Abstract
Satellite-based precipitation products can be a better alternative of rain gauges for hydro-meteorological studies in data-poor regions. This study aimed to evaluate how regional and seasonal precipitation and drought patterns had changed in the Ganga–Brahmaputra Basin between 1983 and 2020 with PERSIANN-CDR precipitation data. The spatial pattern of winter drought, monsoon drought, and Standardized Precipitation Index (SPI) calculated for different time scales were evaluated using principal component analysis. Ganga–Brahmaputra is one of the most populated river basins that flows through different geographical regions. Rain gauges are heterogeneously distributed in the basin due to its complex orography, highlighting the significance of gridded precipitation products over gauge observations for climate studies. Annual and monthly precipitation trends between 1983 and 2020 were evaluated using the original and modified Mann–Kendall trend test, and annual precipitation in the basin was found to be declining at a rate of 5.8 mm/year. An increasing trend was observed in pre-monsoon rainfall, whereas precipitation exhibited a decreasing trend for other months. Results of the Pettitt test showed precipitation time series was inhomogeneous and changepoint occurred around 2000. Decreasing trends of SPI indicated increasing frequency and intensity of drought events. Winter drought showed a clear spatial pattern in the basin; however, SPIs calculated for different time scales and monsoon drought had complex spatial patterns. This study demonstrates the applicability of satellite-based PERSIANN-CDR precipitation data in climate research in the Ganga–Brahmaputra Basin.
Highlights
Precipitation has a significant impact on the environment; vegetation health; crop choices; and, eventually, the economy of an area
Annual precipitation trend was analyzed with MK and modified MK trend test for the whole basin and in three different elevation regions: 0–200 m, 200–2000 m, and 2000+ m
A large negative slope of −11.6 mm/year was observed in the low elevation region, wherein average annual precipitation was higher as compared to other regions
Summary
Precipitation has a significant impact on the environment; vegetation health; crop choices; and, eventually, the economy of an area. Accurate prediction of precipitation trends can be useful in disaster management and future economic development [1]. Natural disasters such as droughts, floods, and landslides occur due to change in precipitation patterns [2]. Gauge measurements and gauge-based products are mainly used for meteorological and climate studies worldwide. Even though in situ observation of climate variables such as precipitation, temperature, and soil moisture are considered the most accurate, such products are not efficient for climate studies in data-poor regions such as the Himalayas [3]. Satellite observations have more complete coverage, especially across seas, high altitudes, and isolated locations where gauge data are few or unavailable [4]
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