KNUSTRocks v2.0 · A KREW scientific application
KNUSTRocks
Ghana Rock Enhanced Weathering Opportunity Index
An uncertainty-aware national reconnaissance platform for prioritizing enhanced rock weathering research and field validation across Ghana. The application integrates hydroclimatic conditions, acid-soil co-benefit potential and mapped feedstock-access evidence on a 2.5 arc-minute grid (approximately 4.6 km north–south).
Scope of interpretation. KNUSTRocks reports a relative opportunity index. It does not quantify net carbon dioxide removal, feedstock safety or reserves, project economics, or eligibility for carbon-credit issuance.
National evidence surfaceGREW-OI · Application v2.0
10,680grid cells2.5 arc-min analytical grid
Intended analytical uses
A common evidence base for complementary analytical tasks
KNUSTRocks supports research prioritization, validation planning and scientific due diligence while maintaining a clear distinction between national reconnaissance and verified project performance.
Scientific investigation
Examine environmental gradients
Inspect grid cells, component indices, source variables and uncertainty envelopes without reducing the evidence to district means.
Open the national explorer MRV study designStructure validation programmes
Translate reconnaissance evidence into sampling strata, measurement workstreams and independently verifiable outputs.
Review the MRV framework Scientific and investment due diligenceEvaluate evidence maturity
Separate supported screening inferences from unresolved feedstock, environmental, logistics and carbon-accounting requirements.
Review the evidence register Regional reportingCompare administrative reporting areas
Review area-weighted district distributions while retaining the continuous grid as the primary analytical unit.
Compare district profilesProject governance
Institutional stewardship and research project structure
NCEL provides institutional leadership, KREW coordinates the research project, and KNUSTRocks provides access to its national analytical outputs.
NCEL
The Net-Zero Carbon Emission Lab leads and operates the KREW project at KNUST and maintains this scientific application.
KREW
KNUST Rock Enhanced Weathering integrates national prioritization, feedstock characterization, field experimentation and MRV research.
KNUSTRocks
The application provides public access to GREW-OI outputs for reconnaissance, comparative analysis and validation planning.
National evidence explorer
Examine the national evidence grid
Select an evidence layer, examine alternative decision weights, locate a district or inspect an individual grid cell. Stored uncertainty statistics refer to the specified reference model.
Analytical scopeThis relative reconnaissance index must not be used to calculate CO₂ removal, issue carbon credits, infer quarry reserves or safety, determine project feasibility, or estimate financial returns.
Tap or click a grid cell to view its evidence profile. Areas without a complete national input record are not mapped.
District reporting profiles
Area-weighted summaries that retain within-district variability
District boundaries are reporting overlays rather than environmental calculation units. Filter and sort the profiles to examine central tendency, high-index area, structural robustness and within-district variation.
| District | Region | Mean GREW-OI | Area ≥70 | Area ≥70 in all structural cases | Mean P10–P90 width | Spatial IQR |
|---|
Methodological framework
An explicit component model with uncertainty and structural-sensitivity analysis
GREW-OI is a weighted geometric co-location index. It is neither a mechanistic mineral-weathering model nor an estimator of gross or net carbon dioxide removal.
Index components
Hydroclimatic opportunity, H
Mean annual precipitation and temperature represent broad hydroclimatic conditions for investigation.
Acid-soil co-benefit, B
Soil pH and CEC represent amendment relevance and cation-retention context, not carbon removal.
Mapped access, F
Candidate-lithology quality and straight-line distance provide low-confidence reconnaissance evidence.
Noncompensatory composite
A low component constrains the composite; the weights encode decision priorities rather than causal effects.
Core equations
H = (0.10 + 0.90μM)0.80 (0.55 + 0.45μT)0.20
B = (0.10 + 0.90μA)0.70 (0.20 + 0.80μR)0.30
F = max[0.01, q exp(−d / 75)]
GREW-OI = 100 exp[0.45 ln(H) + 0.25 ln(B) + 0.30 ln(F)]
Here, μM and μT are precipitation and temperature memberships; μA and μR are acidity and retention memberships; q is mapped source quality; and d is straight-line source distance in kilometres.
Interpretation of pH and thresholds
The current model uses pH only within the acid-soil co-benefit component, avoiding double counting and preventing strong-acid mineral dissolution from being interpreted as carbonic-acid CDR.
