Monitoring agricultural water in the desert environment of New Valley Governorate for sustainable agricultural development: a case study of Kharga

The New Valley Governorate (NVG) is characterized by a desert climate, with almost no rainfall during the year. Water shortages are a significant problem in this region, and farmers depend on underground water to irrigate their crops, which is reflected in the quantity and quality of the water used for cultivation. The primary aim of this study was to track the interaction between agricultural water use and changes in the agricultural system in the NVG. To distinguish between significant crops, the multitemporal normalized vegetation difference index (NDVI) derived from Sentinel-2 imagery was used. The FAO Penman-Monteith model (FPM) is considered a global standard method for estimating the reference evapotranspiration (ETo). However, this requires the values of several environmental variables (air temperature, relative humidity, wind speed, and solar radiation) obtained from weather reports. Based on NDVI data, the crop coefficient (Kc) is calculated. The Kc and ETo equations were used to estimate the crop evapotranspiration (ETc). Based on data from Sentinel-2, Kc was found to range from 0 to 1.2 in the study area and ETc ranged from 0 to 7.5 mm/day during the winter season of 2019/2020. While the vegetation cover increased from 6721 fed in 2000 to 9375 fed in 2010, there was a much greater increase from 9375 fed in 2010 to 22,869 fed in 2020. Over the period 2000-2020, the agricultural area increased by 244% in the NVG, thus greatly increasing water consumption in this region. Therefore, more detailed studies of groundwater depletion and quality in the NVG are needed.