Assessment of water erosion in the Oued Aghrouz catchment (Morocco): comparative approach between RUSLE modelling and rainfall simulation

Water accumulation is a critical challenge in arid and semi-arid regions, significantly degrading soil quality and threatening land sustainability. This study focuses on the Oued Beht watershed in Morocco, covering 6,200 km², representative of semi-arid geographical conditions. Using satellitebased Earth observation data, including Landsat 9 and SRTM, this research assesses water erosion by comparing two models: PAP/CAR, a qualitative approach, and RUSLE, a quantitative model.Key datasets, such as NDVI, slope, and land use, were extracted from satellite imagery to calibrate and validate the models. For the RUSLE model, the rainfall erosivity factor (R) was estimated using two distinct methods. The first applies the formula developed by Renard and Freimund (1994), which links annual precipitation to erosivity. The second employs a modified formula by Rango and Arnoldus (1987), adapted to Moroccan conditions, using monthly and annual precipitation to estimate erosivity.Rainfall data covering 65 years (1958–2023), obtained from 23 meteorological stations, were utilized to ensure robust and reliable analysis. By comparing the performance of these two RUSLE methods with the PAP/CAR model, this study aims to determine their respective effectiveness inevaluating erosion risks.The findings contribute to advancing knowledge on erosion processes, offering valuable insights for sustainable land management practices and mitigating land degradation in semi-arid environments. This research underscores the critical role of satellite data and modeling inaddressing natural hazards, aligning closely with the conference’s focus on leveraging Earth observation technologies for risk assessment and management.

Water erosion assessment using farmers' indicators in the West Usambara Mountains, Tanzania

Water erosion caused by rainfall and runoff, in the Morocco is the main threat of fertile agricultural soil losses causing important silting-up of dams. Most watersheds are characterized by excessive values of Soil Specific Degradation (Average annual soil loss per year and per Km2), exceeding in many regions 2000T/Km2/year. The main objective of this study is to investigate this phenomenon in the Tamdrost watershed located in northwestern Morocco. The methodology is based on integrating water erosion RUSLE model to Geographic Information System and satellite image processing. The aim of the study is to develop digital mapping for the main factors involved in the erosion processes as well as the variation of the average annual quantity of soil losses. The results outcome are: (i) the average value of the specific degradation is about 80 (T/ha/year), reaching a maximum value of 800 T/ha/year and a minimum value of 3 T/ha/year; (ii) The main factors that control water erosion by order of importance are successively: R, LS, K, and C factors. Finally, different maps representing erosion and the main factors involved, are be very helpful for decision makers to better assess this phenomenon and to implement anti-erosion measures in the threatened areas to support and control the water erosion.

The Iguerferouane watershed, located in the western High Atlas of Morocco, is highly vulnerable to soil erosion for its geomorphological and climatic characteristics.This process threatens the physical environment, agricultural productivity, and local socio-economic development.The present study aims to quantitatively assess soil erosion in this watershed and to map the spatial patterns of erosion risk, to achieve this, the erosion potential method (EPM) was applied by integrating multiple factors such as climate, slope, land cover, and soil type.Spatial datasets were processed using geographic information systems (GIS) to generate thematic layers, which were subsequently incorporated into the EPM framework to estimate both the magnitude and spatial variability of erosion.The results reveal significant spatial heterogeneity, with erosion rates ranging from 64 to 34,000 m/km/year and an annual mean soil loss of 5,312.36m/km.Severely affected areas, representing 33.76% of the watershed, are concentrated in the south, where steep slopes (40-267%), sparse vegetation, fragile lithology, and intense rainfall converge to accelerate erosion.Central and eastern sectors are moderately impacted, whereas northern areas experience limited erosion due to gentler topography and lower rainfall.These findings demonstrate that soil erosion in the Iguerferouane basin is driven primarly by the interaction topography, a degrading vegetation, rainfall aggressiveness, and lithological fragility.This study represents the first quantitative assessment of erosion in the iguerferouane watershed, providing insights into the spatial dynamics and main controlling factors of soil erosion in this area.

The anthropogenic problems in richly sculpted areas (mountain and submontane) are mainly related to agricultural activity, which shapes the quality of surface waters. This paper presents an analysis of the results of the hydrochemical tests carried out in the years 2007–2018 at check-control spots. The heavy metal pollution index (HPI < 100) indicated a low risk for aquatic organisms. The statistical calculations obtained by means of multivariate adaptive regression splines (MARS) designated that the hazard quotient (HQ) index can be combined with the electrical conductivity (EC) and total dissolved substances (TDS) parameters used in the assessment of water erosion. The HQ index showed that the concentration of individual heavy metals is lower than their value in the 0.5 percentile of the value. In subsequent studies, it should be assessed whether the size of arable land has an impact on the increased concentration of heavy metals in the surface water. We recommend small retention reservoirs as a potential management measure to improve the quality of the surface water at a regional scale. This study has great potential to mitigate the degradation processes related to the insufficient storage capacity, and to promote natural water retention.

This work is inscribed in the general problem of analysis and modeling of water erosion phenomenon. Its aim is to determine the erosion rate in the Khmiss watershed (Northern Morocco). This erosion modeling was performed using the US LE hydrological model (Universal S oil Loss Equation) integrated into a Geographic Information S ystem (GIS ) platform and adapted to Moroccan con ditions. The modeling of erosion in the Khmiss watershed required the evaluation of various factors of the US LE over the entire drainage area and their expression in the form of thematic maps. This is a multiplicative function of five factors that control water erosion: rainfall erosivity, soil erodibility, slope gradient and length, vegetation cover and erosion control practices. The multiplication of those factors allowed us to produce a quantitative map with an average rate of erosion of 36t/ha/year. The description of the resulting map shows that areas with low erosion ( 120t/ha/year) cover only 8% of the basin area. A comparative analysis was conducted to highlight correlations between erosion rates and the various factors of this process.

