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Community based rainfall measurement in Nepal: Rainfall Variability of Kathmandu Valley in 2016
Sadikshya Rai, Manisha Rai

Last modified: 2017-08-24

Abstract


Community based rainfall measurement in Nepal: Rainfall variability of Kathmandu valley in 2016

Sadiksha Rai1, Manisha KC1, Sangeeta Ghising2, Resham Baniya3, and Suresh Marahatta1

1Department of Meteorology, Trichandra Campus, Tribhuvan University, Kathmandu, Nepal

2Department of Environmental Sciences, Khowpa College

ABSTRACT

 

The rainfall pattern in Nepal is dominated by the South Asian Monsoon; here 80% of annual precipitation is between June and September under the influence of summer monsoon. Water resource managers/ development planners needs rainfall as well as river flow data to make wise decision. However, these data are often lacking over both space and time. Citizen science, the process of involving ordinary citizens (i.e. non-scientists, basically schoolchildren) in the scientific process as researchers, has the potential to help fill this data gap. Though there are various studies on the precipitation pattern over Nepal, however there are limited studies on the precipitation pattern and the change in distribution pattern of daily rain rate of different threshold over valleys of Nepal. This study is the comparison of the variability of rainfall of 2016 A.D with the long-term means annual Precipitation of upper Kathmandu valley. The valley received 83.6% of the annual rainfall in the monsoon season of 2016 (Jun-Sep). Similarly the valley received 4.2%, 1.2% and 10.9% of the annual rainfall in post monsoon (Oct-Nov), winter (Dec-Feb) and pre-monsoon (Mar-May) respectively. Besides this study revealed that a large variation in the spatial distribution of monsoon rainfall in a small geographical area, from 846.1 mm at Khumaltar (1334 masl), central of valley floor to 1754.7 mm at Sundarijal (1658m asl), north of the valley. Highest monthly rainfall was measured in July, where all the stations received rainfall in excess of 300mm. Sundarijal (ID 1074) recorded 760.7 mm, the highest in the region followed by Sankhu, 620.9 mm and Nagarjun 614.1 mm while Bhaktapur recorded 363.3 mm, the lowest. The south facing slopes in the northern belt of Kathmandu valley receives the heaviest rainfall considered as the windward slopes of the south west monsoon system.

 

Keywords: Monsoon, citizen science, variability

 


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