M. Mowjood - Academia.edu (original) (raw)

Papers by M. Mowjood

Tropical Agricultural Research, 2017

Minor irrigation systems are very unique to Sri Lankan agriculture for centuries for its role in ... more Minor irrigation systems are very unique to Sri Lankan agriculture for centuries for its role in food security, livelihood and ecosystem sustainability. The objective of this study was to evaluate constraints and potentials of paddy field system layout in a minor irrigation system for other field crop (OFC) cultivation. The study was done in Bayawa minor irrigation system, in Sri Lanka during 2014 and 2015. Data were collected and analyzed to evaluate, system components and their sustainability, canal uniformity, accessibility, and land and farmer plots distribution in the command area. Results according to the system layout reveal that, irrigation canals' uniformity varies along with the distance from head to tail endswith a water conveyance efficiency of 60%. Canal depth increases mainly due to sand mining, thus,requires a large amount of irrigation water for maintaining a hydraulic head in canals in order to supply irrigation water to fields under gravity. Positive hydraulic head of the right canal up to 70% of its length facilitates water distribution from canal to fields, but negative hydraulic head of the left canal constrains for that. As of the system layout and canal distribution, plot to plot irrigation is the common practice in the command area. The number of plots vary from 2-19 with the highest frequency of 6 plots. Cultivation of OFCrequires individual access to water to each plot. Hence, this irrigation and drainage system restrict OFC cultivation. Furthermore, 56% farmers hold less than 0.4 ha farmer fields due to land fragmentation over the years. This also leads to, low accessibility of individual field plots to irrigation canal and identified as major constraint to OFCcultivation.

Open dumping of municipal solid waste is a common practice in Sri Lanka. The leachate produced fr... more Open dumping of municipal solid waste is a common practice in Sri Lanka. The leachate produced from these dumpsites indiscriminately pollutes the surface water and groundwater. Mitigation of the risk through implementation of treatment systems requires information on the leachate quality and its variability over the time. In this study, an open dumpsite was selected from wet zone of the Sri Lanka and its perched waterinside waste layer and groundwater quality was monitored for one year (May 2013 to April 2014) and leachate pollution index (LPI) was used to quantify and compare the leachate contamination potential of the particular dumpsite. Dumpsite is located near to right bank of MahaweliRiver, in UdapalathaPradeshiyaSabhaCentral Province of Sri Lanka. This site has been running for about 7 years and abandoned in 2011. Dump site has two sections, old and new with the age of 7 and 0.5 years, respectively. Two types of boreholes, groundwater borehole (BH) and perched water borehole(...

Tropical agricultural research, 2017

Wastewater generated in white pepper (Piper nigrum L.) processing contains high Biochemical Oxyge... more Wastewater generated in white pepper (Piper nigrum L.) processing contains high Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD) and hydrolyzable tannins that results dark tan/brown colour effluent which cannot be discharged to the environment without proper treatment. Therefore, these experiments were conducted to investigate the effectiveness of electro-coagulation using aluminum (Al) electrodes and coagulation-flocculation with Alum [Al2(SO4)3.18H2O] in reducing the strength of pepper soaked effluent. A laboratory scale electro-coagulation unit was made using two aluminium plates (9 cm × 5 cm × 0.3 cm) as electrodes leaving a 0.5 cm gap between plates and powered with a 12 V DC power supply through a resistance box which is used to regulate the current density. The current density could be controlled between 0-1 A. Coagulation flocculation with Alum was tested at five doses; 1 to 5 g/L with 1 g increments at laboratory scale. The effluent colour was measured using a ...

Managing leachate is one of the problems associated with municipal solid waste landfills. Leachat... more Managing leachate is one of the problems associated with municipal solid waste landfills. Leachate generation highly varies with type of waste, climate, site and surface condition. Several mathematical computer models have been used for prediction of leachate for controlled sanitary landfills. However, the prediction of leachate for an open dumpsite is rarely reported. The applicability of Hydrologic Evaluation of Landfill Performance (HELP) model which is based on water balance method was evaluated in this study for Udapalatha open dump site in the Central Province, Sri Lanka. Input weather data (rainfall, temperature, Relative Humidity, wind velocity, solar radiation) and site specific data (area, depth, profile characteristics) were obtained from nearby weather station and site investigation, respectively. Model output leachate was validated (quasi) with changes in groundwater level in percussion boreholes which were installed at the dump site and monitored from May 2013.The leac...

Combined paddy and other field crops (OFC) fields are unique from other wetland or upland soils, ... more Combined paddy and other field crops (OFC) fields are unique from other wetland or upland soils, because of seasonal alternation of wetting and drying conditions resulting anaerobic and aerobic conditions. Therefore, objective of this study was to assess spatio-temporal variation of soil properties in paddy fields under minor tanks with respect to OFC cultivation. Soil samples were collected at two soil depths from 24 locations covering the entire command area of the Bayawa Minor Irrigation Tank (MIT), Sri Lanka. Soil properties were analyzed and mapped using Arc GIS. Hardpan depth (HPD) was also determined by collecting undisturbed core samples at 0, 15, 25, 30, 45 and 60 cm depths from the same locations Statistical analysis was done to identify spatio-temporal variability of each property. Results revealed that, Bayawa command area showed low coefficient of variation (CV) for pH and bulk density, but high CV for saturated hydraulic conductivity (K s ). HPD was found to be varied ...

