Empirical Approach-Based Potential Impact Analysis of Climate Change and
Land-Use Conversions on Streamflow Variations: A Case Study of the
Brahmani Catchment
Abstract
Streamflow, the fundamental element of catchment-scale hydrology, is
expressed as a complex response of many hydrological processes that
includes atmospheric forcing (precipitation and temperature) and human
activities (land-use change, reservoir/dam construction, and excessive
water exploitation). Thus, change in climate variables and land-use
alter a catchment’s streamflow pattern, which is a critical concern to
the researchers. In the present study, the potential contributions of
Climate Change (CC) and Land-use Conversions (LC) on streamflow
variations are quantified for the Brahmani catchment (36800 km2) of
eastern India. The estimation procedure is followed by two empirical
approaches, i.e. (i) the modified Double Mass Curve (m-DMC) method and
(ii) the modified Slope Change Ratio of Accumulative Quantity (m-SCARQ)
method. The abrupt changes in streamflow data series are checked by the
sequential Mann-Kendall method. Multiple change points, including 1981,
1985, 1993, 1994, 2011, and 2013 are observed in streamflow data series
in the study area. However, 1994 is selected as the break-point, which
has the highest significance value, i.e. 1.92. Therefore, the entire
analysis period (1979-2018) is divided into two sub-periods, i.e. the
baseline period (1979-1994) and the assessment period (1995-2018).
Further, the statistical characteristics (trend, slope, and
significance) of hydro-climatic variables (precipitation, temperature,
and streamflow) are analysed by applying the Mann-Kendall method
followed by the Sen’s slope estimator for all the periods. Using the
m-DMC method, the potential contributions of CC (βCC) and LC (βLC) in
the assessment period are quantified as 93.09% and 6.91%,
respectively. However, from m-SCARQ, the contributions of precipitation
(βP), temperature (βT), CC (βCC), and LC (βLC) on streamflow variations
are 0.26%, 19.74%, 20%, and 80%, respectively. The outcomes of the
m-DMC other than the m-SCARQ method showed that streamflow variation is
more sensitive to climate change of the study area. Further, the m-SCARQ
method is relatively strategic compared to the m-DMC method since it can
signify the contributions of precipitation (βP) and temperature (βT) on
the streamflow variations. Still, both the empirical approaches are
attributed to different sources of errors and uncertainty with
individual advantages. Accordingly, this study can provide new insights
concerning the relative resistance of the Brahmani catchment’s response
to CC and LC that is vital for the prudent planning and management of
future water resources. Keywords: Climate change; Land-use conversions;
m-DMC method; m-SCARQ method; Brahmani