Modelling Land Degradation (Ld) Using Geospatial Techniques for Agricultural and Environmental Management Case Study: Alla Catchment; Dekemhare-eritrea

Abstract

Eritrea is faced with significant environmental and agricultural hurdles stemming from human activities, rugged terrain, and climatic fluctuations, including recurrent droughts and erratic rainfall patterns. Key concerns encompass desertification, deforestation, and soil erosion, gravely impacting soil quality, water resources, and vegetation, particularly in regions like the Alla catchment. This area, characterized by steep slopes and scant forest cover, experiences notable soil erosion and water depletion during rainy seasons, exacerbating land degradation. Recent assessments in 2019 revealed declining vegetation and precipitation levels over four decades, alongside escalating temperatures, attributed to heightened desertification and land degradation driven by climate variations and prolonged droughts, notably affecting western and eastern regions. Reduced productivity, biodiversity, and ecosystem health underscore the urgent need for sustainable land management practices. The study sought to inform agricultural and environmental management in Alla catchment, Dekemhare, Eritrea, by modelling land degradation using geospatial methodologies. The research explored five critical parameters for soil erosion control: the erosive potential of rainfall, the erodibility of the soil, the length and steepness of slopes, the management of ground cover, and data on support practices. For assessing desertification, vegetation indices like the NDVI were utilized, and empirical soil erosion modeling techniques, such as the Revised Universal Soil Loss Equation, were applied. The outcome was a land degradation model categorizing susceptibility into five quantiles: very low (3.21%), low (2.34%), moderate (6.13%), high (14.13%), and very high (74.20%). Major hotspots of land degradation vulnerability, primarily categorised as high and very high susceptibilities were identified, indicating widespread land degradation and desertification. Moreover, the study pinpointed vegetation-covered areas in the northern parts of the study area experiencing minimal degradation. Soil loss in the catchment was predominantly influenced by factors such as cover and management practices, slope length and steepness, soil erodibility, rainfall erosivity, and support practices. Deforestation and unsustainable agricultural practices exacerbate soil erosion, emphasizing the need for comprehensive restoration efforts, including tree planting, soil conservation measures, and promoting alternative livelihoods. Recommendations include enhancing community capacity for land management and climate adaptation and expanding nationwide assessments to align with Sustainable Development Goals (SDGs) and achieve Land Degradation Neutrality (LDN)