t5 a TECHNICAL ASSISTANCE PROGRAM FOR THE MINISTRY OF WATER RESOURCES, SULTANATE OF OMAN TASK 3: SURFACE WATER DATA COLLECTION TASK 4: GROUNDWATER DATA COLLECTION AND MANAGEMENT WASH Field Report No. 332 July 1991 WATER AND SANITATION for HEALTH PROJECT Sponsored by the U.S. Agency for International Development Operated by CDM and Associates WASH Field Report No. 332 TECHNICAL ASSISTANCE PROGRAM FOR THE MINISTRY OF WATER RESOURCES, SULTANATE OF OMAN Task 3: Surface Water Data Collection Task 4: Groundwater Data Collection and Management Prepared for the Omani-American Joint Commission for Economic and Technical Cooperation under WASH Task Nos. 229 and 230 by Steve S. Luxton Charles E. Fuller John Kent Kane III Ralph E. Preble and Mark G. Utting July 1991 Water and Sanitation for Health Project Contract No. DPE-5973-Z-00-8081-00, Project No. 936-5973 is sponsored by the Office of Health, Bureau for Research and Develorment U.S. Agency for International Development Washington, DC 20523 RELATED REPORTS Evaluation of Alternatives for Interim Treatment and Disposal of 'Trucked Wastewater in Salalah Town, Sultanate of Oman. WASH Field Report No. 243. By Leo A. St. Michel and Albert B. Pincince. July 1988. Proposed Hydrological Monitoring and Evaluation Unit for the Ministry of Agriculture and FisheriesAquifer Recharge Program (Oman). WASH Field Report No. 285. By Charles E. Fuller and John Kent Kane III. February 1990. Technical Assistance Programfor the Ministry of Water Resources Sultanate of Oman. Task 5: Water Management. Task 6: Technology Development. WASH Field Report No. 353. By Steven S. Luxton et al. Dec-mber 1991. " Parts 1 & 2: Introduction and Background; * Part 3: Wadi Gauging Network Rationalization and Upgrade; " Part 4: Salt Water In..rusion Monitoring and Remediaton; " Part 6: Small Basin Management; * Part 7: Geophysics; " and Part 8: Applications. CONTENTS ACKNOWLEDGMENTS ................................... xiii ABOUT THE AUTHORS .................................. xiv LIST OF ACRONYMS AND ABEREVIATIONS .................... xv EXECUTIVE SUMMARY ................................... xvii 1. INTRODUCTION .......................................... 1 1.1 Project Introduction ....................................... 1 1.2 Purpose of the Project ................... ........... 1 1.3 Preparation for the Assignment ........................... 2 1.4 Scope of Work ..................................... 3 1.5 Conduct of the Study . ............................... 3 1.6 Report Contents .................................... 3 2. BACKGROUND ........................................... 5 2.1 General Background and Information ...................... 5 2.2 Physiography and Regional Gaology ...................... 5 2.3 Climate and Rainfall . ................................ 6 2.4 Ministry of Water Resources Mandates ..................... 6 3. HYDROMETEOROLOGICAL NETWORK RATIONALIZATION AND UPGRADE ......................................... 9 3.1 Introduction and General Overview ........................ 9 3.1.1 Scope of Work ............................... 9 3.2 Summary of Conclusions .............................. 10 3.3 The Institutional Setting ............................... 11 3.4 Network Planning Criteria .. ........................... 12 3.5 Existing Conditions .................................. 14 3.5.1 Existing Conditions in the Network ................ 14 3.5.2 Support for the Network within the Ministry .......... 14 3.5.3 Quality of Existing Date........................ 15 3.6 Oman's Rainfall and Weather ........................... 16 3.7 The Statistical Pattern of Oman's Rainfall ................. 17 3.7.1 Temporal Variability of Rainfall in Musandam ........ 18 3.7.2 Impacts of Temporal Variation in Rainfall on Network Planning ........................... 18 3.7.3 Statistical Behavior of Rainfall Observations of Different Time-Scales ........................ 19 3.7.4 Impact of Time-Scale Effects on the Rain Gauge Network ................................. 19 3.7.5 Analysis of Expected Error in Areal Rainfall Estimates ................................. 20 3.7.6 Impact of Variations on Network Planning .......... 21 3.8 Fitting the Rain Gauge Network to the MWR's Needs ......... 22 3.8.1 General .................................. 22 3.8.2 Rainfall Data for Management of Groundwater ....... 22 3.1.2.1 Water Balance Modeling to Predict Safe Yield ............................. 22 3.8.2.2 Adaptive Management of Groundwater ..... 23 3.8.2.3 Use of Direct Correlation Models ......... 23 3.8.3 Rainfall Data for Flood Prediction ................ 23 3.8.4 Rainfall Data for Desktop Runoff Models ........... 24 3.8.5 Rainfall Data for Recharge Enhancement Schemes .... 24 3.8.6 Formatting and Analyzing Data for Ministry Use ...... 