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Rainfall is one of the major parts that constitute the hydrological cycle, when the rain falls on a built-up area, the water flowing over that area is known as storm water. The storm is characterized mainly by: Intensity, Duration and Frequency. Due to production of greenhouse gases, hydrologic cycle is changing day by day which is causing variations in terms of intensity, duration and frequency of rainfall events. By pinpointing the potential effects of climate change and adapting to them, is the one way to reduce regions susceptibility. Since rainfall characteristics are often used for planning and design of various water resources project, reviewing and bring up-to-date rainfall characteristics which is Intensity-Duration-Frequency (IDF) curves for future climate situations is important. The main objective of this study is to establish the empirical equations of rainfall intensity which can be used in the Upper Nyabarongo catchment (NNYU) for hydraulic structures design. It was found that intensity of rainfalls decreases with increase in rainfall duration. Further, a rainfall of any given duration will have a larger intensity if its return period is large. In other words, for a rainfall for a given duration, rainfalls of higher intensity in that duration are infrequent than rainfalls of smaller intensity.

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The government of Rwanda through its Ministry of Infrastructure (MININFRA), the authority in charge of energy has initiated different initiatives aimed at finding long term solutions to energy shortage in the country where no investment has been done the last 20 years in electricity generation. Among these solutions, biogas has been identified as one of the sector to be developed. Energy plays a major role in development process of every country. This research is conducted in order to handle energy shortage problems in secondary schools located in rural areas by using a modern biogas. To achieve the aims of this research, the field survey was conducted at G. S de Ntarama and data about numbers of students and teachers, type and amount of waste produced, and impacts of lack of electricity on education were collected through interviews and questionnaires. The data were analyzed and the size of digester was estimated to be 118.524 m 3 . In addition to reducing the emission of carbon dioxide to 7 times lesser than which is emitted by firewood, it was also found that the use of biogas proves to be economical by covering the cost of firewood consumed in one month to five months. The produced energy allocated both in lighting for 4 hours and cooking for 3 hours was proved to be more advantageous and cost effective. The use of modern biogas contributes to the quality of education, environmental protection, agriculture productivity, and improve the lives of Rwandan people in general.