CLEAN - Soil, Air, Water, 2016

The hydraulic loading rate (HLR) plays a vital role in pollutant removal in constructed wetlands.... more The hydraulic loading rate (HLR) plays a vital role in pollutant removal in constructed wetlands. This study evaluated the effects of HLR variation on pollutant removal in continuously fed vertical subsurface flow (VSSF) constructed wetlands in tropical conditions. Three VSSF wetland beds (Length: 1.4 m, Width: 0.5 m and Depth: 0.6 m), filled with 10–20 mm gravel media, were set up in a tropical region. Two beds were planted with a locally available emergent macrophyte narrow-leaf cattail (Typha angustifolia), and the remaining bed was used as a control without plants. The performance of these wetland mesocosms was tested at different HLRs of 2.5, 5, 7.5, 10, 12.5, 15, 20, 25, and 30 cm day−1 changing at 2 week intervals in two phases over a period of 6 months. The results revealed that both VSSF wetland systems are capable of substantial reduction of pollutants with a good buffering capacity up to 25 cm day−1 HLR.

Tropical Agricultural Research, 2015

The objective of this study was to evaluate the ground penetrating radar (GPR) wave responses to ... more The objective of this study was to evaluate the ground penetrating radar (GPR) wave responses to different levels of electrical conductivity (EC) in contaminant plumes. GPR wave simulations were carried out using GprMax2D and the simulated data were compared with GPR surveys on Lysimeter test. Trace amplitude of the reflected wave was plotted with two-way travel time and the 2D GPR images were developed to observe the variation of GPR responses with increasing EC. Simulation study showed the disappearance of the subsurface reflection and wave amplitude reaching zero at higher EC levels (when EC>0.28 S/m). In addition, when the EC level was higher, the plume thickness did not have a significant effect on the amplitude of the reflected wave. However, it was also found that reflected signal strength decreases with increasing plume thickness at a given EC level. Further research is needed to verify the results under heterogeneous aquifer conditions.

Tropical Agricultural Research, 2015

Textile industries use dye such as Rhodamine B, Brilliant Red and Reactive Orange for the fabrics... more Textile industries use dye such as Rhodamine B, Brilliant Red and Reactive Orange for the fabrics. Thus the colour of the effluent even after the normal treatment is not within the standard to discharge into the environment. A study was conducted to identify suitable bio-sorbents and to optimize the conditions for selected bio-sorbent to reduce the colour of treated waste water (TWW) from a textile industry. Sieved and air dried sawdust from Rubber (Hevea brasiliensis), Trincomalee wood (Berrya cordifolia), and Breadfruit (Artocarpus altillis) timber were tested with TWW. Rubber sawdust showed a better performance in colour removal than the sawdust from Trincomalee wood and Breadfruit. In order to optimize the conditions with the rubber sawdust, colour removal efficiency of TWW was measured at different pH, sawdust amount, initial dye concentration and different contact times. Sorption data was modelled by Langmuir and Freundlich adsorption isotherms for each dye; Rhodamine B, Brilliant Red, Reactive Orange. Results showed that the best performances of adsorption of dye into Rubber sawdust was obtained at 5 g/L sawdust dosage with 6 minutes contact time up to 0.2 ml of 0.5 M dye concentration under pH 2. Adsorptions of acidic dye (Brilliant Red) and anionic reactive dye (Reactive Orange) followed the Langmuir isotherm. Sorption of cationic dye Rhodamine B was better represented by the Freundlich model. It is recommended to use the sawdust of rubber to remove the colour in wastewater in acidic condition and neutralize the effluent before discharge to the environment.

Biodiversity assessment is considered in making decisions concerning declaration of protected are... more Biodiversity assessment is considered in making decisions concerning declaration of protected areas, management of nature reserves and assessment of the success of management decisions within a particular area. Biodiversity indicators are used as measures of biodiversity. Degree of disturbance or fragmentation of a definite habitat can be measured using specific indicator species. A variety of invertebrates and vertebrates are widely used as indicators of biodiversity. Birds are one of the best species for the national and international biodiversity schemes to be used as a biodiversity indicator. This study focused on the use of birds as an ecological indicator to assess the paddy field ecosystem. The study was carried out in a minor irrigation system in Awlegama Agrarian Service area in Wariyapola Divisional Secretariat. Bayawa was the selected tank with nearly a 38 ha of command area. A standard fixed-radius point count method with the radius set at 25 m was used to sample birds in the paddy field ecosystem. Shanon index was used to explain the results. During a single rice cycle, rice plants undergo three main phenological stages namely; vegetative, reproductive and ripening. All these stages are influenced by farming practices such as tillage, irrigation, crop establishment, agrochemical application and weeding. Different stages with different farming practices create distinct habitats for various bird species. According to the results, the highest Shanon index value (highest diversity) was recorded during the vegetative stage. Birds" diversity had a significant, strong (p=0.05) negative correlation with the age of the paddy. Initial land preparation and vegetative stages provide more food sources for the predatory birds who feed on worms, insects and snails; some of whom act as pests of paddy. Mixing of upper and the subsoil layers in land preparation stages supply more feed for predatory birds. Cattle Egret, Red Wattled Lapwing, Intermediate Egrets, Indian Pond Heron, Black Necked Stroke were in abundance at land preparation and vegetative stage. Yellow crowned woodpecker and White throated munia were recorded during the later stages. A variety of management practices such as land preparation, crop establishments, irrigation, nutrient and pest management, harvesting within the paddy field facilitate to create different habitats with different eco systems and suitable food for bird species. The birds as a biodiversity indicator, symbolise the ecosystem and it reflects the existing condition of an ecosystems. A detailed study will reveal how these birds would help to manage different pests in the paddy fields to bring benefits to the farmers.

