1,720,976 research outputs found
Analysing Plastic Pollution: A Case Study of Coastal Pollution from Inland Urban Waterways in Galle City, Sri Lanka
Get PDFThe coastal stretch of Galle city is currently facing an acute pollution with the aggregation of various types of waste on beaches due to malpractices of the community living around the coastal as well as inland areas of the country. Rivers or canals play a key role in the transport of wastes from source to sea and are estimated to emit around 1 metric ton of plastics into the ocean annually. Mainly five sea outfalls are existing along the Galle coastal zone and those transfer various waste towards the beaches. The present case study aims to identify the coastal pollution caused by inland waterways in Galle municipal council area and to detect the main plastic pollutants flow into coastal zone through inland waterways from month of April to June 2023. The waste trap constructed at the main inland waterway located at Galle municipal council area, the Moda Ela trapped different types of waste and the CCTV camera fixed directing to the above-mentioned canal, captures images, uploaded to a cloud system and feed the data to an Artificial Intelligence model to detect the litter type and their counts which flows along the canal daily and get recorded in the smart plastic litter monitoring web-based system using feature extraction techniques in AI. This smart system has mainly identified the count of plastic fragments, plastic bottles, Styrofoam, and trash bags separately, as the main pollutants of this canal and has interpreted graphically and numerically in the smart system which can be freely accessed. Weights of waste were taken manually. Finally, recorded counts of waste in the smart system emphasis that most abundant causative agent affected on pollution of Moda Ela was plastic bottles (58%) while effect of Styrofoam and trash bags were 34% and 8% respectively. Further, average weight of plastic bottles was recorded highest during the study period (130 kg) when compared to other waste categories. According to the results, plastic bottles have become the main source of pollution comes through inland canals which contribute to coastal pollution. Visual observations further convince that the highest pollution source was Moda Ela while less contribution was from Mahamodara canal. The present study highlights plastics as the main pollutants in inland waterways which effect on coastal pollution. Therefore, it is necessary to identify the polluters and need to implement proper rules and regulations while suggesting any alternatives for plastics.
Keywords: Coastal pollution, Inland waterways, Waste trap, Galle Municipal Council area, Artificial intelligence technolog
Paired Watershed Delineation and an Analysis to Identify Its Morphological Features in Yagirala Forest Reserve
Get PDFWatersheds are the basic hydrological unit for water resource management. Watershed morphological characteristics like shape, watersheds area, perimeter, axial length, form factor, compactness factor, circulatory ratio, elongation ratio, basin slope channel length, stream frequency, drainage density, stream texture and overland flow are important in understanding the hydrology of the watershed. Thus, computation of watershed morphological characteristics is a prerequisite for detailed hydrological studies. Therefore, this study focused delineation of paired watershed and identification of their morphological features in Yagirala Forest Reserve (YFR) (6o 21/ to 6o 26/ N and 80o 06/ to 80o 11 / E) a secondary lowland rainforest in southern Sri Lanka. Manual and automated approach based on Triangulated Irregular Network (TIN), Digital Elevation Model (DEM) was made for the delineation of paired watersheds. Two watersheds; Watershed one (WS1) located in forest enriched with Pinus caribaea and the second was in natural forest (WS2). Morphological characteristics were examined using ArcGIS and mathematical formulas. Morphometric analysis showed that the watersheds areas were 0.91 km2 of WS1 and 1.60 km2 of WS2 which both are smaller in size with elongated and oval in shape respectively. According to the results perimeter was 5.14 km, axial length 1.46 km and channel length 1.29 km of the delineated watershed in WS1 whereas perimeter was 5.16 km, axial length 1.62 km and channel length 3.34km of the WS2. The present study computed that Form factor was 0.43, Compactness factor 1.50, Circulatory ratio 0.43, Elongation ratio 0.6 and Basin slope 2.70% in WS1 whereas with values 0.61, 1.14, 0.75, 0.8 and 5.46% for the same parameters respectively in WS2.The stream frequency was 1.09 (No of streams per km2 ), Drainage density 1.41 (km per km2 ), Stream texture 1.53 km andOverland flow 0.35 km of WS1 whereas they were 1.25 (No of streams per km2 ), 2.08 (km per km2 ), 2.60 km and 0.20 km of the WS2. In conclusion, delineation of paired watershed and estimation of its morphological analysis in YFR provides a prerequisite for advanced forest hydrological studies in tropical lowland rain forest.
