Soil erosion and sediment transport modelling for river basins in Afghanistan using gis-based models
Başlık:
Soil erosion and sediment transport modelling for river basins in Afghanistan using gis-based models
Yazar:
Ansari, Ahmad, author.
Yazar Ek Girişi:
Fiziksel Tanımlama:
xviii, 194 leaves: illustrarions, charts; 29 cm + 1 computer laser optical disc.
Özet:
Soil erosion is a critical environmental issue with significant impacts on agricultural productivity, water quality, and land degradation. Afghanistan has five major river basins; Kabul River Basin (KBL), Helmand River Basin (HRB), Harri RodMurghab River Basin (HMRB), Northern River Basin (NRB), and Amu Darya River Basin (AMRB). Afghanistan is prone to soil erosion due to various natural and anthropogenic factors. This study is the first-ever assessment at the country scale, estimating the rainfall erosivity from measured and satellite rainfall products, calculating the soil erodibility factor based on two known databases (HWSD and ISRIC), the slope length and steepness factor (LS), the crop management factor (C), and the support practice factor (P). Finally, the average annual soil erosion potential is computed by multiplying the developed raster data from each Revised Universal Soil Loss Equation (RUSLE) analysis using the GIS and R-Studio software. Furthermore, the sediment delivery ratio for the Upper-Helmand and Arghandab Catchments are also estimated. The RUSLE model estimates showed that the entire watersheds in Afghanistan produce an average soil loss rate of 13.8 t ha-1 yr-1, of which the most severe classes of soil losses occurred in the southeast and northeast regions of the study area. The soil classes of very high, severe, and very severe cover an area of 30.4% (19,258,056 ha) of the entire study region with 273,763,211 t yr-1 of soil loss. Approximately 30.4% of the total area should be placed under urgent soil conservation measures, specifically the regions located in the KRB and AMRB watersheds. In addition, the SDR is computed for Upper-Helmand and Arghandab Catchments, and it is found to be 23.5% and 24.2%, respectively. The rainfall erodibility, slope-length gradient, and crop management factors are identified as the most crucial elements associated with soil erosion in the study area, and the rate of soil erosion gradually increases with the increasing soil erodibility and slope gradient. Six erosivity maps are generated using the TRMM-3B42 precipitation, Local raingauges stations (using MFI and mean annual precipitation), TRMM3B43-monthly product, ERA5 monthly product (spanning 1990 to 2020), and Global Rainfall Erosivity map. The correlation between the R-factor derived from the TRMM-3B42 and the Rfactor estimated from measured rainfall are compatible, implying the suitability of the employed methods. This study revealed that satellite products of the Tropical Rainfall Measuring Mission (TRMM-3B42), Harmonized World Soil Database (HWSD), International Soil Reference and Information Centre (ISRIC) of soil data, the Digital Elevation Model (DEM) of the Shuttle Radar Topographic Mission (SRTM), and the Moderate Resolution Imaging Spectroradiometer (MODIS-13Q1) can be used as an alternative input while estimating RUSLE factors. This study provides valuable soil, water conservation, and management insights for the entire watersheds in Afghanistan. This research also establishes a technical foundation for utilizing the RUSLE model to estimate soil erosion in the region.
Yazar Ek Girişi:
Tüzel Kişi Ek Girişi:
Tek Biçim Eser Adı:
Thesis (Doctoral)-- İzmir Institute of Technology: Civil Engineering
İzmir Institute of Technology: Civil Engineering. (Doctoral).
Elektronik Erişim:
Access to Electronic Versiyon.