Mapping Irrigated Area Fragments for Crop Water Use Assessment Using Handheld Spectroradiometer

As climatic change and land use are altering the hydrographic regime, most catchments are
progressively becoming drier and farmers are shifting from rainfed agriculture to irrigation practices to
enable them to carry out income-generating activities throughout the year. The Ghanaian government
has recently been promoting irrigation agricultural practices as the population keeps increasing and
the demand for food keeps soaring. In order to keep pace with high demand for food coupled with
increasing aridity of the subregion, some farmers resort to informal irrigation practices. In this study,
hyperspectral reflectance data of the irrigated crops under informal practices were collected to assess
their efficiency of water use. Photochemical reflectance index (PRI), soil-specific nitrogen index
(SSN), and water band index (WBI) were computed. The PRI and WBI were significantly correlated,
while there was no significant correlation between PRI and SSN. The map showing the probability of
water stress indicated that informal irrigation practices are not an efficient water management
approaches.