LIFE 02 NAT/UK/8544 New Forest Wetland Management Plan
Tab
le 3
-4: G
eolo
gic
al C
har
acte
rist
ics
Peri
od
Qu
ater
nar
y
Tert
iary
Epo
ch*
Rec
ent
25,0
00 y
ear
BP
Plei
sto
cen
e1
mill
ion
year
s B
P
Olio
gen
e40
mill
ion
year
BP
Eoce
ne
60 m
illio
nye
ars
Dri
ft &
So
lidG
eolo
gy
Shin
gle
Allu
viu
m
Peat
Val
ley
Gra
vel
Bri
ckea
rth
Plat
eau
Gra
vel
Hea
do
n B
eds
Bar
ton
San
ds
Bar
ton
Cla
y
Bra
ckle
sham
B
eds
Bag
sho
t B
eds
Key
Ch
arac
teri
stic
s
Fou
nd
alo
ng
co
asta
l fri
ng
es o
fLy
min
gto
n c
atch
men
t in
clu
din
g H
urs
t Fo
un
d l
inin
g m
od
ern
day
riv
erfl
oo
dp
lain
san
d v
alle
ys
Flin
ty in
ch
arac
ter
wit
h a
co
mp
lex
mix
of
gra
vel,
san
d a
nd
cla
y.U
nst
rati
fied
mix
ture
of
fin
e-g
rain
edq
uar
tz s
and
or
flin
t. L
aid
do
wn
as
flo
od
dep
osi
ts a
lon
g y
ou
ng
er r
iver
terr
aces
an
d m
ay h
ave
a p
arti
ally
aeo
lian
(w
ind
blo
wn
) o
rig
inC
om
po
sed
alm
ost
exc
lusi
vely
of
flin
tw
ith
so
me
peb
ble
s o
f sa
rsen
(si
licif
ied
san
dst
on
e) la
id d
ow
n o
n o
ld r
iver
terr
aces
Hea
ldo
n f
orm
atio
ns
dep
osi
ted
infr
esh
wat
er la
go
on
co
mp
risi
ng
sh
elly
clay
s, s
ilts
and
san
ds
Lyn
dh
urs
t m
emb
er d
epo
site
d in
bra
ckis
h o
r m
arin
e co
nd
itio
ns
and
com
pri
ses
mo
re s
and
y se
dim
ents
.U
pp
er H
ead
on
fo
rmat
ion
is s
hel
lysa
nd
. Sa
nd
s o
f m
arin
e o
rig
inC
lay
dep
osi
t la
id d
ow
n in
dee
p w
ater
.M
arks
sta
rt o
f B
arto
n g
rou
pFo
ssil
rich
dep
osi
ts la
id d
ow
n in
war
m,
mar
ine
and
fre
shw
ater
co
nd
itio
ns.
San
dy
bed
s o
f co
arse
, po
rou
s m
ater
ial
Avo
nLy
min
gto
nB
eau
lieu
Bar
tley
Cad
nam
Ham
psh
ire
Wat
erA
von
Tr
ibu
tari
es✓
✓✓
✓✓
✓✓
✓✓
✓
✓✓
✓✓
✓ ✓✓
✓✓
✓✓
✓✓
✓
✓✓
✓✓
✓
✓✓
✓✓
✓✓
✓
✓✓
3.7
LIFE 02 NAT/UK/8544 New Forest Wetland Management Plan
3.8
Tab
le 3
-5:S
ites
of
Geo
log
ical
or
Phys
iog
rap
hic
Inte
rest
Riv
er B
asin
Ham
psh
ire
Avo
n
Trib
uta
ries
Ham
psh
ire
Avo
n
Trib
uta
ries
Ham
psh
ire
Avo
n
Trib
uta
ries
Cad
nam
Lym
ing
ton
Lym
ing
ton
Lym
ing
ton
Site
of
Spec
ial
Geo
log
ical
or
Phys
iog
rap
hic
Inte
rest
Stu
dle
y W
oo
d
SU 2
27 1
58
Cra
nes
Mo
or
SU 2
47 0
69
Wo
od
Gre
en
Gra
vel P
it
SU 1
72 1
70
Shep
her
d’s
Gu
tter
SU 2
63 1
53
Park
Hill
Incl
osu
re
SU 3
16 0
59
Mar
k A
sh W
oo
d
SU 2
47 0
69
Hig
hla
nd
Wat
er
SU 2
72 0
73
SU 2
39 1
23
Key
Fea
ture
s o
f In
tere
st
Pro
lific
Ter
tiar
y lo
calit
y ex
po
sin
g t
he
on
ly c
om
ple
te e
xpo
sure
of
the
silt
y H
un
tin
gb
rid
ge
Form
atio
n o
f th
e B
rack
lesh
am
Gro
up
, rem
arka
ble
fo
r it
s m
ollu
scan
fau
na
and
th
e n
um
ber
of
spec
ies
limit
ed t
o t
he
form
atio
n.