The index threshold of 70 is an analytical reporting convention used for comparative summaries. It is not an empirically validated feasibility or deployment threshold.
Review evidence scopeUncertainty characterization
Parameter and model-structure dependence
Epistemic scenario envelope
Four hundred draws vary SoilGrids predictions, climate, membership breakpoints, source quality, haul-decay assumptions and decision weights. P10–P90 is a scenario envelope, not a calibrated probability interval.
Structural sensitivity
Alternative weighting structures and haul-decay models quantify dependence on normative model choices.
Evidence provenance and interpretation
Source datasets, analytical roles and principal limitations
The evidence register distinguishes mapped predictions and reporting geographies from model-derived quantities, context-specific observations and unresolved project requirements.
Evidence sourceSpatial support / periodAnalytical rolePermitted interpretationPrincipal limitation
SoilGrids 2.0250 m predictions; 0–15 cmModel inputBroad relative patterns in soil pH and CECDoes not replace measured site chemistry or crop-response data
WorldClim 2.12.5 arc-min; 1970–2000Model inputBroad long-term precipitation and temperature gradientsDoes not represent field soil moisture, future climate or event-scale variability
National geology map1:1,000,000 reconstructionReconnaissance inputPreliminary identification of candidate-source areasDoes not establish mineralogy, quarry status, reserves or material safety
GSS district boundaries261 polygons; 2023Reporting layerArea-weighted summaries for official administrative unitsDoes not imply environmental homogeneity within districts
Ghana maize trialOne material and site programmeContext-specific studyCrop response under the tested material, site and management conditionsDoes not establish national agronomic response or carbon removal
Interpretation register
Relative national co-location
The application supports comparison of mapped H, B and F under explicitly stated assumptions.
Candidate-source access
Broad geological patterns identify priorities for follow-up; source verification remains mandatory.
Carbon removal or credit issuance
The index contains no weathering kinetics, alkalinity-fate assessment, life-cycle balance or field MRV.
MRV study-design framework
Define the evidence pathway from reconnaissance to MRV
This framework helps research and project teams specify the evidence required after a location has been shortlisted. It neither calculates carbon removal nor certifies project readiness.
Purpose of the MRV planning workspace
Stratify field investigation
Use the opportunity components, scenario width and structural minimum to define contrasting sampling strata.
Specify measurement domains
Connect site, feedstock, soil, hydrological and life-cycle questions to measurable evidence.
Prepare an assurance pathway
Define outputs, responsibilities and independent review requirements before claims are made.
Evidence pathway
Six validation workstreams beyond national reconnaissance
Land and environmental eligibility
Confirm land use, tenure and consent, slope, erosion, hydrology, protected areas, settlements and permits.
Output: documented site-eligibility dossierFeedstock qualification
Measure mineral proportions, grain size, neutralization potential, trace elements, asbestos, radionuclides, sulfides and batch consistency.
Output: feedstock specification and safety recordSupply-chain accounting
Verify source capacity, road routes, comminution energy, transport, spreading, cost and counterfactual material use.
Output: operational inventory and ex-ante life-cycle modelBaseline and field design
Preregister treatments, controls, spatial baselines, sampling frequency, agronomy and hydrological monitoring.
Output: auditable field protocol and data-management planCarbon attribution and fate
Separate carbonic- and strong-acid weathering, quantify alkalinity generation, secondary phases, transport and leakage.
Output: gross-removal estimate with propagated uncertaintyNet removal and assurance
Subtract life-cycle emissions, apply the selected MRV protocol, document safeguards and complete independent review.
Output: assurance-ready net-removal statementInstitutional governance and project context
NCEL, KREW and KNUSTRocks
KNUSTRocks is the scientific decision-support application developed within the KNUST Rock Enhanced Weathering project and operated by the Net-Zero Carbon Emission Lab at KNUST.
KNUST Rock Enhanced Weathering
KREW is NCEL's enhanced rock weathering research project. Its workstreams progress from national prioritization through feedstock characterization to field validation and locally relevant MRV research. KNUSTRocks provides the project's national reconnaissance and planning interface.
01 Prioritize02 Characterize03 Validate04 Verify
Model development, feedstock assessment, field experimentation and MRV research are treated as connected but distinct workstreams.
The grid preserves local variation while official district overlays support planning and comparative reporting.
Feasibility, safety, carbon accounting and investment claims remain outside the index until independently supported.