Tipping bucket is an accurate and reliable device that is used to measure runoff water flows, especially in small scale catchments. However, the performance of the tipping bucket device depends on magnitude of the runoff water flow, dimension of the tipping bucket and the accuracy of the calibration. This paper discusses technical guidelines that govern the design, construction, field installation, calibration and error minimizing of tipping bucket gauges used for runoff estimation in small-scale catchments under agricultural land use systems. The proposed tipping bucket system is a cost effective and simple device that can be fabricated in a basic mechanical workshop. The device proved to be a sensitive and reliable instrument on which accurate measurements can be read out easily with minimal maintenance.

An analysis was conducted to estimate the agro-climatic changes, which would incur due to projected climate change scenarios on sugarcane cultivation in Sevanagala, Sri Lanka over the next 70 years. The general circulation model developed by the Beijing Meteorological Centre was used with Representative Concentration Pathways scenario 6.0 to simulate the climate variables of maximum and minimum temperatures, and rainfall for years 2030, 2050, and 2090. The goodness of fit test was conducted against simulated and observed data using 10-year dataset from 2010 to 2019. The future climate was compared using a baseline data set, which was generated by averaging 10 years of data from 2010 to 2019. The results indicated that by 2090, the average annual minimum and maximum temperatures would increase by 1.2°C and 1.4°C, respectively. However, annual maximum and minimum temperatures may remain within the favourable range for sugarcane cultivation. The annual rainfall is expected to increase by 6.0% in 2090 relative to baseline values. The results demonstrated the stability of the effective rainfall. The evapotranspiration would increase by 3.7% by the year 2090 relative to baseline values. The soil moisture deficits for sugarcane planted in the Yala and Maha planting seasons are also expected to increase by 6.7% and 12.6%, respectively in 2090. As a result of increased evapotranspiration, additional irrigation might be needed to maintain the productivity of sugarcane cultivation indicating the climate-related risks for future rain-fed sugarcane cultivations in Sevanagala, Sri Lanka.

The present study explored how environmental factors such as rainfall, temperature, and solar radiation affect sugarcane quality in the Sevanagala sugarcane plantation area of Sri Lanka. The research covered the period from 2017 to 2021. To identify the most suitable planting times and characterize the environmental interactions, the APSIM crop simulation model was utilized. This approach enables precise predictions based on regional climatic data and crop growth patterns. The current findings revealed a significant negative correlation between sugarcane quality and rainfall received during the period of three months prior to harvest. A positive relationship was observed between sugarcane quality and the average daily sunshine hours experienced over the five months prior to harvest. Based on the current results, the ideal planting time for the Yala season planting crops to maximize sugarcane quality was from the fourth week of March to the second week of April. For the Maha season commenced crops, the optimal planting period was from the fourth week of September to the second week of October. These findings offer valuable guidance for stakeholders in the Sevanagala sugar industry to strategically plan planting and harvesting schedules. Implementing these optimal timings can enhance sugarcane quality, improve overall productivity, and contribute to the sustainability and profitability of sugar production in the Lanka sugar Sevanagala, Sri Lanka.