HYDROLOGICAL SUSTAINABILITY AND CISTERN SIZING: IMPACT ON SANITARY SECURITY - SEMIARID REGION OF THE STATE OF PERNAMBUCO

Abstract

The problem of water scarcity is a global limiting factor for development, being particularly pronounced in the semi-arid region of Northeast Brazil, which presents low annual rainfall (between 400mm and 900mm) and high climatic variability. This study aimed to quantify the hydrological reliability of 16m³ slab cisterns for supplying water to dispersed rural communities in Pernambuco. The operational sustainability analysis was conducted using a sequential water balance model, utilizing historical rainfall series of up to 73 years from 280 rain gauge stations of SUDENE (Superintendency for the Development of the Northeast). The design criteria included a minimum roof catchment area of ​​40m², and performance was evaluated by the failure rate over time index for different demand scenarios. The results demonstrate that, hydrologically, the 16 m³ infrastructure is unfeasible to meet the consumption of 100 liters/day (UN standard), due to high failure rates. Viability is strictly conditioned on a daily withdrawal of less than 50 liters/day. However, significant operational failures (above 30% of the time) persist in 34 municipalities, requiring the adoption of mitigation strategies, such as the use of multiple cisterns in microclimates. It is concluded that the success of the program depends on the mandatory implementation of filtration and disinfection (chlorination) mechanisms and a consumption management program aligned with the sustainable limit of 50L/day. Such measures are vital for maintaining water quality and mitigating health risks and infant mortality from waterborne diseases in the region.