By Rachael McDonnell, Strategic Program Director – Water, Climate Change and Resilience, at the International Water Management Institute.
Managing drought has become a critical challenge for many countries, especially those in the Middle East and North Africa (MENA) region, where water scarcity is an ongoing issue. Among its actions to tackle drought, the Ministry of Agriculture, Fisheries, Rural Development, Water, and Forests (MAFRWF) in Morocco has published countrywide satellite-based drought maps online for the first time.
The maps visually present satellite data on rainfall, land surface temperature, soil moisture, and vegetation health, which have been compiled into an easy-to-interpret enhanced Composite Drought Index (eCDI). By analyzing the colour-coded maps, and seeing how the underlying value of the eCDI changes from the start of the growing season onwards, users can detect early on if a drought is emerging – even before its effects are visible on the ground.
Droughts are becoming more frequent and severe in Morocco, and climate change is projected to continue this trend in the future. Half of the population live in rural areas, and two out of three countryside dwellers work in farming. Therefore, when a severe drought strikes, it can have a major impact on food and water security, as well as on livelihoods and health. Making drought maps readily available to government agencies, universities, and research institutes is a first step towards developing a drought early warning system, where automatic alerts can trigger government agencies to take action to mitigate the worst impacts.
The drought maps have been developed as part of the Morocco arm of the USAID-funded MENAdrought project, being conducted by the International Water Management Institute and partners. We developed the eCDI in collaboration with the National Drought Mitigation Center at the University of Nebraska-Lincoln, NASA Hydrological Sciences Laboratory, and Daugherty Water for Food Global Institute, USA, in collaboration with the Department of Strategy and Statistics of MAFRWF. The data on rainfall, land surface temperature, soil moisture, and vegetation health, compiled from various satellite missions, is incorporated in the eCDI, with a weighting of 40% for precipitation and 20% for the other three parameters.
Morocco’s rainy season usually extends from September to June, with the start of the growing season coinciding with heavy Autumn rains. Examining data from the satellite drought maps enables users to identify the onset and progression of drought. First, if September-November rainfall falls below the norm (calculated from past satellite data), this will be evident through a lower-than-usual precipitation signal in the eCDI. And, if this cecso-called ‘meteorological drought’ progresses in winter, the soil moisture signal will, too, fall below the average.
Having an adequate level of soil moisture at key stages of the growing season is critical for crop health and development. If the deficit of soil moisture drops to the extent that it begins to affect vegetation and crops, causing an ‘agricultural drought’, this will be apparent through the vegetation health index in the eCDI during winter and spring seasons. Called the Normalized Difference Vegetation Index, this works by calculating light reflected by plants. Healthy biomass reflects more near infra-red light, while stressed or sparse vegetation reflects more visible light. If drought continues beyond a season it becomes a ‘hydrological’ drought, with impacts on the overall water budget of basins and the nation.
Presently, users can download the satellite map data files and undertake their own analyses to verify the presence and progression of drought. However, in the MENAdrought team, we are working to develop thresholds that can automatically trigger response and mitigating actions. Our initial focus for this work has been the rainfed cereals across the country, and the arid and water-scarce region of Souss-Massa in southwest Morocco.
Home to more than 2.5 million people, Souss-Massa is bounded to the west by the North Atlantic ocean and to the east by the Sahara desert. We are using the evidence on known impacts of past droughts on the region to develop the trigger thresholds. These will underpin a drought-risk framework encompassing institutional planning and the work of a task force on drought management. Once we have proven the technology and framework for Souss-Massa, the next step will be to scale it up across the nation.
We are also working to calibrate and validate the drought maps for pastoral use for the whole of Morocco. This will support the enforcement of laws on rangeland and transhumance management. Pastoralism has traditionally been widespread in Morocco but the degradation of rangelands, through drought and overuse, is prompting some nomadic herders to seek new grazing lands, leading to tension. Once validated, using data from the field to ‘ground-truth’ the satellite data, the drought maps will enable Moroccan authorities to forecast where drought will affect grazing lands, and to authorize herders to take their livestock to areas where vegetation is healthy.
The eCDI drought maps are colour-coded, with shades of red depicting Extreme, Severe and Moderate Drought, and shades of green showing conditions from Normal to Very, Highly and Extremely Humid. Even the untrained eye can easily relate the dramatic change from widespread red in September 2020, to predominantly green in October, to the coming of seasonal rains. In the hands of trained meteorologists, agricultural planners, and statisticians, who can detect trends in the underlying data, the maps have the potential to cushion many Moroccans from the effects of prolonged dry spells.
Morocco’s decision to publish the satellite maps has implications for drought management across the wider MENA region, too. If Morocco is effective in using the maps to steer actions that ameliorate the impacts of drought, then other countries may be minded to do likewise. But first they must have confidence that the satellite maps can generate robust data. In the long term, the hope is that the technology will be routinely used across MENA in drought management, helping to strengthen resilience to climate change, promote accountability and transparency, and inform scarcity management in arid watersheds. This will help to support farmers and pastoralists, and ensure everyone has sufficient food to eat.