Jacaré Pepira Basin (Brazil)

Basin Overview

The Jacaré‐Pepira basin is located in the central region of São Paulo state (Brazil) draining an area of about 2,500 km2 in the upper portion of the Tietê‐Jacaré basin (Water Resources Management Unit 13 or UGRHI 13), and the main source of the river is located in the Serra de Itaqueri, at an approximate 960 meter of altitude. The geological framework of the Jacaré-Pepira River Basin is constituted predominantly by sandy clastic sediments of the Botucatu and Pirambóia Formations, covered by the basalts of the Serra Geral Formation of the Paraná Sedimentary Basin, both aged from Mezosoic. In addition to those units, it also has sedimentary rocks from the Bauru Group (Cretaceous age), sediments from Itaqueri Formation and related deposits (Cenozoic age) and quaternary aluvial sediments. At this basin is included a part of the Guarani Aquifer, which has 3,682.55 km² of outcrop area, it means 31.20% of the total area of the basin. And it is also included part of the Bauru Aquifer, which his outcrop corresponds 37% of the total area of the basin.

 

Facts and Figures

Country:  Brazil
State: São Paulo
Major Population Centers (people in 2010): São Pedro (31,662), Torrinha (9,330), Brotas (21,580), Dourado (8,609), Dois Córregos (24,761), Ribeirão Bonito (12,135) and Itirapina (15,524).

River Length: 174 km
Watershed Area: 15,411 km2
Köppen Climate Classification: tropical humid, with rainy summer (October to March) and dry winter (April to September)

Source: Guarani and Bauru aquifers
Mean annual precipitation: — cm/yr

Mouth: Tietê River
Mean annual precipitation: 1,110 to 1,400 mm/yr
Mean annual discharge at mouth: 2,500 m3/s

People and Land Use

Total population living in the Jacaré Pepira basin is about 140,000 inhabitants, mostly in small cities (less than 25,000 inhabitants), that relies in groundwater for their water supply. Major land use in the basin is associated to agriculture (sugar cane, orange, reforestation and pasture), and the most relevant industrial activities are directly related to the agriculture production, such as sugar and alcohol industry, followed by sand mining, foundry and vegetable oils refining. The Jacaré Pepira basin has more than 20% of its area occupied by native vegetation, that associated to the existence of water falls in the rivers and the landscape, are responsible for sustaining an important economic touristic activity.

Major Issues

Jacaré Pepira river drains sandstones from Guarani Aquifer System and the protection of the of these areas against pollution sources and modification in soils uses associated to agricultural practices represent one of the most important issues to warrantee water quality and quantity for recharge and maintenance of river flows during dry season. The basin has recently experienced impacts related to climate changes, intense droughts have impacted negatively in water availability.

Research Questions:

  • How does rainfall seasonality and related isotopic composition variability exert controls on groundwater recharge, and how this signal can be used to track water exchanges between surface and groundwater?
  • How does recent changes in land use (coverage) and agricultural practices impact on water quality (surface and groundwater)?
  • Estimation of mean residence times of groundwater in shallow portion of the Guarani Aquifer System using dating tracers (3H/3He)

Skillset: Physical hydrology, isotopes, geospatial analyses.