Toward continental hydrologic–hydrodynamic modeling in South America

Abstract

Abstract. Providing reliable estimates of streamflow and hydrological fluxes is a major challenge for water resources management over national and transnational basins in South America. Global hydrological models and land surface models are a possible solution to simulate the terrestrial water cycle at the continental scale, but issues on parameterization and limitations in representing lowland river systems put into question their utility for basin-scale analysis and to deliver daily 15 discharges to meet local needs. In an attempt to overcome such limitations, we extended a regional, fully coupled hydrologic-hydrodynamic model (MGB) to the continental domain of South America and assessed its performance using daily river discharges, water levels from independent sources (in situ, satellite altimetry), estimates of terrestrial water storage (TWS) and evapotranspiration (ET) from remote sensing and other available global datasets. In addition, river discharges were compared with outputs from global models acquired through the eartH2Observe project (HTESSEL/CaMa-20 Flood, LISFLOOD and WaterGAP3), providing the first cross-scale assessment (regional/continental  global models) that makes use of spatially consistent daily discharge data. A satisfactory representation of discharges and water levels was obtained (NSE > 0.6 in 55 % of the cases) and MGB was able to capture patterns of seasonality and magnitude of TWS and ET especially over the largest basins of South America. Continental-scale modeling significantly improved discharge estimates when compared with global models, which resulted in a large number of gauges with negative (or close to 0) NSE 25 values. Models were largely affected by positive bias mainly over East/Northeast Brazil and Argentina as well as over regions of Sao Francisco and Parnaiba basins, while major issues on flow timing were observed in regions affected by floodplain processes such as the Amazon, La Plata, Tocantins-Araguaia, Orinoco and Magdalena basins. We state that efforts in calibrating rainfall-runoff parameters within large basins are necessary to simulate daily river discharges appropriately in this continent, but implementing a hydrodynamic routing component is also important. We hope that our 30 study provides further insights about hydrological simulation in South America, helping to reduce the gap between global and regional hydrological modeling communities.Hydrol. Earth Syst. Sci. Discuss., https://doi

Impact of large reservoirs on simulated discharges of Brazilian rivers

“…The continental MGB model version for South America (MGB-SA) (Siqueira et al, 2018) is used in this study. It uses the inertial equation of propagation in rivers described in Pontes et al, (2017), with sufficient physical basis to represent river hydrodynamics and floodplains effects.…”

“…Advances in modeling techniques, computer capabilities and big data has taken place in the last years (Siqueira et al, 2018), and assessing reservoir impacts over large spatial domains has become even more a reality. For instance, in Global Hydrology and Water Resources models (GHWRM), which aim to assess the anthropogenic impacts over the entire globe (see Bierkens, 2015), numerous generic algorithms have been developed to explicitly represent the influence of lakes and reservoirs on river flows (Döll et al, 2003;Haddeland et al, 2006;Hanasaki et al, 2006;Wada et al, 2014;Zajac et al, 2017;Shin et al 2018).…”

“…MGB (Collischonn, 2001;Collischonn et al, 2007;Paiva et al, 2013) is a large scale hydrological model which was already applied to the whole South America in a multi-basin manner with satisfactory performance (Siqueira et al, 2018). Although some studies have explored the explicit simulation of reservoirs in MGB (Larentis et al, 2008;Collischonn et al, 2011;Fleischmann et al, 2015Fleischmann et al, , 2019bFleischmann et al, , 2019c, reservoir modeling is not yet consolidated in MGB.…”

Complexity to Forecast Flood: Problem Definition and Spatiotemporal Attention LSTM Solution

“…To minimize impacts brought by floods, researchers have proposed quantity of methods to accurate forecasting in the past decade [1,2]. Based on core ideas to forecast, we divide their proposed methods into two categories: physical model [3,4] and data-driven model [5,6]. Physical model explains hydrological procedures with conceptual math equations, such as rain, evaporation, and flow concentration.…”

Assessing two precipitation data sources at basins of special interest to hydropower production in Brazil

“…These products usually provide monthly estimates of surface precipitation from merged analyses that blend precipitation estimates from satellite data and in-situ rain gauge observations. While they can be useful for global climate change impact studies, finer space and temporal resolutions are often needed for hydrological applications that involve daily decision-making at continental or national scales, such as flood forecasting or hydropower operations (Alfieri et al, 2013;Fan et al, 2016;Emerton et al, 2016;Siqueira et al, 2018).…”