D.D.G.L. Dahanayaka

Monitoring mangrove distribution and changes in Mekong delta, Vietnam using remote sensing approach

This study provides the capability of mapping, monitoring distribution and changes of regional mangroves using remote sensing data. The study area located in Mekong delta, Vietnam. Landsat ETM+ and digital elevation model (DEM) were used to enhance the discrimination between mangrove and non-mangrove forests and MAD technique was used to assess the changes in the mangrove cover in study area. Results showed that information from satellite remote sensing can play a useful role in determining the changes in land area and mangrove cover in Mekong Delta, especially mangrove forests has been significantly reduced in Tra Vinh province during 2000-2005.

Prototype of E-Learning Management System for secondary school in Sri Lanka

With the advancement of Information communication Technology in Sri Lanka, teachers should take advantage to upgrade their teaching techniques. Because, E-learning techniques are getting very popular in Sri Lanka. Students should be allowed to learn anytime, anywhere and at their own place. Teachers should be able to keep collection attractive questions and course materials online. Teachers who are from different schools should be able to share resources and exchange ideas through the Internet. The motivation for this research is to solve the problems of shortage of online resources for students under the condition of high student-teacher ratio in Sri Lanka. In order to solve this problem, our research group developed a prototype system called KISSEL. The Knowledge Integration Servers System for E-Learning (KISSEL) is a knowledge sharing platform for E-learning and sustainability sciences which is focused mainly on Asian-Pacific countries. Our system is mainly for school teachers and school children in Asian Pacific countries.

Integration of multisource data for chlorophyll-a monitoring in Negombo estuary, Sri Lanka

In order to estimate chlorophyll-a concentration (Chl-a) for tropical coastal estuarine environments using satellite optical sensor, observations were conducted from 1987 to 2009 in Negombo estuary, Sri Lanka, with support with available in-situ measurements. Landsat band ratios were regressively analyzed with available in-situ Chl-a data. This relationship was used for correcting MODIS OC3 Chl-a values, and then ASTER band ratios were regressively analyzed with the corrected MODIS values. The regression equations obtained for ASTER and Landsat were used to develop algorithms for generation of 15m and 30m resolution Chl-a distribution maps, respectively, in Negombo estuary using atmospherically-corrected time-series imageries. The results indicate that some parts of the estuary have increased eutrophication conditions during 1987–2009.

Monitoring and predicting eutrophication of Sri Lankan inland waters using ASTER satellite data

This study focused on determining the past changes and predicting the future trends in eutrophication of the Bolgoda North lake, Sri Lanka using in situ Chlorophyll-a (Chl-a) measurements and Advanced Spaceborne Thermal Emission and Reflectance Radiometer (ASTER) satellite data. This Lake is located in a mixed land use area with industries, some agricultural lands, middle income and high income housing, tourist hotels and low income housing. From March to October 2013, water samples from five sampling sites were collected once a month parallel to ASTER overpass and Chl-a, nitrate and phosphate contents of each sample were measured using standard laboratory methods. Cloud-free ASTER scenes over the lake during the 2000-2013 periods were acquired for Chl-a estimation and trend analysis. All ASTER images were atmospherically corrected using FLAASH software and in-situ Chl-a data were regressed with atmospherically corrected three ASTER VNIR band ratios of the same date. The regression equation of the band ratio and Chl-a content with the highest correlation, which was the green/red band ratio was used to develop algorithm for generation of 15-m resolution Chl-a distribution maps. According to the ASTER based Chl-a distribution maps it was evident that eutrophication of this lake has gradually increased from 2008-2011. Results also indicated that there had been significantly high eutrophic conditions throughout the year 2013 in several regions, especially in water stagnant areas and adjacent to freshwater outlets. Field observations showed that this lake is receiving various discharges from factories. Unplanned urbanization and inadequacy of proper facilities in the nearby industries for waste management have resulted in the eutrophication of the water body. If the present trends of waste disposal and unplanned urbanization continue, enormous environmental problems would be resulted in future. Results of the present study showed that information from satellite remote sensing can play a useful role in the development of time series Chl-a distribution maps. Such information is important for the future predictions, development and management of this area as well as in the conservation of this water body.

