Hydromorphology and geomorphology guidelines
Hydromorphological indices derivation
1
Produced by Riverdene Consultancy, 08/03/2016.
Based on Environment Agency guidelines for calculating HMS scores, 2003.
www.riverdeneconsultancy.com; www.riverhabitatsurvey.org
Instructions for calculating the
Habitat Modification Score using
River Habitat Survey data
These rules were derived by the Environment Agency in 2003 and supersede
the previous scoring system (Environment Agency, 1998).
HMS: Culverts sub-score
A) Spot-check Channel Modification – Culverts (CV)
For each spot-check where CV is recorded and the associated entries for
bank material, bank modification and channel substrate are all recorded as
either NV or NK, score 400 points.
For each spot-check where CV is recorded and the associated entries for
bank material, bank modification and channel substrate are not NV or NK,
calculate scores as per rules C) Spot-check Bank Material, D) Spot-check
Bank Modification – Reinforced and G) Spot-check Channel Substrate. Total
these scores together and add a further 50 points to obtain the score for that
spot-check.
Total up the scores for culverts recorded in spot-checks.
B) Sweep-up Artificial Features – Culverts
Subtract the number of occurrences of CV in spot-checks from the number of
culverts recorded in Artificial Features and for each remaining culvert score
400 points.
e.g. if there are 4 culverts recorded in Artificial Features and 2 occurrences of
CV in spot-checks you would score 800 points.
To derive the HMS Culverts sub-score, total up the scores from rules A
& B.
HMS: Bank and Bed Reinforcement sub-score
C) Spot-check Bank Material
Score appropriate points for each spot-check on the left bank which have the
artificial bank materials listed below recorded. Exclude spot-checks which
have already been used to calculate the culvert sub-score.
Hydromorphology and geomorphology guidelines
Hydromorphological indices derivation
2
Produced by Riverdene Consultancy, 08/03/2016.
Based on Environment Agency guidelines for calculating HMS scores, 2003.
www.riverdeneconsultancy.com; www.riverhabitatsurvey.org
Bank Material
2003
acronym
’94-97
acronym
Points per
spot-check
Concrete CC CC 40
Sheet piling SP SP 50
Wood piling WP WP 30
Gabions GA GA 40
Brick/laid stone BR BR 50
Rip rap RR RR 40
Tipped debris TD BW 20
Bioengineering BI - 20
Fabric FA - 10
Repeat for the right bank and add together the scores for both banks.
D) Spot-check Bank Modification – Reinforced (RI)
Score 20 points for each spot-check on the left bank which does not have
artificial bank material but has RI recorded for the bank modification. Exclude
spot-checks which have already been used to calculate the culvert sub-score.
Repeat for the right bank and add together the scores for both banks.
E) Sweep-up Bank Profiles – Reinforced
If a culvert is recorded in spot-checks or Artificial Features ignore this
rule and proceed to rule F.
If there is no RI bank modification recorded for spot-checks on the left bank,
score points as per the table below for left bank reinforcement recorded in
sweep-up.
Bank Profile Points for Present Points for Extensive
Reinforced whole bank 40 160
Reinforced top only 20 80
Reinforced toe only 20 80
Repeat for the right bank and add together the scores for both banks.
F) Sweep-up Artificial Features – Revetments (1997 survey format only)
If there is no artificial bank material or bank reinforcement recorded at spotchecks
or in sweep-up, score points as per the table below for revetments.
Artificial
Structure
Points for
Major
Points for
Intermediate
Points for
Minor
Revetment 50 25 10
G) Spot-check Channel Substrate
Score 200 points for each spot-check where AR is recorded as the channel
substrate. Exclude spot-checks where channel modification is FO or which
have already been used to calculate the culvert sub-score.
Hydromorphology and geomorphology guidelines
Hydromorphological indices derivation
3
Produced by Riverdene Consultancy, 08/03/2016.
Based on Environment Agency guidelines for calculating HMS scores, 2003.
www.riverdeneconsultancy.com; www.riverhabitatsurvey.org
H) Spot-check Channel Modification – Reinforcement (RI)
Score 200 points for each spot-check which does not have AR recorded for
channel substrate but has RI recorded for the channel modification. Exclude
spot-checks which have already been used to calculate the culvert sub-score.
To derive the HMS Bank and Bed Reinforcement sub-score, total up the
scores from rules C–H.
HMS: Bank and Bed Resectioning sub-score
I) Spot-check Bank Modification – Resectioned (RS)
Score 40 points for each left bank spot-check which has RS recorded for bank
modification.
For surveys conducted between 2003 and 2005, add 40 points for each spotcheck
where EM is recorded with no associated RS.
Repeat for the right bank and add together the scores for both banks.
J) Sweep-up Bank Profiles – Resectioned
If there is no RS bank modification recorded for spot-checks on the left bank,
score points for left bank resectioning recorded in sweep-up. If resectioned is
present score 40 points, or if it is extensive score 160 points.
Repeat for the right bank and add together the scores for both banks.
K) Spot-check Channel Modification – Resectioned (RS)
Score 200 points for each spot-check which has RS recorded as channel
modification.
L) Sweep-up Channel Modification – Over-deepened (2003 survey format
only)
If RS is not recorded as the channel modification at any spot-check score
points for channel obviously over-deepened in Artificial Features. If overdeepening
is recorded as present score 40 points, or if it is extensive score
160 points.
To derive the HMS Bank and Bed Resectioning sub-score, total up the
scores from rules I–L.
