Your search found 11 records
1 Premalal, W. P. R.; Taylor, J. C.; Bird, A. C.; Dayawansa, N. D. K.. 1995. Development of optimum crop distribution spatial model using GIS capabilities. Tropical Agricultural Research, 7:1-12.
GIS ; Models ; Crop production ; Optimization ; Land management ; Economic aspects ; Maps / Sri Lanka
(Location: IWMI-HQ Call no: P 4580 Record No: H021401)
2 Pieris, W. R.; Dayawansa, N. D. K.; Molle, Francois; De Silva, W. P. R. P. 2004. Tertiary level irrigation water management practices at tail end: a case study from Uda Walawe Irrigation Scheme. Tropical Agricultural Research, 16:181-192.
Irrigation programs ; Irrigation canals ; Discharges ; Seepage ; Percolation ; Water deficit ; Farmer managed irrigation systems ; Operations ; Maintenance ; Irrigation requirements ; Water allocation ; Water balance ; Land use ; Paddy fields ; Rice ; Constraints ; Farmer-led irrigation ; Case studies / Sri Lanka / Uda Walawe Irrigation Scheme / Bataatha / Gajamangama
(Location: IWMI-HQ Call no: IWMI 631.7.6.2 G744 PIE Record No: H038165)
3 Wickramasinghe, M. P. A.; Dayawansa, N. D. K.; de Silva, R. P. 2006. Crop area estimation in Mahweli System C, Sri Lanka using remotely sensed data. SAARC Journal of Agriculture, 4:221-234.
Remote sensing ; Land use ; Mapping ; Crop yield ; Forecasting ; Rice ; Paddy fields ; Estimation / Sri Lanka / Mahaweli System C
(Location: IWMI HQ Call no: P 7925 Record No: H040239)
4 Gunawardana, I. P. P.; de Silva, R. P.; Dayawansa, N. D. K.. 2005. Identification of appropriate technology for rainwater harvesting in Moneragala District. In Galagedara, L. W. (Ed.). Water resources research in Sri Lanka: Symposium Proceedings of the Water Professional’s Day 2005. Peradeniya, Sri Lanka: PGIA. pp.63-67.
Water harvesting ; Surveys ; Water balance ; Simulation models ; Domestic water ; Water storage ; Tanks / Sri Lanka / Moneragala District
(Location: IWMI HQ Call no: IWMI 631.7 G744 DAY Record No: H040706)
5 Dayawansa, N. D. K.. (Ed.) 2006. Water resources research in Sri Lanka: symposium proceedings of the Water Professional’s Day 2006, Postgraduate Institute of Agriculture, University of Peradeniya, Sri Lanka, 1 October 2006. Peradeniya, Sri Lanka: University of Peradeniya. Postgraduate Institute of Agriculture (PGIA). 170p.
Water resource management ; Irrigation systems ; Irrigation equipment ; Groundwater ; Wells ; Water quality ; Climate change ; Indicators ; Soil moisture ; Tanks ; Crop production ; Watersheds ; Farmers ; Training ; Sanitation / Sri Lanka / Matara / Mapalana / Hulanda Oya / Anuradhapura District / Gambirigaswewa Cascade Tank / Kala Oya Basin / Mahaweli / Lunuwewa
(Location: IWMI HQ Call no: 631.7 G744 DAY Record No: H040719)
(0.54 MB)
6 Dayawansa, N. D. K.. (Ed.) 2006. Geo-informatics for environmental conservation and management: proceedings of the Third National Symposium on Geo-Informatics, 25 August 2006. Peradeniya, Sri Lanka: Geo-Informatics Society of Sri Lanka (GISSL) 124p.