Assessing the potential of satellite and ground spectral data for Chlorophyll-a monitoring in Lake Kasumigaura, Japan

The suitability of a handheld spectrometer and ASTER satellite data for monitoring Chlorophyll-a (Chl-a) in Lake Kasumigaura, Japan was tested in July 2010 to December 2013. ASTER based Chl-a retrieval algorithms were developed support with in-situ Chl-a, MODIS OC3 Chl-a and Kakemaoki and Koshin automated water quality monitoring stations Chl-a. ASTER VNIR band ratio were regressively analyzed with the corrected MODIS Chl-a and automated station values obtained for each ASTER date on a day by day basis. The regression equation of the ASTER band ratio (B1/B2), with highest correlation was used to generate high-resolution Chl-a distribution maps. Significant correlation between the ratio of the reflectance peak at 705 nm and the Chl-a absorption at 678 nm and the in-situ Chl-a content was observed and these reflectance ratios were used to establish spectrometric Chl-a estimation algorithms. Proposed algorithms can be successfully adopted to determine localized environmental effects in the Lake.

Development of coastal water body database on KISSEL server

Monitoring of coastal water bodies in all the relevant aspects was highly important for the sustainable use of those. To achieve this all the research findings should be easy access and presenting those in a user friendly manner will be more advantage. In Sri Lanka, there was not fully or never developed database on research findings especially on coastal water bodies. Thus we developed a Sri Lankan coastal water body database (CWBDS) on KISSEL server system which can be benefitted all the interest communities including general public. Presently it include water quality data over two decades of lagoons and estuaries and in near future it will update with support from universities and research organizations including research on biodiversity, fisheries, land use, socio economics, topography, water circulation, pollution etc.

The planning, implementation and economics of the Knowledge Integration Server System for E-Learning (KISSEL)

E-learning is about bringing education to people instead of bringing people to education. It involves the delivery of contents, courses and training via electronic media such as the Internet and intranet. E-Learning provides just-in-time training delivery as well as flexible access to lifelong learning. It can help organizations re-train their staff and motivate individuals to upgrade their skills with less disruption to work and family life. The Knowledge Integration Servers System for E-Learning (KISSEL) is a knowledge sharing platform for E-learning and sustainability sciences which is focused mainly on Asian-Pacific Countries. It is a kind of open source program to build and setup communities. The KISSEL online courseware management system was developed by the research group of the Ibaraki University, Japan. KISSEL can provide E-learning and information technology base training through its virtual platform. It is a student-centered E-learning environment that satisfies the learning-on-demand need of working with IT professionals, and reduces the learning time by assembling customized courses on demand to meet specific individual needs. The first server under this KISSEL project was established in Bandaranayke College, Gampaha, Sri Lanka in the year 2009.

Retrieval of chlorophyll-a using satellite and ground spectral data in Japanese and Sri Lankan water bodies

The suitability of a handheld spectrometer and ASTER satellite data for monitoring water quality in coastal waters of Sri Lanka and inland waters of Japan was tested in November 2010 to March 2012. In-situ Chlorophyll-a (Chl-a), turbidity, total suspended solid, secchi depth and reflectance data were measured at ASTER overpass times in Negombo estuary, Trincomalee bay, Puttalam and Chilaw lagoons, Sri Lanka, and in Lake Senba and Lake Kasumigaura, Japan. ASTER based Chl-a retrieval algorithms were developed support with in-situ Chl-a and MODIS OC3 Chl-a. The original MODIS Chl-a and the in-situ Chl-a were regressively analyzed for determination of a MODIS Chl-a correction equation because it may overestimate in tropical coastal waters. Then, three ASTER VNIR band ratios were compared for correlation with the corrected MODIS Chl-a and in-situ Chl-a. Finally, the regression equation of the ASTER band ratio, B1/B2, with highest correlation was used for generation of high-resolution Chl-a distribution maps. Significant correlation between the ratio of the reflectance peak at 705 nm and the Chl-a absorption at 678 nm and the in-situ Chl-a content was observed and these reflectance ratios were used to establish spectrometric Chl-a estimation algorithms. The proposed algorithms successfully determined localized environmental effects in the study areas. ASTER-based high resolution Chl-a distribution maps will be derived more precisely by further correction of these algorithms, which will be useful in mitigate impacts of the environment change in those coastal and inland water environments.