International Conference on Agricultural Engineering: New Technologies for Sustainable Agricultural Production and Food Security, 2014

ABSTRACT Water pollution due to indiscriminate discharge of domestic wastewater is one of the maj... more ABSTRACT Water pollution due to indiscriminate discharge of domestic wastewater is one of the major issues limiting access to safe water. A study was conducted to characterize water use and effluent in communities in a tea estate in the upper watershed in Sri Lanka. A questionnaire survey, field visits and focus group discussions were conducted to quantify water consumption. At a pilot scale, concentric rings with diameters of 0.3, 0.75 and 1.5 m were used for constructed wetland. Aggregates and soil were used to fill the rings. Scirpus grossus and Nasturtium officinale were planted in the middle and outer rings respectively. Wastewater from a collection tank was fed into the inner ring and treated wastewater was discharged through the outer ring. Water was sampled at the inlet – at the inner ring, middle ring and outer ring for analysis of Biological Oxygen Demand (BOD5) and other quality parameters. Domestic water usage varied with income, education and access to water. Per capita daily water use was higher in high-income and medium-level educated people. Per capita daily water usage of stream water users and pipe-borne water users were 246 and 194 L, respectively. Major consumption was for bathing followed by laundry. BOD5 of greywater varied from 20-55 mg/L and was highly contaminated with total coliform and E coli. The pilot-scale constructed wetland showed higher removal efficiency of BOD5, SS and TDS at 85, 65 and 55%, respectively. The constructed wetlands were in concentric rings. The hydraulic retention time of 2.3 days increased the pathways and facilitated the filtration, biodegradation and plant uptake of nutrients. This system can be recommended for small communities in the upper watershed in Sri Lanka.

Dissolved oxygen (DO) concentration affects the treatment processes in constructed wetlands. This... more Dissolved oxygen (DO) concentration affects the treatment processes in constructed wetlands. This study examined the dissolved oxygen dynamics and total nitrogen removal in constructed wetlands with submerged and floating plants. Four constructed wetland units each with the surface area of 3 x 1 m 2 were constructed at University of Peradeniya. Two of those with the depths of 0.3 m (A) and 0.6 m (B) were planted separately with Hydrilla verticillata (submerged) and Lemna minor (floating), respectively. Other two (C and D) were constructed with two sections of 0.3 and 0.6 m depths and planted with H. verticillata and L. minor, respectively in each section. Secondary effluent from student hostel was fed with hydraulic retention time of 6 days. DO was measured at different depths of water, 0.0, 0.1, 0.2, 0.4 and 0.5 m from the water surface and along the longitudinal axis of the wetland at 6 hours interval. The total nitrogen was measured for water samples at inlet and outlets. The average dissolved oxygen concentrations of A and B were 17.7 and 0.4 mg L-1 respectively. Oxic condition was maintained in the submerged plant units. Anoxic condition resulted throughout the day in floating plant system. DO varied significantly with depths in oxic condition. DO dynamics in these wetlands can be explained by photosynthesis, respiration, deaeration and reaeration processes. The highest total nitrogen removal was achieved in unit D where combined anoxic and oxic conditions were maintained together H. verticillata and L. minor could effectively be used to maintain required dissolved oxygen in constructed wetlands for nitrate removal.

The number of presently operating small tanks in then Kurunegala district is 4,482 of which 2873 ... more The number of presently operating small tanks in then Kurunegala district is 4,482 of which 2873 tanks have less than 6 ha of command area. Capacity of these tanks is low and the amount of water stored is not sufficient to fulfil the water requirement of the rice crop throughout the cropping season. Many farmers in Udakadawala area in the Kurunegala district adopts to start land preparation (LP) after filling tanks and start LP using tank water. This situation results in the delaying of the cultivation and limiting the use of rain water during the initial stages of the crop. On the other hand, due to high variability of rainfall, severe crop damages are frequently experienced. The objectives of this study were to identify the factors affecting low water productivity and to introduce and evaluate a new land and water management approach to increase rice yields. A trans-disciplinary research methodology was used employing participatory research tools. Seedling broadcasting (parachute)...

