<p><span class="TextRun SCXW169904913 BCX0" lang="EN-GB" xml:lang="EN-GB" data-contrast="none"><span class="NormalTextRun SCXW169904913 BCX0">The groundwater depletion </span><span class="NormalTextRun SCXW169904913 BCX0">o</span><span class="NormalTextRun SCXW169904913 BCX0">ver the past two decades</span><span class="NormalTextRun SCXW169904913 BCX0"> in the</span><span class="NormalTextRun SCXW169904913 BCX0"> Indo-Gangetic Plains ha</span><span class="NormalTextRun SCXW169904913 BCX0">s</span> <span class="NormalTextRun SCXW169904913 BCX0">been extensively </span><span class="NormalTextRun SCXW169904913 BCX0">documented. </span><span class="NormalTextRun SCXW169904913 BCX0">On a smaller scale, </span><span class="NormalTextRun SCXW169904913 BCX0">t</span><span class="NormalTextRun SCXW169904913 BCX0">he Bundelkhand sub-region</span><span class="NormalTextRun SCXW169904913 BCX0"> (</span><span class="NormalTextRun SCXW169904913 BCX0">rectangular box in the Figure</span><span class="NormalTextRun SCXW169904913 BCX0">)</span><span class="NormalTextRun SCXW169904913 BCX0"> has been experiencing an extended period of meteorological drought. </span><span class="NormalTextRun SCXW169904913 BCX0">In this region, as with </span><span class="NormalTextRun AdvancedProofingIssueV2Themed SCXW169904913 BCX0">a majority of</span><span class="NormalTextRun SCXW169904913 BCX0"> the Gangetic Plains, the contribution of local evaporation is comparable to the moisture brought in from afar.  </span><span class="NormalTextRun SCXW169904913 BCX0">It is unclear whether the below-normal rainfall in this region is due to low-frequency climate variability or a result of a "negative" feedback loop in the regional hydrologic cycle where less rain leads to less soil wetness, which in turn leads to lower evaporation and less moisture available for rain. </span><span class="NormalTextRun SCXW169904913 BCX0">An analysis of th</span><span class="NormalTextRun SCXW169904913 BCX0">is</span><span class="NormalTextRun SCXW169904913 BCX0"> region's daily rainfall records from the past century shows that while most droughts in and around Bundelkhand coincide with larger-scale Indian monsoon droughts</span><span class="NormalTextRun SCXW169904913 BCX0"> (Type-1 in the Figure)</span><span class="NormalTextRun SCXW169904913 BCX0">, some appear to be localized</span><span class="NormalTextRun SCXW169904913 BCX0"> (Type-2 in the Figure)</span><span class="NormalTextRun SCXW169904913 BCX0">. In addition, </span><span class="NormalTextRun SCXW169904913 BCX0">our</span><span class="NormalTextRun SCXW169904913 BCX0"> analysis </span><span class="NormalTextRun SCXW169904913 BCX0">shows</span> <span class="NormalTextRun SCXW169904913 BCX0">that </span><span class="NormalTextRun SCXW169904913 BCX0">while </span><span class="NormalTextRun SCXW169904913 BCX0">north central India typically experiences a rainfall deficit in early July, </span><span class="NormalTextRun SCXW169904913 BCX0">western India often sees more than normal rainfall. </span><span class="NormalTextRun SCXW169904913 BCX0">We present our </span><span class="NormalTextRun SCXW169904913 BCX0">assessment of t</span><span class="NormalTextRun SCXW169904913 BCX0">he causes of these droughts, including the role of local hydrology and potential large-scale drivers</span><span class="NormalTextRun SCXW169904913 BCX0">.</span></span><span class="EOP SCXW169904913 BCX0" data-ccp-props="{"> </span></p> <p><span class="EOP SCXW169904913 BCX0" data-ccp-props="{"><img src="" alt="" /></span></p> <p><span class="EOP SCXW169904913 BCX0" data-ccp-props="{"><img src="" alt="" /></span></p>

<p>Floods are known to cause extensive damage to property and life, which makes it necessary to determine the plausible magnitude and frequency of these hydrologic extremes. In this study, we use a combined hydrologic and hydraulic modelling approach to study the flood characteristics of Brahmaputra - a large transboundary river (580,000 km<sup>2</sup>) associated with complex topography, geomorphology, and a dense network of tributaries. A semi-distributed process-based model HEC-HMS, (forced with different precipitation datasets, -(APHRODITE, GLDAS, IMD and TRMM) is used to simulate an ensemble of its historical streamflow at a daily timescale. These calibrated and validated flows are used in conjunction with a network of level gauge stations (within Arunachal Pradesh & Assam in India) to quantify and improve flood mapping with the help of a two-dimensional hydraulic model HEC-RAS. The historical flood extents (2015 to 2022) obtained using the hydrologic & hydraulic modelling approach is further validated with the help of satellite earth observation data products. Such a multi-pronged, ensemble-based modelling strategy has the potential to create a more informed flood risk management system, in terms of providing better likelihood and uncertainty estimates, in the lower reaches of Brahmaputra often prone to prolonged inundation.</p>