GIS ; Mapping ; Models ; Hydrology ; Watersheds ; River basins ; Climate change ; Irrigation requirements ; Rice ; Wildlilfe ; Conflict ; Farmers / Asia / India / Sri Lanka / South Asia / Andaman Bay Islands / Hambantota / Colombo / Dehiwala / Mount Lavinia / Hulanda Oya Catchment / Nilwala Ganga / Badulla Oya / Kirama Oya / Kulsi River Basin / Ratnapura / Giribawa
(Location: IWMI HQ Call no: 526.0285 G570 DAY Record No: H040856)
7 Jayasekare, A. S.; Dayawansa, N. D. K.; De Silva, R. P.; Muthuwatta, Lal P. 2005. Spatially distributed hydrological modeling of Upper Uma Oya Catchment using soil and water assessment tool SWAT. In De Silva, R. P. (Ed.). Sweden International Training Course on Remote Sensing Education for Educators, Decadal Proceedings 1990-2004: a collection of selected papers submitted by former participants. Peradeniya, Sri Lanka: Geo Informatics Society of Sri Lanka (GISSL) pp.65-85.
River basins ; Catchment areas ; Hydrology ; Groundwater recharge ; Land use ; Planning ; Simulation models ; GIS / Sri Lanka / Upper Uma Oya Catchment
(Location: IWMI HQ Call no: 526.0285 G570 DES Record No: H040879)
8 Amarasekara, M. G. T. S.; Kumarihamy, R. M. K.; Dayawansa, N. D. K.; De Silva, R. P. 2010. The impact of inappropriate soil management on river water quality: a case study in the Kurundu Oya Sub-catchment of the Upper Mahaweli Catchment, Sri Lanka. In Evans, Alexandra; Jinapala, K. (Eds). Proceedings of the National Conference on Water, Food Security and Climate Change in Sri Lanka, BMICH, Colombo, Sri Lanka, 9-11 June 2009. Vol. 2. Water quality, environment and climate change. Colombo, Sri Lanka: International Water Management Institute (IWMI). pp.49-60.
Soil management ; Soil degradation ; Catchment areas ; Erosion ; Sedimentation ; Water pollution ; Fertilizer application ; Nitrogen ; Vegetable growing / Sri Lanka / Upper Mahaweli Catchment Area / Kurundu Oya Sub-Catchment / Batagolla / Kumbalgamuwa / Mahakudugala
(Location: IWMI HQ Call no: IWMI 631.7 G744 EVA Record No: H042858)
The results of many studies have revealed that intensive farming on steep slopes, coupled with over application of fertilizers and accumulation of nutrients in downstream water bodies due to soil erosion, have contributed to environmental hazards in the Upper Mahaweli Catchment Area (UMCA) of Sri Lanka. The encroachment of riparian zones for exotic vegetable cultivation has aggravated this situation. In view of this, a study was conducted in the Kurundu Oya catchment, a micro-catchment of the UMCA, to investigate the soil management practices within the farming systems and their impacts on river water quality. Three villages were selected along the Kurundu Oya: Mahakudugala, Kumbalgamuwa and Batagolla. The study consisted of a survey of 150 households in 2007 and 2008, to gather information on the characteristics of householders and on soil management practices. A soil survey was carried out to analyze the soil fertility of farmlands. Water quality parameters were measured periodically in different sections of a selected stream. The results revealed that nearly 50 % of the riparian zones in the upper catchment of the Kurundu Oya stream are encroached to cultivate potato and other exotic vegetables. In addition, it was observed that over application of fertilizers on the vegetable plots was causing nutrient accumulation and the plots also recorded high levels of phosphorous (P) (above 75 ppm). Results of the water quality analysis showed that nitrate and available P levels were within the standard limits, but nitrate nitrogen (NO3-N) levels were close to the upper level of the standard limit. Therefore, in order to minimize water pollution, it is strongly recommended that fertilizer application is based on soil tests. In addition, encroachment of sensitive lands has to be addressed. Priority should be given to strengthening institutional capacity in order to facilitate the implementation of existing environmental legislation.
9 Bandara, M. A. C. S.; De Silva, R. P.; Dayawansa, N. D. K.. 2010. Household water security through stored rainwater and consumer acceptability: a case study of the Anuradhapura District. In Evans, Alexandra; Jinapala, K. (Eds). Proceedings of the National Conference on Water, Food Security and Climate Change in Sri Lanka, BMICH, Colombo, Sri Lanka, 9-11 June 2009. Vol. 2. Water quality, environment and climate change. Colombo, Sri Lanka: International Water Management Institute (IWMI). pp.87-97.