Nu
mer
ou
s co
rals
, sca
ph
od
a,
biv
alve
s an
d g
astr
op
od
s m
ake
it a
n o
uts
tan
din
g E
oce
ne
loca
lity
of
gre
at in
tere
st in
stu
die
s o
f Te
rtia
ry s
trat
igra
ph
y an
d
pal
aeo
nto
log
y.
A la
rge
mir
e co
mp
lex
set
in a
sh
allo
w b
asin
co
nta
inin
g s
ign
ific
ant
pea
t ac
cum
ula
tio
ns
dat
ing
bac
k to
Dev
ensi
an la
te g
laci
al
tim
es.
A k
ey r
efer
ence
sit
e fo
r p
alyn
olo
gic
al a
nd
pal
aeo
eco
log
ical
stu
die
s in
so
uth
ern
En
gla
nd
. Als
o u
nu
sual
fo
r th
e
app
aren
tly
rap
id a
ccu
mu
lati
on
s o
f p
eat
in t
he
Bo
real
Per
iod
an
d is
th
us
imp
ort
ant
for
the
stu
dy
of
earl
y im
mig
rati
on
an
d
exp
ansi
on
of
flo
ra in
po
st-g
laci
al t
imes
.
The
pit
exp
ose
s g
rave
l, d
epo
site
d b
y th
e R
iver
Avo
n, r
ich
in p
alae
olit
hic
art
efac
ts.
Pala
eolit
hic
ass
emb
lag
es p
rovi
de
maj
or
evid
ence
fo
r th
e su
bd
ivis
ion
of
the
terr
ace
seq
uen
ce in
th
e So
len
t B
asin
, wh
ere
they
are
par
ticu
larl
y im
po
rtan
t o
win
g t
o
a d
eart
h o
f p
alae
on
tolg
ical
sit
es.
The
site
als
o h
as s
ign
ific
ant
po
ten
tial
to
elu
cid
ate
the
com
ple
x h
isto
ry o
f th
e R
iver
Avo
n
gra
vels
an
d t
he
evo
luti
on
of
The
Sole
nt
Riv
er.
Loca
lity
ren
ow
ned
fo
r it
s ri
ch T
erti
ary
mar
ine
fau
nas
, kn
ow
n t
o g
eolo
gis
ts s
ince
th
e m
id 1
9th
C. S
ho
ws
a se
ctio
n t
hro
ug
h
the
Sels
ey F
orm
atio
n o
f th
e B
rack
lesh
am G
rou
p, o
f M
idd
le E
oce
ne
age,
an
d in
clu
des
sev
eral
mo
llusc
-ric
h h
ori
zon
s an
d
on
e ki
nd
of
Nu
mm
ulit
es c
orr
elat
able
wit
h t
he
Isle
of
Wig
ht
and
Bra
ckle
sham
sec
tio
ns.
