First order catchments morphometrics in agricultural areas under no-till farming: Delineation and proneness to flooding and rainfall erosion

Abstract

No-till farming (NTF) uses agricultural techniques for soil conservation, controlling erosion processes. For this, it is necessary to know the characteristics of the relief that affect the dynamics and the erosive power of the water in the catchment where NTF is adopted. The study aimed to adapt a methodology for the delineation of 12 catchments of about 1 km2 under NTF from digital terrain (DTMs) and elevation models (DEMs). Four morphometric indices related to the water dynamics and erosive power in the catchment were calculated, including: slope gradient, compactness coefficient (CC), circularity index (CI) and form factor (FF). To delineate the catchments, it was necessary to combine data from different sources and spatial resolutions (Pleiades and Ultracam D DTMs, and ALOS Palsar and SRTM DEMs), and ArcSWAT was used. MBH were distributed in the states: SP, GO, MS, RS and PR. In agreement with the slope values, the Sarandi and Coxilha catchments are the most prone to erosion, while the Maracaju 1 and Itaí 1 are the least ones. According to the CC, CI and FF indices, the Toledo 2 and Coxilha catchments are the most prone to flooding, and the Maracaju 1 and 2 and Itaí 1 catchments are the least ones. The applied methodology was successfully adapted for the delineation of first-order catchments. Furthermore, the calculated morphometric indices will subsidize the NTF management, allowing to adopt erosion control measures, reducing impacts of soil and nutrient loss in these agricultural areas.