CASE STUDY OF THE GROUNDWATER RESOURCES USAGE FOR A COASTAL ARID REGION IN THE AL BATINAH, OMAN

Transcription

1 CASE STUDY OF THE GROUNDWATER RESOURCES USAGE FOR A COASTAL ARID REGION IN THE AL BATINAH, OMAN M. Walther 1, J.O. Delfs 2, T. Graf 3, A. Al-Saidi 4, J. Grundmann 5, O. Kolditz 2, R. Liedl 1 1 Institute for Groundwater Management, Technische Universität Dresden 2 Helmholtz-Centre for Environmental Research, Leipzig 3 Institute of Fluid Mechanics and Environmental Physics in Civil Engineering, Leibniz Universität Hannover 4 Ministry of Municipalities and Water Resources, Muscat, Oman 5 Institute of Hydrology, Technische Universität Dresden Hannover, March, 14th 2012 Gefördert vom

2 THE IWAS INITIATIVE PROJECT REGIONS Eastern Europe Ukraine Central Asia Mongolia Middle East Oman/Saudi-Arabia South-East Asia Vietnam Latin America Brasil Hannover, March, 14th 2012 Walther et al. Density Dependent 3D Groundwater modeling Slide 2

3 STUDY REGION AL BATINAH COAST Hannover, March, 14th 2012 Walther et al. Density Dependent 3D Groundwater modeling Slide 3

4 STUDY REGION AL BATINAH COAST Three wadis in northern coastal area along Gulf of Oman Highest population density of Oman, strong economical and population growth Highly productive soils Large amount of agriculture Hannover, March, 14th 2012 Walther et al. Density Dependent 3D Groundwater modeling Slide 4

5 TRADITIONAL WAYS OF IRRIGATION AFLAJ SYSTEM Hannover, March, 14th 2012 Walther et al. Density Dependent 3D Groundwater modeling Slide 5

6 NOWADAYS IRRIGATION Hannover, March, 14th 2012 Walther et al. Density Dependent 3D Groundwater modeling Slide 6

7 Monitoring Socio-economic Development Faculty of Forestry, Geosciences and Hydrosciences, Department of Hydrosciences, Institute for Groundwater Management IWRM FOR STUDY AREA APPM Prognosis: Future Climate Scenarios Assessment Water Resources Availability Water Demand Surface and Subsur- Water supply Agriculture Potential and actual face Water Module Technical System water use Groundwater Module Water-Backbone Irrigation Module Aquifer Pumping Artificial Recharge Water Productivity Robust Simulation of Agriculture Tool of Water Resources System (ANN) Optimisation and Management Tool Management: optimal and sustainable management strategies of water resources operative optimal control of the technical system Planning: Evaluating the effects of planning scenarios for a most beneficial policy Decision Making: Objectives, Management Options, Constraints, etc. Grundmann, et al., 2011 Hannover, March, 14th 2012 Walther et al. Density Dependent 3D Groundwater modeling Slide 7

8 CHALLENGES FOR GROUNDWATER MANAGEMENT Rapid decrease of GW-level due to overpumping/mining of GW (since 1970s) (quantitative constraint) Reversion of natural groundwater gradient Marine saltwater intrusion (qualitative constraint) Hannover, March, 14th 2012 Walther et al. Density Dependent 3D Groundwater modeling Slide 8

9 CHALLENGES FOR GROUNDWATER MANAGEMENT ~7km Decreasing Groundwater Level Saltwater intrusion (2000) Hannover, March, 14th 2012 Walther et al. Density Dependent 3D Groundwater modeling Slide 9

10 PROJECT GOALS FROM GROUNDWATER S VIEW Target region: Protection and securing of local (ground-)water resources in the frame of an IWRM Evaluation of fresh/saltwater interface Three-dimensional, density dependent model Different scenarios of water usage and agricultural irrigation Define target values: Who gets how much water? (agriculture, industry ) Evaluation of most-likely scenarios considering an optimized groundwater usage Reduction of marine saltwater intrusion Hannover, March, 14th 2012 Walther et al. Density Dependent 3D Groundwater modeling Slide 10