HMS: Berms & Embankments sub-score
M) Spot-check Bank Modification – Berms (BM)
Score 20 points for each left bank spot-check which has BM recorded for
bank modification.
Hydromorphology and geomorphology guidelines
Hydromorphological indices derivation
4
Produced by Riverdene Consultancy, 08/03/2016.
Based on Environment Agency guidelines for calculating HMS scores, 2003.
www.riverdeneconsultancy.com; www.riverhabitatsurvey.org
Repeat for the right bank and add together the scores for both banks.
N) Spot-check Bank Modification – Embankments (EM)
Score 20 points for each left bank spot-check which has EM recorded for
bank modifications.
Repeat for the right bank and add together the scores for both banks.
O) Sweep-up Bank Profiles – Artificial two-stage
If there is no BM bank modification recorded for spot-checks on the left bank,
score points for artificial two-stage channel recorded for the left bank in
sweep-up. If artificial two-stage is present score 20 points, or if it is extensive
score 80 points.
Repeat for the right bank and add together the scores for both banks.
P) Sweep-up Bank Profiles – Embanked
If there is no EM bank modification recorded for spot-checks on the left bank,
score points for embanked recorded for the left bank in sweep-up. If
embanked is present score 20 points, or if it is extensive score 80 points.
Repeat for the right bank and add together the scores for both banks.
Q) Sweep-up Bank Profiles – Set-back Embankment
Score 4 points if set-back embankment is recorded as present on the left
bank. If it is recorded as extensive score 16 points.
Repeat for the right bank and add together the scores for both banks.
To derive the HMS Berms and Embankments sub-score, total up the
scores from rules M–Q.
HMS: Weirs/Dams/Sluices sub-score
R) Sweep-up Artificial Features – Weirs/dams/sluices
For 1996, 1997 and 2003 survey formats;
Score 75 points if ‘is water impounded by weir/dam?’ is recorded as present in
<33% of the site. Score 300 points if it recorded as being present in >33% of
the site.
For 1997 & 2003 survey formats, Score points as per the table below for each
weir and sluice recorded in Artificial Features.
Artificial
Structure
Points for
Major
Points for
Intermediate
Points for
Minor
Weir/sluice 300 180 50
Hydromorphology and geomorphology guidelines
Hydromorphological indices derivation
5
Produced by Riverdene Consultancy, 08/03/2016.
Based on Environment Agency guidelines for calculating HMS scores, 2003.
www.riverdeneconsultancy.com; www.riverhabitatsurvey.org
For 1994, 1995 & 1996 survey formats all weirs score 300 points each.
To derive the HMS Weirs/Dams/Sluices sub-score, total all the points
scored for impoundment and weirs and sluices.
HMS: Bridges sub-score
S) Sweep-up Artificial Features – Bridges
Score points as per the table below for each bridge recorded in Artificial
Features.
Artificial
Structure
Points for
Major
Points for
Intermediate
Points for
Minor
Bridge 250 200 100
For 1994, 1995 & 1996 survey formats, footbridges are considered as minor
and roadbridges are considered major.
To derive the HMS Bridges sub-score, total all the points scored for
bridges.
HMS: Poaching sub-score
T) Spot-check Bank Modification – Poaching (PC or PC(B))
Score 10 points for each left bank spot-check which has PC or PC(B)
recorded for bank modification.
Repeat for the right bank and add together the scores for both banks.
U) Sweep-up Bank Profiles – Poached
If there is no PC or PC(B) bank modification recorded for spot-checks on the
left bank, score points for poached recorded for the left bank in sweep-up. If
poached is present score 10 points, or if it is extensive score 40 points.
Repeat for the right bank and add together the scores for both banks.
To derive the HMS Poaching sub-score, total up the scores from rules T-
U.
HMS: Fords sub-score
V) Sweep-up Artificial Features – Fords
Score points as per the table below for each ford recorded in Artificial
Features.
Hydromorphology and geomorphology guidelines
Hydromorphological indices derivation
6
Produced by Riverdene Consultancy, 08/03/2016.
Based on Environment Agency guidelines for calculating HMS scores, 2003.
www.riverdeneconsultancy.com; www.riverhabitatsurvey.org
Artificial
Structure
Points for
Major
Points for
Intermediate
Points for
Minor
Ford 200 120 40
For all survey formats prior to 2003, all fords were recorded as major.
To derive the HMS Fords sub-score, total all the points scored for fords.
HMS: Outfalls/Deflectors sub-score
W) Sweep-up Artificial Features – Outfalls
Score points as per the table below for each outfall recorded in Artificial
Features.
Artificial
Structure
Points for
Major
Points for
Intermediate
Points for
Minor
Outfall 100 50 25
For all survey formats prior to 2003, all outfalls score 25 points each.
X) Sweep-up Artificial Features – Deflectors
Score points as per the table below for each deflector recorded in Artificial
Features.
Artificial
Structure
Points for
Major
Points for
Intermediate
Points for
Minor
Deflector 150 100 50
For all survey formats prior to 2003, all deflectors score 50 points each.
To derive the HMS Outfalls/Deflectors sub-score, total up the scores
from rules W-X.
HMS final site score
To derive the total HMS score, add up all of the sub-scores above.
Use the table below to assign the Habitat Modification Class.
HMC HMC Description HMS Score
1 Pristine/semi-natural 0-16
2 Predominantly unmodified 17-199
3 Obviously modified 200-499
4 Significantly modified 500-1399
5 Severely modified 1400+