Droughts in the Anthropocene

Saudi Arabia – Sustainable solutions for making the desert bloom

The Kingdom of Saudi Arabia – the largest country on the Arabian peninsula – is located in a tropical and subtropical desert region. Almost all of the country is arid, and its cloudless skies provide little rain, with just 114 mm/year of precipitation estimate for the whole country [1]. In summer months, temperatures can reach over 50°C and winds can stir up great sand and dust storms. Although the climate and environmental conditions are not well-suited to agricultural production, it has long been part of the country’s food security plans. Saudi Arabia’s policies and programmes have encouraged private sector investment in its agricultural sector and provided uncultivated land along with attractive finance and Government subsidies [1]. The country has also made investments in the development of infrastructure to accommodate agricultural production, such as roads, dams, drainage canals and irrigation systems. These interventions have, at different stages, led the country to be self- sufficient in several agricultural products such wheat, dates, eggs and milk. In recent years, there has been growing awareness regarding the unsustainable use of water driving this agricultural expansion. In the 1980–2006 period, the volume of water used for agriculture tripled from 6.8 km 3 to 21 km 3 [1]. The water used for cultivation comes almost exclusively from fossil groundwater formed around 20,000 years ago that is stored in six major sedimentary aquifers [1]. The total reserve of these aquifers is difficult to quantify, but it is clear that with the low natural recharge simple mass balance means that these systems will eventually run dry. Given these concerns, Saudi Arabia’s policies have changed in recent years, removing incentives for agricultural production and implementing guidelines for

reducing water use for farming, industry and household consumption [2]. The situation in Saudi Arabia requires solutions for effective and sustainable water use. Although Saudi Arabia has a permanently dry landscape, its problems are similar to those that occur during a drought, though at a different timescale. Desalinating seawater is one effort being put in place. With more than 30 plants in operation, the country is the largest producer of desalinated water in the world [3]. Another solution being implemented and developed on the ground in Saudi Arabia is precision agriculture. Precision agriculture aims to minimize the inputs required for agricultural production (water, nutrients, chemicals), while maximizing the crop yield. The approach helps farmers understand the variation of water and nutrients across an area of land, while monitoring crop health and condition, allowing them to determine what each crop needs to be most productive [4]. These farm-level data can then be used to efficiently allocate resources such as irrigation water and fertilizers to maximize output and limit waste for farmers, instilled in the concept of more crop per drop. This is especially valuable in arid regions or during drought, when water resources are at their most scarce. Precision agriculture can also be used to identify early stages of disease, crop stress or infestation, allowing farmers to implement preventative measures [4]. Precision agriculture relies on a wide variety of information spanning vegetation, soil condition and crop water use via evapotranspiration, and uses remote-sensing approaches to observe these details and to monitor changes. This includes data from the European Space Agency’s Sentinel-2

satellite, which has a higher spatial and temporal resolution than previous platforms [4]. Another form of satellite information comes from CubeSats, miniaturized and relatively low-cost satellites that provide much higher resolution in space and time when flown in ‘flocks’ or constellations [5]. The information collected through satellites can be supplemented by the use unmanned aerial vehicles (UAVs), which provide an incredibly precise level of detail [6]. Together, CubeSats and UAVs can provide information on crop health, condition and production through their use of optical, multi- and hyperspectral sensors, which can be used to map everything from basic vegetation indices through to chlorophyll content as an indicator of productivity, stress and yield. Other forms of monitoring from UAVs are also possible, with a range of hydrological variables being explored from these emerging platforms. Although the concept of precision agriculture is quite mature, there is still much that needs to be done to realize its full potential and turn it from a research tool into an active agent in combating food security, water scarcity and drought-related issues. In Saudi Arabia, the work on using UAVs is still research focused and primarily used to help identifying crops that are suited to particular environments (resiliency to heat, drought, etc). For CubeSats the objective is to quantify crop water use and provide feedback on crop-health, with the aim to turn it into useable products.

ARAB STATES

30