The SAD-IPH mathematical model applicability in concession processes analysis: the Taquaruçu Stream’s Catchment case

Abstract

In order to issue a water permit, which allows abstraction of water in a given place, the issuer needs to make sure, based on the hydrology of the region, that the amount of water available in the water body is sufficient to meet not only the demand associated with the required entitlement, but also all the existing demands from other users in the basin. This paper aims at evaluating the usefulness of the SAD-IPH mathematical model to simulate water demand scenarios in the Ribeirão Taquaruçu basin, located in the city of Palmas, state of Tocantins. Simulations provided by the SAD-IPH model indicate that the balance between water availability and demand is already critical in some parts of the basin, especially during the dry season, and the situation worsens over time. These results clearly suggest the local water utility needs to search for new water sources to meet the growing demand, mainly during the dry season. Results show the mathematical tool used in the analysis provides new and valuable information to decision makers (water resources institutions and river basin committees), potentially reducing the risk of making bad decisions. Additionally, as a water security measure, it is crucial to enforce the preservation of sensitive areas in the watershed because there is already an intense occupation in preserved areas next to water sources, a process that is likely to result in water yield reduction, which combined with an increase in the water demand over time, will compromise water security.