Gravity WaveMediterranean Leakage ModelGravity Wave · Alliance 2045

MLM v1.0

Methodology

Purpose: create the first unified leakage intelligence system for the Mediterranean Basin, identifying, quantifying and prioritising all major pathways through which plastic reaches the sea, to support investment decisions, policy design, infrastructure deployment and impact measurement under the Mediterranean Treaty 2045.

One question

“If I invest 1€, where do I achieve the largest reduction of plastic reaching the Mediterranean?”

No single database answers this today. MLM v1.0 answers it with documented estimates and proxies, unifying the three entry pathways (urban, riverine, maritime) plus tourism and fishing communities into one investment logic.

Leakage framework

Plastic enters the Mediterranean through three primary pathways:

  • Urban coastal leakage (~50%): littering, storm drains, sewer overflows, ramblas and seasonal watercourses, tourism pressure.
  • Riverine leakage (~30%): large basins transporting mismanaged waste from inland populations (Nile, Po, Rhône, Ebro, Drin…).
  • Maritime leakage (~20%): fishing gear (ghost nets, ropes, EPS boxes), aquaculture, port operations, shipping, recreational boating.

Units of analysis (first deployment wave)

  • 100 priority coastal cities (plus critical basin cities such as Cairo)
  • 50 priority river basins
  • 200 ports: 25 mega, 75 regional, 100 priority fishing ports
  • 100 tourism destinations (300M+ tourists per year)
  • 500 fishing communities and cofradías

Estimation model (v1 proxies)

Every entity receives an estimated annual leakage (t/yr) derived from population, tourism pressure, national waste-generation rates, mismanaged-waste-share proxies and pathway transfer coefficients (coastal 25%, basin-city 8%, riverine export 3%). Ports scale with throughput or fleet size; communities with vessel counts. Coefficients follow the ordering of published MPW literature (UNEP MED POL, Jambeck-class studies) and are deliberately conservative.

v1.0 does not attempt to be perfect. It attempts to be the first model that unifies the three entry pathways into a single investment logic. Data partnerships planned: UNEP, Union for the Mediterranean, World Bank, EEA, EMSA, FAO, port authorities and the environment ministries of the 22 countries.

Mediterranean Priority Index (MPI)

MPI = Leakage × Impact Potential × Feasibility × Cost Efficiency → 0-100

  • Leakage: log-normalized estimated tonnage.
  • Impact potential: interceptable share per layer (fishing 90%, ports 85%, rivers 75%, tourism 60%, cities 55%).
  • Feasibility: governance and implementation capacity proxy per country.
  • Cost efficiency: inverse of intervention cost per tonne (gear take-back €400/t → urban systems €2,500/t).

Tiers by basin-wide rank: Tier A Critical (top 8%), Tier B Strategic (next 17%), Tier C Regional (next 35%), Tier D Monitoring (rest).

Priority infrastructure portfolio

  • Urban: storm drain capture, smart litter traps, beach interception, flood barriers
  • Rivers: floating barriers, interceptors, waste hubs, AI flood prediction
  • Maritime: port collection systems, fishing-for-litter, gear take-back, net recycling

Investment strategy

  • Phase I (2028-2032): €2B · top 20 cities, top 10 rivers, top 25 ports
  • Phase II (2032-2038): €5B · regional expansion
  • Phase III (2038-2045): €10B · full Mediterranean deployment

Success metric: net plastic inflow into the Mediterranean reduced by 90%. The Mediterranean becomes the first large sea basin operating under a positive marine regeneration model.