Message from the Chair 5th International Symposium – 2015 South Eastern University of Sri Lanka

South Eastern University of Sri Lanka, one of the national universities in the country, is in the fore front in the region in research and development, innovation and dissemination. IntSym 2015, the fifth international symposium of the South Eastern University of Sri Lanka, is one of the major events organized in the Eastern Sri Lanka to facilitate dissemination of research findings. The theme of the fifth international symposium is “Emerging Trends and Challenges in Multidisciplinary Research” an important aspect in research which is focused nationally and globally. Multidisciplinary research brings different disciplines together to talk about issues from each of their perspectives where different disciples may collaborate, but maintaining a separation of their disciplines within that process. Researchers from different disciplines can initiate multidisciplinary research by simple teaming. Multidisciplinary research integrates data from different disciplines, incorporates different methodologies, and combines multiple perspectives and concepts to solve real world problems. Multidisciplinary research, therefore, requires either an individual researcher involves in two or more disciplines or two or more researchers bring together two or more different disciples or multidisciplinary teams assemble and create a platform for discovery and innovation. Multidisciplinary research not only brings expertise together but also other limited resources in many contexts such as equipment, resources, time and motivation. Hence, multidisciplinary research leads to findings that exceed the possibilities of a uni-disciplinary research. The steering committee of the international symposium has selected this timely theme in order to be on par with national and global trends and needs. This symposium allows the researchers, academics and students to share the novel findings of multidisciplinary research and development initiatives. This symposium will also provide ample opportunity to the participants to share knowledge and collaborate and network with different experts from different parts of the country and the globe. This symposium will emerge as a platform that encourages and enhances multiple disciplines to merge together to yield more and more fruitful research findings. I wish to thank the organizing committee of the fifth international symposium of the South Eastern University of Sri Lanka for selecting an appropriate and timely theme for this year. I also wish to thank all others who have contributed to make this symposium a reality. I wish the fifth international symposium of the South Eastern University of Sri Lanka all the success

Evaluation of the performance of Hydrologic Engineering Centre - Hydrologic Modelling System (HEC-HMS) model in hydrological simulation of long term flow of Uruwal Oya, Sri Lanka.

Lack or non-availability of long term river flow data has been one of the major limiting factors in many tropical countries, which restricts the planning and designing of ecologically sustainable water management approaches. Employment of computer models in synthesizing daily flow data via hydrological simulation has been recognized as an ideal solution to address the above requirements. As the HEC-HMS model is one of the most reliable and widely used models that could be devised for hydrological simulations, the current study attempts to evaluate the performance of three different modelling approaches of HEC-HMS in the synthesis of long term daily flow data of the Uruwal Oya. Twenty year (1984 – 2014) daily rainfall data from Henarathgoda and Horagahalanda rain gauging stations and monthly evapotranspiration data for the Henarathgoda agro meteorological station together with daily flow data at the confluence point of Uruwal Oya and Aththanagalu Oya were used in the current study. GIS layers that were needed as input data for the flow simulation were developed by using Arc GIS 10.2. HEC-HMS (version 3.5) model was calibrated and validated for the periods of 1984 – 1994 and 1995 – 2014 respectively for the Uruwal Oya basin based on three selected methods viz Snyder unit hydrograph method, Deficit and Constant loss method and Initial and constant loss method in order to determine the most suitable simulation method. The flows simulated from each method were statistically evaluated against the actual flows by employing the coefficient of performance (CPA’), the relative error (RE), scatter plot method (R2) and the residual method. The Snyder unit hydrograph method that yielded 76.8%, 96.4%, 0.670, 1.65 and +0.25 values for residual points within mean ±1SD, mean ±2 SD, R2, CPA’ and RE, respectively and the Deficit constant loss method that yielded 74.2%, 95.4%, 0.610, 1.70 and +0.28 values for residual points within mean ± 1SD, mean ± 2 SD, R2, CPA’ and RE, respectively were recognized as the best performing transformation and loss methods, respectively in runoff simulation of the Uruwal Oya basin. Thus, the HEC-HMS model could be recommended as a reliable and effective approach for runoff simulation of similar wet zone river basins in Sri Lanka

Evaluation of traditional “micro catchment management” practices in respect with basic concepts of modern water resources management.

