Ground Water in the Teresina-Campo Maior Area, Piaui, Brazil
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Ground Water in the Teresina-Campo Maior CO Area, Piaui, Brazil I GEOLOGICAL SURVEY WATER-SUPPLY PAPER 1663-G « Prepared in cooperation with the | Superintendencia do Desenvolvimento do " Nordeste of Brazil under the auspices of the U.S. Agency for International Development 06 B J? 1 <§ Ground Water in the Teresina-Campo Maior Area, Piaui, Brazil By HARRY G. RODIS and EDSON F. SUSZCZYNSKI CONTRIBUTIONS TO HYDROLOGY OF LATIN AMERICA AND THE ANTILLES GEOLOGICAL SURVEY WATER-SUPPLY PAPER 1663-G Prepared in cooperation with the Superintend encia do Desenvolvimento do Nordeste of Brazil under the auspices of the U.S. Agency for International Development w A r i - R C C L I V fc- ! JUL1U1972 UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1972 UNITED STATES DEPARTMENT OF THE INTERIOR ROGERS C. B. MORTON, Secretary GEOLOGICAL SURVEY W. A. Radlinski, Acting Director Library of Congress catalog-card No. 79-183064 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 - (paper cover) STOCK NUMBER 2401-1222 CONTENTS Page Abstract-_____________________________________________________________ Gl Introduction __--_____--__-_-_-___-_---___-_-_-________________________ 2 Purpose and scope of report_________________________________________ 2 Location of area.__----_--_--------_-_-_____-___________________-__ 3 Previous reports.__________________________________________________ 4 Methods of investigation.__________________________________________ 4 Acknowledgments _________________________________________________ 5 Geography_ _"_ _______________________________________________________ 5 Topography, drainage, and vegetation___________________.____________ 5 Climate._-----_---_-__---_-_---_-_-_____-_____________________-_- 6 Economic and cultural features.-----_-_._-___________________-_-_-.- 6 Geology._---_----__---__-_-_-_-_-----_-_______._________________-____ 8 Regional geologic setting._--_-__---_________________________-___-_- 8 Summary of stratigraphy and areal geology_.____________.____________ 8 Rock formations and their water-bearing properties.___________________ 9 Igneous and metamorphic rocks (Precambrian).____._____._________-_- 9 Serra Grande Formation (Lower Devonian).,.______..___..__.___._-__ 9 Pimenteiras Formation (Lower Devonian)____________________________ 12 Cabegas Formation (Middle Devonian)..________._____._._____._._-_. 12 Longa Formation (Upper Devonian)_.________._._______._____._._._- 13 Poti Formation (Mississippian)_______________________________.______ 13 Piauf Formation (Pennsylvanian)____________________________________ 16 Pedra de Fogo Formation (Permian).._______________________________ 17 Matuca Formation (Permian)_______________________________________ 17 Pastes Bons (Upper Triassic)__ _ ____________________________________ 18 Alluvium (Quaternary)_____________________________________________ 18 Ground water_ --_-_-_--_-_-_____-_______________________________-_-_- 18 Occurrence _______________________________________________________ 18 Aquifer system.-_-_._-_-.-_._._____._._._._._______._______._-_.__ 19 Recharge.___-_______________._!.__.__________________________ 20 Movement- -_-_-___---_-__.--.-____________.___________-_.___- 20 Discharge -------__-----_____-___-___-_____-_____-_____-----__ 21 Chemical quality.-_---__----_________-_____________________-_-_-_- 22 Relation to geographic area and geologic source____________-_----- 22 Suitability of water for domestic use.___________._._-___-_--_---- 25 Suitability of water for irrigation. ______._____._________.__--__-- 25 Suitability of water for livestock______________-_______._-___._._- 28 Present utilization.________________________________________________ 28 Future development._.__--__-_-_-___-_________________,_._______-_- 31 Selected references._._-_---_---_-_-_________________-_______-___._.___- 33 III IV CONTENTS ILLUSTRATIONS Page PLATE 1. Geohydrologic maps and section of the Teresina-Campo Maior area, Piaui, Brazil ________________________________ In pocket FIGURE 1. Location of report area__-_-_____---_-.---___-_-_-_-_-_--- G3 2. Average monthly precipitation, 1930-58, for Campo Maior, Jose" de Freitas, Teresina, and Uniao.___________________ 7 TABLES Page TABLE 1. Generalized stratigraphic section for the Teresina-Campo Maior area.__________________________________________ GIO 2. Hydrologic data on selected wells in the Teresina-Campo Maior area.-.-___-___---_-_j--__-_-_-___-_-_-_-__-__- 14 3. Chemical analyses of water from selected wells in the Teresina- Campo Maior area.___-_-___-_--_-_-_-_---_-_--------- 23 4. Comparative chemical characteristics of water from the Longa, Potf, and Piaul Formations.