Domestic water ; Water security ; Water harvesting ; Water quality ; Rural areas ; Case studies / Sri Lanka / Anuradhapura District
(Location: IWMI HQ Call no: e-copy only Record No: H042862)
Rainwater harvesting has increased in popularity in Sri Lanka over the past two decades due to the number of water supply projects funded by the government and non-governmental organizations (NGOs). The stored rainwater can provide accessible, reliable, timely and adequate supplies of water to households but there are uncertainties as to safety, in terms of water quality, and consumer acceptability. A study was, therefore, conducted in the Anuradhapura District, in the dry zone, to assess consumer acceptability of stored rainwater for household purposes and to conduct rainwater quality tests in a laboratory. The majority of households in Anuradhapura meet their drinking water requirements from protected wells (59.6 %). Prior to the project, people greatly preferred open wells as a source of domestic water, followed by tubewells, because they believed that water in open wells is of good quality and drinkable. However, stored rainwater has become the priority source now, especially through roof rainwater harvesting (RRWH), which is used during the dry periods. The study revealed that more than 85 % of households use stored rainwater for drinking although some have concerns over the quality and only drink it after boiling. The easy accessibility of water and the assurance by the project team that it is of good quality are the main reasons that people are willing to drink it. The acceptability of stored rainwater for consumption was very high in water-scarce areas and with the increasing distance to the nearest and alternative sources of good-quality water. Of those who felt that they had adequate water, 84 % of the sample households found it adequate in the wet season but only 21 % in the dry season. Water quality analysis revealed that the chemical and physical quality of stored rainwater is within the acceptable range with respect to Sri Lankan Standards, SLS: 614, for potable water quality (SLIS 1983). Other domestic water sources exceeded standards for electrical conductivity, total alkalinity, hardness, ammonium nitrogen, fluorides and total iron. However, stored rainwater was of lower biological quality than other domestic water sources.
10 Jayasiri, M. M. J. G. C. N.; Yadav, S.; Dayawansa, N. D. K.; Ingold, K. 2022. Managing agricultural water resources: addressing the complexity of innovation, social perspectives, and water governance in Sri Lanka. Irrigation and Drainage, 15p. (Online first) [doi: https://doi.org/10.1002/ird.2693]
Water resources ; Water management ; Water governance ; Innovation ; Climate change ; Water productivity ; Irrigation efficiency ; Sustainability ; Water use efficiency ; Water demand ; Irrigation water ; Irrigation systems ; Irrigation schemes ; Irrigation management ; Water conservation ; Water policies ; Institutions ; Social aspects ; Infrastructure / Sri Lanka / Deduru Oya Basin
(Location: IWMI HQ Call no: e-copy only Record No: H050986)
(1.53 MB)
Irrigation plays a vital role in world food security. Agriculture accounts for 70% of freshwater withdrawals worldwide, and the figure is even higher in developing countries like Sri Lanka. The rapid expansion of anthropogenic activities, together with the anticipated climatic risks associated with them, is exacerbating the problem of increasing agricultural water demand. Although it has been recognized for decades, improving irrigation water-use efficiency and water productivity is still considered the most realistic option for addressing the challenge of sustainable management of water resources. However, adoption of recommended water-efficient technologies and concepts remains elusive in practice, highlighting the gaps created by failing to consider social perspectives in developing water management strategies. As a result, the effectiveness of water governance has often been questioned in terms of performance and adoption of innovative technologies. This paper reviews and discusses the complexity of innovation through a technical, social, and institutional lens by reviewing available research on Sri Lanka's river basins and presents a perspective on opportunities for improving irrigation water management.