Water, Mar 16, 2018

Water in agricultural catchments is prone to pollution from agricultural runoff containing nutrie... more Water in agricultural catchments is prone to pollution from agricultural runoff containing nutrients and pesticides, and contamination from the human population working and residing therein. This study examined the quality of water in a drainage stream which runs through a congested network of 'line houses' (low-income housing, typically found arranged in straight 'lines' on estates) in the tea estate catchment area of Pussellawa in central Sri Lanka. The study evaluated the applicability of vertical subsurface flow (VSSF) and horizontal subsurface flow (HSSF) constructed wetlands for water polishing, as the residents use the stream water for various domestic purposes with no treatment other than possibly boiling. Water flow in the stream can vary significantly over time, and so investigations were conducted at various flow conditions to identify the hydraulic loading rate (HLR) bandwidth for wetland polishing applications. Two wetland models of 8 m × 1 m × 0.6 m (length × width × depth) were constructed and arranged as VSSF and HSSF units. Stream water was diverted to these units at HLRs of 3.3, 4, 5, 10, 20, and 40 cm/day. Results showed that both VSSF and HSSF wetland units were capable of substantially reducing five-day biochemical oxygen demand (BOD 5), total suspended solids (TSS), fecal coliform (FC), total coliform (TC), ammonia nitrogen (NH 4 +-N), and nitrate nitrogen (NO 3 −-N) up to 20 cm/day HLR, with removal efficiencies of more than 64%, 60%, 90%, 93%, 70%, and 59% for BOD 5 , TSS, FC, TC, NH 4 +-N, and NO 3 −-N, respectively, in the VSSF wetland unit; and more than 66%, 62%, 91%, 90%, 53%, and 77% for BOD 5 , TSS, FC, TC, NH 4 +-N, and NO 3 −-N, respectively, in the HSSF wetland unit.

Tropical Agricultural Research

Nonpoint source water pollution is one of the most critical pollution problems all over the world... more Nonpoint source water pollution is one of the most critical pollution problems all over the world. This study was conducted to assess the status of water pollution, prevention and management and to investigate the awareness of farmers about water quality, water pollution and riparian buffer zones in Moonplains and Blackpool in Nuwara Eliya. Surface and shallow groundwater samples were collected representing natural, agricultural landscapes to test pH, Electrical Conductivity, Nitrate and Phosphate. High Electrical Conductivity (151 dS/m) was reported in cultivated area throughout the study period compared to the forest area. Higher amount of nitrate (32 ppm) was reported in shallow groundwater and lower level of P was observed in both vegetable cultivated areas and natural forest. A questionnaire survey was carried out among 30 farmers to gather information on fertilizer and pesticide usage, agronomic practices and knowledge about the riparian buffer zones. Farmers were selected based on the land proximity to the adjacent water sources. Majority of the Farmers were males and belonged to age group 30-40 years. Eighty percent of the land extent belonged to 0.04-0.2 ha and above 0.2 ha categories out of which 67 % were in medium slope category. Majority of the lands were owned by the farmers themselves. Irrigation water requirement is mainly supplied through the surface water. Majority (83%) were aware of the water pollution and knowledge is transferred via generations and not by the education. Nearly 73% of the respondents were aware on riparian buffer zone as a soil conservation method but not as a water quality improvement method. However, due to landlessness, 43% of the farmers did not like to maintain the riparian buffer zone, therefore, capacity building, proper farmer awareness on water pollution and need of maintaining a riparian buffer zone are essential to protect water sources in this intensively agricultural area.

Environmental Monitoring and Assessment, 2017

AGRIEAST: Journal of Agricultural Sciences, 2016

Ihus, traltsl'rort ol' No, atrd elrralrtifying the rninirnizirrg tlrc nitrogorr lbrtilizer losscs... more Ihus, traltsl'rort ol' No, atrd elrralrtifying the rninirnizirrg tlrc nitrogorr lbrtilizer losscs liont tlrc ctlttcctttratitltt ol'tlitratt: bc5re11fl lhc root zotte is crop liclds is a grcat oonccnl in view ol'irrcrcasirrg vcry itnpt-lt'tattt to av,,tid thr.' liround rvutcr fertilizeruso cfllcicrrcy artcl reducittg grouttclwater contarnination. contaminatiorr. Mathcuratical rnodel".; anc uscl'ul tools lbi' I'liglrcr levclol'N0.-irr rvatcr is unsal'c lbrrJrinking iltcgrlting tScsc difli:rclt prrl:css,.)s irrv,.riverel irr astheNitrate-Nitrogcn concentratit'rn irr drirrkirrg N transport irr soil alclcair hc rrsq:4 iu loreeastitrg watcrahove Maxintuttt Coutaurinarrt Lcvcl (MCL) llrw a systcrl will lrchavc urit[g1t actually rnakirrg of l0 rng/l causcs scrious lrealth thr.cat tcl infants llcasurepletrts'i1 a ltltvsic:r i systcr' ('l'*ir.i i arrcl t7 ACRIUAS'l 20lo (e)

Journal of the Air & Waste Management Association, 2016

A long-term monitoring of composition of landfill gases in the region with high rainfall was cond... more A long-term monitoring of composition of landfill gases in the region with high rainfall was conducted using an argon assay in order to discuss air intrusion into the dump site. Gas samples were taken from vertical gas monitoring pipes installed along transects at two sections (called new and old) of an abandoned waste dump site in Sri Lanka. N 2 O concentrations varied especially widely, by more than three orders of magnitude (0.046-140 ppmv). The nitrogen/argon ratio of landfill gas was normally higher than that of fresh air, implying that denitrification occurred in the dump site. Argon assays indicate that both N 2 and N 2 O production occurred inside waste and more significantly in the old section. The Ar assay would help for evaluations of N 2 O emission in developing countries. Implications: A long-term monitoring of composition of landfill gases in the region with high rainfall was conducted using an argon assay in order to discuss air intrusion into the dump site. Argon assays indicate that both N 2 and N 2 O production occurred inside waste and more significantly in the old section.

