Assessment of Crop Changes in Southern Uzbekistan for Better Crop Allocation and Water Resource Management

Water scarcity has a direct impact on food security, climate change, and energy efficiency. The role of water in the environment and its effects on nature are critical considerations in sustainable water management systems. Improper crop allocation can lead to land degradation, changes in groundwater levels, and reduced food security. Crop pattern changes over time are essential for better water management in the region. This study aims to analyze crop pattern changes in the Karshi Steppe, a region in southern Uzbekistan that is experiencing water availability challenges. The study area consists of six regions located in the western part of Kashkadarya province, with irrigation fed by the Talimardjan reservoir. The reservoir is filled during winter and used during summer, with water pumped up to the reservoir through the Karshi Magisterial canal. The study used freely available medium-resolution remote sensing data from the United States Geological Survey (USGS) to analyze crop pattern changes. The Landsat data obtained had a temporal resolution of 16 days and a spatial resolution of 30 meters. The data was preprocessed, and the area of interest was extracted to make analysis in the study area. QGIS open-source software was used to build phonological curves of different crops, with a focus on classifying major crops such as cotton and wheat, as well as bare soils, water bodies, grasslands, orchards, and alfalfa. The Normalized Difference Vegetation Index (NDVI) was used to classify crop types. NDVI is a technique developed by Rouse et al. (1974) that gives values ranging from -1 to 1, with most vegetation ranging from 0.1 to 0.8. Values close to 1 indicate the most vigorous vegetation. NDVI helps to compensate for changing illumination conditions, viewing aspects, atmospheric conditions, and slope variations. The NDVI technique used in this study was applied to 30-meter Landsat spectral data in the visible channel 3 (0.63-0.69 micrometer) and near-infrared channel 4 (0.76-0.90 micrometer) regions of the electromagnetic spectrum. Decision criteria for different crops were established based on NDVI values. The results show how crop types changed over time in the Karshi Steppe, with a focus on the last 30 years, from 1987 to 2017. The study provides valuable information for sectors dealing with similar cases in other parts of Central Asian countries, aiming to protect the environment and ensure sustainable water management systems. The study area has undergone significant changes over the past 30 years, with the irrigated area increasing from 100,000 hectares in the 1970s to 350,000 hectares in recent years. The main reason for this increase was the extension of agricultural fields with mismanaged crop rotation and irrigation systems. The study highlights the importance of understanding crop change dynamics to make proper decisions that mitigate possible changes in the study area for the future, if further irrigation extension or reduction is required. The results of the study show that the Karshi Steppe has undergone significant changes in crop types over the past 30 years. The study provides valuable information for sectors dealing with similar cases in other parts of Central Asian countries, aiming to protect the environment and ensure sustainable water management systems. The study's findings can be used to inform decision-making and policy development in the region, with a focus on improving water management and reducing the environmental impacts of agriculture.