11 Wickramasinghe, M. R. C. P.; Dayawansa, N. D. K.; Jayasiri, M. M. J. G. C. N.; De Silva, R. P. 2023. A study on external pressures of an ancient irrigation cascade system in Sri Lanka. Agricultural Systems, 205:103593. [doi: https://doi.org/10.1016/j.agsy.2022.103593]
Irrigation ; History ; Villages ; Tanks ; Systems ; Water quality ; Agrochemicals ; Runoff ; Land use change ; Climate variability ; Population growth ; Intensification ; Farming systems ; Water management ; Arid zones ; Agroclimatic zones ; Precipitation ; Water availability ; Sustainability ; Fertilizers ; Salinity ; Soil erosion ; Forest cover ; Water management / Sri Lanka / Anuradhapura / Maha Illuppallama / Mahakanumulla
(Location: IWMI HQ Call no: e-copy only Record No: H051615)
(3.87 MB)
CONTEXT: Village Tank Cascade Systems (VTCSs), which are ancient irrigation systems in Sri Lanka have undergone various pressures over time including climate variability, population growth, land use changes and agricultural intensification. VTCSs have provided irrigation and vital ecosystem services for generations, while facing these pressures. As external pressures have increased drastically over the last century, it is worthwhile to investigate VTCS's current capacity to tolerate pressures exerted on them while sustaining their functions.
OBJECTIVE: The objectives of this study were to (i) assess the pressures exerted on Mahakanumulla VTCS due to climate change, population growth, land use changes and agricultural practices, (ii) evaluate the impacts of the pressures on the system in terms of water quality and quantity.
METHODS: Rainfall data from 1906 to 2020 were analyzed to identify the rainfall trends over the last century. Land use maps were developed for 1910, 1979, 2002 and 2018. To identify current farming practices, a questionnaire survey was carried out targeting 357 respondents followed by field investigations. Environmental impacts due to pressures on the system were evaluated using water quantity estimations and quality tests.
RESULTS AND CONCLUSIONS: Paddy extent has increased from 6.3% to 20.2% while the homestead extent has increased from 1.6% to 11.5% during the last century. The lands used for sustainable shifting cultivation have encroached with permanent agricultural lands and human settlements. The runoff coefficient rose from 0.29 to 0.45, indicating a high outflow of water during rains and limiting water retention within the system. This is an indication of increasing water scarcity in dry periods due to limited recharge capacity. Although the system continues to function without significant water quality deterioration, agricultural activities can cause threats in the future. Hence, the system needs immediate attention in the context of proper land use planning, farmer awareness and integrated nutrient management at the cascade level to minimize these pressures exerted upon the system.
SIGNIFICANCE: Identifying and quantifying various pressures exerted on VTCSs is the fundamental step in setting management and mitigation plans. Project planners and policymakers need evidence-based information in this regard. Therefore, this study's findings and the research framework that may be extended to other VTCSs and similar systems are significant in creating a favorable policy environment and implementation programmes to reduce the risks the VTCSs are exposed to.
OBJECTIVE: The objectives of this study were to (i) assess the pressures exerted on Mahakanumulla VTCS due to climate change, population growth, land use changes and agricultural practices, (ii) evaluate the impacts of the pressures on the system in terms of water quality and quantity.
METHODS: Rainfall data from 1906 to 2020 were analyzed to identify the rainfall trends over the last century. Land use maps were developed for 1910, 1979, 2002 and 2018. To identify current farming practices, a questionnaire survey was carried out targeting 357 respondents followed by field investigations. Environmental impacts due to pressures on the system were evaluated using water quantity estimations and quality tests.
RESULTS AND CONCLUSIONS: Paddy extent has increased from 6.3% to 20.2% while the homestead extent has increased from 1.6% to 11.5% during the last century. The lands used for sustainable shifting cultivation have encroached with permanent agricultural lands and human settlements. The runoff coefficient rose from 0.29 to 0.45, indicating a high outflow of water during rains and limiting water retention within the system. This is an indication of increasing water scarcity in dry periods due to limited recharge capacity. Although the system continues to function without significant water quality deterioration, agricultural activities can cause threats in the future. Hence, the system needs immediate attention in the context of proper land use planning, farmer awareness and integrated nutrient management at the cascade level to minimize these pressures exerted upon the system.
SIGNIFICANCE: Identifying and quantifying various pressures exerted on VTCSs is the fundamental step in setting management and mitigation plans. Project planners and policymakers need evidence-based information in this regard. Therefore, this study's findings and the research framework that may be extended to other VTCSs and similar systems are significant in creating a favorable policy environment and implementation programmes to reduce the risks the VTCSs are exposed to.
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