Spatial Relationship between Irrigation Water Salinity, Waterlogging, and Cropland Degradation in the Arid and Semi-Arid Environments

Water scarcity in arid and semiarid regions has resulted in using of low-quality waters for crop irrigation. This study aims to investigate the spatial relationship of low-quality irrigation water and waterlogging in arid and semiarid environments. The multi-decadal (1990-2020) time series Landsat images and hadrochemical water analysis were employed within geographical information system mapping (GIS) to understand the relationship between irrigation water, soil salinity, and waterlogging in the western Nile Delta, Egypt. The normalized difference water index (NDWI) and the normalized difference vegetation index (NDVI) from the Landsat images were combined to quantify the Spatiotemporal changes in the croplands and waterlogging from 1990 to 2020. ArcGIS inverse distance weighted (IDW) interpolation was used to create spatial layers of irrigation water salinity from electrical conductivity (EC), sodium adsorption ratio (SAR), and soluble sodium percentage (Na%). The results demonstrated a significant spatial relationship between waterlogging and EC, SAR, and Na% in irrigation groundwater. Long-term irrigation with high salinity groundwater led to increased soil salinity, low soil permeability, and waterlogging. This study offers a time- and cost-efficient geospatial method for regional monitoring of surface waterlogging and mitigation strategies for cropland degradation and agricultural drainage water recycling that would benefit stakeholders and decision-makers.

Automated summary

This study investigated the spatial relationship between low-quality irrigation water and waterlogging in arid and semiarid environments in the western Nile Delta, Egypt, using multi-decadal Landsat images and hydrochemical water analysis. The results demonstrated a significant spatial relationship between waterlogging and soil salinity, resulting from long-term irrigation with high salinity groundwater, which led to soil salinity increase, low permeability, and waterlogging. The study offered a time- and cost-efficient geospatial method for regional monitoring of waterlogging and provided mitigation strategies for cropland degradation and agricultural drainage water recycling.