Browsing by Author "Wanniarachchi, S"

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Open Access
Application of GIS Techniques in Identifying Artificial Groundwater Recharging Zones in Arid Regions: A Case Study in Tissamaharama, Sri Lanka
(MDPI, 2022-12-10) Kariyawasam, T; Basnayake, V; Wanniarachchi, S; Sarukkalige, R; Rathnayake, U
Groundwater resources are severely threatened not only in terms of their quality but also their quantity. The availability of groundwater in arid regions is highly important as it caters to domestic needs, irrigation, and industrial purposes in those areas. With the increasing population and human needs, artificial recharging of groundwater has become an important topic because of rainfall scarcity, high evaporation, and shortage of surface water resources in arid regions. However, this has been given the minimum attention in the context of Sri Lanka. Therefore, the current research was carried out to demarcate suitable sites for the artificial recharging of aquifers with the help of geographic information system (GIS) techniques, in one of the water-scarce regions in Sri Lanka. Tissamaharama District Secretariat Division (DSD) is located in Hambanthota district. This region faces periodic water stress with a low-intensity seasonal rainfall pattern and a lack of surface water sources. Hydrological, geological, and geomorphological parameters such as rainfall, soil type, slope, drainage density, and land use patterns were considered to be the most influential parameters in determining the artificial recharging potential in the study area. The GIS tools were used to carry out a weighted overlay analysis to integrate the effects of each parameter into the potential for artificial groundwater recharge. The result of the study shows that 14.60% of the area in the Tissamaharama DSD has a very good potential for artificial groundwater recharge, while 41.32% has a good potential and 39.03% and 5.05% have poor and very poor potential for artificial groundwater recharge, respectively. The southern part of the DSD and the Yala nature reserve areas are observed to have a higher potential for artificial groundwater recharge than the other areas of Tissamaharama DSD. It is recommended to test the efficiency and effects of groundwater recharge using groundwater models by simulating the effects of groundwater recharge in future studies. Therefore, the results of the current research will be helpful in effectively managing the groundwater resources in the study area.
Open Access
Importance of Hydrologic Simulation for Lids and BMPs Design Using HEC-HMS: A Case Demonstration
(MedCrave, 2017-11-16) Khaniya, B; Wanniarachchi, S; Rathnayake, U. S
Best management practices (BMPs) and the Low impact development (LIDs) is water management tools used to mitigate hydrological impact resulting from unpremeditated urbanization. For the proper functioning of the LID and BMP features the volume of the runoff generated, peak runoff rate before and after the installation, need to be accessed. Modeling by comparing different developmental scenarios helps to characterize the impact of BMPs and LIDs practices on the surface runoff. Therefore, this paper describes a modeling approach to predict the performance of these BMPs and LIDs in an existing hydrological model. This type of modeling approach is important to understand the long-term operation of the watershed post-development plan. A single rainfall event in May 2013 has been modeled and the characteristics graphs such as outflow, precipitation, runoff, infiltration have been analyzed. Run-off volume after retrofitting infiltration trench has decreased by 351m3 at the outlet with an increase of 39 L/s in peak discharge. Time series study of reservoirs depicts low performance of infiltration trench at latter phase of rainfall event. This leads with a rational that infiltration trench cannot result favorable for longer rainfall events unless underlying soil has superior geo-technical properties with low level water table. Results manifest the benefits of using hydrologic modeling software to understand the watershed hydrology.
Open Access
Rainfall analysis in Uma Oya basin, Sri Lanka
(Faculty of Engineering, Sri Lanka Institute of Information Technology, 2016) Senadeera, D; Wanniarachchi, S; Rathnayake, U. S
Climate change is believed to be a critical issue and there is enough evidence to identify the impact of climate change. Sri Lanka is expected to be one of the most affected countries from adverse impact of climate change. Various climatic models propose a rise of rainfall intensity to south Asian region while the number of rainy days are to be reduced. Therefore, the necessity is raised to find the clear trends in climatic factors in the region. However, a very few research work was carried out to see the climatic changes over the last few decades in Sri Lanka. Temporal variation of precipitation (rainfall) can be a good indicator to identify the trends in climate. In addition, these rainfall variations are used in many engineering aspects, including design of massive civil engineering structures like dams, design of water supply networks, etc. Furthermore, the rainfall variations are not only important in engineering aspects but also heavily in agriculture. Therefore, this research paper presents an analysis of temporal variation of rainfall in Uma Oya basin, Sri Lanka. Initial results show some interesting trends in rainfall over a period of 24 years. Furthermore, research is being conducted using advanced statistical data analysis techniques to present comprehensive trends in rainfall in Uma Oya basin
Open Access
A Review on Evapotranspiration Estimation in Agricultural Water Management: Past, Present, and Future
(maps and institutional affiliations., 2022-07-08) Wanniarachchi, S; Sarukkalige, R
Evapotranspiration (ET) is a major component of the water cycle and agricultural water balance. Estimation of water consumption over agricultural areas is important for agricultural water resources planning, management, and regulation. It leads to the establishment of a sustainable water balance, mitigates the impacts of water scarcity, as well as prevents the overusing and wasting of precious water resources. As evapotranspiration is a major consumptive use of irrigation water and rainwater on agricultural lands, improvements of water use efficiency and sustainable water management in agriculture must be based on the accurate estimation of ET. Applications of precision and digital agricultural technologies, the integration of advanced techniques including remote sensing and satellite technology, and usage of machine learning algorithms will be an advantage to enhance the accuracy of the ET estimation in agricultural water management. This paper reviews and summarizes the technical development of the available methodologies and explores the advanced techniques in the estimation of ET in agricultural water management and highlights the potential improvements to enhance the accuracy of the ET estimation to achieve precise agricultural water management
Open Access
A Review on Evapotranspiration Estimation in Agricultural Water Management: Past, Present, and Future
(MDPI, 2022-07) Wanniarachchi, S; Sarukkalige, R
Evapotranspiration (ET) is a major component of the water cycle and agricultural water balance. Estimation of water consumption over agricultural areas is important for agricultural water resources planning, management, and regulation. It leads to the establishment of a sustainable water balance, mitigates the impacts of water scarcity, as well as prevents the overusing and wasting of precious water resources. As evapotranspiration is a major consumptive use of irrigation water and rainwater on agricultural lands, improvements of water use efficiency and sustainable water management in agriculture must be based on the accurate estimation of ET. Applications of precision and digital agricultural technologies, the integration of advanced techniques including remote sensing and satellite technology, and usage of machine learning algorithms will be an advantage to enhance the accuracy of the ET estimation in agricultural water management. This paper reviews and summarizes the technical development of the available methodologies and explores the advanced techniques in the estimation of ET in agricultural water management and highlights the potential improvements to enhance the accuracy of the ET estimation to achieve precise agricultural water management.