PERFORMANCE EVALUATION OF IRRIGATION SYSTEM USING REMOTE SENSING AND GEOGRAPHIC INFORMATION SYSTEMS – A CASE STUDY OF NEPAL

Abstract

Traditionally, ground-based methods have been used to assess irrigation system performance, but these methods are often labor-intensive, time-consuming, and may not provide comprehensive coverage. Satellite data offers a more efficient and effective alternative. Satellites can capture large-scale agricultural landscapes in high resolution, providing detailed information on factors such as soil moisture levels, crop health, and water distribution. By integrating satellite data with ground observations, a comprehensive understanding of irrigation system performance can be achieved. Satellite imagery can be used to monitor overall water distribution patterns and identify areas of over- or under-irrigation. In this study, the irrigation system performance of the Kankai Irrigation System (KIS) in Jhapa, Nepal, during the monsoon paddy season from June to October 2022 was evaluated by using Remote Sensing (RS) and the Geographic Information System (GIS). The assessment involved analyzing water delivery performance indicators, physical performance indicators, agricultural performance indicators and financial performance indicators. The results showed a strong correlation (r2=0.96) between crop coefficient and NDVI, indicating that higher NDVI values correspond to increased crop water requirements. Furthermore, the study found that the Kankai Irrigation System’s relative water supply value has been determined as 1.01, depleted fraction as 0.99, and relative irrigation supply as 1.02, which shows the adequacy of the water supply. The system's condition was satisfactory, with irrigation efficiency at 97.94% and overall system efficiency at 58.27%. The irrigation ratio of the system was 0.924, which means 92.4% of the command area was currently under irrigation, and the sustainability of the irrigable area was 1.06, which indicates more sustainable irrigation than was initially irrigated. Agricultural performance indicators such as output per unit irrigated area (1408.85 US$/ha), output per unit command area (1301.95 US$/ha), output per unit irrigation supply (0.19 US$/m3), and output per unit water consumed (0.20 US$/m3) highlighted the system's effectiveness. In addition, financial performance indicators such as fee collection and cost recovery ratios were estimated as 27.30% and 0.66%, respectively indicates poor irrigation service fee collection. While the Kankai Irrigation System's overall performance was good, opportunities for enhancing irrigation efficiency and collection of irrigation service fee were identified.