Tropical Agricultural Research, 2017

Minor irrigation systems are very unique to Sri Lankan agriculture for centuries for its role in ... more Minor irrigation systems are very unique to Sri Lankan agriculture for centuries for its role in food security, livelihood and ecosystem sustainability. The objective of this study was to evaluate constraints and potentials of paddy field system layout in a minor irrigation system for other field crop (OFC) cultivation. The study was done in Bayawa minor irrigation system, in Sri Lanka during 2014 and 2015. Data were collected and analyzed to evaluate, system components and their sustainability, canal uniformity, accessibility, and land and farmer plots distribution in the command area. Results according to the system layout reveal that, irrigation canals' uniformity varies along with the distance from head to tail endswith a water conveyance efficiency of 60%. Canal depth increases mainly due to sand mining, thus,requires a large amount of irrigation water for maintaining a hydraulic head in canals in order to supply irrigation water to fields under gravity. Positive hydraulic head of the right canal up to 70% of its length facilitates water distribution from canal to fields, but negative hydraulic head of the left canal constrains for that. As of the system layout and canal distribution, plot to plot irrigation is the common practice in the command area. The number of plots vary from 2-19 with the highest frequency of 6 plots. Cultivation of OFCrequires individual access to water to each plot. Hence, this irrigation and drainage system restrict OFC cultivation. Furthermore, 56% farmers hold less than 0.4 ha farmer fields due to land fragmentation over the years. This also leads to, low accessibility of individual field plots to irrigation canal and identified as major constraint to OFCcultivation.

Open dumping of municipal solid waste is a common practice in Sri Lanka. The leachate produced fr... more Open dumping of municipal solid waste is a common practice in Sri Lanka. The leachate produced from these dumpsites indiscriminately pollutes the surface water and groundwater. Mitigation of the risk through implementation of treatment systems requires information on the leachate quality and its variability over the time. In this study, an open dumpsite was selected from wet zone of the Sri Lanka and its perched waterinside waste layer and groundwater quality was monitored for one year (May 2013 to April 2014) and leachate pollution index (LPI) was used to quantify and compare the leachate contamination potential of the particular dumpsite. Dumpsite is located near to right bank of MahaweliRiver, in UdapalathaPradeshiyaSabhaCentral Province of Sri Lanka. This site has been running for about 7 years and abandoned in 2011. Dump site has two sections, old and new with the age of 7 and 0.5 years, respectively. Two types of boreholes, groundwater borehole (BH) and perched water borehole(...

Tropical agricultural research, 2017

Wastewater generated in white pepper (Piper nigrum L.) processing contains high Biochemical Oxyge... more Wastewater generated in white pepper (Piper nigrum L.) processing contains high Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD) and hydrolyzable tannins that results dark tan/brown colour effluent which cannot be discharged to the environment without proper treatment. Therefore, these experiments were conducted to investigate the effectiveness of electro-coagulation using aluminum (Al) electrodes and coagulation-flocculation with Alum [Al2(SO4)3.18H2O] in reducing the strength of pepper soaked effluent. A laboratory scale electro-coagulation unit was made using two aluminium plates (9 cm × 5 cm × 0.3 cm) as electrodes leaving a 0.5 cm gap between plates and powered with a 12 V DC power supply through a resistance box which is used to regulate the current density. The current density could be controlled between 0-1 A. Coagulation flocculation with Alum was tested at five doses; 1 to 5 g/L with 1 g increments at laboratory scale. The effluent colour was measured using a ...

Managing leachate is one of the problems associated with municipal solid waste landfills. Leachat... more Managing leachate is one of the problems associated with municipal solid waste landfills. Leachate generation highly varies with type of waste, climate, site and surface condition. Several mathematical computer models have been used for prediction of leachate for controlled sanitary landfills. However, the prediction of leachate for an open dumpsite is rarely reported. The applicability of Hydrologic Evaluation of Landfill Performance (HELP) model which is based on water balance method was evaluated in this study for Udapalatha open dump site in the Central Province, Sri Lanka. Input weather data (rainfall, temperature, Relative Humidity, wind velocity, solar radiation) and site specific data (area, depth, profile characteristics) were obtained from nearby weather station and site investigation, respectively. Model output leachate was validated (quasi) with changes in groundwater level in percussion boreholes which were installed at the dump site and monitored from May 2013.The leac...

Combined paddy and other field crops (OFC) fields are unique from other wetland or upland soils, ... more Combined paddy and other field crops (OFC) fields are unique from other wetland or upland soils, because of seasonal alternation of wetting and drying conditions resulting anaerobic and aerobic conditions. Therefore, objective of this study was to assess spatio-temporal variation of soil properties in paddy fields under minor tanks with respect to OFC cultivation. Soil samples were collected at two soil depths from 24 locations covering the entire command area of the Bayawa Minor Irrigation Tank (MIT), Sri Lanka. Soil properties were analyzed and mapped using Arc GIS. Hardpan depth (HPD) was also determined by collecting undisturbed core samples at 0, 15, 25, 30, 45 and 60 cm depths from the same locations Statistical analysis was done to identify spatio-temporal variability of each property. Results revealed that, Bayawa command area showed low coefficient of variation (CV) for pH and bulk density, but high CV for saturated hydraulic conductivity (K s ). HPD was found to be varied ...

