Hydrological drought
Hydrological drought is associated with the effects of periods of precipitation (including snowfall) shortfalls on surface or subsurface water supply (i.e., stream-flow, reservoir and lake levels, groundwater). Although all droughts originate with a deficiency of precipitation, hydrologists are more concerned with how this deficiency plays out through the hydrologic system. Hydrological droughts are usually out of phase with or lag the occurrence of meteorological and agricultural droughts. It takes longer for precipitation deficiencies to show up in components of the hydrological system such as stream-flow, and groundwater and surface water storages. This portal provides the information on Hydrological drought accounting for all the above mentioned factors in the form of multiple indices including a comprehensive index known as composite Hydrological Drought Index.
Standardized Runoff Index
Standardized runoff index (SRI) is the unit standard normal deviate associated with the percentile of hydrologic runoff.
Standardized Water Spread Index
Satellite derived surface water spread area is used to estimate the abnormalities related to availability of surface water resources.
Standardized Ground-water Index
Standardized Groundwater Index (SGWI) is used to estimate the abnormalities related to usual ground-water levels in a region
Standardized Reservoir Storage Index
Standardized Reservoir Storage Index (SGWI) is used to estimate the abnormalities related to usual reservoir levels .
Composite Hydrological Drought Index
A hybrid index generated by considering the impact of each of the previously mentioned indicators on the ground.