Objectives

The ambition of the ANIN project’s team is to develop a drought early warning system for preparedness, mitigation and response with the following characteristics:

• Generating quality data to support a drought early warning system by combining meteorological, agricultural, and hydrological indices.
• Customizing EO information for specific user needs by answering practical questions for the users.
• Enhance drought capacity and decision-making mechanisms to bring drought forecasts to grassroots level.
• Integrating EO information with other information resources such as real-time weather forecasting, seasonal forecasts, and in-situ data from existing network information.
• Perform enhanced analytics and modelling to provide information that allows better decision-making.
• Facilitate decision-making by providing a drought monitoring by providing an open visualization platform.

Background

Drought is a recurrent feature of all climates that results from a shortfall in precipitation over an extended period, its inadequate timing compared to the needs of the vegetation cover, or a negative water balance due to an increased potential evapotranspiration caused by high temperatures. These conditions may be exacerbated by strong winds, atmospheric blocking patterns and antecedent conditions in soil moisture, reservoirs and aquifers, for example. If this situation leads to an unusual and temporary deficit in water availability, it is termed a drought.

Droughts are slow-onset events that can last from weeks to years. They are often defined as meteorological, agricultural or hydrological droughts. However, these are actually progressive manifestations of the same drought event propagating through the hydrological cycle. Recently, the concept of flash droughts has emerged, describing quick-onset, severe events of water stress due to high temperatures and a high evaporative demand.

Figure 1: Schematic representation of drought propagation through the hydrological cycle, related drought stages and key indicators.
Source: UNDRR, 2021, adapted from the National Drought Migitation Centre; Wilhite et al. (2014).

Due to the different types of droughts, its monitoring is based on the analysis of a series of drought indicators and indices, representing different components of the hydrological cycle (e.g., precipitation, soil moisture, reservoir levels, river flow, groundwater levels) or impacts (e.g., vegetation water stress). Usually, indicators represent statistical anomalies of the current situation with respect to the long-term climatology at a given location and time interval.

South Africa is one of many African countries vulnerable to droughts, as climate change projections show that more frequent and intense droughts and increased warning are anticipated. Therefore, there is a need for more scientific research on drought impacts, drought indicators and responses by vulnerable groups such as smallholder farmers. In recent years, an ongoing period of drought has taken place in Southern Africa. In the late 2015 – early 2016 season, an El Niño event caused a drought in some parts of Southern Africa and as of the start of the 2018-19 El Niño-induced drought, some parts had not yet recovered from the effects of the earlier drought. In 2021, the South Africa National Disaster Management Centre declared a drought disaster due to the persistent drought conditions in the Northern Cape, Eastern Cape and Western Cape.

Because drought occur gradually, are widespread, and often indiscernible until a more significant loss, e.g., loss in productivity, has been experienced, the impacts of droughts can be devastating in the short and long-term time scales. One of the alarming consequences of droughts is the decline in river flow, groundwater recharge, runoff, and dam-levels, ultimately affecting various socio-economic sectors. Moreover, low precipitation and high temperatures during droughts result in rapid moisture loss from plants and soils (through evapotranspiration), causing significant losses in agricultural productivity and incomes, habitats, and ecosystem services. For example, the 1992 droughts in South Africa led to approximately 70% in crop failure, livestock deaths, and malnutrition in humans. Therefore, information on drought early warning and monitoring for preparedness, mitigation, and response is dire and requires urgent attention from multi-sectoral stakeholders.