1 Task 7B Thoughts Task 7 Workshop Oxford 13/05/08 G W Lanyon Mircea Cantor The need for uncertainty Until 1 st June: Museum of Modern Art Oxford Open Tuesday to Saturday 10am - 5pm Ansel Adams: Photographs

Task 7B Issues (from evaluation perspective) Does the simulation strategy support the task objectives? How does the transverse flowmeter testing fit within model development and simulation strategy? Have we “embedded” treatment/quantification of uncertainty (in what?) within the task structure and performance measures? Do the modellers have sufficient resources to address the dataset, develop conceptual models, perform simulations, understand results within the proposed schedule? 2

Task 7B Aims and Objectives (version ) 3 The fundamental objectives of the 7B task are: to quantify the reduction of uncertainty in the properties of the fracture network, and to assess the Posiva Flow-logging (PFL) data when analysing the rock (rock mass) Task 7 aims to provide a bridge between the information derived from site characterisation (SC) and performance assessment (PA). how information from PFL data can be used to maximum benefit, to reduce key uncertainties for the PA. develop an understanding of the effects of open boreholes on the groundwater system and the use of data from such boreholes to inform the site characterisation and performance assessment. Goals (1)to understand how major features could be used as boundary conditions, (2)to understand the minor features of the groundwater system, (background rock) (3)to understand the consequences of the tests and measurement systems used, e.g. the open boreholes, (4)to understand how to model open boreholes within site characterisation studies and for the provision of parameters for PA, (5)to understand how PFL measurements could reduce uncertainty in models as compared to models calibrated with only head measurements, and (6)to increase understanding of compartmentalisation and connectivity at the block scale

Does the simulation strategy support the task objectives? 4 Natural conditions with/without boreholes. Aim to determine effect of boreholes? Stepwise Prediction&calibration cycle for KR14, KR18 pump tests open/packed off conditions. 4 tests in all. Aim to identify impact of open boreholes on testing and value of PFL? Forward transient model of KR15 and KR14 (transverse flowmeter?) Aim to test value of calibration to KR14/18 tests? PA model Aim to show reduction in uncertainty? Near surface features? Boundary conditions? Zone heads from 7A studies vary significantly between groups? Updating approach so final calibration to data from all 4 tests. Many simulations & PMs! Why not just calibrate to a) 2 open holes tests, b) 2 packed off tests c) all data and compare? Only forward modelling – issue on storativity data. Transient modelling useful to assess impact of diffusivity variation on test responses (compartmentalisation). Nothing to compare with how can we show uncertainty reduction?

Roles of transverse flowmeter testing Currently included as forward transient simulations calibrated to steady-state models of KR14,18 tests. Storativity of zones and background rock free parameter? No chance to use transverse flowmeter data to condition models and demonstrate any reduction in PA uncertainty from this new type of measurement. 5 qiqi Q q bh Observation

Have we “embedded” treatment/quantification of uncertainty (in what?) within the task structure and performance measure? Uncertainty in what? No PA measures/parameters defined yet. How is uncertainty defined? Within models distributions of properties (advective travel times? F,  )? GUM? To demonstrate/quantify reduction we need a baseline measurement Not clear who/when this is produced 6

Do the modellers have sufficient resources to address the dataset, develop conceptual models, perform simulations, understand results within the proposed schedule? For the modellers to answer! If not enough resources options are: 1.More time (but may not work see Parkinson’s Law * ) 2.Simplify task to concentrate on key issues? 7 *Parkinsons Law: Work expands to meet the time available! Largely based on analysis of number of administrators in the Navy versus number of capital ships.

Recommendations for Task 7B (general) 8 More work on conceptual model development/documentation? The large volume of data in 7a1,2 meant that most groups took over the “Structural model” provided in the Task Description and did not question/develop it. Trade-off between data handling/modelling Synthetic world/specified structural model: minimises data handling Data analysis: opportunities for development of alternative structural/ conceptual models Robust consideration of uncertainty needs both “inside model” and alternative model treatments. Prescriptive simulation list? 7A1/2 had strong prescriptive list of simulations designed to address particular questions Advantages: Clear goals and ability to compare relevant simulations Disadvantages: Seemed to have discouraged experimentation/sensitivity studies (maybe just lack of resources) 7A3-5 very flexible – but little came out of them (again maybe just lack of resources).

Recommendations for Task 7B (specific) 9 Look at near surface/depth interactions and impact of site-scale trends early in task Transient modelling Greater influence of diffusivity contrasts with background rock. Need to look at relationship of steady state to transient in background rock Lack of storativity information/calibration To address PA Uncertainty needs more work on transport simulations for different conceptualisations/parameterisations