A k
ey lo
calit
y fo
r sh
ow
ing
co
rrel
atio
ns
bet
wee
n c
lass
ic E
oce
ne
loca
litie
s o
f th
e H
amp
shir
e B
asin
, an
d f
or
its
pro
lific
mo
llusc
an f
aun
as.
On
ly e
xpo
sure
in
En
gla
nd
ou
tsid
e th
e Is
le o
f W
igh
t to
sh
ow
up
per
mid
dle
Hea
do
n B
eds.
Th
e o
ccu
rren
ce o
f C
erit
hid
ea
ven
tric
osa
an
d o
ther
mo
llusc
a in
th
e H
ead
on
cla
ys a
llow
s co
rrel
atio
n w
ith
th
e ty
pe
of
sect
ion
s o
f th
e Is
le o
f W
igh
t.
The
fau
na
of
wel
l-p
rese
rved
sh
ells
an
d f
ish
rem
ain
s m
akes
th
is o
ne
of
the
rich
est
Tert
iary
fau
nal
loca
litie
s o
n t
he
mai
nla
nd
.
Als
o a
n im
po
rtan
t si
te f
or
its
pal
aeo
nto
log
y an
d f
or
corr
elat
ion
s w
ith
in t
he
Tert
iary
Ham
psh
ire
Bas
in.
A v
alle
y m
ire
com
ple
x o
f co
nsi
der
able
imp
ort
ance
fo
r p
alyn
olo
gic
al a
nd
pal
aeo
eco
log
ical
stu
die
s. P
eat
gro
wth
at
the
site
dat
es f
rom
th
e ea
rly
par
t o
f th
e D
even
sian
late
-gla
cial
to
th
e su
b-A
tlan
tic
Peri
od
. Als
o c
on
tain
s o
lder
po
st-g
laci
al p
eats
in
the
New
Fo
rest
an
d is
exc
epti
on
al f
or
hig
h a
ccu
mu
lati
on
rat
es d
uri
ng
late
-gla
cial
tim
es.
Mac
rofo
ssil
and
po
llen
an
alys
es
hav
e yi
eld
ed s
om
e o
f ea
rly
Bri
tish
po
st-g
laci
al r
eco
rds
of
bry
op
hyt
es. S
ite
also
imp
ort
ant
for
trac
ing
ear
ly p
ost
-gla
cial
imm
igra
tio
n a
nd
exp
ansi
on
of
flo
ra in
po
st-g
laci
al t
imes
.
Un
iqu
e ar
ea d
emo
nst
rati
ng
a c
om
bin
atio
n o
f lo
w m
anag
emen
t an
d lo
w h
um
an im
pac
t o
n f
luvi
al p
roce
sses
. Th
e h
ydro
log
ical
and
flu
vial
ch
arac
teri
stic
s o
f H
igh
lan
d W
ater
are
typ
ical
of
tho
se t
hat
fo
rmer
ly o
ccu
rred
in m
uch
of
sou
ther
n E
ng
lan
d.
The
site
pro
vid
es v
alu
able
op
po
rtu
nit
y to
stu
dy
bo
th t
he
role
an
d in
flu
ence
of
veg
etat
ion
in h
ydro
log
ical
an
d f
luvi
al
pro
cess
es a
s w
ell a
s th
e ef
fect
of
deb
ris
dam
s.
LIFE 02 NAT/UK/8544 New Forest Wetland Management Plan
3.3.2 Geomorphology
The New Forest can be viewed as a plateau dipping gently from north to south. The steeperwestern escarpment is flanked by the broad Avon Valley while the lower valley of the RiverTest and Southampton Water provide a boundary to the to east. The gently sloping southernflank is bounded by the Solent. The smaller tributaries and streams draining the Forest haveeroded down through the plateau to create gently sloping valleys between flat-topped hillsgiving rise to an undulating topography (Figure 5). The highest point in the Forest isaround 125m OD to the north of the Forest along the watershed between basin of theCadnam and Hampshire Avon Tributaries.
