Department of Civil Engineering
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Publication Open Access Implementation of water–saving agro technologies and irrigation methods in agriculture of Uzbekistan on a large scale as an urgent Issue(Springer Science and Business Media Deutschland GmbH, 2022-10) Rathnayake, U; Chathuranika, I; Khaniya, B; Neupane, K; Rustamjonovich, K. MUsable water resource is limited, even though 71% of world is covered by water. Therefore, enough conficts to the usable water can be found throughout the world. Usable water for irrigation is a top priority, probably it would be seconding only to the drink water supply. However, prioritizing one usage over another is challenging to many stakeholders. Therefore, sustainable water usage is essential to avoid any conficts among the stakeholders; nevertheless, highly challenging in the developing world. Therefore, this paper discusses the water saving irrigation practices and ways to use agriculture around the world, including Uzbekistan. Relying on the ancient irrigation technologies used by ancestors and also modern irrigation methods, diferent irrigation water management technologies are presented to apply for various weather conditions and water availability situations. Suitable irrigation practices are discussed based on the water needs especially the arid countries, such as Uzbekistan. The results of an experiment conducted for hilly areas of Uzbekistan using “mulching” agro-technology is presented along with its suitability for Uzbekistan. Therefore, the expectations of sustainable water usage for irrigation is proposed.Publication Open Access Comparison of Instrumented Pile Load Test Results with Finite Element Simulation(World Congress on Civil, Structural, and Environmental Engineering, 2022-04-10) Diyes, G. H. I.; Thilakasiri, H.S.; de Silva, L.I.NDue to the proximity of the bedrock, rock socketed bored and cast in-situ piles are used to support the heavy super structure loads from the high-rise structures transferring to bedrock. In order to design single piles or group of piles, it is very important to know the carrying capacity of the bedrock in terms of skin friction distribution along the pile shaft and the load carried by the pile toe. Such information can be obtained by using the instrumented pile load tests but the instrumented pile load tests are expensive and not always carried out in most of the piling sites in Sri Lanka. In this study, it was aimed to find out the carrying capacity of cast in-situ bored single piles using commonly used finite element software PLAXIS 2D and compare the results with the instrumented pile load test results obtained in the field. Prior to the use of software package based on finite element analysis to find out the carrying capacity of the pile, the accuracy of the model used was verified by the results instrumented pile load test and the nearby borehole test results. Further, the differences and the difficulties of the interpretation of results with their potential reasons were discussed within the study. In the current study, the soil and rock properties were used from the nearby borehole results. It was shown that the best match results with the field instrumented pile load tests for weathered rocks were obtained when the elastic modulus for rock layers were twice the value suggested by Hong Kong geo guidelines (Geo,2006) whereas the best match results with instrumented pile load test results were given when half the value of the Young’s modulus of rock suggested by the Hong Kong geo guidelines (Geo,2006).Publication Embargo The deflectors influence on flow complexity, bed morphology, sediment transport and water quality of urban lotic waters - A laboratory study(wiley, 2022-11-25) Sooriyaarachchi, D. T. A; Gomes, P. I. AIn this laboratory study different combinations of bed (sand, pebble gravel [gravel], and a mix of sand and gravel) and flow (typical and overtopping) were experimented with to investigate the impact of porous deflectors in flow diversity, water quality, and fish performance in prismatic open channels. Deflectors changed the gradually varied flow to a rapidly varied flow, as a sudden change in the water depth was observed at the deflectors, and this change was large for smooth beds. With the presence of gravel, the scouring near the downstream deflector was almost twice that of the sand bed, and with the scouring at its own upstream deflector, irrespective of whether the flow was typical or overtopping. This behavior was a result of sand mobilization due to shear stress and sand mobilization aided gravel transport. The mixed bed showed less gravel movement compared to the gravel-only bed. The percentage of sediment washed out was minor for all bed scenarios, indicating that sediment transport was local. Relative to the sand bed without deflectors (representing a typical urban canal), deflectors resulted in reduced and improved water quality (in terms of sediment load) for sand, and mixed bed, respectively. The fishes found refuge and were comfortable in the pool areas created by deflectors unlike in channels without deflectors where they showed exhaustionPublication Open Access Introduction of a Simple Estimation Method for Lane-Based Queue Lengths with Lane-changing Movements(Springer, 2022-12-21) Jayatilleke, S; Wickramasinghe, V; Amarasingha, NTraffic congestions are increased globally due to rapid urbanization and expedited economic developments in many countries. Vehicle queue is a governing aspect of traffic congestion, studied over the past decades. Most of the existing queue estimation approaches are limited to homogeneous traffic conditions. However, the traffic conditions in many developing countries are heterogeneous and are heavily influenced by mixed vehicle composition, lane changing, and gap-filling behaviours. This study aims to estimate the queue length at signalized intersections having heterogeneous traffic conditions. The heterogeneity was assimilated with the consideration of Passenger Car Units (PCU) in the