Optimizing Climate Resilient and Productivity in Flood Dependent Agricultural Systems

This paper aims to advance our scientific understanding of optimizing flood productivity in climate-impacted regions through integrated interventions at strategic and operational levels. In arid and semi-arid regions of Africa and Asia, short-duration floods cover about 50 million cultivable hectares and support some 100 million farming families. Such flood-dependent systems have long been overlooked due to concerns over unreliable water supply. However, with increasing climate change impacts and water scarcity, there is growing recognition of the potential for sustainable growth that short-duration floods can offer.

 

This paper is based on a study conducted as part of a three-year USAID-supported initiative (2022–2024) focused on promoting economic growth and peace in the Gash Agricultural Scheme (GAS) in the water-stressed eastern region of Sudan. GAS, the largest flood-dependent scheme in the country, covers 100,800 hectares and could support the water and food security needs of over a quarter of a million agro-pastoralists. It relies on the ephemeral Gash River, which originates from the Ethiopian and Eritrean highlands and flows sporadically between July and October. Over the past two decades, climate-induced changes have led to fluctuations in the river's flow, affecting its timing, frequency, and volume, which has ranged between 650 million and 1.2 billion m³ annually.

 

The study conducted water balance analyses using a 16-year dataset of Gash River flow, irrigated area, and the evapotranspiration demand of the major sorghum crop. Data collection included field measurements, surveys, remote sensing, and CropWat modelling. The analysis revealed that the current three-year rotation-based irrigation system, capping cultivated land at 33,000 hectares annually, is excessively risk-averse. While this strategy reduced conflicts by consistently delivering promised land, it increased GAS's vulnerability to flood damage. The floodwater use efficiency over the past decade was around 26%, leaving significant amounts of floodwater untapped, which caused damage to infrastructure and agricultural land.

 

The three-rotation system also led to inadequate infrastructure maintenance due to infrequent land tillage, allowing the invasive mesquite tree to overtake 70,000 hectares in the past 20 years, reducing the sorghum cropped area and contributing to reduced agricultural productivity. The water balance analysis suggests a shift to a two-year rotation system, cultivating approximately 50,000 hectares annually while maintaining risk aversion. This change could increase annual agricultural production from about 50,000 to 75,000 tons at the current sorghum yield of 1.5 tons/ha without significant infrastructural or farming improvements. Introducing integrated interventions that combine improved canal maintenance, better field water distribution, and effective coordination of farmer organizations could increase the cultivated area of large irrigation plots (ranging from 420 to 756 hectares) from 40% to 70%. These interventions could increase sorghum yield by two-thirds to 2.5 tons/ha and triple water productivity to 0.24 kg/m³.

 

Keywords: Floodwater Optimization, Climate-induced Changes, Integrated Interventions, Improved and Resilient Crop and Water Productivity