11 NUMERICAL MODELING SOFTWARE PACKAGE Open source code developed at Helmholtz Centre Leipzig OpenGeoSys (OGS) addresses many THMC processes (thermal, hydraulic, mechanical, chemical) incl. coupling Kolditz, et al., 2012 Hannover, March, 14th 2012 Walther et al. Density Dependent 3D Groundwater modeling Slide 11

12 Effort vs. Result DENSITY DEPENDENCY WHY? Hannover, March, 14th 2012 Walther et al. Density Dependent 3D Groundwater modeling Slide 12

13 MODEL WITH/WITHOUT DENSITY DEPENDENCE Hydrostatic pressure c ini = 0 (fresh water) 10m c = 1 (Saltwater) z k f = m. s -1 x 10m Hannover, March, 14th 2012 Walther et al. Density Dependent 3D Groundwater modeling Slide 13

14 MODEL WITHOUT DENSITY DEPENDENCE GW-Velocity, Saturation Salinity, GW-Surface Hannover, March, 14th 2012 Walther et al. Density Dependent 3D Groundwater modeling Slide 14

15 MODEL WITH DENSITY DEPENDENCE GW-Velocity, Saturation Salinity, GW-Surface Hannover, March, 14th 2012 Walther et al. Density Dependent 3D Groundwater modeling Slide 15

16 Verifying the Modelling Software OpenGeoSys DENSITY DEPENDENT BENCHMARK Hannover, March, 14th 2012 Walther et al. Density Dependent 3D Groundwater modeling Slide 16

17 BENCHMARK AFTER GOSWAMI ET AL. (2007) 26cm 53cm Hannover, March, 14th 2012 Walther et al. Density Dependent 3D Groundwater modeling Slide 17

18 EXPERIMENT VS. SIMULATION (SMALL SCALE MODEL) Hannover, March, 14th 2012 Walther et al. Density Dependent 3D Groundwater modeling Slide 18

19 EXPERIMENT VS. SIMULATION (SMALL SCALE MODEL) Isolines for C=0.5 Concentration & Velocity field Hannover, March, 14th 2012 Walther et al. Density Dependent 3D Groundwater modeling Slide 19

20 Regional Scale Application for Al Batinah TARGET AREA MODEL Hannover, March, 14th 2012 Walther et al. Density Dependent 3D Groundwater modeling Slide 20

21 MODEL AREA 30x40km² 25 Layer Elements Hannover, March, 14th 2012 Walther et al. Density Dependent 3D Groundwater modeling Slide 21

22 HYDROGEOLOGY IN COASTAL PLAINS Fluviatile, Marine, Aeolian Deposits Hannover, March, 14th 2012 Walther et al. Density Dependent 3D Groundwater modeling Slide 22

23 HYDROGEOLOGY DATA COLLECTION Data gathering from various sources Tables, Figures, Drilling Logs Meetings/Conversations with Omani hydrogeologists 12 major materials (e.g. gravel, silt, clay, bedrock ) Hannover, March, 14th 2012 Walther et al. Density Dependent 3D Groundwater modeling Slide 23

24 HYDROGEOLOGY INTERPOLATION USING MODIFIED INVERSE DISTANCE WEIGHTING Blue = high permeabiliy Red = low permeablilty Two layered aquifer Thickness Total ~400m Coast ~50m Trough ~250m Ma awil trough Thin coastal aquifer Walther, M., et al Hannover, March, 14th 2012 Walther et al. Density Dependent 3D Groundwater modeling Slide 24

25 VELOCITY FLOW FIELD Red = high velocity Blue = low velocity Velocities 1m/d - 0.1mm/d Hannover, March, 14th 2012 Walther et al. Density Dependent 3D Groundwater modeling Slide 25

