IRRIGATION PERFORMANCE ASSESSMENT USING REMOTE SENSED DATA: THE CASE OF UBOMBO SUGARCANE SCHEME, ESWATINI

Abstract

The rising need to feed the ever-growing population with the limited resources of land and water has put pressure on agriculture to improve on its water use efficiency. This study aimed to assess the performance of Ubombo Sugar Irrigation Scheme using remote sensing data by comparing ET estimates from WaPOR and SEBAL, focusing on their implications for adequacy, equity and water productivity in water distribution. SEBAL recorded an average seasonal ET of 1514 mm with a coefficient of variation (CV) of 0.14, an average relative ET of 0.88 and 26 kg/m3 average of water productivity and an average Crop Water Deficit (CWD) of 154mm, indicating greater spatial variability due to its sensitivity to surface energy balance components. In contrast, WaPOR data yielded slightly higher values with an average seasonal ET of 1775 mm, a CV of 0.26, a relative ET of 0.82, an average water productivity of 14.5 kg/m3 and a CWD of 242mm, suggesting more stable long-term trends that support large-scale water resource assessments. The results highlight the strengths of SEBAL in capturing localized irrigation disparities and the advantages of WaPOR in providing consistent temporal assessments. Integrating both approaches can enhance irrigation management by improving spatial and temporal water allocation, supporting more efficient and sustainable agricultural practices.