The main Forest watershed runs approximately north to south and separates the HampshireAvon tributaries from the other five main river basins. The Blackwater and Cadnam Riversdrain east into the lower end of the River Test and Southampton Water respectively. TheLymington, Avon Water and Beaulieu all drain in a southeasterly direction to the Solent.
The Hampshire Avon tributaries have cut deeply incised U-shaped valleys, which are separatedby long, narrow, gravel-capped ridges. Their short, steep profiles have evolved in responseto recurrent down cutting by the River Avon whose course has remained reasonably stablethrough recent geological history.
In contrast, the drainage networks east of the main watershed seem to have evolved inresponse to a retreating river or shoreline. The Cadnam, Bartley and Lymington rivers allhave their sources close to the watershed in the north east of the forest around the 90m OD.The Beaulieu rivers rises at a lower level (46m OD) toward the middle of the Forest atLyndhurst while the Avon Water rises to the south of Burley (50m OD).
3.3.3 Soils
The soils of the New Forest have been mapped by the Soil Survey of England and Wales at1:250,000 scale and are described in Bulletin No. 15 Soils and their use in South-EastEngland. Ten different soil associations can be found across the river basins as summarisedin Table 3-6. More detailed soil surveys have been carried out for the Inclosures (Pyatt 1964)as shown in Figure 6.
The majority of soils are seasonally waterlogged as indicated by the soil wetness class.However, drainage in many parts of the Forest has improved the drainage characteristics.The humose, waterlogged surfaces of the many soils are highly susceptible to poaching andstructural damage during the winter months.
3.9
Tab
le 3
-6:S
oil
Ch
arac
teri
stic
s
(So
urc
e: J
arvi
s et
al 1
984)
* F0
r d
escr
ipti
on
of
Soil
Wet
nes
Cla
ss r
efer
to
Ap
pen
dix
K
Soil
Ass
oci
atio
n
Wic
kam
3 (
711g
)
(42m
OD
)
Bo
lder
wo
od
(64
3c)
(On
rid
ges
ab
ove
43m
OD
)
Ho
liday
s H
ill (
643a
)
25m
OD
Shir
rell
Hea
th 1
(631
c) 9
5m O
D
Sou
tham
pto
n (
634)
47m
OD
Bu
rsle
do
n (
572j
)
40m
OD
Hu
rst
(841
b)
20m
OD
Shab
bin
gto
n
(841
d)
Isle
ham
1 (
861a
)
(121
m O
D)
Effo
rd (
571s
)
Ch
arac
teri
stic
s
Typi
cal s
tagn
ogle
y so
il. F
ine
loam
y or
fin
e si
lty
drif
t ov
er c
laye
y pa
ssin
g to
slo
wly
per
me-
able
clay
or
mu
dst
on
e. D
uri
ng
hea
vy w
inte
r ra
in e
xces
s w
ater
is d
isp
ose
d o
f b
y la
tera
l
flo
w. I
n N
ew F
ore
st s
oils
oft
en h
ave
thin
hu
mo
se s
urf
ace
ho
rizo
ns
and
po
ach
eas
ily
Wat
erlo
gg
ed f
or
lon
g p
erio
ds
du
rin
g w
inte
r b
ut
mo
der
atel
y d
rou
gh
ty d
uri
ng
su
mm
er
Ver
y ac
id S
tag
no
gle
y-p
od
zols
. O
ccu
r w
her
e ri
ver
terr
ace
dri
ft a
nd
Pla
teau
Gra
vel
cove
r Te
rtia
ry c
lays
, lo
ams
and
san
ds.
Co
arse
loam
y, f
linty
, ho
rizo
ns
ove
r cl
ayey
sto
nel
ess
dri
ft. S
ub
soil
pan
s an
d o
ther
slo
wly
per
mea
ble
laye
rs im
ped
e ve
rtic
al w
ater
mo
ve-
men
t ca
usi
ng
sea
son
al w
ater
log
gin
g. E
xces
s w
inte
r ra
in is
ab
sorb
ed s
low
ly a
nd
po
nd
s
on
su
rfac
e b
ut
ther
e is
litt
le r
un
-off
. Su
rfac
es a
re w
et a
nd
mu
dd
y in
win
ter
and
hu
mo
se o
r p
eaty
to
pso
ils a
re s
lipp
ery
and
vu
lner
able
to
ero
sio
n.
