THE PORTO PRIMAVERA DAM AND THE FLUVIAL TRANSPORT ON THE PORTO SÃO JOSÉ SECTION, PARANA RIVER

Abstract The Porto Primavera Dam caused the decrease of the concentration of suspended load and reduction of the size of the bed forms of Paraná River, but the effects of the construction on fluvial transport have not yet been quantified. In order to do that, this paper aims to evaluate the influence of the dam on the sediment transport in the section of Porto São José. Thus, data of Porto São José Fluviometric Station, field and orbital images information available in literature were used. The data were analyzed by linear regression to obtain significant correlation between sediment transport and river discharge. The equations with significant coefficient of determination were used to estimate the annual average transport for different time periods. The suspended transport before construction was 214.1 kg/s, increased to 222.2 kg/s during construction and decreased to 56.4 kg/s after completion of the dam. The bed load transport was 99.7 kg/s during the construction, decreased to 86.2 kg/s during 1999 and 2000 and to 41.2 kg/s after 2001. In the same period the total transport decreased from 321.9 kg/s to 177.8 and finally to 91.2 kg/s. These results indicated that the Porto Primavera Dam reduced 74.6% of the suspended transport, 58.7% of the bed load transport, 71.7% of the total transport and increased the proportion of the bed load of 33, 9% to 44.5% of total.

摘要 波尔图普里马韦拉水坝（Porto Primavera Dam）导致巴拉那河（Paraná River）悬移质浓度降低，床沙形体尺寸减小，但该大坝建设对河流输沙（fluvial transport）过程的影响尚未得到量化。为完成该量化工作，本文旨在评估该大坝对圣若泽港（Porto São José）河段输沙过程的影响。为此，研究采用了圣若泽港水文站（Porto São José Fluviometric Station）的实测数据、公开文献中的野外实测影像与轨道遥感影像资料，通过线性回归（linear regression）分析法对数据进行处理，以明确输沙量与河流径流量之间的显著相关性。选取判定系数（coefficient of determination）具有统计学意义的回归方程，对不同时段的年平均输沙量进行估算。结果显示，大坝建设前的悬移质输沙（suspended load transport）量为214.1 kg/s，施工期间升至222.2 kg/s，大坝完工后降至56.4 kg/s；施工期推移质输沙（bed load transport）量为99.7 kg/s，1999至2000年间降至86.2 kg/s，2001年之后进一步降至41.2 kg/s。同期总输沙量则从321.9 kg/s降至177.8 kg/s，最终降至91.2 kg/s。本研究表明，波尔图普里马韦拉水坝使悬移质输沙量减少74.6%，推移质输沙量减少58.7%，总输沙量减少71.7%，同时使推移质输沙占总输沙的比例从33.9%提升至44.5%。