CLEAN - Soil, Air, Water, 2016

The hydraulic loading rate (HLR) plays a vital role in pollutant removal in constructed wetlands.... more The hydraulic loading rate (HLR) plays a vital role in pollutant removal in constructed wetlands. This study evaluated the effects of HLR variation on pollutant removal in continuously fed vertical subsurface flow (VSSF) constructed wetlands in tropical conditions. Three VSSF wetland beds (Length: 1.4 m, Width: 0.5 m and Depth: 0.6 m), filled with 10–20 mm gravel media, were set up in a tropical region. Two beds were planted with a locally available emergent macrophyte narrow-leaf cattail (Typha angustifolia), and the remaining bed was used as a control without plants. The performance of these wetland mesocosms was tested at different HLRs of 2.5, 5, 7.5, 10, 12.5, 15, 20, 25, and 30 cm day−1 changing at 2 week intervals in two phases over a period of 6 months. The results revealed that both VSSF wetland systems are capable of substantial reduction of pollutants with a good buffering capacity up to 25 cm day−1 HLR.

Tropical Agricultural Research, 2015

The objective of this study was to evaluate the ground penetrating radar (GPR) wave responses to ... more The objective of this study was to evaluate the ground penetrating radar (GPR) wave responses to different levels of electrical conductivity (EC) in contaminant plumes. GPR wave simulations were carried out using GprMax2D and the simulated data were compared with GPR surveys on Lysimeter test. Trace amplitude of the reflected wave was plotted with two-way travel time and the 2D GPR images were developed to observe the variation of GPR responses with increasing EC. Simulation study showed the disappearance of the subsurface reflection and wave amplitude reaching zero at higher EC levels (when EC>0.28 S/m). In addition, when the EC level was higher, the plume thickness did not have a significant effect on the amplitude of the reflected wave. However, it was also found that reflected signal strength decreases with increasing plume thickness at a given EC level. Further research is needed to verify the results under heterogeneous aquifer conditions.

Tropical Agricultural Research, 2015

Textile industries use dye such as Rhodamine B, Brilliant Red and Reactive Orange for the fabrics... more Textile industries use dye such as Rhodamine B, Brilliant Red and Reactive Orange for the fabrics. Thus the colour of the effluent even after the normal treatment is not within the standard to discharge into the environment. A study was conducted to identify suitable bio-sorbents and to optimize the conditions for selected bio-sorbent to reduce the colour of treated waste water (TWW) from a textile industry. Sieved and air dried sawdust from Rubber (Hevea brasiliensis), Trincomalee wood (Berrya cordifolia), and Breadfruit (Artocarpus altillis) timber were tested with TWW. Rubber sawdust showed a better performance in colour removal than the sawdust from Trincomalee wood and Breadfruit. In order to optimize the conditions with the rubber sawdust, colour removal efficiency of TWW was measured at different pH, sawdust amount, initial dye concentration and different contact times. Sorption data was modelled by Langmuir and Freundlich adsorption isotherms for each dye; Rhodamine B, Brilliant Red, Reactive Orange. Results showed that the best performances of adsorption of dye into Rubber sawdust was obtained at 5 g/L sawdust dosage with 6 minutes contact time up to 0.2 ml of 0.5 M dye concentration under pH 2. Adsorptions of acidic dye (Brilliant Red) and anionic reactive dye (Reactive Orange) followed the Langmuir isotherm. Sorption of cationic dye Rhodamine B was better represented by the Freundlich model. It is recommended to use the sawdust of rubber to remove the colour in wastewater in acidic condition and neutralize the effluent before discharge to the environment.

Biodiversity assessment is considered in making decisions concerning declaration of protected are... more Biodiversity assessment is considered in making decisions concerning declaration of protected areas, management of nature reserves and assessment of the success of management decisions within a particular area. Biodiversity indicators are used as measures of biodiversity. Degree of disturbance or fragmentation of a definite habitat can be measured using specific indicator species. A variety of invertebrates and vertebrates are widely used as indicators of biodiversity. Birds are one of the best species for the national and international biodiversity schemes to be used as a biodiversity indicator. This study focused on the use of birds as an ecological indicator to assess the paddy field ecosystem. The study was carried out in a minor irrigation system in Awlegama Agrarian Service area in Wariyapola Divisional Secretariat. Bayawa was the selected tank with nearly a 38 ha of command area. A standard fixed-radius point count method with the radius set at 25 m was used to sample birds in the paddy field ecosystem. Shanon index was used to explain the results. During a single rice cycle, rice plants undergo three main phenological stages namely; vegetative, reproductive and ripening. All these stages are influenced by farming practices such as tillage, irrigation, crop establishment, agrochemical application and weeding. Different stages with different farming practices create distinct habitats for various bird species. According to the results, the highest Shanon index value (highest diversity) was recorded during the vegetative stage. Birds" diversity had a significant, strong (p=0.05) negative correlation with the age of the paddy. Initial land preparation and vegetative stages provide more food sources for the predatory birds who feed on worms, insects and snails; some of whom act as pests of paddy. Mixing of upper and the subsoil layers in land preparation stages supply more feed for predatory birds. Cattle Egret, Red Wattled Lapwing, Intermediate Egrets, Indian Pond Heron, Black Necked Stroke were in abundance at land preparation and vegetative stage. Yellow crowned woodpecker and White throated munia were recorded during the later stages. A variety of management practices such as land preparation, crop establishments, irrigation, nutrient and pest management, harvesting within the paddy field facilitate to create different habitats with different eco systems and suitable food for bird species. The birds as a biodiversity indicator, symbolise the ecosystem and it reflects the existing condition of an ecosystems. A detailed study will reveal how these birds would help to manage different pests in the paddy fields to bring benefits to the farmers.