24 3.9 Recommended Network Improvements ................... 25 3.9.1 Rain Gauge Network Design and Layout ........... 25 3.9.2 Area-by-Area Recommendations ................. 26 3.10 Equipment Upgrade Recommendations ................... 28 3.11 The Network Expansion Project ........................ 29 3.11.1 General .................................. 29 3.11.2 Planning Gauge Deployment ................... 29 3.11.3 Installation of Gauges ........................ 30 3.11.4 Costs of the Expansion Project .................. 30 3.11.5 Long-term Costs ............................ 31 3.11.6 Costs Versus Benefits ........................ 31 3.12 Planning Future Network Expansions .................... 31 32 3.13 Training Aspects .................................. 3.14 Other Enhancements to the Network .................... 33 3.14.1 Weather Images and Remote Sensing ............. 33 3.14.2 Satellites ................................. 33 3.14.3 Sources of Processed Weather Information .......... 34 3.14.4 Ground Moisture Flux Measurement .............. 35 37 4. SALINITY TRANSECTS .................................... II 5. DRAINAGE BASIN CHARACTERISTICS ........................ 39 5.1 Introduction ...................................... 39 5.1.1 General .................................. 39 5.1.2 Scope of Work ............................. 39 5.1.3 Background ............................... 40 5.2 Summary and Conclusions ............................ 40 5.3 Physiographic Regions of Oman ........................ 41 5.3.1 The Batinah ............................... 41 5.3.2 The Interior ............................... 42 5.3.3 The Salalah Plain ........................... 42 5.4 Review of Rainfall/Runoff and Catchment Area Yields ......... 43 5.4.1 Rainfall During Storm Periods ................... 43 5.4.2 Flow Data from Wadi Gauge Monitoring ........... 43 5.4.3 Flood Hydrograph Shapes Related to Rainfall Patterns ................................. 44 5.5 Review of Flow Hydrographs and Drainage Basin Characteristics .................................... 45 5.5.1 Basin Characteristics Method ................... 45 5.5.2 Channel Width Method ....................... 46 5.5.3 Unit Hydrographs ........................... 46 5.5.4 Flood Hydrograph Shapes and Correlations.......... 47 5.5.5 Definition of Drainage Basin Characteristics ......... 48 5.6 Feasibility of Relating Drainage Basin Characteristics to Flood Hydrographs ..................................... 49 5.6.1 Problems in Arid Zone Hydrology ................ 49 5.6.2 Preliminary Approach-Development of Correlations for Gauged Basins .......................... 49 5.6.3 Data Requirements to Develop Correlations for Ungauged Basins ................................... 55 5.6.4 Flood Frequency Data Using Channel-Width Method for Relative Results .......................... 56 5.7 Recommendations .......................... ...... 56 5.7.1 Channel-Geometry Program--WadI Flows .......... 56 5.7.2 Expectations of the Program ................... 57 5.7.3 Altemativs to the Program .................... 57 5.8 Implementation ................................... 57 5.8.1 Personrql ................................. 57 5.8.2 Schedule ................................. 58 5.8.3 Costs ................................... 58 ill 59 6. REPRESENTATIVE BASINS ................................. 59 6.1 Introduction ...................................... 6.1.1 General .................................. 59 6.1.2 Scope of Work ............................. 59 6.1.3 Background ............................... 60 6.2 Summary and Conclusions ............................ 60 6.3 Background-Representative Basin Candidates .............. 61 6.3.1 Types and Locations of Catchments in Oman ........ 61 6.3.2 Determination of Criteria for Representative Basin Selection ................................. 62 6.4 Suggested Representative Basins ....................... 62 6.4.1 Wadi Ahin ................................ 62 6.4.2' Wadi Bani Ghafir ........................... 63 6.4.3 Wadi Ghul-Wadi Misfah-Wadl Bahia .............. 64 6.5 Recommendations ................................. 64 6.5.1 Pilot Program ............................. 64 6.5.2 Expectations of the Program ................... 65 6.5.3 Alternatives to the Program .................... 65 6.6 Implementation ................................... 65 6.6.1 Personnel ................................ 65 6.6.2 Schedule ................................. 66 6.6.3 Costs ................................... 66 67 7. AFLAJ FLOW MONITORING PROGRAM ....................... 7.1 Introduction ...................................... 67 7.2 Summary of Conclusions ............................. 67 7.3 Background ...................................... 68 7.3.! Aflaj in Oman