Stag
no
gle
y-p
od
zols
wit
h p
erm
eab
le s
and
y su
rfac
e h
ori
zon
s p
assi
ng
to
loam
y an
d
slo
wly
per
mea
ble
laye
rs b
elo
w. W
et a
t th
e su
rfac
e fo
r lo
ng
per
iod
s in
win
ter
wit
h
thin
hu
mo
se o
r p
eaty
su
rfac
e h
ori
zon
s d
evel
op
ing
un
der
hea
thla
nd
. At
risk
of
po
ach
-
ing
& c
om
pac
tio
n in
win
ter.
Ver
y ac
id, s
and
y-h
um
o-f
erri
c p
od
zols
. Per
mea
ble
an
d w
ell d
rain
ed a
nd
dro
ug
hty
in
sum
mer
Pala
o-a
rgill
ic p
od
zol w
ith
ver
y st
on
ey, v
ery
acid
, san
dy
soils
Stag
no
gle
yic
arg
illic
bro
wn
ear
ths
wit
h f
ine
loam
y h
ori
zon
s p
assi
ng
to
cla
y an
d s
and
.
Seas
on
ally
wat
erlo
gg
ed
Typ
ical
arg
illic
gle
y so
ils w
ith
co
arse
loam
y h
ori
zon
s o
ver
no
n-c
alca
reo
us
gra
velly
dep
osi
ts, d
evel
op
ed in
riv
er t
erra
ce g
rave
ls.
Wat
erlo
gg
ed b
y g
rou
nd
wat
er f
or
mu
ch
of
the
win
ter
wit
h s
ho
rt p
erio
ds
of
win
ter
flo
od
ing
. C
an b
e d
rou
gh
ty in
su
mm
er.
Arg
illic
gle
ys d
evel
op
ed in
loam
y d
rift
wh
ich
var
y in
sto
nin
ess
and
co
mm
on
ly r
est
on
bed
ded
san
dy
or
gra
velly
mat
eria
l at
dep
th. F
ou
nd
in r
iver
ter
race
dri
ft. T
end
to
be
affe
cted
by
hig
h w
ater
leve
ls a
nd
are
sea
son
ally
wat
erlo
gg
ed.
Typ
ical
hu
mic
-san
dy
gle
y so
ils d
evel
op
ed in
per
mea
ble
, san
dy,
so
met
imes
sto
ney
dri
ft
fou
nd
in v
alle
y b
ott
om
s an
d d
epre
ssio
ns.
Pe
ren
nia
lly w
ater
log
ged
an
d s
up
po
rt m
uch
bo
gg
y ve
get
atio
n.
Arg
illic
bro
wn
ear
ths
wit
h w
ell d
rain
ed b
row
n f
ine
loam
y so
ils a
sso
ciat
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3.3.4 Geological, Geomorphological & Soil Issues
a) Susceptibility of the soil to damage
In certain areas of the Forest, the waterlogged nature of some of the soils makes themsusceptible to structural damage (compaction and erosion) when working with machinery.It is often not feasible to work with heavy machinery on soils during the late autumn, winterand early spring months (unless the ground is likely to be frozen for an appropriate lengthof time) which significantly limits the time period available to carry out certain restorationworks. Even in summer, heavy rainfall events have resulted in machinery standing idle toprevent undue damage to the soil structure which can add to the final project costs.
These limitations require careful planning of the timing of the works and an appreciationthat periods of poor weather can result in increased project costs.
