Runoff, soil loss, and water balance in a restored Karst area of the Brazilian Savanna

On‐ and off‐site erosion impacts of restoration measures in a tropical karst watershed

“…Since the Tarimba cave downstream was found to be silted up with sand-sized sediments (Caldeira et al, 2021), the reduction in that textural class (Table 5) would contribute to restore the original Across the watershed, the ecological restoration also contributed to the reduction of the risk of permanent soil degradation by erosion (Figure 9a), a fact reported by Chaves (2010a) in restored areas of the Brazilian savanna. Similarly, the off-site impact (sinkhole sedimentation) was reduced in the watershed, since the ecological restoration reduced the sediment exported from basin pixels (Figure 9b) as a consequence of the higher ground cover, protecting against erosion and retaining the eroded sediment on-site (Fonseca et al, 2023). With respect to sediment texture leaving the watershed, the ecological restoration of the Tarimba watershed contributed to a reduction of the sand and clay fractions of the sediment reaching the sinkhole, which cause the highest impacts with respect to water quality, because of its higher nutrient adsorption characteristics (Vale et al, 2023).…”

“…The degraded pasture surrounding the P5 plot on the Quartzsamment soil was restored with Andropogon gayanus grass. In an earlier work in the same area (Fonseca et al, 2023), a water balance was carried during the 3-year period, using precipitation, runoff, and evapotranspiration data to assess potential leakages in the karst fissures, but no evidence of it was found.…”

“…The soil loss (A) in each watershed pixel (1 m 2 ) was obtained by spatial analysis in the GIS, using the USLE (Wischmeier & Smith, 1978): The USLE factors were obtained locally, as much as possible. In case data were lacking, they were obtained from updated literature from the Brazilian savanna, such as Fonseca et al (2023). The rainfall erosivity of each hydrologic year was obtained with a regional Fournier-type equation, developed for the Brazilian savanna (Silva, 2004), using precipitation data recorded at the site:…”

“…Evaluating the hydrological effectiveness of ecologically restored plots in a karst area of the Brazilian savanna, Fonseca et al (2023) found that runoff and soil loss were reduced by 50 and 95%, respectively, compared to degraded plots. Although runoff plots are useful to assess the degree of erosion in basin slopes, in both natural (Renard & Foster, 1985) and agricultural areas (Hudson, 1993), if plot estimates are extrapolated to the watershed, sedimentation can be overestimated (Evans et al, 2017).…”

“…The significant land conversion which occurred in the last 100 years in the Tarimba watershed, situated upstream of a sinkhole in Central Brazil, has silted the underground cave with sand‐sized sediments (Caldeira et al, 2021). However, the conservation efforts recently introduced in the watershed are expected to reduce not only the on‐site impacts of erosion and soil degradation in the watershed slopes, including soil loss and soil degradation (Fonseca et al, 2023), but also the off‐site consequences, such as sedimentation of the downstream sinkhole and underground cave. Considering the aspects above, the present study aimed to assess the soil loss, the sediment yield, and the sediment quality of the ecologically restored Tarimba watershed, comparing the results to the local on‐ and off‐site soil loss tolerances.…”