Keywords: Paired watersheds, Watershed morphology, Watershed delineation, Yagirala Forest Reserve, GIS, DE
A Comparative Analysis of Invasive Tree Decay Detection Techniques
No full textTree decay detection is a crucial component in Urban Forestry. There are invasive as well as non-invasive tools available worldwide for tree decay detection. This study is about a comparative analysis of different invasive techniques for detecting tree decay and cavities. The techniques compared here are traditional decay detection drills, radiographic techniques, acoustic detection, acoustic tomography, and electrical resistivity methods. Traditional tools such as decay detecting drills, increment borers and borescopes are suitable for preliminary investigations. Holes drilled into wood tissue by these tools may lead to fungal invasion. Radiographic techniques use X-ray or Gamma ray radiation where decay is detected by the decreasing wood density resulting from the biodegradation of cell walls. It is very effective in analyzing microscopic decay processes, but power consumption is heavy and has a high risk of radiation hazards. The resolution of radiographic methods is very high compared to other techniques. Acoustic techniques measure the increased transit time of an ultrasound or a stress wave pulse across a tree stem. Tools that use acoustic techniques can provide detailed information on wood quality with moderate to high resolution with quick results but are unable to locate and give the extent of decay. Acoustic tomography techniques generate images of internal wood structures using the principle of reduced velocity of sound waves in decayed wood. Tools such as Picus Sonic Tomograph can locate the defects, estimate their size, shape and determine the relative strength loss of degraded wood. Electrical resistivity techniques measure the reduction of electrical resistance in decayed wood due to the increasing concentration of mobile cations in the decayed region. Electrical resistivity tools such as Shigometers are most suitable for early detection of wood decay. But results should be validated with other methods such as tomography techniques for better accuracy and validation since fungal activities without decay can also cause lower electrical resistivity. In terms of the cost of these tools, radiographic tools are the most expensive while electrical resistivity meters are the cheapest. Apart from these, emerging techniques such as advanced mechanical probes, innovative ultrasonic and stress wave devices for detailed internal imaging, digital microprobes, acoustic emitting monitoring for real time decay tracking and computed tomography for three-dimensional analysis focus on reduced invasiveness alongside increased accuracy and detailing.
Keywords: Urban forestry, Tree decay detection, Invasive, Accurac
Assessing the Spatial Arrangement of Reach Morphology along a Headwater Stream A Case Study in Yagirala Forest Reserve
Get PDFHeadwater streams are the initiation points of river networks. They are important areas for the investigation of geomorphological features of stream channels due to the proximity to sediment supply sources and fewer disturbance from anthropogenic activities. In this study, the spatial arrangement and characteristics of bed morphologies in a headwater stream in Yagirala Forest Reserve investigated at reach scale. The study was conducted by establishing 11 sites along the headwater stream. Montgomery and Buffington classification was used to identify different reach morphologies. Detailed observations of the classification criteria were recorded, along with measurements such as stream width, depth, and boulder sizes at each location. The study’s findings show three major channel morphologies: alluvial, bedrock and mixed alluvial morphology along the headwater stream. Furthermore, various reach morphologies such as step pool, plane bed, pool riffle, regime (sand bed) under alluvial morphology were identified. Field investigations revealed that step-pool reaches were found in relatively high-gradient areas, while plane-bed and pool-riffle reaches were in mid-gradient areas, and regime reaches were found in lower-gradient areas. At the reach scale, the plane bed occupied the majority of the stream. Under the spatial arrangement of channel reaches, the expected general downstream pattern of Montgomery and Buffington classification was not observed in this study. Fluvial processes were dominated in all the reach types along the stream. Bed morphology characteristics at reach scale were closely related with the longitudinal profile of the headwater stream. The outcomes of the study have the potential to future restoration of the region's degraded headwater streams and similar environments while providing a better understanding of the major aspects of headwater streams.