measurements of the traffic flow and the lane-changing movement within the considered road section. The influential factors of the queue length were contemplated with the arrival flow, discharge flow, outbound lane change, inbound lane change, and signal configuration. A Vector Auto Regression (VAR) model was developed to estimate queue length, with a lag time of 15 s for each variable. The results have indicated a higher accuracy in the queue estimation as well as the practical application for prediction, constituting the traffic characteristics of the formed vehicle queue. The R squared of the VAR model was 0.97, along with a Mean Absolute Percentage Error (MAPE) of 21.55%. The model estimation results of right turning lanes were well accurate with MAPE ranging from 15 to 17%, whilst for through movement lanes, accuracy was slightly low with MAPE in the range of 23–26%. The study manifests the functionality of the developed methodology for accurate queue estimations, asserting the practical applicability of VAR models in other locations constituting mixed traffic.Publication Open Access A NOVEL TREATMENT FOR DETERMINING THERMAL CONDUCTIVITY OF THE SOIL SUBSTRATES FOR SELECTING SUSTAINABLE GROWING MEDIUMS IN TERMS OF THERMAL RESISTANCE(University of Montenegro, 2022-09-30) Kader, S; Jaufer, LThe Thermal conductivity of the soil is important to determine the horticultural performance of growing medium. Microclimatic features influence the viability of soil mixtures for vegetation. The goal of this study is to assess the heat conductivity of soil mixture samples comprising Coir, Biochar, Sawdust, Wood bark, and Compost in order to discover the best growth medium in terms of thermal resistance. Specimens were prepared by mixing 60% of raw materials with 40% topsoil and moulded into cylinders. Each sample were converted into semi solids and undergone for thermal conductivity apparatus measurements. Thermal conductivity of each specimen was determined using mathematical analysis based on experimental readings. The calculated results were used to deduce thermal resistance. Thermal conductivity values of all specimens were observed in the range from 0.64 W/mK to 0.91 W/mK. The maximum and minimum thermal conductivity magnitudes were exhibited by Sawdust (60:40) and Wood bark (60:40) respectively. In terms of suitability as a growing medium, Wood bark (60:40) contains highest thermal resistance while the lease thermal resistance was determined in Sawdust (60:40) due to its high thermal conduction. This research concludes that Wood bark (60:40) is the most convincing substrate in terms of thermal sustainability. © 2022, University of Montenegro. All rights reserved.Publication Open Access SOIL MANAGEMENT IN SUSTAINABLE AGRICULTURE: ANALYTICAL APPROACH FOR THE AMMONIA REMOVAL FROM THE DIARY MANURE(University of Montenegro, 2022-12-15) Shuraik, K; Novicevic, R; Jaufer, LThis study analyses the viability of converting the organic nitrogen possessed by dairy manure from Sri Lankan cows into ammonia using hydrolysis. Furthermore, ammonia removal from anaerobically digested dairy manure was evaluated with the experimental analysis. Hydrolysis was conducted to determine the impact of total solids, retention time, and temperature on the ammonia recovery. Experimental studies have shown that 85% of organic nitrogen in dairy manure was recovered into ammonia at 35O C within 7 days a 12.1 – 13.8 Total Solid (TS) content. Furthermore, it was also inferred that acidification occurs along with ammonium in the diary manure. Ammonia removal from anaerobically digested manure was investigated using Head Space Flushing (HSF), where it was identified that 73% of influent ammonia was removed at 35O C after 7 days. This result can be effectively used as an appropriate method for converting and removing ammonia from dairy manure in countries with large cattle herds. © 2022, University of Montenegro. All rights reserved.Publication Open Access Feasibility study for estimating optimal substrate parameters for sustainable green roof in Sri Lanka(Springer Science and Business Media B.V., 2022-12-21) Kader, S. A; Spalevic, V; Dudic, BIn twenty-frst century buildings, green roof systems are envisioned as great solution for improving Environmental sustainability in urban ecosystems and it helps to mitigate various health hazards for humans due to climatic pollution. This study determines the feasibility of using fve domestic organic wastes, including sawdust, wood bark, biochar, coir, and compost, as sustainable substrates for green roofs as compared to classical Sri Lankan base medium (fertiliser+potting mix) in terms of physicochemical and biological parameters associated with growing mediums. Comprehensive methodologies were devised to determine the thermal conductivity and electric conductivity of growing mediums. According to preliminary experimental results, the most suitable composition for green roof substrates comprised 60% organic waste and 40% base medium. Sawdust growing medium exhibited the highest moisture content and minimum density magnitudes. Biochar substrate was the best performing medium with the highest drought resistance and vegetation growth. The wood bark substrate had the highest thermal resistance. Growing mediums based on compost, sawdust, and coir produced the best results in terms of nitrate, phosphate, pH, and electric conductivity (EC) existence. This study provided a standard set of comprehensive comparison methodologies utilising physicochemical and biological properties required for substrate characterization. The fndings of this research work have strong potential in the future to be used in selecting the most suitable lightweight growing medium for a green roof based on stakeholder requirements.Publication Open Access Introduction of a Simple Estimation Method for Lane-Based Queue Lengths with Lane-changing Movements(Springer, 2022-10-03) Jayatilleke, S; Wickramasinghe, V; Amarasingha, NTrafc congestions are increased globally due to rapid urbanization and expedited economic