Evaluating soil loss under land use management and extreme rainfall

Area of Science:

• Environmental Science
• Soil Science
• Hydrology

Background:

• Topsoil loss is a critical environmental issue with severe impacts on natural and human systems.
• Erosion degrades soil health, affecting infiltration, water retention, and nutrient content, leading to food insecurity.
• Spatial heterogeneity of rainfall and land use practices are significant, yet often overlooked, drivers of soil loss.

Purpose of the Study:

• To investigate topsoil loss using weather radar data, focusing on extreme rainfall (ER) events and various land use scenarios.
• To evaluate watershed response to different management practices and rainfall concentrations.
• To identify soil loss hotspots and quantify the impact of ERs and land management on erosion rates.

Main Methods:

• Utilized NEXRAD weather radar data to develop extreme rainfall (ER) scenarios.
• Simulated various land use practices, including grazing and farming (nomgt, S0, S1, S2, S3).
• Classified watershed subbasins by soil loss severity and analyzed the influence of rainfall concentration (Concentration Ratio Index - CI) and amount on erosion.

Main Results:

• Grazing and farming practices can increase erosion by up to 3600%, contributing up to 50% of total soil loss.
• Extreme rainfall events can cause substantial soil loss, up to 350 ton/ha/yr, with single events contributing up to 35% of annual loss.
• Increased rainfall concentration and amount significantly escalate soil loss, with vulnerable subbasins experiencing severe erosion (>150 ton/ha/yr) under moderate rainfall increases.

Conclusions:

• Spatial heterogeneity of extreme rainfall is significant, but over time, soil moisture and land management practices are primary drivers of topsoil loss.
• Site-specific management strategies are essential for mitigating soil loss and its associated environmental and agricultural consequences.
• Findings provide valuable insights for improved soil loss management, water quality control, and flood mitigation planning.