Keywords: Headwater streams, Reach, Morphology, Montgomery and Buffington classificatio
Quantification of Stem Flow in Seven Tree Species in an Urban Environment of Sri Lanka
Get PDFStemflow (SF) is a small fraction of precipitation which contacts with the canopy and reaches to the ground by flowing along the stem of the tree. The SF generation of urban environment in single rain events are less frequently reported than in forested ecosystem. Therefore, SF was studied for 20 rain events starting from dry canopy condition for 7 selected tree species with 3 replicates in University of Sri Jayewardenapura with reference to tree morphological characteristics. Stemflow collars werefixed at diameter at breast height (DBH) and connected to storage tanks. Tree height, DBH, canopy height, canopy diameter, and canopy volume, canopy diameter to height ratio, bark thickness, furrow depth and number of furrows per DBH were considered as tree morphological characteristics. Tree architectural models were determined for studied species by leaf shape, leaves arrangement and canopy shape. Gross precipitation was recorded using an automated weather station located in an open area in the study site. According to the results DBH, canopy volume and bark thickness have a negative relationship with SF. Pterocarpus marsupium Roxburgh and Felicium decipien have resulted the highest and the lowest DBH, bark thickness and canopy volumerespectively since, the highest and the lowest SF were generated by F. decipien and P. marsupium Roxburgh respectively. However, there were no significant relationships between SF and other listed morphological characteristics as well as with the tree architectural models. The results suggest a significant variation in SF by species and study trees can be arranged as F. decipiens>Mesua ferrea L.>Diptercarpus zelanicus Thwaites>Delonix regia (Boj. ex Hook.) Raf.>Azodrachata indica> Casuarina eqisetifolia L.>P. marsupium Roxburgh in species specific SF. Thus, the results of the study will be useful for climate sensitive selection and siting of urban trees towards integrated rainwater management.Keywords: Stemflow, Strom water management, Tree architecture, Tree morphology, Urban forestr
Impact of Clear Cutting on Sedimentation Dynamics: A Case Study in Naturalized Mature Pine Plantation, Tropical Lowland, Sri Lanka
Get PDFVegetation plays a crucial role in regulating soil erosion through its roots, canopy, and litter layers, reducing surface runoff and sediment transport. However, removal of vegetation through clear-cutting amplifies soil erosion, increasing the frequency and magnitude of sediment yield. However, limited research has been conducted on the specific effects of clear-cutting on sediment yield. This study investigates the impact of clear cutting and replanting on sediment yield in a naturalized mature Pinus caribaea plantation in the tropical lowlands of Sri Lanka. Three surface runoff plots (10 m × 3 m) were established on slopes within the plantation, representing overall site characteristics. Slope, canopy cover, ground vegetation cover, and litter thickness within each plot were measured. The before-felling (BF) period was considered the control, while after-felling (AF) and after replanting (AR) periods were considered the treatments. Rainfall and sedimentation were recorded for individual storm events from July 2023 to February 2024, covering the southwest monsoon period, second inter-monsoon period and north-east monsoon periods. Out of 92 storm events, 46 events with rainfall between 1 mm and 18 mm were used for the data analysis. Sediment samples were oven-dried at 105°C for 24 hours, and sieve analysis was conducted to assess grain size distribution. The average sediment yield was 1.50 g/m², 2.48 g/m², and 0.42 g/m² during BF, AF, and AR periods, respectively. Clear cutting increased sediment yield by 65.3% while replanting reduced it by 83.1%. The results indicate a significant difference (P<0.05) in sediment yield among the three periods. Positive correlations were found between rainfall and sediment yield, while canopy cover, ground vegetation cover, and litter thickness were negatively correlated with sediment yield. Sieve analysis revealed that coarse grains constituted the highest sediment output, with fine grains being the least represented across all phases. Loss of vegetation cover and canopy cover and soil compaction through forest clear-cutting increases sedimentation yield. Sieve analysis results indicate that the quantity of sediment yield was affected by the felling practices, rather than the texture of the resulting sediment. These findings highlight the importance of forest management practices to mitigate soil erosion and sedimentation in Pinus caribaea plantations in tropical lowlands, ensuring sustainable forest management practices.