The assessment of water erosion using Partial Least Squares-Path Modeling: A study in a legally protected area with environmental land use conflicts.

Estimation and assessment of water erosion in the Peixe Angical basin, Brazil

The aim of this review paper is to provide a comprehensive overview of geographical information system and remote sensing–based water erosion assessment. With multispectral and multi-temporal low cost data at various resolutions, remote sensing plays an important role for mapping the distribution and severity of water erosion and for modeling the risk and/or potential of soil loss. The ability of geographic information system to integrate spatial data of different types and sources makes its role unavoidable in water erosion assessment. The role of satellite data in identification of eroded lands and in providing inputs for erosion modeling has been discussed. The role of GIS in mapping eroded lands based on experts’ opinion, in generating spatial data inputs from sources other than remote sensing and in integrating the inputs to model the potential soil loss has been discussed.

The update of the SWC planning study for the Kairouan Governorate is part of the Watershed Management Framework Financing (FCGBV) project and the implementation of the national Water and Soil Conservation (WSC) strategy. This strategy, whose primary objective is the conservation and enhancement of natural resources, is based on the integration of SWC projects into agricultural development projects and on a participatory approach in the development of SWC management plans. For the Kairouan Governorate, areas moderately and highly susceptible to erosion represent approximately 250,000 ha, or 38% of the governorate’s total area. Existing SWC developments cover 153,000 ha, representing a development rate of 61%. This figure does not include traditional developments (tabias) carried out by farmers, which results in a higher development rate. Existing SWC developments in the Kairouan Governorate consist primarily of mechanical dikes and river structures, with 71 hillside lakes and 22 hillside dams. Given the scale and nature of existing SWC projects in the governorate, the average volume of water that can be mobilized by these various projects has been estimated at approximately 32 million cubic meters per year. The implementation of the SWC development plan selected for the Kairouan Governorate requires the mobilization of various material and financial resources, which largely determine its implementation schedule.

Assessment of water erosion using the ICONA model in arid and semiarid regions of northeastern Iran

L’étude de l’érosion hydrique dans les sous bassins versants d’Inaouène représente un phénomène dynamique au fil du temps, avec le changement d’un ou plusieurs facteurs responsables. Dans le bassin versant Bou Lajraf qui représente un sous bassin versant d’Inaouène, la fragilité des sols, les pentes élevées et la succession des années sèches favorisent de plus l’exposition des versants vers la dégradation de la couche superficielle, plus particulièrement dans la partie amont du BV. Utilisation de l’approche PAP/CAR pour une étude descriptive de l’érosion hydrique dans le BV Bou Lajraf fournira une connaissance géomorphologique de l’état des versants. La méthode d’approche adoptée, basée sur l’observation systématique de divers phénomènes sur le terrain. Ainsi pour chaque type de milieu défini composant le bassin versant, nous avons relevé toutes les manifestations morphogéniques. Les interprétations sont basées sur l’analyse des éléments du milieu physique et humain (modes d’exploitation du sol). L’analyse qualitative de l’érosion hydrique dans le bassin versant Bou Lajraf par la méthode PAP/CAR, permis de donner des résultats sur la situation géomorphologique de la surface au niveau de l’érosion hydrique. L’approche prédictive montre que 75% du BV présentent un état érosif élevé et très élevé. La fragilité des matériaux et leur sensibilité à l’érosion hydrique revêtent d’autant plus d’importance que la plupart des terrains sont dénudés et directement exposés aux effets morphogéniques des évènements pluviométriques.

The research focused on studying and analyzing the Wadi Hawran basin, the largest dry basin in Iraq, located within the administrative borders of Anbar Governorate.The study aimed to build a geographical database that would identify the problems that the region's soils suffer from, most notably soil erosion.The Gavrilovic Erosion Potential Method (EPM) was applied to estimate soil erosion, and the natural characteristics of the basin were analyzed: slope, temperature, rainfall, and the effect of vegetation cover were analyzed in determining the volume of lost soil.The application of the EPM model revealed the presence of a risk in the severe erosion category concentrated in the western regions, where the slope degree increased by 1.7%, and the area was 306.6/km 2 .As for the weak erosion category, it constituted the highest percentage at 44.11% and an area of 7917.07/km 2 .The use of remote sensing techniques showed a high possibility of determining the amount of eroded soil in Wadi Hauran.Here, it was possible to create a spatial database in the form of maps and tables that would clarify the spatial distribution of areas exposed to erosion.

Water erosion assessment and control in Northern Iraq

In Tunisia, soil degradation is mostly caused by water erosion. It represents a multidimensional natural risk and an environmental challenge for the ecosystem. This phenomenon is very complex and is linked to natural and anthropogenic factors that are difficult to control in time and space scales. Thereby, understanding the quintessence of those factors is crucial for the long-term management of our environment. The choice of method for estimating water erosion depends on the available data and the conditions of the study area. This study aims to quantify and map the risk of water erosion in the Governorate of Jendouba, in the North-West of Tunisia. The proposed methodology aims to implement the Revised Universal Soil Loss Equation (RUSLE) model in order to develop a potential erosion map for the study area in 2010; the average soil loss is about 25 t/ha/year. This model could be considered a powerful tool for land management and erosion control in the semi-arid areas of Tunisia.