SCIMAP: modelling and mapping diffuse pollution risk. The North Pennines.

David Higgins: Tees and Wear Rivers Trust

Tees and Wear River Trusts: EA funded Metal Mines Project

Introduction and background

GIS-based desktop – SCIMAP and literature

Walkover surveys

Developing costed restoration plans

SCIMAP

www.scimap.org.uk

Risk map for fine

sediment

Route risk through catchment

Point scale risk

Surface flow index

Saturation propensity

channelserodability

Stream power

Upslope area

slope

Land

cover

DEM Rain

map

Farmer 1:

‘a mile out and not representing thesituation on the farm.’

‘the model is simply wrong anddoesn’t fit with what actuallyhappens’

‘had not known a time when thedrain couldn’t cope with the amountof runoff even in severe downpours.’

Testing the model

Farmer 2:

‘when the culvert becomesblocked with debris, the waterdoes follow the locations shownon the map (SCIMAP).’

Farmer 3:

‘the model is right but the farmingsystem changes the result’

‘the farm is a very low risk (due to)the farming system we have whichreduces runoff.’

Farmer 4:

‘above the road (SCIMAP)appears to be reasonablyaccurate but the water ispicked up by drains once itreaches the road and isredirected away from thelower sections of the farm.’

SCIMAP outputs in channel

Erosion sources x

surface flowIn channel fine sediment risk

Tees and Wear River TrustsMetal Mines Project

GIS-based desktop – SCIMAP

Four catchments failing WFDPb, Zn, Cd.

The SCIMAP Model: Identifying risky locations

Connection and disconnection

Hillslope

Spoil heap

Surface flow

Connection or disconnection

River

Strong connection and risk of fine sediment delivery, here the stream bank is severely eroded.

Area of eroding spoil heap undercut by stream.

Area of extensive mine spoil, workings and bare earth. SCIMAP confirms strong connectivity and risk of fine sediment delivery and by implication heavy metal delivery. This fits with the EA investigations so offers ground truthing of the model.

SCIMAP outputs for Hudeshope Beck.

Blue and brown colours show hydrological connectivity and fine sediment risk with the brown areas posing the greatest risk of fine sediment delivery.

SCIMAP: Coldberry and Marl Beck, 1m LIDAR

A step change in risk factor?

Overlaying metal mine/spoil heap locations

Tees and Wear River TrustsMetal Mines Project

Walkover Surveys

Proposed Methodology for Metal Mines Project

River Catchment Zone Description Priority

(1 high priority…3 lowest priority) Comments

Riparian

Eroding bank passing through lead mining zone

1

Eroding bank undermining spoil heap 1

Eroding bank 100 m d/s of lead mining zone

2

Eroding bank u/s of lead mining zone

3

Floodplain

Bare/un-vegetated soil in lead mining zone

1: > 50m2

2: 20 – 50m2 3: < 20m2

Lead mines, workings or spoil heaps present

1: if connected by surface flow to a watercourse as identified by SCIMAP

2: if not connected to a watercourse in SCIMAP

Locations closest to the river bank can be assumed to pose the greatest risk. Wherethese are being undercut by the river it seems likely the risk is being realised.

Proposed Methodology for Metal Mines Project

River Catchment Zone Description Priority

(1 highest priority…3 lowest priority)

Comments

Riparian

Eroding bank passing through lead mining zone

1

The lead mining locations closest to the river bank can be assumed to pose the highest risk. Where these locations are being undercut by the river the risk it seems likely that the risk is being realised.

Eroding bank undermining spoil heap 1

Eroding bank 100 m d/s of lead mining zone

2

Eroding bank u/s of lead mining zone 3

Floodplain

Bare/un-vegetated soil in lead mining zone

1: > 50m2

2: 20 – 50m2 3: < 20m2

Lead mining locations within the floodplain are likely to be impacting especially if they are shown to be creating patches of bare soil. Smaller patches of bare soil may well suggest other issues, such as small patches of livestock erosion, whereas the larger patches could well be due to heavy metal pollution that could easily be

Lead mines, workings or spoil heaps present

1: if connected by surface flow to a watercourse as identified by SCIMAP 2: if not connected to a watercourse in SCIMAP

Floodplain

Bare/un-vegetated soil in lead mining zone

1: > 50m2

2: 20 – 50m2 3: < 20m2

Lead mines, workings or spoil heaps present

1: if connected by surface flow to a watercourse as identified by SCIMAP

2: if not connected to a watercourse in SCIMAP

Catchment

Bare/un-vegetated soil within lead mining area connected to a watercourse as identified by SCIMAP

1: > 50m2

2: 20 – 50m2 3: < 20m2

Spoil heaps connected to a watercourse as identified by SCIMAP

1

Bare/un-vegetated soil in wider catchment that is not connected by surface flows and is located outside of any known lead mining zone

3

Notes: These methods are a proposed working route to identifying sources of heavy metal pollution, assessing their priority and developing restoration methods in data-poor catchments. Where data exists that suggests a diffuse pollution source any location can be assigned a higher priority if required.

Pollution sources in the floodplain will be impact rivers if connected and if they create patches of baresoil. Smaller patches of bare soil may suggest other issues, e.g. livestock erosion, larger patches could bedue to heavy metal pollution. SCIMAP can describe which pollution sources are connected by surface flow.

Floodplain

Bare/un-vegetated soil in lead mining zone

1: > 50m2

2: 20 – 50m2 3: < 20m2

Lead mines, workings or spoil heaps present

1: if connected by surface flow to a watercourse as identified by SCIMAP

2: if not connected to a watercourse in SCIMAP

Catchment

Bare/un-vegetated soil within lead mining area connected to a watercourse as identified by SCIMAP

1: > 50m2

2: 20 – 50m2 3: < 20m2

Spoil heaps connected to a watercourse as identified by SCIMAP

1

Bare/un-vegetated soil in wider catchment that is not connected by surface flows and is located outside of any known lead mining zone

3

Notes: These methods are a proposed working route to identifying sources of heavy metal pollution, assessing their priority and developing restoration methods in data-poor catchments. Where data exists that suggests a diffuse pollution source any location can be assigned a higher priority if required. The wider catchment poses less of a risk due to greater distance from a watercourse.

However, SCIMAP can describe where pollution sources maybe connected to awatercourse by surface flow. These can then be assigned a higher risk rating.

Gully formation and erosion scars delivering direct to watercourse

Numerous seepages and dressing floor sediments delivering to watercourse

Bank erosion of contaminated soils

Car parking area is the main area of concern

Designed from dressing floor sediments, unconsolidated and highly erodible…abutting stream

2nd area of main concern spoil heaps eroding into stream

Tees and Wear River TrustsMetal Mines Project

Developing costed restoration plans

Key

Area of mine spoil

SCIMAP outputs, browns show high connectivity and eeeeeeeeee fine sediment delivery, blues moderate and whites very e low, or no, risk.

Hudeshope Beck

Map 1

Map 2

Map 3

Map 4

Map 5

The blue and brown zones within this spoil area require surveying.Again the blue and brown zones need surveying as does the area where the stream cuts through the spoil area.

The same here, blue and brown zones as well as the locations where watercourses cut through the spoil area require surveying.

Map 2

Aerial view of bare soils

©Google maps

Overview

Restoration Plans