Rio Doce watershed has centuries of land degradation and it was the main victim of the worst environmental disaster in Brazil’s history. This process of deforestation and soil erosion could be significantly mitigated if compliance to the new Brazilian Native Vegetation Protection Law (NVPL) would be ensured. Here, we show how the percentage of forest kept in areas of permanent preservation (APP) required by the NVPL drives the overall resilience and resistance of the entire Rio Doce watershed and how it contributes to the national restoration commitments. We used water quality as a proxy for watershed resilience and resistance and we found that compliance to NVPL would require restoration of about 716 thousand hectares of riverine forest across the watershed. We found that increased forested areas improved watershed resistance and resilience during the rainy and dry seasons, respectively. Our estimates suggest that the implementation of the NVPL could improve water quality, in addition to removing 14 Gt CO2 yr?1 ha?1 from the atmosphere. At this scale, the forest restoration effort would represent 6% of Brazil’s restoration commitment. Financial feasibility of such a restoration enterprise is also achievable; at the highest possible estimate, it would compromise about 59% of the total fund proposed by the mining companies responsible for the accident. Given the low socioeconomic indicators of this basin, intervention should be designed so as to improve local livelihoods and, therefore, contribute to local adaptation and sustainable development.
Native Vegetation Protection Law (the so-called New Forest Code; NVPL hereafter) that establishes the proportion of land within rural properties that must be maintained under protection or should be restored with native vegetation NVLP establishes the full protection of riparian vegetation of rivers, springs and other water sources in rural properties as areas of permanent preservation, hereafter APPs. The NVLP is not yet fully implemented. They first looked at the % of vegetation cover and % of native vegetation in the APPs upstream each sampling point. They then also assessed the potential impacts (and costs) of implementing the NVLP (protection and restoration) over the entire watershed The increase in the watershed resilience and resistance were estimated based on the equation that describes the correlation between the WQI slope values and 1/CV values and the percentage native vegetation in APPs, respectively.
|Climate change impacts||Effect of Nbs on CCI||Effect measures|
|Reduced water quality||Positive||the water quality index (WQI), as suggested by the US – National SanitationFoundation (ANA, 2015a). Water quality index integrates ninelimnologic variables (i.e. thermotolerant coliforms, dissolvedoxygen, turbidity, nitrates, total phosphorus, total suspendedsolids, biological oxygen demand, temperature variation and pH)to determine a single value for water qualityWe determined watershed resilienceand resistance by verifying the temporal behavior of WQI for eachsampling point (Box 1).Watershed resilience was defined as the ability of the systemto return the WQI value to a natural condition, where the hypothetical WQI value is maximum (100)Watershed resistance was defined asthe ability to keep the WQI close to its mean temporal behavior, determined as the coefficient of variation (CV).|
Rio Doce river runs 888 km and its basin area is about 84 000 km2, of which 86% are in the state of Minas Gerais and 14% in the state of Espírito Santo, in southeast Brazil.