developments in many countries. Vehicle queue is a governing aspect of trafc congestion, studied over the past decades. Most of the existing queue estimation approaches are limited to homogeneous trafc conditions. However, the trafc conditions in many developing countries are heterogeneous and are heavily infuenced by mixed vehicle composition, lane changing, and gap-flling behaviours. This study aims to estimate the queue length at signalized intersections having heterogeneous trafc conditions. The heterogeneity was assimilated with the consideration of Passenger Car Units (PCU) in the measurements of the trafc fow and the lanechanging movement within the considered road section. The infuential factors of the queue length were contemplated with the arrival fow, discharge fow, outbound lane change, inbound lane change, and signal confguration. A Vector Auto Regression (VAR) model was developed to estimate queue length, with a lag time of 15 s for each variable. The results have indicated a higher accuracy in the queue estimation as well as the practical application for prediction, constituting the trafc characteristics of the formed vehicle queue. The R squared of the VAR model was 0.97, along with a Mean Absolute Percentage Error (MAPE) of 21.55%. The model estimation results of right turning lanes were well accurate with MAPE ranging from 15 to 17%, whilst for through movement lanes, accuracy was slightly low with MAPE in the range of 23–26%. The study manifests the functionality of the developed methodology for accurate queue estimations, asserting the practical applicability of VAR models in other locations constituting mixed trafc.Publication Open Access A GIS-Based Comparative Analysis of Frequency Ratio and Statistical Index Models for Flood Susceptibility Mapping in the Upper Krishna Basin, India(MDPI, 2022-11-20) Pawar, U; Suppawimut, W; Muttil, N; Rathnayake, UThe Upper Krishna Basin in Maharashtra (India) is highly vulnerable to floods. This study aimed to generate a flood susceptibility map for the basin using Frequency Ratio and Statistical Index models of flood analysis. The flood hazard inventory map was created by 370 flood locations in the Upper Krishna Basin and plotted using ArcGIS 10.1 software. The 259 flood locations (70%) were selected randomly as training samples for analysis of the flood models, and for validation purposes, the remaining 111 flood locations (30%) were used. Flood susceptibility analyses were performed based on 12 flood conditioning factors. These were elevation, slope, aspect, curvature, Topographic Wetness Index, Stream Power Index, rainfall, distance from the river, stream density, soil types, land use, and distance from the road. The Statistical Index model revealed that 38% of the area of the Upper Krishna Basin is in the high- to very-high-flood-susceptibility class. The precision of the flood susceptibility map was confirmed using the receiver operating characteristic and the area under the curve value method. The area under the curve showed a 66.89% success rate and a 68% prediction rate for the Frequency Ratio model. However, the Statistical Index model provided an 82.85% success rate and 83.23% prediction rate. The comparative analysis of the Frequency Ratio and Statistical Index models revealed that the Statistical Index model was the most suitable for flood susceptibility analysis and mapping flood-prone areas in the Upper Krishna Basin. The results obtained from this research can be helpful in flood disaster mitigation and hazard preparedness in the Upper Krishna Basin.Publication Open Access Water Footprint Assessment for Irrigated Paddy Cultivation in Walawe Irrigation Scheme, Sri Lanka(MDPI, 2022-11-25) Janani, H. K; Abeysiriwardana, H. D; Rathnayake, U; Sarukkalige, RWater footprint (WF) is a comprehensive summation of the volume of freshwater consumed directly and indirectly in all the steps of the production chain of a product. The water footprint concept has been widely used in agricultural water resources management. Water for irrigation is supplied in Sri Lanka to farmers at no cost, and thus the question is arising, whether the current management strategies the authorities and the farmers follow are appropriate to achieve productive water utilization. Therefore, this study aims at evaluating the water footprint of rice production in an irrigation scheme in the dry zone of Sri Lanka, the Walawe irrigation scheme. Due to the unreliability of the rainfall in the study area paddy cultivation depends entirely on irrigation, thus, the (Formula presented.), in other terms the volume of water evaporated from the irrigation water supply is considered as the total WF ( (Formula presented.) in this study. Actual crop evapotranspiration (equivalent to (Formula presented.)) was estimated based on the Penman-Monteith (P-M) model integrating effective rainfall, and crop coefficient published in Sri Lankan Irrigation Design Guidelines. The study spanned for three irrigation years from 2018–2021. Actual irrigation water issued to the field was estimated based on the data recorded by the government body responsible for irrigation water management of the area—Mahaweli Authority of Sri Lanka. The total volume of percolated water was computed employing the water balance method while assuming runoff is negligible. Results show that the average annual (Formula presented.) found to be 2.27 m3/kg, which is higher than global and national (Formula presented.). As the crop yield in the study area (6.5 ton/ha) is also higher than the global (4.49 ton/ha) and national (3.5 ton/ha) yields, a conclusion was drawn that the irrigation water usage ( (Formula presented.) in the area may be significantly higher. It was then noted the higher (Formula presented.) was due to relatively higher evapotranspiration in the area. Thus, it is vital to reduce excess water usage by shifting irrigation practices from flooded irrigation to the System of Rice Intensification (SRI). © 2022 by the authors.
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