International Conference on Agricultural Engineering: New Technologies for Sustainable Agricultural Production and Food Security, 2014

ABSTRACT Water pollution due to indiscriminate discharge of domestic wastewater is one of the maj... more ABSTRACT Water pollution due to indiscriminate discharge of domestic wastewater is one of the major issues limiting access to safe water. A study was conducted to characterize water use and effluent in communities in a tea estate in the upper watershed in Sri Lanka. A questionnaire survey, field visits and focus group discussions were conducted to quantify water consumption. At a pilot scale, concentric rings with diameters of 0.3, 0.75 and 1.5 m were used for constructed wetland. Aggregates and soil were used to fill the rings. Scirpus grossus and Nasturtium officinale were planted in the middle and outer rings respectively. Wastewater from a collection tank was fed into the inner ring and treated wastewater was discharged through the outer ring. Water was sampled at the inlet – at the inner ring, middle ring and outer ring for analysis of Biological Oxygen Demand (BOD5) and other quality parameters. Domestic water usage varied with income, education and access to water. Per capita daily water use was higher in high-income and medium-level educated people. Per capita daily water usage of stream water users and pipe-borne water users were 246 and 194 L, respectively. Major consumption was for bathing followed by laundry. BOD5 of greywater varied from 20-55 mg/L and was highly contaminated with total coliform and E coli. The pilot-scale constructed wetland showed higher removal efficiency of BOD5, SS and TDS at 85, 65 and 55%, respectively. The constructed wetlands were in concentric rings. The hydraulic retention time of 2.3 days increased the pathways and facilitated the filtration, biodegradation and plant uptake of nutrients. This system can be recommended for small communities in the upper watershed in Sri Lanka.

Dissolved oxygen (DO) concentration affects the treatment processes in constructed wetlands. This... more Dissolved oxygen (DO) concentration affects the treatment processes in constructed wetlands. This study examined the dissolved oxygen dynamics and total nitrogen removal in constructed wetlands with submerged and floating plants. Four constructed wetland units each with the surface area of 3 x 1 m 2 were constructed at University of Peradeniya. Two of those with the depths of 0.3 m (A) and 0.6 m (B) were planted separately with Hydrilla verticillata (submerged) and Lemna minor (floating), respectively. Other two (C and D) were constructed with two sections of 0.3 and 0.6 m depths and planted with H. verticillata and L. minor, respectively in each section. Secondary effluent from student hostel was fed with hydraulic retention time of 6 days. DO was measured at different depths of water, 0.0, 0.1, 0.2, 0.4 and 0.5 m from the water surface and along the longitudinal axis of the wetland at 6 hours interval. The total nitrogen was measured for water samples at inlet and outlets. The average dissolved oxygen concentrations of A and B were 17.7 and 0.4 mg L-1 respectively. Oxic condition was maintained in the submerged plant units. Anoxic condition resulted throughout the day in floating plant system. DO varied significantly with depths in oxic condition. DO dynamics in these wetlands can be explained by photosynthesis, respiration, deaeration and reaeration processes. The highest total nitrogen removal was achieved in unit D where combined anoxic and oxic conditions were maintained together H. verticillata and L. minor could effectively be used to maintain required dissolved oxygen in constructed wetlands for nitrate removal.

The number of presently operating small tanks in then Kurunegala district is 4,482 of which 2873 ... more The number of presently operating small tanks in then Kurunegala district is 4,482 of which 2873 tanks have less than 6 ha of command area. Capacity of these tanks is low and the amount of water stored is not sufficient to fulfil the water requirement of the rice crop throughout the cropping season. Many farmers in Udakadawala area in the Kurunegala district adopts to start land preparation (LP) after filling tanks and start LP using tank water. This situation results in the delaying of the cultivation and limiting the use of rain water during the initial stages of the crop. On the other hand, due to high variability of rainfall, severe crop damages are frequently experienced. The objectives of this study were to identify the factors affecting low water productivity and to introduce and evaluate a new land and water management approach to increase rice yields. A trans-disciplinary research methodology was used employing participatory research tools. Seedling broadcasting (parachute)...