Keywords: Clear-cutting, Forest management, Pinus caribaea, Sediment yield, Sieve analysis 
Temporal Variations of River Morphology: A Case Study Wey Ganga, Sri Lanka
Get PDFRivers are among the natural ecosystems most threatened by natural factors and human activities. Tools and techniques of remote sensing, geographical information system and Google earth satellite imagery have been used to determine the morphological changes along Wey Ganga, located in Sabaragamuwa province, Sri Lanka, is a victim of intense riverbed gem mining activities. By using Google earth satellite images of 2006, 2014 and 2018, changes of wetted river area (WR), water covered area (W), bar covered area (B), B/W ratio and sinuosity index (SI) were analysed for the 5km river segment. Then the river segment was divided into five reaches and changes of same parameters were evaluated. According to the results, WR of the river segment and five reaches were decreased over the period from 2006 to 2018. Similarly B were also decreased in the river segment and in three river reaches out of five. At the same time W was also decreased in river segment and four river reaches except one reach over the period. Nevertheless, from 2006 to 2018 B/W ratios were also decreased in river segment and three reaches out of five. When considering the SI, it was also decreased from 2006 to 2018. The study revealed that the narrowing trend (2006-2018) of the morphological plan of the Wey Ganga form certainly decrease the active channel area. The findings of the study will be important for the wise management of river ecosystems.Keywords: GIS, Google earth platform, Remote sensing, River parameters, River morphological change
Assessment of Vegetation Changes and Seawater Intrusion in the Lower Bentota Ganga Sub River Basin: A Study of Land Use and Land Cover Change
No full textThe Lower Bentota Ganga sub-river basin faces challenges associated with both Land Use and Land Cover changes (LULCC) and seawater intrusion (SWI), impacting environmental sustainability and community livelihoods. This study investigates these issues using a multi-method approach. The primary objectives were to analyze historical LULCC and to understand community experiences of these changes. Landsat images were analyzed and classified using satellite imagery from 1988 to 2022 using ArcGIS Pro, to determine changes in LULC. A questionnaire survey was conducted among 150 respondents in key locations identified through the image classification, offering qualitative insights into the community's experience of LULCC and SWI impacts. 135 groundwater samples were taken around the region to determine electrical conductivity (EC) and geographic changes in salinity levels. The study reveals significant alterations in the landscape between 1988 and 2022. A notable reduction in vegetation cover was observed, alongside a rise in built-up and barren land, while water bodies remained relatively stable. A questionnaire survey provided valuable insights into the adverse effects of SWI on daily activities and local livelihoods, with respondents reporting increased salinity in groundwater affecting household and agricultural activities. These perceptions were corroborated by EC measurements, which showed significant spatial variation in salinity levels, particularly near the estuary and upstream areas. The study provides critical insights into LULCC and SWI in the Lower Bentota Ganga sub-river basin by integrating community insights with remote sensing (RS) and geographic information system (GIS) data. The findings emphasize the need for targeted interventions and ongoing monitoring to mitigate the impacts of these changes effectively and efficiently. This underscores the need for improved maintenance of floodgates and seawater exclusion structures and greater community involvement in land use planning. The study highlights the importance of addressing environmental challenges in coastal regions to develop effective sustainable development and environmental management strategies.
Keywords: Land use and land cover changes, Seawater intrusion, Geographic information systems, Lower Bentota ganga sub-river basin, Community experience
Water Hyacinth (Eichhornia crassipes) As a Possible Alternative Energy Source: A Case Study for INSEE Cement Manufacturing Plant in Puttalam, Sri Lanka
Get PDFCement manufacturing is typically energy-intensive process and currently using alternative fuels partially or totally to replace fossil fuels to reduce the energy and environmental costs. Biomass is one of the main alternative fuel utilized by the cement industry with the potential to replace up to 20% of total energy demand. Water hyacinth (WH) is a problematic invasive alien species in aquatic ecosystems of all climatic zones in Sri Lanka. Because of it is non-edible, rapid growth, and freely available in larger quantities, WH has the potential to be used as biomass energy. Several countries have been studied for WH as feedstock for bioenergy production while physical and chemical composition of WH biomass has been tested by many researchers. However, biomass physiochemical properties may be varied by different place and conditions and there