Analyzing the impact of agricultural water-demand management on water availability in the Urubu River basin – Tocantins, Brazil

Abstract

The Urubu River is part of the Formoso River Basin located in Tocantins State in northern Brazil. It is an important agricultural region where irrigation has an important role in rice and soybean crops, cultivated during the rainy and the dry seasons, respectively. The high levels of irrigation associated with below-average precipitation in 2016 and in the following years resulted in a water crisis in the Urubu Basin, with serious consequences to the environment and the economy of the region. This work evaluated the impact of reducing irrigation on environmental flows in the Urubu River Basin using hydrological modeling in WEAP. Irrigation water demand scenarios were simulated and analyzed from July 2018 through June 2019. Results indicated the need to reduce 35% of all water withdrawls in order to avoid the interruption of flow in the Urubu River Basin. This percentage was even greater when only some of the farmers cooperated. The paper emphasized that it is important that all farmers be involved and cooperate to reduce their water withdrawal by any means, including improving their irrigation system efficiency. The water regulator may also motivate water withdrawal reduction by modifying water permits and applying water withdrawal restrictions during the dry season.
 Keywords: hydrological modeling, scenario analysis, water balance.

Influence of climatic phenomena and deforestation on hydroenvironmental fragility, Gurupi River watershed, Northern Brazil

“…This scenario contributes to significant environmental impacts, as the removal of natural vegetation reduces evapotranspiration and, consequently, rainfall recharge (Llopart et al, 2018;Leite-Filho et al, 2021). Another environmental harm due to uncontrolled soy-driven deforestation is the water deficit, as soy requires a large amount of water for its maintenance and production (Volken et al, 2022), which can affect the river system (Yasarer et al, 2020). Considering this information, the advance of soy and pasture near the source of the Gurupi River and throughout its surroundings is concerning, once it jeopardizes regional water availability and could even impact agriculture.…”

Temporal Dynamics of the Hydropower Water Reservoirs of the Tocantins–Araguaia Basin, Brazil, Based on Remote Sensing and Hydrometeorological Station Datasets

“…The Tocantins-Araguaia Basin showed an intense LULC change over the last two decades: natural environments were progressively replaced by anthropic environments, such as agricultural and pasture areas. The biomes that cover the Tocantins-Araguaia Basin (Amazonia and Cerrado) have suffered widespread degradation [64][65][66]. Agricultural area growth also augments the water demand due to the need to irrigate crops.…”

“…Agricultural area growth also augments the water demand due to the need to irrigate crops. Moreover, Volken et al [64] observed that the low flows are critical during the dry season in the Urubu River Basin, which is part of the Tocantins-Araguaia Basin. Irrigation in this period is mainly associated with seed crops (soybeans) sown at the beginning of May that require large amounts of water.…”

Temporal trends in sand bars and water bodies on the right side of the world's largest fluvial island - Javaés River

“…The hydrological drought was worsened by increased demand during drought periods, leading to the temporary suspension of water abstraction from tributaries and the Javaés River, and the installation of the first real-time monitoring system for water abstraction from a river for irrigation in Brazil (FLEISCHMANN et al, 2017). Hydrological analyses indicate that irrigation systems in the region have a significant impact on the water balance of the tributaries of the Javaés River and show that the collection and distribution systems in the plains are inefficient, resulting in wasted water and greater pressure on the rivers (VOLKEN et al, 2022). These models suggest that a 35% reduction in the volume of water used for crops would be necessary to avoid an increase in intermittency due to human activities.…”