People in Nepal are accustomed to adapting to the seasonal changes the monsoon brings to their lives. This includes changes in movement of people and goods, adjustments to livelihood methods, and challenges in terms of storage of assets that need to be protected from damp and wet conditions and the risk of flooding.
The timing of the earthquake just prior to monsoon season means that challenges this year will be greater than usual and that the capacity of communities and households to be prepared for the monsoon will be stretched. The impending monsoon increases the urgency for humanitarian stakeholders to respond as rapidly as possible prior to the onset of the rains and to find ways to modify response during the monsoon to continue to meet the most urgent needs.
According to data from the Indian Meteorological Department (IMD), the 2015 monsoon is forecast to arrive in the southeastern part of Nepal around 5 June, and to spread westward across the country by 20 June (AGU Landslide Blog 20/05/2015). The monsoon lasts for an average of 105 days, with much higher rainfall experienced in the eastern region compared with the western region, with a peak in the central region (Sigdel and Ikeda 2012, Ichiyanagi et al. 2007). This means that, of the districts highly-affected by the earthquake, the monsoon will reach Okhaldhunga, Sindhuli, and Ramechhap first, followed by the central region (Dolakha, Khabrepalanchok, Kathmandu, Bhaktapur, Lalitpur, Makawanpur, Sindhupalchok, Nuwakot,
Rasuwa, Dhading), and will reach Gorkha last. In terms of agro-ecological zones, the hills receive higher annual rainfall than the mountains (Panthi et al. 2015). 80% of Nepal’s annual rainfall occurs during the monsoon period (Neupane 2008). When the monsoon withdraws it moves from west to east, the opposite sequencing of the onset (Gautam and Regmi 2013). Long-term trends point to a delayed withdrawal, which would see monsoon rains lasting progressively later into the year (Panthi et al. 2015).