Variation of the water table and salinity in alluvial aquifers of underground dams in the semi-arid region of Rio Grande do Norte, Brazil

Abstract

Despite the growing progress in the construction of underground dams, there are few studies to evaluate and monitor these reservoirs after their construction. Thus, a research study was carried out to evaluate the water table level in alluvial aquifers and water salinity in four underground dams selected in the Cobras river basin, Parelhas municipality, Rio Grande do Norte. Water level variation was monitored using the traditional method and the Ground Penetrating Radar with generation of 3D virtual models. Water samples were collected between the months of December 2010 and December 2011 for electrical conductivity analysis. The results indicate that the accumulation of groundwater and salinity (expressed by electrical conductivity) in the reservoirs were affected by the spatial position within the hydrographic basin (limited occurrence of alluvial aquifer recharge area in headwater sectors) and the presence of surface reservoirs (upstream dams), which promote a more continuous recharge, greater renovation, and reduction of the salinity of the waters of the alluvial aquifer downstream.

Spatial variability of water electrical conductivity in underground dam areas in the semi-arid region of Rio Grande do Norte, Brazil

“…The same climatological influence was observed by Andrade et al (2012), in the water from alluvial valleys of the semi-arid region of Pernambuco, and by Lima et al (2019), in underground dams located in the Cobra river basin, which covers the municipalities of Parelhas, Carnaúba dos Dantas and Jardim do Seridó, located in the state of Rio Grande do Norte. Andrade et al (2012) warn that the continuous use of water with electrical conductivity above 0.7 dS m -1 in irrigation, without proper management, may contribute to increasing the concentration of salts in the soil.…”

“…In recent years, the federal government has prioritized funding for the construction of underground dams as a social technology to meet the water needs of the rural population of the semi-arid region (LIMA et al, 2019). This fact can be observed in the state of Rio Grande do Norte, where 1591 underground dams were implemented only by the Technical Assistance and Rural Extension Company of the state (EMATER/RN) between 2008 and August 2018.…”

Effects of Silicon Alone and Combined with Organic Matter and Trichoderma harzianum on Sorghum Yield, Ions Accumulation and Soil Properties under Saline Irrigation

“…Agriculture 2023, 13, 2146 2 of 23 In much of the Brazilian semiarid region, producers already suffer from problems related to the availability of good quality water for use in irrigated agriculture [5]. This has caused an increase in groundwater use for irrigation purposes, which generally have high saline contents, with high concentrations of sodium and chlorine in their composition [6,7].…”

Water quality in underground dam areas in the semiarid region of rio grande do norte, Brazil

“…Other studies reported the same climatological effect on water in alluvial valleys in the semiarid region and in underground dams in the agreste region of Pernambuco (ANDRADE et al, 2012;SANTOS;PAIVA;SILVA, 2016), and in underground dams in the Cobra River Basin, in Parelhas, Carnauba dos Dantas, and Jardim do Serido, in the state of Rio Grande do Norte (LIMA et al, 2019b). Electrometric method (Teckna T-1000 pHmeter) Total solids (TS)…”