Drought is among the costliest natural disasters that affect the economy, food and water security, and socioeconomic well-being of about 1.4 billion people in India. Despite the profound implications of droughts, the propagation of meteorological to hydrological droughts in India is not examined. Here, we use observations and simulations from a well-calibrated and evaluated Variable Infiltration Capacity (VIC) model to estimate drought propagation in India. Standardized Precipitation Index (SPI), Standardized Soil Moisture Index (SSMI), and Standardized Streamflow Index (SSI) were estimated for 223 catchments in India to represent meteorological, agricultural, and hydrological droughts, respectively. We estimated drought propagation time for these catchments located in 18 major Indian subcontinental river basins. Internal propagation of hydrological drought was estimated using optimal hydrological Instantaneous Development Speed (IDS) and Instantaneous Recovery Speed (IRS) from onset to the termination. Indus, Sabarmati, and Godavari river basins have higher propagation time of meteorological to hydrological droughts. The high (low) development rate of hydrological drought is followed by the high (low) recovery rate for most of the locations. We find significant influence of Seasonality Index (SI) and Base Flow Index (BFI) on propagation time of meteorological to hydrological droughts in the Indian subcontinental river basins. Overall, understanding of drought propagation, development/recovery speed, and their deriving factors can assist in the management and planning of water resources in India.

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<p>The understanding of the propagation of meteorological droughts to hydrological droughts is an important phenomenon to take pre-emptive action to mitigate the effects of droughts. In this study, we have correlated the Standardized Streamflow Index (SSI) with the Standardized Precipitation Index (SPI-n) for 224 stations across India to analyze drought propagation time, which is specific to each catchment. Results indicate higher propagation times for basins lying in arid and semi-arid climate regions whereas lower propagation time is found for basins lying in wetter climate regions. The run theory is applied to SSI to identify all streamflow drought events for each station and the optimal Hydrological Drought Instantaneous Development (IDS) and Instantaneous Recovery Speeds (IRS) are calculated along with parameters; duration and severity. Drought propagation speeds can be used to simulate drought duration and severity for a catchment. Simulated drought duration for various catchments shows good agreement (R<sup>2</sup> > 0.7) with observed drought duration, therefore calculated optimal IDS and IRS can be used in forecasting drought conditions for each catchment. The effect of catchment characteristics on drought parameters was evaluated statistically by using heatmaps and bivariate correlation. This study provides comprehensive catchment-specific drought analysis for all major basins of India, which can be used by water managers to promptly and effectively avert drought and related disasters.</p>

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