Analysis of sediment production through InVEst and Aries modeling in the Brazilian Cerrado

In the last few decades, many studies have focused on the hydrologic effects and sediment regulation by LULC changes. Besides, land degradation by soil erosion is a major problem in many tropical developing countries, particularly when natural vegetation is converted to farmland. In Brazil, the MATOPIBA Region located in the Cerrado biome, has been considered the greatest national agricultural frontier, responsible for a large part of the Brazilian production of grains and fibers. The flat topography, the deep soils and the favorable climate for the cultivation of the main crops of grains favored the accelerated agricultural expansion in the last 30 years. In order to analyze and measure erosion and sediment regulation in the Rio Grande watershed were performed using two models: InVEST and ARIES. The aim of the InVEST model is to map and quantify the sediment delivery and retention services. It is a spatially-explicit model working with calculations at the pixel scale. The ARIES program works through ecosystem services modeling and calculations that, depending on the used module, considers both supply and demand. The mean sediment retention, in InVEST model, which is the difference in the amount of sediment delivered by the current watershed and a hypothetical watershed where all land use types have been converted to bare ground, was 42.76 ton/year/ha. These results should be taken as a good first estimate of the current scenario for the sediment retention service. This is due to some limitations of the SDR model. It uses the revised universal soil loss equation (RUSLE), which is limited in scope with regards to sediment source. ARIES model, for the Sediment Regulation analysis, used RUSLE to calculate soil loss and soil retention by vegetation in tons of sediments per hectare per year. The data of rain erosivity comes from the Global Rainfall Erosivity database (factor R) and the soil erodibility data (factor K) from Soil Grids. The sediment retention calculation is done through the application of RUSLE twice, first with the current land use and land cover and then with bare soil (Martínez-López et al., 2019). Then a subtraction is made between the two outputs, which determines the collaboration that current use and coverage has on sediment retention. The basin presents a mean value of 905.37, standard deviation of 1854.58 and maximum and minimum value of 39982.67 and 0, respectively. A limitation of the InVEST sediment model compared and ARIES is the temporal and spatial scale of its outputs. It is able to provide only average annual impacts under steady state conditions, limiting the model’s usability for ecosystem services in need of assessment via timescales shorter than one year.