Spatio-temporal variability in evapotranspiration and moisture availability in different agroclimatic regions of Punjab
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Date
2019
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Punjab Agricultural University, Ludhiana
Abstract
Water scarcity is faced by the state of Punjab due to depletion of groundwater resources. This
situation urges more detailed study, in terms of region-wise water availability over long-term
period. A number of studies have been conducted in the past examining the supply side of
hydrological cycle i.e precipitation. But the current study deals with demand side i.e reference
evapotranspiration (ETO), a parameter directly relating climate change in terms of water
requirements. In addition to this, two other parameters viz. Aridity Index (AI) and Moisture
Index (MI) were also studied. Computation of ETO was done by HS method, MI by Krishnan
and Singh method and AI by UNESCO method. Trend analysis was studied with Mann-
Kendall test and classical statistical procedures. Spatial interpolation was done in Arc GIS
10.4 software. The results concluded that annual ETO increased in north-east region and
south-west @ 1.46 mm year-1 and 0.97 mm year-1 respectively. Rabi season ETO increased in
north-east region @ 1.27 mm year-1. Annual MI was observed to be dry during first decade
(1971-80), there was increase in water availability during the next two decades and again dry
from 2000 onwards. Annual and seasonal AI values were observed to be highest in north-east
followed by Central and lowest in south-west. A critical analysis of the study indicated
decreased ETO till 2000 contributed to higher AI & MI values denoting more moisture
availability till 2000 and decreased thereafter annually as well as seasonally due to higher
ETO. The results also indicated spatial variability in moisture availability in the state from
north-east to south-west. There was prominent difference in moisture ranges during earlier
decades, but this difference was reduced in recent decades which might be due to huge impact
of climate change in the north-east region. To conclude, south-west region faced severe water
crisis even from earlier decades, but under recent conditions of climate change north-east
region is also coming under the stress situation. This alarms the need for judicious water
management in all regions of state.
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