Role Summary We are seeking a Senior Hydrogeologist to lead the city-wide Water Balance Study determining water availability and quantifying every inflow and outflow across the study area, validating the groundwater and dewatering systems both separately and combined, and assessing the potential for water reuse. The role owns the water-balance model and its field-data foundation: it divides the study area into sub basins, instruments control points, quantifies recharge and losses, reconciles the balance against monitoring, and delivers the water-balance, water-reuse and reuse-pilot outputs. It also supplies the water-balance interface and recharge understanding that the numerical groundwater model depend Accountability The Senior Hydrogeologist is accountable for a defensible, monitoring-validated city-wide water balance with quantified uncertainty, for the water-reuse assessment and pilot design, and for supplying the recharge and water-balance inputs on which the groundwater model and Master Plan depend. Key Competencies Water-balance leadership Uses satellite imagery and NDVI/land-use analysis to validate the balance. Recharge & losses Quantifies recharge, evapotranspiration, leakage and seepage in an arid urban setting. Field & instrumentation Designs and directs monitoring, sampling and controlled measurement of flows, levels and quality. Remote sensing Uses satellite imagery and NDVI/land-use analysis to validate the balance. Reuse assessment Defines reuse potential and designs a monitored pilot study. Integration Feeds the water-balance and recharge inputs the groundwater model and Master Plan require. Core Responsibilities (Task D) 1.1 Water-Balance Model & Components Develop the city-wide water-balance model to determine water availability and assess all in- and out flowing volumes, accounting for (but not limited to) the following components: Inflows/Outflows Rainfall / Actual evaporation / evapotranspiration Waste-water system leakage / Occasional outflowing rainfall runoff (via wadis) Fresh-water system leakage / Downward seepage to deeper aquifers Occasional inflowing runoff (peak flow, via wadis) / Water extraction (e.g. irrigation) Continuous upward seepage (base flow) 1.2 Study-Area Characterization & Sub-Basins Divide the project area into at least 15 sub-basins and fit all control points with gauges, meters and instruments to validate the balance; run monitoring over at least 12 months. Collect, compile and update geological and hydrogeological information and the natural-setting base map; complete missing data through field investigation. Investigate all factors influencing the balance land use, public/private landscaping, sewered/non-sewered leakage, supply source, infrastructure age, geology, weather/evapotranspiration, watersheds and runoff, and recharge. Give special attention to the differing ground characteristics of eastern Riyadh, and evaluate existing dewatering projects efficiency in water-table control. Field Data, Remote Sensing & Quality Conduct geophysical and remote-sensing investigations (including radar survey), and procure high-precision satellite imagery to validate balance inputs and outputs and derive land-use, levels and surface type. Quantify actual irrigation practices and application rates on public land to improve accuracy. Install flow meters, gates, isolation valves, level sensors and pressure loggers, and consider online quality monitoring, to establish a controlled monitoring system; collect water samples to examine quality and source. Validate received data against field measurements and estimate uncertainty/error margins for each factor to generate an overall error range. Water Reuse & Groundwater Resources Apply the water-balance model to assess possibilities for water reuse for irrigation and other purposes. Define the potential uses of groundwater available and usable quantities, fields of usage, optimum use, and parameters affecting use. Design a water-reuse pilot study to investigate capability and future potential, identifying all monitoring items, performance indicators and related parameters. Integration & Reporting Provide the water-balance interface and recharge parameterization that the numerical groundwater model and Master Plan rely upon. Deliver the Task Inception Report, Water Balance Final Report, Water Reuse Final Report, Reuse Pilot Design Package and Task Completion Report to the client s acceptance. Contribute to the analysis and assessment of all data collected through the history of the groundwater program. Task D Deliverables the Role Leads The Senior Hydrogeologist leads the Task D (Water Balance Study) deliverables across the program term: Task Inception Report Methodology, water resources, water-reuse potentials, action plan. Term M3 Water Balance Final Report City-wide inflow/outflow balance across sub-basins with error ranges. Term M20 Water Reuse Final Report Potential uses, usable quantities, optimum use, monitoring indicators. Term M22 Reuse Pilot Design Package Pilot study design for water reuse capability and potential. Term M25 Task Completion Report Consolidated water-balance and reuse study closeout. Term M30 Minimum Qualifications & Experience A minimum of fifteen (15) years of professional experience in hydrogeology and water-resources assessment, with substantial experience leading water-balance / water-budget studies, is required. Candidates below this threshold will not be considered. 15+ years in hydrogeology / water resources, including lead responsibility for city- or catchment scale water-balance studies. Postgraduate degree (MSc or PhD preferred) in hydrogeology, hydrology, water-resources engineering or a related discipline. Deep expertise in recharge estimation, evapotranspiration, surface-water/groundwater interaction, and leakage quantification from water and sewer networks. Experience quantifying urban recharge in arid settings (low rainfall, high potential evaporation, irrigation return flow) and reconciling water budgets against monitoring data. Command of remote sensing for water balance (e.g. land-use/NDVI, satellite imagery) and of field instrumentation for flows, levels and quality. Experience assessing water-reuse potential and designing reuse pilot studies with monitoring indicators. Strong data-validation and uncertainty-analysis skills; ability to express error/uncertainty ranges on each balance component

Desired Candidate Profile

A minimum of fifteen (15) years of professional experience in hydrogeology and water-resources assessment, with substantial experience leading water-balance / water-budget studies, is required. Candidates below this threshold will not be considered. 15+ years in hydrogeology / water resources, including lead responsibility for city- or catchment scale water-balance studies. Postgraduate degree (MSc or PhD preferred) in hydrogeology, hydrology, water-resources engineering or a related discipline. Deep expertise in recharge estimation, evapotranspiration, surface-water/groundwater interaction, and leakage quantification from water and sewer networks. Experience quantifying urban recharge in arid settings (low rainfall, high potential evaporation, irrigation return flow) and reconciling water budgets against monitoring data. Command of remote sensing for water balance (e.g. land-use/NDVI, satellite imagery) and of field instrumentation for flows, levels and quality. Experience assessing water-reuse potential and designing reuse pilot studies with monitoring indicators. Strong data-validation and uncertainty-analysis skills; ability to express error/uncertainty ranges on each balance component.