Seminario de Gestión integral de cuencas hídricas: teoría y práctica

Transcription

1 Seminario de Gestión integral de cuencas hídricas: teoría y práctica Cuenca subterránea y superficial, coinciden? Estudios de caso: Cuencas de San Luis Potosí y México 1 Carrillo-Rivera, JJ 2 Angeles-Serrano, G 3 Cardona, A 1 Hergt, T 1 Instituto de Geografía y 2 Posgrado en Geografía, UNAM; 3 Facultad de Ingeniería, UASLP

2 Are surface and groundwater basins the same? Study cases: basins of San Luis Potosí and Mexico Content Importance usage, of surface water and groundwater Surface basin and Groundwater basin San Luis Potosí Mexico City Concluding remarks

3 Importance usage, of surface water and groundwater Water resources of the world < 0.1% Surface water (rivers, lakes, atmosphere, soil, biosphere) 94 % seawater 2 % icecapes and glaciers 4 % Groundwater 99.0% Groundwater 1 % Surface water Freshwater in the continent Minor changes in groundwater volume severely affect surface water Groundwater is paramount to mantain ecosystems functions and human welfare

4 Importance usage, of surface water and groundwater EXTRACTION AND WATER USE IN MEXICO WATER USES GROSS EXTRACTION SURFACE WATER 72 km 3 44 km 3 Surface water Ecosystems?? 25% URBAN 25% INDUSTRY <70% AGRICULTURE GROUNDWATER 28 km 3 Groundwater 75% URBAN (75 M. people) 75% INDUSTRY >30% AGRICULTURE

5 Surface basin and groundwater basin

6 Surface basin and groundwater basin Water balance Rf R? Flow hor P = Evt + Rf + Q ± h S ± Flow hor + R It hardly shows any conditions and fails to include processes

7 Surface basin and groundwater basin WB is not a tool to define Gw / Sw interaction in regard of: Ecosystem functioning Environmental response (subsidence, flooding, health hazards, erosion, deterioration of vegetation, water quality change, etc) Sw parametres in WB have limited reliability and are difficult to validate in time and space and to be reproduced

8 Surface basin and groundwater basin Sw parametres in WB only deal with lumped water volumes in geographic areas with arbitrary space and time boundaries WB might be used to calculate the water availability but fails to characterize related processes as: Quantity and quality of water needed by the ecosystems Recharge and discharge areas (Gw flow hierarchy and GW vulnerability to contamination)

9 Surface basin and groundwater basin Alternative Water Resource Evaluation Gw is a geologic agent, so it keeps record of processes in time and space Gw parametres in WB are reliable and may be validated in time and space, could be reproduced Gw processes and manifestations must be integrated through linked multidisciplinary approaches

10 Surface basin and groundwater basin

11 Surface basin and groundwater basin Hydrologic system Recharge Transit discharge

12 Surface basin and groundwater basin Theoretical Framework: Flow Systems Theory (Toth 1995)

13 Case a san n study 1, SLP basin a a

14 SAN LUIS POTOSI

15 SLP, STUDY AREA W E

16 SLP, STUDY AREA

17 SLP, STUDY AREA

18 THE SLP, STUDY GENERAL AREA DATA water abstraction to the deep aquifer started in the 1940 s drawdown data collection started from the 1970 s initial water levels in boreholes were 120 m deep abstraction increased from 0.8 m 3 /s in 1972 (90 boreholes) to 2.7 m 3 /s in 1987 (280 boreholes), the mean drawdown rate increased from 0.90 to 1.35 m/yr, respectively no geothermal activity has been identified within 300 km of this basin

19 SLP, GENERAL DATA Additional information thermal water is related to a regional GW flow system, supported by B + (0.17 mg/l), F - (3.1 mg/l), Na + (53.2 mg/l), and Li + (0.19 mg/l) which implies water has a long residence time and interaction with rhyolitic rocks colder water (25.5ºC ±1ºC) implies an intermediate GW flow system with lower concentrations of B + (0.03 mg/l), F - (0.4 mg/l), Na + (14.6 mg/l), Li + (0.01 mg/l) which suggests shorter residence time and interaction with granular material