Further Reading
Institute of Geological Sciences. Lymington Sheet 330 1:50 000 SeriesBournemouth Sheet 329Ringwood Sheet 314
Jarvis M.G., Allen R.H., Fordham S.J., Hazelden J., Moffat A.J. & Sturdy R.G. (1984).Soils and their Use in South East England, Harpenden 1984
Melville R.V. & Freshney E.C. (1982) British Regional Geology – The HampshireBasin and adjoining areas. Institute of Geological Sciences
Soil Survey of England & Wales, Soils of England and Wales - Sheet 6 South EastEngland Scale 1:250,000
LIFE 02 NAT/UK/8544 New Forest Wetland Management Plan
3.4 HYDROLOGY & DRAINAGE
3.4.1 Introduction
The six main river basins are drained by a complex network of rivers, streams and drains asshown in Figure 7 and Table 3-7. Although many have different local names, for the purposesof this Plan they are referred to by the names cited on the New Forest 1:25,000 OrdnanceSurvey map.
A significant amount of data exists for the Lymington Catchment as this has been studiedfor many years by Southampton University and has been subject to specialist studies for theLife 3 Project . However, the majority of watercourses within the New Forest are not classifiedas Main River and data is limited for many of the streams. The locations of Monitoring andGauging Stations are also shown in Figure 7.
Since the 1870’s, well over half the total length of main streams and first order tributarieshave been modified to some extent by drainage schemes to improve areas for forestry orgrazing. For example, 78% of surveyed channel in the Black Water and 44% along theHighland Water have been modified in the past. Even so, the rivers and stream still representan excellent example of a relatively undisturbed lowland river system.
3.4.2 The River Basins
Lymington River Basin
The Lymington River Basin is the largest basin (127km2) in the New Forest and comprises adense network of steams and tributaries draining a highly wooded catchment. The highesttributaries (Highland Water & Bratley Water) rise at 100- 110m OD around Ocknell Inclosurejust to the north of the A31. Highland Water is joined by Bagshot Gutter at SU263 084before continuing south east via Millyford Bridge and the A35 (SU 276066) to join the mainRiver Lymington at Bolderford Bridge (SU291041)
Bratley Water rises at 98m OD from spring lines around the valley occupied by SluftersInclosure, to the north of the A31. It flows south through North Oakley Inclosure where itbecomes the Blackensford Brook (SU237066) and on through Anderwood Inclosure to meetthe Black Water just upstream from Dog Kennel Bridge (SU 241052).
The small network of tributaries feeding the Warwickslade Cutting rise around 75-55mODin the area of Mark Ash Wood, Wooson’s Hill Inclosure and Holidays Hill Inclosure to thenorth of Bolderwood Arboretum Ornamental Drive. The Warwickslade Cutting joinsHighland Water at SU282051.
The Black Water rises around 68m OD to the outside edge of South Oakley Inclosure andflows south-east via Dog Kennel Bridge and Dames Slough Inclosure to pass under the A35at Blackwater Bridge (SU244047) and Rhinefield Ornamental Drive before flowing througha long, straightened reach known as Fletchers Water. Fletchers Water joins Highland Waterat SU 287044
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Mill Lawn Brook rises at 90m OD from Ridley Bottom just to the south of the A31. It is fedby additional tributaries rising from Harvest Slade Bottom before flowing through Burleyand then eastward via Markway Bridge (SU 250039) and Puttles Bridge (SU278 028) whereit becomes known as Ober Water. The Silver Stream draining Redhill Bog also enters OberWater at Puttles Bridge. The Ober Water continues to flow eastwards to the north ofBrockenhurst where it joins the Lymington River at Bolderford Bridge (SU 291 041). TheWeir Stream rises from White Moor at SU275019 and flows eastwards through Brockenhurstbefore entering the Lymington River at SU 304031.
From Bolderford Bridge the Lymington River is classified as main river . It continues to meandersouthwards through woods and agricultural land before passing to the east side ofLymington where it enters the sea. The normal tidal limit extends to Walhampton(SZ329963). Tidal flaps control the flow at its outfall.
