistic information about the impacts of sand mining on the riverine ecosystem and have sufficient accuracy for use in morphological analysis of rivers.Item Land evaluation and land use planning in Eruthavoor watershed of Western Ghat region using GIS and remote sensing(Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, 2017) Dathan, C S; Usha, C BItem Landslide hazard zonation of Nilambur taluk using remote sensing(Academy of Climate Change Education and Research Vellanikkara, 2016) Asla, K; Vishnu, B