Dr Indishe Senanayake

The dry zone of Sri Lanka periodically faces drought conditions due to uneven distribution of annual rainfall. Hambantota district in the dry zone can be identified as a severely drought affected area, on the basis of surface water availability. With the ongoing massive development projects in the district, the demand for water will increase significantly in the next few years. Therefore, implementation of a proper water management system is a pre-requisite in facilitating this requirement. The drought severity of Hambantota district was analysed meteorologically, hydrologically and physically using remote sensing and GIS techniques. The combined effect of the above drought components were spatially identified through a matrix overlay operation. The results illustrate that 20% of Hambantota district faces severe water stress conditions, while 11% of the district faces moderate water stress conditions. The resultant drought severity map can be used as a reference in a future water management endeavour to enhance the effectiveness of the project. Copyright© (2013) by the Asian Association on Remote Sensing.

Soil depth is closely related to topography and influences vegetation health and landscape productivity at both hillslope and catchment scales. Soil depth also influences land management and ecosystem sustainability. However, comprehensive hillslope and catchment scale soil depth data remain scarce. In response, this study investigates the relationship between soil depth, surface and bedrock topographic metrics (elevation, slope, aspect, and SAGA topographic wetness index - SWI), and pasture response within a semi-arid hillslope ecosystem in south-eastern Australia. The Normalized Difference Vegetation Index (NDVI) was used as an indicator of vegetation health. A dataset of 183 soil depth measurements was collected using a petrol-powered auger across a 6-ha catchment. Our findings reveal that the relationships between soil depth, topography and vegetation response are complex. There was a general increase in soil depth downslope, indicating potential fluvial transport processes involving erosion and deposition. A subtle increase in NDVI was observed upslope. Soil depth showed no strong correlations with aspect or SWI, but a weak inverse relationship was observed with slope angle. Notably, NDVI displayed a positive correlation with SWI while showing an inverse correlation with slope. Furthermore, the study highlights instances of shallower soils and reduced grass cover beneath two isolated trees, potentially attributable to cattle movement. Soil erosion rates for the catchment are known and soil production rates can be estimated. The data suggests that under current land use practices, soil is being lost at a rate faster than it is being produced. These findings provide valuable insights for land management strategies and sustainable ecosystem maintenance, while demonstrating the complexity of the soil-landscape system.

The government of Sri Lanka has embarked on a massive development programme of the country in all spheres of the economy, with the conclusion of war in May 2009. Sri Lanka is witnessing a new era with a rapid increase especially in infrastructure development projects. With the annihilation of the threats of terrorism, new prospects in satellite and space related technologies and their applications are flourishing. Navigation satellite (NAVSAT) technology plays the core role in a majority of the modern location based services (LBS) and consequent applications can be productively utilized for the development of the country. Global Positioning System (GPS) technology and related services are currently utilized in numerous location based applications in the country. India has launched navigation service providing satellite programmes, including a regional navigational satellite system. Whilst being covered under the footprint of Indian navigational satellite programmes, neighbouring countries of India can positively use their services for the benefit of the country through collaborative approaches. In this paper, positive impacts of 3 Indian Navigational Satellite programmes (GAGAN, IRNSS and INSAT-MSS reporting system) for the civilian applications over Sri Lanka are discussed. Other neighbouring countries covered under the footprint of Indian navigational satellite programmes can also employ these services for the location based applications productively. © 2012 National Authority for Remote Sensing and Space Sciences. Production and hosting by Elsevier B.V. All rights reserved. 70.

Urbanisation leads to rapid constructions, which use low albedo materials leading to high heat absorption in urban centres. In addition, removal of vegetation cover and emissions of waste heat from various sources contribute to the accumulation of heat energy, leading to formation of urban heat islands (UHIs). UHIs have many adverse socio-environmental impacts. Therefore, spatial identification of UHIs is a necessity to take appropriate remedial measures to minimise their adverse impacts. Satellite remote sensing provides a cost-effective and time-saving methodology for spatio-temporal analyses of land surface temperature (LST) distribution.In this study, thermal bands (10.40-12.50. µm) of Landsat-7 ETM+ imagery acquired in 3 distinct dates covering Colombo city of Sri Lanka were analysed for the spatio-temporal identification of UHIs. Vegetation cover of Colombo city was extracted by using NDVI method and subsequently examined with the distribution of LST.A deductive index was defined to identify the environmentally critical areas in Colombo city based on the distribution of LST and availability of vegetation cover. Accordingly, Colombo harbour and surrounding areas were identified as the most critical areas. Remedial measures can be taken in future urban planning endeavours based on the results of this study. © 2013 Elsevier Ltd.

Around two thirds of the area in Sri Lanka is covered by the dry zone, which receives less than 1750 mm average annual rainfall, but not equally distributed over the land. Due to rainfall variations, dry zone of Sri Lanka faced periodic drought conditions in the past. On the basis of surface water availability, Hambantota District appears to be a highly affected area. Tanks have been constructed in order to harvest rainwater to overcome this problem. But, there are many abandoned tanks in Hambantota, which decrease the effectiveness and efficiency of water harvesting. In order to minimize the number of abandoned tanks, an analysis is carried out to find the cause for the abundance of abandoned tanks in the area. Integrating GIS techniques with the relevant data such as rainfall, topographic contours, spot heights, land use, temperature, geology, etc. gives an accurate and updated database, which helps to analyze the reason for the abundance of the abandoned tanks in the area, and hence facilitate the increase of efficiency and effectiveness of rainwater harvesting through a proper water management system. © 2012 National Authority for Remote Sensing and Space Sciences.