____._-_-___-_--__-_-----_- 24 CONTRIBUTIONS TO HYDROLOGY OF LATIN AMERICA AND THE ANTILLES GROUND WATER IN THE TERESINA-CAMPO MAIOR AREA, PIAUI, BRAZIL By HARRY G. RODIS and EDSON F. SUSZCZYNSKI ABSTRACT The Teresina-Campo Maior area lies in a presently developing farming and grazing region near the margin of drought-prone northeast Brazil where irrigated farming offers the best potential for economic development. The area comprises 9,700 square kilometers largely of catinga-covered tabular uplands which are drained by the peren nial Rio Parnaiba. The climate is hot and humid most of the year but with distinct wet and dry seasons. Temperature extremes range from 20°C to 39°C and the annual rainfall averages 1,200 millimeters. The area's ground-water reservoir is contained chiefly in sandstone aquifers of six westward-dipping sedimentary rock formations, all part of the Maranhao sedimentary basin. The youngest of these formations, namely the Piaui (Pennsylvanian), Poti (Mississippian), Longa (Upper Devonian), and Cabegas (Middle Devonian), contain the principal aquifers. Precipitation is the primary source of recharge to these aquifers and is more than sufficient to replenish current withdrawals from wells. Underlying the principal aquifers are the untapped Pimenteiras and Serra Grande Formations (both Lower Devonian) which in areas adjacent to the report area are moderately good to excellent water producers. These aquifers are recharged principally by lateral inflow from the east. Water also occurs in the alluvial deposits (Quaternary) underlying the flood plain of the Rio Parnaiba but recurrent and uncontrolled flooding at present (1966) precludes their development. Of little economic importance, because they lie above the zone of saturation, are the thin erosional remnants of the Pastos Bons (Upper Triassic), Matuca, and Pedra de Fogo (both Permian) Formations. There are in the report area about 200 drilled wells most of which are pumped with power-driven engines. The wells range from 40 to 500 meters deep but most do not exceed 150 meters, and practically all are completed open hole. Yields range from 500 liters per day for 6-inch-diameter domestic wells to 240,000 liters per hour for 10-inch high-capacity municipal wells. Although there are many more dug wells than drilled wells, dug wells account for less than 1 percent of the current (1966) draft. The current annual withdrawal from the principal aquifers is approximately 5 million cubic meters of which almost half is used for municipal supply and the rest for rural household and irrigation uses. Additional water for public supply is available from aquifers now being pumped, and larger yields probably could be obtained from rural wells designed to take full advantage of the aquifer. Gl G2 HYDROLOGY OF LATIN AMERICA AND THE ANTILLES Analyses of 28 samples show that the chemical quality of the water is well below the accepted limits of mineral concentration for most uses. Water from the Longa Forma tion averages 842 milligrams per liter in total dissolved solids and is more mineralized than that in the Piaui and Poti Formations which contain water averaging less than 300 milligrams per liter. The water in the Piaui and Potf aquifers is the most suitable in the area for irrigation and has SAR values of Cl-Sl and C2-S1. The quantities of water currently being used for irrigation are relatively small (600,000 cubic meters annually) but will increase substantially when intensive irriga tion becomes a reality. Divisao de Hydrogeologia da Superintende"ncia do Desenvolvi- mento do Nordeste estimates that about 2,500 million cubic meters of water per year would be needed to irrigate about 250,000 hectares in the Teresina-Campo Maior area (about 25 percent of the total area). This goal, however, is not likely to be realized as the water requirement is five times the estimated natural recharge to the aquifers of the area. Most of the water-bearing formations in the report area have barely been tapped and can be developed a great deal more. In fact, the current annual withdrawal from the principal aquifers is less than 0.0025 percent of a conservative estimate of annual replenishment from rainfall. Additionally, only the upper one-third of the principle water-bearing formations have been penetrated by wells. Development of water from the deeper formations, however, will lag behind that of the shallower aquifers because well construction and pumping costs will inhibit their development under current (1966) economic conditions. INTRODUCTION PURPOSE AND SCOPE OF REPORT The Teresina-Campo Maior area is part of a traditionally subsistance- level farming and grazing region but has ample rainfall and an abundance of virtually untapped ground water. This report points out opportunities for enhancement of the welfare of the people living in the area