20 SLP, GENERAL DATA More additional information well-head temperature in 1950 s for deep aquifer water was 28-35ºC; late in the 1980 s, it was as much as 40.4 C, with an average temperature increase of 15ºC groundwater with temperature greater than 30 C accounts for 70% of total current abstraction from the deep aquifer fluoride content in extracted groundwater has increased from 80 kgday -1 in 1960 s to 530 kgday -1 in 1980 s sodium content has also increased in extracted GW Carrillo-Rivera JJ, et al 2002, Journal of Hydrology (261)

21 SLP, BALANCE RESULTS GW hydraulics / storativity Storage coefficient (from pumping-test analyses) S estimate for the 300 km 2 of the deep confined aquifer (1986 Oct Sept ) using E(1), and negligible vertical flow: (4.7 x 10 6 )+(0) + (0) = (85 x 10 6 ) (300 x 10 6 x S)..(2) L infl = 4.7 x 10 6 m 3 /s; R v = R va +R vb = 0; Q = 85x10 6 m 3 /s the calculated value of S is 0.19 (unconfined) a condition different from the actual hydrogeological situation if S=0.001 is used, the change in hydraulic head would have to be of about 200 m this value differs from field observations, 1.35 m/yr

22 GW BALANCE RESULTS Carrillo-Rivera JJ, 2000, Journal of Hydrogeology (v8)

23 SLP, RESULTS a realistic interpretation of the change in storage suggests an additional source of GW flow to that of lateral (horizontal) flow an additional source is indicated by temperature increase and fluoride content change of abstracted GW with abstraction time vertical inflow is about 70% of the 2.7 m 3 /s abstracted chemistry and hydraulic response suggests regional flow is induced to abstraction area lack of discharge areas within the basin further suggests GW flows beyond the limits of the basin, indicating inter-basin flow

24 Case Study 2, Mexico City

25 MEXICO BASIN 18 o C Cl, 5 mg/l pmc MODERN 44 o C Cl, 650 mg/l 12-2 pmc > 6,000 years Local Flow EXPLANATION FLOW SYSTEM Basement (Sierra de la Cruces) (Sierra Rio Frío) Intermediate Flow Regional Flow (Source)? Horizontal scale: km 5, QUATERNARY/RECENT ALLUVIAL (AQUITARD) 4, PLIOCENE/QUATERNARY BASALTIC- ANDESITES 3, LOWER PLIOCENE LACUSTRINE AND PYROCLASTICS 2, MIDDLE TERTIARY VOLCANICS BASALTS & RHYOLITES 1, CRETACEOUS LIMESTONE Edmunds W, Carrillo-Rivera JJ y Cardona A. 2002, Journal of Hydrology (V258)

26 Zonas Recharge de Recarga areas Potencial by topography por Región Centro de México dh/dl = K = m/s n = 0.01 Gw Velocity m/y Minimum Distance for 6,000 y km

27 Concluding remarks Potential effects due to the neglect of inter-basin GW flow Severe ecosystem damage Xochimilco

28 Concluding remarks Potential effects in the neglect of intra-basin GW flow Disappearance of water bodies Obvious major areas affected Lake Cuitzeo Lake Patzcuaro Xochimilco springs and lake Wetlands in Alto Lerma Springs in Aguascalientes

29 Concluding remarks Potential effects in the neglect of intra-basin GW flow Health hazards by water quality change

30 Concluding remarks Potential effects in the neglect of intra-basin GW flow Subsidence, Celaya, Aguascalientes, Toluca,

31 International Association of Hydrogeologists Asociación Latinoamericana de Hidrología Subterránea para el Desarrollo XXXIII Congress IAH 7º ALHSUD Congress Zacatecas City October 11 15, 2004