Assessing climate change impacts on Upper Grande River Basin hydrology, Southeast Brazil

Abstract

Brazilian electric power is mostly based on hydraulics sources through hydropower plant reservoirs that are fed by rivers located in Southeast Brazil. Possible changes in climate can affect the energy supply of the country. The objective of this work is to assess the possible changes in the hydrology of the Upper Grande River Basin (UGRB) under a future climate change scenario, using the Lavras Simulation of Hydrology (LASH) model forced by the outputs of the Eta model, a regional climate model, which was driven by HadCM3 A1B scenario for three time slices in the period between 2011 and 2099. Owing to the surface heterogeneity of the region, the hydrologic model was previously calibrated for four watersheds of the UGRB, which are located in its headwater region and evaluated against observational time series of the present climate period, 1961–1990. In the first future time slice, 2011–2040, the results showed a small reduction in the annual run‐off, but for the other time slices, the trend changed to strong increase in most of the watersheds. The water budget in the region calculated from the Eta model agreed with the run‐off trends, as water excess reduced in the first time slice and gradually increased towards the end of the century. The run‐off components showed intraseasonal variability. The reduction of rains in the end of winter, the dry period in the region, and in the beginning of spring, may cause a change in the dynamics of the groundwater recharge, affecting the base flow, which can extend and intensify the flow recession period, and therefore affect the availability of water resources. On the other hand, the increase of rains during the summer, the rainy season of the region, caused an increase of the direct surface run‐off, which can modify the flood regimes of the rivers in the region.

Hydrological responses to climate changes in a headwater watershed

“…Analysis in monthly time steps is used in most studies of climate changes impacts (Leung;Wigmosta, 1999;Viola et al, 2015); however, these studies simplify some numerical processes because the objective is to evaluate the impacts on hydrology in average terms. Thus, DHSVM was calibrated in the daily and monthly time step in this study because if the model is calibrated for daily time step with good results, the monthly time step is good enough as well.…”

“…Taking into account that the water cycle is affected by possible climate changes and by the vegetation dynamics, the region of the Mantiqueira Range, located in southeastern of Brazil, should be highlighted as an important headwater region in terms of water dynamics (Viola et al, 2015). In addition, the Atlantic forest in these areas is an important biome threatened with extinction.…”

Land-use effect on hydropedology in a mountainous region of Southeastern Brazil

“…Therefore, the spatial identification of promising areas in the context of water recharge allows for better land-use planning in order to maintain a sustainable water supply (Viola et al, 2015). Tsui, Chen and Hsieh (2004), researching the relationships between soil properties and slope positions in a lowland rain forest of Southern Taiwan, found an increase of organic carbon and a lower rate of decomposition in the summit forest.…”

“…Soils with degraded structure tend to have increased bulk density and consequently a decrease in soil porosity and its continuity, which also affects water movement in the soil profile, since those soil attributes are closely related to soil-water dynamics (Pinto et al, 2015a). In this context, deforestation in the MRR has caused a rapid reduction of the natural regulation of streamflows, leading to water scarcity, with climate drought events becoming more acuter (Menezes et al, 2009;Viola et al, 2015).…”

The Eta Model: Design, Use, and Added Value

“…Studies of possible impacts of climate change have been produced to the Brazilian hydropower availability [60], to water resources considering small river basins and river springs [61], to Amazon biome and general tropical forest conservation [62,63], and to coffee crops [64,65]. Indices of vulnerability and susceptibility to climate change have been designed, for example as in [66], in order to help to construct adaptation measures.…”