Rainfall extremes under future climate change with implications for urban flood risk in Kathmandu, Nepal

摘要: Increased rainfall extremes cause severe urban flooding in cities with adverse socio-economic consequences, and Kathmandu city is no exception. Rainfall events are projected to become more intense and frequent in a warm and wet future, and they pose a major challenge to the sustainable development of Kathmandu city. This paper analyses historical extreme rainfall patterns across the city and uses these as the basis for future projections in combination with a range of General Circulation Models. Future projections of extreme rainfall are then fed into the numerical flood model HAIL-CAESAR (Lisflood), using a high-resolution digital elevation model of Kathmandu. We show that rainfall intensity, such as the annual maximum 1-day rainfall (RX1day), is projected to increase by up to 72% in the future, and the historical 100-year return period rainfall will become a 20 or 25-year return period rainfall. The flood …