Gradual resumption of the rain regime guarantees the highest water levels in rivers in the last four years

Considering the natural climatic seasonality in the Cerrado area, and the arrival of the dry period in western Bahia, those who live in riverside cities, such as Barreiras, Correntina, Jaborandi, among others, must follow the natural reduction in river flow until the next rains, scheduled for the month of October. The good news is that the amount of water flowing down the rivers is the highest in the last four years. The explanation is simple and is linked to the rainfall regime. 

According to data from the phytosanitary program of the Bahian Association of Cotton Producers (Abapa), in the period 2017/2018, there were 1097,01 mm/m², and in 2016/2017, there were 949,25 mm/m² of rain. The worst year was in the 2015/2016 season, when it rained only 810,79 mm/m², which interfered not only with river levels, but also harmed agricultural production in western Bahia, where 94% of all production is in rainfed, that is, it depends directly on rainfall.

Having studied for ten years in western Bahia, which culminated in doctoral research on paleoclimatology, the professor and researcher at the Federal University of Western Bahia (UFOB), geographer Ricardo Reis is emphatic in stating that the rainfall regime directly interferes in the volume of surface waters. For him, natural climate variables have much more weight on water availability in western Bahia than the so-called anthropogenic climate variables. “In the case of the rivers in western Bahia, the pressures caused by man, with the use by users of the river basin, such as irrigation, industry and supply for those who live in cities, are smaller when compared to the climate, such as low rainfall, for example”, he states.

In corroborating Reis' opinion, the meteorologist and researcher at the Federal University of Alagoas, PHD in Meteorology and post-doctorate in Forest Hydrology, Luiz Carlos Molion, also believes that the water restrictions of the last four seasons are associated with the climate cycle and not to irrigation of crops, as disseminated by those who live in cities. During an event in October last year in Jaborandi (BA), Molion predicted the arrival of the la niña phenomenon, which would guarantee good distribution of rain, promoting good harvest productivity, as well as the normalization of river levels. “The end of one cycle and the beginning of another is predicted, because in nature nothing is definitive. I see a good forecast for the next ten years, but in the short term I can say that 2018 and 2019 will be better in terms of rainfall”, he predicts, understanding the low rainfall in recent years as cyclical.

Faced with the need for more information related to the water potential of the Urucuia aquifer, which works as a recharge box for the rivers of Western Bahia, the Federal University of Viçosa (UFV) and researchers from the University of Nebraska, in the United States, with the support from the Association of Farmers and Irrigators of Bahia (Aiba), has been working to measure the water availability of groundwater and surface water in western Bahia. To date, preliminary studies do not show any indication that the Urucuia Aquifer is being harmed by agricultural activity, regardless of the scale of production – small, medium or large.

The information obtained through the study of water potential will be made available to society in general and will support the management of water resources in order to guarantee the use of water for human consumption and food production in a sustainable manner. The study of water potential also counts on the partnership of the State Secretariat for the Environment (SEMA), Secretariat of Agriculture, Irrigation, Livestock, Fisheries and Aquaculture (SEAGRI), Secretariat of Water Infrastructure (SIHS) and the Institute of Environment and Resources Water (INEMA).

Water resources - Aiba's environmental director, Alessandra Chaves, also clarifies that, during the dry period, after July, there is a reduction in the pace of agricultural production in the West region, when we enter the soybean sanitary void that lasts until October, naturally reducing water use in agriculture. “It is worth highlighting that another study, carried out by Embrapa based on data from the Rural Environmental Registry (CAR), has reinforced that farmers have been respecting environmental legislation, and that the percentage preserved in areas of Legal Reserve, Permanent Preservation (APP's ) on riverbanks, springs, paths, and other surpluses of native vegetation exceed 4 million hectares”, he states. According to her, these data demonstrate that rural producers have been, little by little, gathering subsidies to demonstrate to society the role of rural producers in the conservation and preservation of the environment and associated ecosystem services.

For the president of the Bahian Association of Cotton Producers (Abapa), Júlio Busato, a lot of wrong information has been circulating about the use and availability of water resources in the region and which directly blames the farmer. “This study of the potential will be fundamental to understanding how the aquifer works and to understanding the availability and demand to be met. If it proves that it is collapsing, the entities, through the farmers, will be the first to review and draw up a plan for rational use that does not impact the future of the region's rivers”, he states, reinforcing that the farmer entities are investing R$ 500.000 in work to restore springs in eleven municipalities, which have already covered the municipalities of Correntina, Cocos, Jaborandi and São Desidério.