Sri Lanka has been considered as one of the agricultural countries that had maintained sustainable hydraulic and agricultural production system since the early civilizations. Various varieties of paddy have been the dominant among the agricultural crops. Well planned management of water resources is one of the key requirements to obtain high yields, since the water requirement of paddy is relatively high. Thus traditional concepts and methods have been developed, to ensure the sustainable and optimum management of water resources especially within the dry and intermediate zones. The storage, conservation and the sustainable usage of water has been practiced traditionally since the precipitation is limited temporally and spatially. Specified approaches known as Micro Catchment Management (MCM) have been practiced to prevent and cope with water scarcity. Thus the ancient concepts of MCM is studied and evaluated on a scientific basis along with the modern concepts of water resources management, to identify the eco-consciousness of the ancient practices. Different practices on MCM were gathered from literary sources such as ancient manuscripts, palm leave books, publications and were verified through oral interviews with experienced traditional practitioners of the discipline of Vasthu Shastra. The verified concepts were scientifically evaluated and were compared with the basic concepts of modern water resources management. In this approach, localities have been identified and managed as separate entities due to which the term MCM has been referred to. With the identification of such boundaries of land that defines the catchment area, all the available water resources were identified and sustainably managed to minimize any losses of water without optimal use. The surface water flows of the area were often diverted to nourish tanks, allowing a sufficient ecological flow downstream. Thus, different practices have been followed in the ancient times such as specific land selections, diversion practices, dam and tank constructions, specific techniques to store water, minimize water infiltration and seepage, minimize evaporation and wind action, etc.. Importance of establishing and maintaining patches of forest within the catchment areas, the ecofriendly methods of forest establishment and management, specific tree species that should be grown are also stated. Thus, the key practices of traditional MCM facilitate the ecofriendly sustainable utilisation and management of water resources in harmony with the environment

Evaluation of traditional plantation management techniques with respect to modern concepts of plantation management.

The traditional Sri Lankans led a simple yet a sustainable life in harmony with the nature utilising its resources wisely and appropriately. Since the vitality of forest resources were well known, properly designed plantation management techniques were followed by them even in ancient times. The traditionally practiced plantation management techniques are highly significant since most of these methods are more or less similar to the plantation management practices which are used in modern plantations leading to a sustainable management of forest resources. These traditional practices are evaluated on a scientific basis along with the modern concepts of sustainable plantation management to signify the eco consciousness of traditional plantation management techniques. Different traditional plantation management practices were gathered from literary sources such as ancient manuscripts, palm leave books, publications etc. The gathered methods were verified through oral interviews with experienced traditional experts and the verified methods were scientifically evaluated and were compared with the basic plantation management concepts practiced under sustainable plantation management at present. The methods of assessing soil suitability for various plantations, the specific requirements of floral species, ecofriendly land preparation techniques (such as phytoremediation etc.), different seeding or plantation methods (based upon the used floral species), the optimum spaces or gaps that should be maintained between two trees (for different floral species), plant treatment methods, harvesting ages of different species are discussed in detail within the traditional sources which seem to bear the same core concepts as of the modern techniques. Hence the traditional plantation management techniques can be defined as the fundamentals of sustainable forest resources management that have been gradually evolved into modern concepts of plantation management

Evaluation of the trends in climate change with respect to severity and frequency of occurrence of wet and dry events of rainfall in Aththanagalu Oya basin.

Socioeconomic aspects of life have changed due to alterations in the climatic patterns. Sri Lanka needs to pay more attention to the climate extremes as the available water resources are directly affected by these changes. Hence planning and management of water resources based on climatic patterns play a key role in sustainable development. Sustainable planning and management of water resources of Aththanagalu Oya that feeds many large and small scale multi-purpose water extraction schemes in Sri Lanka is vital in the event of climate change. Thus, an analysis of the shifts and trends of climatic patterns with respect to wet and dry events within the Aththanagalu Oya basin was carried out to evaluate the state and the extent of climate change using Standardized Precipitation Index (SPI). Daily rainfall data covering the period from January 1991 to February 2011 of Henarathgoda, Vincit, Chesterford, Kirindiwela, Nittambuwa and Pasyala rainfall gauging stations which are located within the Aththanagalu Oya catchment area were obtained from the Department of Meteorology, Sri Lanka. Two periodic intervals of years (1991-2000 and 2001-2011) were formulated and monthly accumulated rainfall for each month of the considered periods were used as the input to the SPI Model in Mat Lab R2007b (version 7.5). The events were ranked into five classes (normal, mild moderate, severe and extreme) based on the severity of each event and the variations in climate (with respect to SPI) were evaluated using Paired ChiSquare method. A decrease in dry events and an increase of the wet events in the climatic pattern of recent years (2001-2011) compared to the past (from 1991 to 2000) in Vincit, Kirindiwela, Nittambuwa and Pasyala could be observed in accordance with the SPI analysis while an opposite trend was observed in Henarathgoda and Chesterford. Unlike the predictions of many studies which expect significant alterations in climate patterns in the recent years than the past years, according to the SPI approach, only the wet events of Pasyala (a significant increasing trend of wetness) and the dry events of Vincit (a significant decreasing trend of dryness) indicate significant alterations in climatic patterns while the climatic variations indicated by the rest of the areas are statistically insignificant. Hence, a significant increase in wetness in Vincit and Pasyalain terms of both severity and frequency of occurrence with variations of rainfall seasonality could be predicted in accordance with the SPI

