The climatic water balance captures evolving water resources pressures
on the margins of the Himalaya
Abstract
Evaluation of the climatic water balance (CWB) – i.e. precipitation
minus potential evapotranspiration – has strong potential as a tool for
investigating patterns of variability and change in the water cycle
since it estimates the (im)balance of atmospheric moisture near the land
surface. Using observations from a middle-Himalaya weather station at
Mukteshwar (29.474°N, 79.646°E, Uttarakhand state) in India, we
demonstrate a CWB-based set of analytical procedures can robustly
characterise local climate variability. Use of the CWB circumvents
uncertainties in the soil water balance stemming from limited data on
subsurface properties. We also focus on three key input variables used
to calculate the CWB: precipitation, mean temperature and diurnal
temperature range. We use local observations to evaluate the skill of
gridded datasets –specifically meteorological reanalyses – in
representing local conditions. Reanalysis estimates of Mukteshwar
climate showed large absolute biases but accurately captured the timing
and relative amplitude of the annual cycle of these three variables and
the CWB. This suggests that the reanalyses can provide insight regarding
climate processes in data-sparse regions, but caution is necessary if
extracting absolute values. While the local observations at Mukteshwar
show clear annual cycles and substantial interannual variability,
results from investigation of their time-dependency were quite mixed.
Pragmatically this implies that while “change is coming, variability is
now.” If communities can adapt to the observed historical hydroclimate
variability they will have built meaningful adaptive capacity to cope
with on-going environmental change. This follows a ‘low regret’ approach
advocated when facing a substantially uncertain future.