Water, Mar 16, 2018

Water in agricultural catchments is prone to pollution from agricultural runoff containing nutrie... more Water in agricultural catchments is prone to pollution from agricultural runoff containing nutrients and pesticides, and contamination from the human population working and residing therein. This study examined the quality of water in a drainage stream which runs through a congested network of 'line houses' (low-income housing, typically found arranged in straight 'lines' on estates) in the tea estate catchment area of Pussellawa in central Sri Lanka. The study evaluated the applicability of vertical subsurface flow (VSSF) and horizontal subsurface flow (HSSF) constructed wetlands for water polishing, as the residents use the stream water for various domestic purposes with no treatment other than possibly boiling. Water flow in the stream can vary significantly over time, and so investigations were conducted at various flow conditions to identify the hydraulic loading rate (HLR) bandwidth for wetland polishing applications. Two wetland models of 8 m × 1 m × 0.6 m (length × width × depth) were constructed and arranged as VSSF and HSSF units. Stream water was diverted to these units at HLRs of 3.3, 4, 5, 10, 20, and 40 cm/day. Results showed that both VSSF and HSSF wetland units were capable of substantially reducing five-day biochemical oxygen demand (BOD 5), total suspended solids (TSS), fecal coliform (FC), total coliform (TC), ammonia nitrogen (NH 4 +-N), and nitrate nitrogen (NO 3 −-N) up to 20 cm/day HLR, with removal efficiencies of more than 64%, 60%, 90%, 93%, 70%, and 59% for BOD 5 , TSS, FC, TC, NH 4 +-N, and NO 3 −-N, respectively, in the VSSF wetland unit; and more than 66%, 62%, 91%, 90%, 53%, and 77% for BOD 5 , TSS, FC, TC, NH 4 +-N, and NO 3 −-N, respectively, in the HSSF wetland unit.

Tropical Agricultural Research

Nonpoint source water pollution is one of the most critical pollution problems all over the world... more Nonpoint source water pollution is one of the most critical pollution problems all over the world. This study was conducted to assess the status of water pollution, prevention and management and to investigate the awareness of farmers about water quality, water pollution and riparian buffer zones in Moonplains and Blackpool in Nuwara Eliya. Surface and shallow groundwater samples were collected representing natural, agricultural landscapes to test pH, Electrical Conductivity, Nitrate and Phosphate. High Electrical Conductivity (151 dS/m) was reported in cultivated area throughout the study period compared to the forest area. Higher amount of nitrate (32 ppm) was reported in shallow groundwater and lower level of P was observed in both vegetable cultivated areas and natural forest. A questionnaire survey was carried out among 30 farmers to gather information on fertilizer and pesticide usage, agronomic practices and knowledge about the riparian buffer zones. Farmers were selected based on the land proximity to the adjacent water sources. Majority of the Farmers were males and belonged to age group 30-40 years. Eighty percent of the land extent belonged to 0.04-0.2 ha and above 0.2 ha categories out of which 67 % were in medium slope category. Majority of the lands were owned by the farmers themselves. Irrigation water requirement is mainly supplied through the surface water. Majority (83%) were aware of the water pollution and knowledge is transferred via generations and not by the education. Nearly 73% of the respondents were aware on riparian buffer zone as a soil conservation method but not as a water quality improvement method. However, due to landlessness, 43% of the farmers did not like to maintain the riparian buffer zone, therefore, capacity building, proper farmer awareness on water pollution and need of maintaining a riparian buffer zone are essential to protect water sources in this intensively agricultural area.

Environmental Monitoring and Assessment, 2017

AGRIEAST: Journal of Agricultural Sciences, 2016

Ihus, traltsl'rort ol' No, atrd elrralrtifying the rninirnizirrg tlrc nitrogorr lbrtilizer losscs... more Ihus, traltsl'rort ol' No, atrd elrralrtifying the rninirnizirrg tlrc nitrogorr lbrtilizer losscs liont tlrc ctlttcctttratitltt ol'tlitratt: bc5re11fl lhc root zotte is crop liclds is a grcat oonccnl in view ol'irrcrcasirrg vcry itnpt-lt'tattt to av,,tid thr.' liround rvutcr fertilizeruso cfllcicrrcy artcl reducittg grouttclwater contarnination. contaminatiorr. Mathcuratical rnodel".; anc uscl'ul tools lbi' I'liglrcr levclol'N0.-irr rvatcr is unsal'c lbrrJrinking iltcgrlting tScsc difli:rclt prrl:css,.)s irrv,.riverel irr astheNitrate-Nitrogcn concentratit'rn irr drirrkirrg N transport irr soil alclcair hc rrsq:4 iu loreeastitrg watcrahove Maxintuttt Coutaurinarrt Lcvcl (MCL) llrw a systcrl will lrchavc urit[g1t actually rnakirrg of l0 rng/l causcs scrious lrealth thr.cat tcl infants llcasurepletrts'i1 a ltltvsic:r i systcr' ('l'*ir.i i arrcl t7 ACRIUAS'l 20lo (e)

Journal of the Air & Waste Management Association, 2016

A long-term monitoring of composition of landfill gases in the region with high rainfall was cond... more A long-term monitoring of composition of landfill gases in the region with high rainfall was conducted using an argon assay in order to discuss air intrusion into the dump site. Gas samples were taken from vertical gas monitoring pipes installed along transects at two sections (called new and old) of an abandoned waste dump site in Sri Lanka. N 2 O concentrations varied especially widely, by more than three orders of magnitude (0.046-140 ppmv). The nitrogen/argon ratio of landfill gas was normally higher than that of fresh air, implying that denitrification occurred in the dump site. Argon assays indicate that both N 2 and N 2 O production occurred inside waste and more significantly in the old section. The Ar assay would help for evaluations of N 2 O emission in developing countries. Implications: A long-term monitoring of composition of landfill gases in the region with high rainfall was conducted using an argon assay in order to discuss air intrusion into the dump site. Argon assays indicate that both N 2 and N 2 O production occurred inside waste and more significantly in the old section.