Assessment of Long-Term Rainfall Variability and Trends Using Observed and Satellite Data in Central Punjab, Pakistan

Abstract

This study explores the spatio-temporal distribution and trends on monthly, seasonal, and annual scales of rainfall in the central Punjab districts of Punjab province in Pakistan by using observation and satellite data products. The daily observed data was acquired from the Pakistan Metrological Department (PMD) between 1983 and 2020, along with one reanalysis, namely the Climate Hazard Infrared Group Precipitation Station (CHIRPS) and one satellite-based daily Precipitation Estimation from Remotely Sensed Information Using Artificial Neural Networks climate data record (PERSIANN-CDR) using the Google Earth Engine (GEE) web-based API platform to investigate the spatio-temporal fluctuations and inter-annual variability of rainfall in the study domain. Several statistical indices were employed to check the data similarity between observed and remotely sensed data products and applied to each district. Moreover, non-parametric techniques, i.e., Mann–Kendall (MK) and Sen’s slope estimator were applied to measure the long-term spatio-temporal trends. Remotely sensed data products reveal 422.50 mm (CHIRPS) and 571.08 mm (PERSIANN-CDR) mean annual rainfall in central Punjab. Maximum mean rainfall was witnessed during the monsoon season (70.5%), followed by pre-monsoon (15.2%) and winter (10.2%). Monthly exploration divulges that maximum mean rainfall was noticed in July (26.5%), and the minimum was in November (0.84%). The district-wise rainfall estimation shows maximum rainfall in Sialkot (931.4 mm) and minimum in Pakpattan (289.2 mm). Phase-wise analysis of annual, seasonal, and monthly trends demonstrated a sharp decreasing trend in Phase-1, averaging 3.4 mm/decade and an increasing tendency in Phase-2, averaging 9.1 mm/decade. Maximum seasonal rainfall decreased in phase-1 and increased Phase-2 during monsoon season, averaging 2.1 and 4.7 mm/decade, whereas monthly investigation showed similar phase-wise tendencies in July (1.1 mm/decade) and August (2.3 mm/decade). In addition, as district-wise analyses of annual, seasonal, and monthly trends in the last four decades reveal, the maximum declined trend was in Sialkot (18.5 mm/decade), whereas other districts witnessed an overall increasing trend throughout the years. Out of them, Gujrat district experienced the maximum increasing trend in annual terns (50.81 mm/decade), and Faisalabad (25.45 mm/decade) witnessed this during the monsoon season. The uneven variability and trends have had a crucial imprint on the local environment, mainly in the primary activities.

Spatiotemporal analysis and predicting rainfall trends in a tropical monsoon-dominated country using MAKESENS and machine learning techniques

“…Increases in rainfall have been found, in particular, in the Middle East, Central Asia 31 , Brazil region, the eastern part of America and Canada, and Northern Europe 32 , 33 , and Australia 34 . Ren et al 35 observed for the annual average rainfall over the Tibetan Plateau in China, similar trends have been seen during the previous few decades, also the same pattern in India 33 , 36 , in northwest Pakistan 17 , 18 , and in the China-Pakistan Economic Corridor area 37 . However, the Yellow River Basin, China 38 , the Mediterranean region 29 , and Iran have all seen a decline in annual mean rainfall 19 .…”

“…There are many different temporal and geographical scales at which precipitation variability as a component of climate change occurs. Worldwide studies have shown increasing rainfall variability on a global scale 14 , 15 , and the Indian Sub-continent, including India 16 and Pakistan 17 , 18 . Many studies 19 – 21 have examined the spatiotemporal patterns of rainfall in climatic zones across the world 22 – 25 .…”

Analysis of canal discharge management through remodeled structure at Guddu Barrage

“…A major part of Pakistan's river basin lies in the province of Sindh, which is prone to floods. Floods pose a major environmental hazard, particularly when they overtop a few km wide river channel [44]; the natural floodplain, confined by the manmade levees (flood protective embankments/bunds) several kilometers apart, constructed on both sides of the channel, forms the riverine area (manmade flood plain) [45,46]. The Guddu Barrage was inaugurated in 1962 on the Indus River in the Kashmore district of Sindh province, Pakistan.…”