26 BOUNDARY CONDITIONS Hannover, March, 14th 2012 Walther et al. Density Dependent 3D Groundwater modeling Slide 26

27 BOUNDARY CONDITIONS ABSTRACTION THROUGH PUMPING Estimate of total abstraction rates until 1970s Q~40 mio m 3 /a (Ministry of agriculture and fisheries, Technical Report, 1992; Al-Shoukri, 2008) Dug wells Borehole wells Hannover, March, 14th 2012 Walther et al. Density Dependent 3D Groundwater modeling Slide 27

28 BOUNDARY CONDITIONS SUBSURFACE UPSTREAM INFLOW Recharge estimations via fuzzy-approach (APLIS model), Gerner, et al. (2012) Bandwidth of subsurface discharge into plains between mio m 3 /a Fuzzy upstream recharge area Hannover, March, 14th 2012 Walther et al. Density Dependent 3D Groundwater modeling Slide 28

29 PEST CALIBRATION STEADY-STATE (1974) PEST = Parameter Estimation Tool, widely used in groundwater applications Only 14 groundwater level observation series starting in 1974, many starting later PEST Results Biased correl. coeff. > 0.9 Inflow ca 68 mio m³/a Extraction ca 37 mio m³/a Material properties (ie hydraulic conductivity) as expected Scatter plot steady state calibration Hannover, March, 14th 2012 Walther et al. Density Dependent 3D Groundwater modeling Slide 29

30 TRANSIENT SCENARIO SIMULATION INITIAL AND BOUNDARY CONDITIONS Abstraction ~40mio m³/a Total Inflow ~70mio m³/a Hannover, March, 14th 2012 Walther et al. Density Dependent 3D Groundwater modeling Slide 30

31 DENSITY DEPENDENT, 3D SIMULATION Hannover, March, 14th 2012 Walther et al. Density Dependent 3D Groundwater modeling Slide 31

32 COMPARISON SALINE INTRUSION MODEL VS. REALITY Simulation Salinity at 10 m below water surface Measurement (Ministry of Regional Municipalities, Environment and Water Resources, 2005) Hannover, March, 14th 2012 Walther et al. Density Dependent 3D Groundwater modeling Slide 32

33 OUTLOOK: TRANSIENT CALIBRATION GW level difference Simulation - Measurement Hannover, March, 14th 2012 Walther et al. Density Dependent 3D Groundwater modeling Slide 33

34 SUMMARY Better transient calibration & validation (also vs. salinity) Scenario simulations for best/worst case Cross-check results of GW-model with other groups results Hannover, March, 14th 2012 Walther et al. Density Dependent 3D Groundwater modeling Slide 34

35 Thank you for your attention! S.S.M. Al-Shoukri, Mathematical Modeling of Groundwater Flow in Wadi Ma awil Catchment, Barka in Sultanate of Oman. Master s thesis; Arabian Gulf University, Bahrain, Gerner, A. and Schmitz, G. H.: Portrayal of fuzzy recharge areas for water balance modelling - a case study in northern Oman. Advances in Geosciences (accepted). Grundmann, J., Schütze, N., Schmitz, G.-H., & Al-Shaqsi, S. (2011). Towards an integrated arid zone water management using /s z. Kolditz, et al: OpenGeoSys: an open-source initiative for numerical simulation of thermo-hydro-mechanical/chemical (THM/C) processes in porous media. Environmental Earth Sciences /s x. Ministry of agriculture and fisheries. Bureau de Recherches Gologiques et Minires, Study of a New Organization of Irrigation in Barka Rumais Area, Data Analysis and Modelling Report, Technical Report, Ministry of Regional Municipalities, Environment and Water Resources (2005): Water Resources in Oman; Ministry of Regional Municipalities, Environment and Water Resources; Sultanate of Oman; 136pp. Walther, M., Böttcher, N., & Liedl, R. (2011). A 3D interpolation algorithm for layered tilted geological formations using an adapted inverse distance weighting approach. ModelCare 2011 Proceedings (accepted). Hannover, March, 14th 2012 Walther et al. Density Dependent 3D Groundwater modeling Slide 35