Flow modelling in NillambeOya, Sri Lanka.

Flooding and flow changes in rivers and streams due to anthropogenic activities are the major problems worldwide as well as in Sri Lanka. To address these issues, proper monitoring of flow patterns and prediction of flow changes are necessary; However, daily monitoring and data collection is greatly time consuming and costly. Therefore, development and application of models for accurate simulation of flow variations will be a vital requirement for the management of these ecosystems. In order to address these concerns, a study was done with the objective of calibrating and validating a model based on climatic, landuse and flow data and to determine whether the calibrated model could be applied to predict flow variations. HEC-HMS 3.5 model which was developed by the United States Army Corps of Engineers was used to simulate flow variation of the Nillambe Oya catchment which is located within the central highlands of the mid and upcountry wet zone. During the period from May 2013 to September 2013, flow was measured in nine selected days. Rainfall data, other meteorological data and flow data for eight years (October 1991 to September 1999) were obtained from the Environment and Forest Division of the Mahaweli Authority and the Meteorology Department of Sri Lanka. Daily flow data for five years (October 1991 to September 1996) were used to calibrate the model and another set of flow data for five years (October 1994 to September 1999) were used to validate the model. The flow values that were measured in situ during May 2013 to September 2013 were statistically tested with flow values simulated by the model. Obtained residual plots and calculated percentage residuals of the calibration and validation produced results with high R squared values (above 0.65) and residual percentages within ±1SD and ±2SD above 85% and 95%, respectively. The properly calibrated and validated HEC-HMS 3.5 computer model can be reliably used to simulate flows of Nillambe Oya. Snyder unit hydrograph method, as the transformation method, simulates flows reliably in the study catchment, along with initial loss method. Therefore, HEC-HMS 3.5 model can reliably be used to estimate flow volumes that are available to Hydropower generation, drinking water supply and agricultural purposes while maintaining ecological harmony with the riverine ecosystem

Environmental flow variation due to mini-hydro diversion at Gurugoda Oya, Sri Lanka.

Quantification of amounts of flows that could be diverted maintaining desired ecosystem conditions is difficult, and thus, water allocation among sectors including the environment, has emerged a growing concern in Sri Lanka. Therefore, this research focused on quantifying optimum flows that has to be maintained below the weir site of a mini-hydro power plant located at Morontota, Sri Lanka through Environmental Flow Assessment and to predict whether the flows of the Hungampola South/Morontota village section of Gurugoda Oya would be sufficient to sustain riverine biodiversity. The HEC-HMS 3.5 model was calibrated and validated for the Holombuwa catchment of the Gurugoda Oya basin. The GIS layers that were needed as input data for flow simulation were prepared using Arc GIS 10.0 and the calibrated and validated model was applied to the Alapalawela sub catchment located within the Holombuwa catchment, to generate flows for the past twenty three years (1991-2013). Simulated stream flows were characterized using thirty two different hydrological parameters. The Range of Variability Approach (RVA) targets to be maintained below the weir site were calculated using flows before hydropower diversions, and the rate of non-attainment of flows were determined for past scenarios (2011-2013). According to the RVA, Environmental Flow is not maintained at present in Gurugoda Oya below the weir. Mean rate of non-attainment of the flow of Gurugoda Oya after mini hydropower diversion is around 45% suggesting moderate level of hydrologic alteration due to impoundment. Rate of non-attainment of the indicators of hydrological alterations (IHA) group 1 parameters are in between 33% - 100%. Except for the magnitude and duration of rate of non-attainment of means of 90 day minima and all maxima values which attain a steady 0%, all other group 2 parameters vary between 33% - 67%. In the IHA group 3, timing of lower limit of annual extreme water condition could not be calculated because flow of Gurugoda Oya assumes the same minimal flow for several days, showing more than one annual minima. Annual maxima show a rate of nonattainment of 33%. Rate of non-attainment of the IHA group 4 and 5 both vary between 0% - 100%. Therefore, Hydropower diversions from Gurugoda Oya that deals with damming of the stream needs extensive analysis of environmental impacts due to changes in flow regimes. The RVA targets defined by this study could be of significance for ecosystem management and restorations plans, and could provide ecological operations for the weir

