A Survey of Hydrological Systems in the Greater Virunga Landscape, Around the Volcanoes National Park, Rwanda Nahayo Déogratias * , Ntwali Janvier * , Nkurunziza Fabrice, * Kamana Emmanuel, * Bitariho Robert ** , Katcho Karume *** , Byamukama James **** *Institut d’Enseignement Supérieur de Ruhengeri (INES-Ruhengeri), Rwanda **Institute of Tropical Forests Conservation (ITFC), Uganda ***Observatoire Volcanologique de Goma (OVG), DRC, ***Greater Virunga Transboundary Collaboration, Executive Secretariat (GVTC-ES) Abstract This research aimed to commission the Survey of Hydrological Systems in the Volcanoes National Park Landscape with the specific objective “Assessment and determination of water resources availability and quality initiated and regional database on availability, quality and water related disasters established”. To achieve this, the following methodologies were used. Socioeconomic data collections were conducted using questionnaire addressed to local authorities, guided interviews conducted in 382 households among 69 650 households found in 11 sectors surrounding the Volcanoes National Park (PNV)and focus groups discussions conducted in small groups of 7 to 11 persons living in the study area. Water demand was estimated based on World Health Organization (WHO) standards, results from socio-economic survey, and addition of environmental flows. Direct observations were used to analyse physical status of different hydraulic infrastructures implemented in the study area and water sources that could be vital for future interventions. Water sampling and quality analysis were conducted using standard methods recommended by regional standardisation bodies. Rainfall, runoff, infiltration, and storage rate analysis were done using Thornthwaite method and Digital Elevation Model (DEM) 30.0 m resolution was used to generate maps and GIS database of the three-sub-catchments around PNV. The socioeconomic results indicated that some sectors do not have even a single water source to supply drinking water to the population. People who live near PNV fetch water in the park or use inadequate rainwater harvesting facilities. In dry season, there is water conflict between the inhabitant and protected areas. Relationship between water supply and water demand indicated that the domestic water consumption was between 4 to 12 l/c/d while the standards provide 20 l/c/d in rural area. Estimation of water demand was done and it was found to be 0.68m 3 /s while the available supply was 2.7m 3 /s. Water quality results showed that quality of water is better in wet season than in dry season. Many water points, Basumba, batikoti, Nyirakigugu, Kagano, etc., had Magnesium values higher than standard recommendations (100 mg/l). Ngando, Cyavumba, Mutobo and Gakingo had higher level of Calcium (150 mg/l). These elements count for water hardness. Results showed that heavy metals content in sampled sources is very little. The variations of zinc content are between 0.003 to 0.049 μg/l. Cadmium content varied between 0 and 0.005μg/l. These values are far below the maximum tolerated values by regional standards. There was no mercury, lead or iron detected in sampled water sources. Nickel and Selenium were also in the range of standards. The water quality parameters that cause most concern are bacteriological quality. Many water points were contaminated by coliforms, and standards require them to be absent. Some water points were contaminated by faecal coliforms and E. coli while they should also be absent. Water sanitation techniques like boiling, chlorination and filtration need to be done before using the water. Hydrological modelling indicated that there was enough water to satisfy water demands if appropriate technologies are introduced in the study area. Peak flows were identified in April and September and lack of available water storage was found between June and August. The results revealed that some areas of the North-Western part of Rwanda are highly prone to floods and landslides, namely in Nyundo, Rugerero and Kanama Sectors in Rubavu District; Muko, Muhoza, Gacaca, Rwaza, Remera and Gashaki Sectors in Musanze District; and Kivuruga Sector in Gakenke District. The total flooded areas are 337.68 ha and 298.03 ha in Sebeya and Mukungwa river basins respectively. This is aggravated by some triggering factors such as steep slopes, soil instability, heavy rains, low level of drainage system, land-use type, land tenure type and others. Intensity and frequency of disaster events varied from sector to sector. Stakeholders’ involvement in water resources management was highlighted and weaknesses were analysed. Pilot projects for sustainable water supply to the community were recommended for future interventions. Finally, land cover restoration, water infrastructure development and maintenance, riverbank protections and capacity building in water resources and environmental management are needed for a sustainable water and land conservation and improved hygienic conditions for the population around PNV. Key words: Water resources management, PNV, Hydrological survey, Water quality and availability assessment, Flood prone areas