is no significant study for industrial application of WH biomass to burn in cement plant kiln as alternative energy source. Thus, this study aimed to elucidate the potential of WH biomass as an alternative energy source for the INSEE cement plant in Puttalam. The study was conducted in three selected reservoirs namely, Tabbowa reservoir (TR), Murukkuwatawana reservoir (MR), and Nawadankulama reservoir (NR) located in Puttalam district Northwestern province of Sri Lanka. The quantity of fresh and dry WH biomass was estimated with the WH covered area and fresh and dry weights of WH in unit area.WH covered area of in each reservoir during 2020 and 2021 was digitized directly in Google earth satellite images using Google Earth Pro software with help of visual interpretation techniques. WH biomass per unit area were measured by the subjective sampling method. WH samples from each reservoir were collected for analyzing biomass, and to determine the fuel characteristics such as net calorific value (NCV), Chlorine and Sulfur content, moisture, volatile matter, fixed carbon, and ash content. According to the results, the fresh WH biomass was recorded as 692.62, 389.85, 23.58 tons in 2020 and 3570.82, 584.53, 33.31 tons in 2021 in the TR, MR, and NR respectively, while the dry WH biomass was recorded as 41.65, 24.65, 1.31 tons in 2020 and 214.74, 36.96, 1.85 tons in 2021 in the TR, MR, and NR respectively. NCV of the WH composite sample was 12.02 MJ/kg. Moisture content, ash content, chlorine and sulfur content were recorded as 13.56%, 10.95%, 1.06%, and 0.14% respectively. Except for chlorine content, other parameters agreed with the acceptable limits for using WH as an alternative energy source for cement industry. To replace 1 ton of coal, 2.2 tons of dry WH were required from 35 tons of fresh WH biomass while to produce 1 ton of clinker, 0.32 tons of dry WH were required from 5.2 tons of fresh WH biomass. Since relatively large quantities are freely available and with high volatile content and calorific value, WH is suitable as an alternative energy source for cement industry. However, economic feasibility should be studied prior to the commercial application.
Keywords: Alternative fuel, Biomass, Water hyacinth, Calorific valu
Avian Nesting Patterns and Preferences in Urban Road Median Trees: A Case Study from Galle Road, Sri Lanka
No full textUrbanization affects the nesting patterns of birds and causes limited selection of nesting trees. Road medians serve as potential nesting sites, to help this issue. The objective of this study is to determine how different trees in the road median islands are utilized by different bird species. The study was conducted from August 2024 to December 2024, involving surveys on the 5 km median island of the Galle Road from Borupana Junction to Kurusa Junction, covering 107 trees. Avifaunal observations were conducted while traveling along the road median between 0700h and 1000h. Birds were observed directly and with the aid of a 10 × 50 binocular. Active nests were located by searching the vegetation and following parent birds carrying nesting materials. Tree species were identified, and tree height, canopy diameter, diameter at breast height and number of branches were recorded. Nest type, concealment, canopy cover, distance from the nest tree to the adjacent tree and distance to the nearest road were measured. Disturbances for the nests were seen and recorded. There were 361 birds observed, representing 21 species from 18 families. The highest number of individuals (251) were recorded from house crow (Corvus splendens). Spot-billed pelicans belonging to the near threatened category (NT) was recorded. A total of 281 nests were recorded during the study period (271 open cup nests and 10 cavity nests) in 46 trees belonging to eight species in four families. Maximum numbers of nests (265) were recorded from house crow and 28% of these nests were in active stage. Highest number of nests were constructed in trees belonging to Family Moraceae: Ficus benghalensis and Ficus religiosa (85 for each species). Nests were constructed utilizing trees belonging to the Fabaceae, Sapotaceae, and Bignoniaceae families. Most of the nests were observed in larger trees characterized by broad canopies and high number of branches. The heights of the nesting trees and nests varied from 18.8 to 3.0m and 18.0 to 2.0m, respectively. The nests were exposed to open spaces characterized by minimal concealment (12%) and limited canopy cover (21%). The trees were found at a distance of 5±1.2 m close to adjacent trees and 2±4.2 m from the nearest road. There were no apex predators, therefore house crows preyed on the majority of the other bird species' nests. The present study reveals that the nests were utilized by Corvus splendens due to their adaptive success in urban environments. To enhance the bird diversity in this habitat, urban development should emphasize the significance of densely foliated trees in attracting and preserving nest sites of native bird populations.
Keywords: Avian nesting, Urban ecology, Road median trees, Nesting preferences, Galle road – Sri Lank
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