Assessment of continuous wet day rainfall frequency distribution in the Intermediate Zone of Sri Lanka.

Changes in rainfall distribution patterns around the world have caused fluctuations in those climate regimes. Agriculture is particularly vulnerable to climatic conditions and it is chief among the systems that are expected to undergo changes as a consequence of climate change. This study analyses the climate change variability through the fluctuation in precipitation pattern and evaporation, in low country intermediate zone (IL1a) agro ecological region based on Gumbel’s frequency distribution analysis on wet day rainfall data. Focusing on a cascade agricultural system in the Katupotha divisional secretariat division of the Kurunegala district that is located in the IL1a, the climate change variability was analysed using daily rainfall data of fifty years (1961-2010) together with long term evaporation data. Experimental methodology considered a day to be wet only if the rainfall exceeded its evaporation. This was considered as the precipitation amount that could potentially be used by the crops. Gumbel’s frequency analysis was employed to derive the variability in continuous wet day rainfall distribution at 25 year time intervals (1961-1985 and 1986-2010). The total continuous wet day rainfall and seasonal total continuous wet day rainfall frequency distributions were analysed using the technique. Results of the analysis show an increasing trend in magnitude of the total continuous wet day precipitations from 1961-2010. This increasing trend is observed beyond 2.2 years recurrence interval. At longer recurrence intervals (20 years) a 50 mm increase is experienced during the last 25 years (1986-2010) while at shorter recurrence intervals (2.2 years), a 6 mm increase is evident. A distinct increasing trend in the total continuous wet day precipitation from 1961-2010 was observed during the second inter-monsoon which was a 165 mm increase at a 10 year recurrence interval. In contrary, the south-west monsoon, first inter-monsoon and north-east monsoon recorded decreasing trends in the total continuous wet day precipitation from 1961-2010

Recent trends in the rainfall patterns of Mannar, Sri Lanka

Evaluation of the variations in rainfall patterns that reflect the trends in climate, is of essence for effective and sustainable management of the available water resources within a country. Sri Lanka being a tropical country that significantly depend upon agriculture for economic viability, has to pay much attention to the variations in rainfall patterns (especially in seasonality and severity of the rainfall and frequency of wet and dry events) for effective planning and management of water resources ensuring their sustainability. Therefore, Standardized Precipitation Index (SPI) and Seasonality Index (SI) were employed to assess the degree of climate change on rainfall patterns (with respect to the temporal variations of wet and dry events and rainfall seasonality) of Mannar District Secretariat Division (DSD) that lie within DL3 and DL4 agro-ecological regions of the dry zone. Daily rainfall data for fifty three years (1961 - 2013) obtained from the Mannar rain gauging station were utilized in this study, under two major periodic intervals of years (1961-1985 and 19862013). Monthly accumulated rainfall for each month of the considered periods of years were calculated and used as the input for SPI modeled in Mat Lab R2007b (version 7.5). Variations in rainfall seasonality were assessed based on the SI values that were calculated for each year in the two periods of years (1961-1985 and 1986-2011) using the standard procedures. Subsequently, the calculated SI values were arranged into 5 groups on a ten year (decade) basis and mean SI values of each 10 year time period were calculated and were analyzed to recognize long term variations in rainfall seasonality. A significant decrease in wetness [Χ2 cal =15.04 > Χ2 tab (4, 0.05)] with an apparent increase in dryness [Χ2 cal = 2.326 < Χ2 tab (4, 0.05)] in terms of severity and frequency of occurrence could be predicted for Mannar. No significant variations in rainfall seasonality were predicted for Mannar in accordance with the SI, except for apparent variations that were not significant