Beaulieu River
The Beaulieu River has its source at Pikeshill on the north side of Lyndhurst rising at 55mOD. It flows south-eastwards draining predominately open heath and woodland exceptwhere it flows through the agricultural land holdings of Decoy Pond Farm and Ipley Manor.The river leaves the perambulation at North Gate (SU384047) from where it meanderssouthwards through fields and woodland before reaching its tidal limits at Beaulieu (SU 387 024)where tidal flaps control the flow. It then follows a long tidal estuary for approximately 8km toreach the sea.
Shepton Water rises at 14mOD at Penny Moor and flows eastwards via Shepton Bridge tojoin the main river at North Lane (SU 384044). Worts Gutter rises at 41m OD at the edge ofStockley Inclosure and flows eastward where it becomes the much straightened PenerleyWater. The Shepton Water and Penerley Water converge at SU 375046.
A number of shorter un-named tributaries also join the Beaulieu throughout its length.
Bartley Water
Bartley Water is one of the smallest river basins. It is fed by two main tributaries – The MillSteam and Fleet Water. The Millstream rises at 99m OD in Ringwood Ford Bottom anddrains south-eastwards via Leominstead Pond before turning north east to converge withBartley Water at SU305105. Fleet Water rises near Stoney Cross at around 109M OD andflows south-eastwards through wooded and agricultural areas before passing through MillPond and converging with the Mill Steam at SU 298102.
Outside the New Forest perambulation the Bartley Water is joined by a series of un-namedtributaries which drain a large part of its catchment south of the M27. This part of thecatchment is semi - rural interspersed with fields and settlements. The Bartley Water passesthrough the National Park Boundary to flow through Totton and enter the sea at the upperend of Southampton Waterr.
2 Main river classification mean that the Environment Agency has permissive powers to maintain the drainage capacity of the
channel and may also carry out works to limit the risk of flood from the river subject to technical, environmental and eco-
nomic feasibility and to the availability of funding.
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Cadnam
The Cadnam is another small river basin draining the north-eastern corner of the Forest.The Cadnam River rises to the north-east of Minstead around 55m OD and drains north andnorth eastwards via a dammed lake at Paultons Park and Ower Bridge (SU 326167) to jointhe River Blackwater at SU 338171.
Avon Water
The Avon Water basin is a small basin draining the south-west edge of the Forest. It riseswithin the southern confines of Burley and flows eastwards where it drains Holmsley Bog.The river continues its journey following the edge of Wootton Coppice Inclosure andBroadley Inclosure where it appears to have been significantly straightened before passingthe perambulation boundary at SZ 266984. From this point it flows through farmland viaSway Lakes and passes to the western side of Lymington before entering the Solent atKeyhaven. Tidal Flaps control its outfall to the sea.
Hampshire Avon Tributaries
The Hampshire Avon tributaries draining the Forest comprise a south-eastern sub-basin ofthe main Hampshire Avon. The tributaries comprise a series of small streams draining thewestern side of the Forest.
The most northerly stream is un-named but drains Deadman Bottom, Millerford Bottom andHale Purlieu.
Black Gutter rises around 108m OD. Where the stream bends southwards at Stone QuarryBottom it becomes the Ditchend Brook. It enters the River Avon at SU 148134.
The Latchmoor Brook rises at 115m OD at Picket Corner and flows south westwards throughIslands Thorns Inclosure, Amberwood Inclosure and Alderhill Inclosure before entering theOpen Forest. Around Ogdens the stream is known as the Huckles Brook where it flowsthrough farmland before entering the River Avon at SU149106
The Dockens Water rises around Fritham at 115m OD and flows south westwards throughthe Open Forest passing close to the northern edge of Holly Hatch Inclosure, BroomyInclosure and Linwood. After passing through the National Park Boundary it flows betweengravel pits and Blashford Lakes Nature Reserve before joining the River Avon at SU 144064.Hampshire Wildlife Trust has carried out some restoration work on the Dockens Waterwhere it flows through Blashford Lakes Nature Reserve.
Linford Brook rises at 94m OD and flows through Milkham Inclosure, Roe Inclosure,Greenford Bottom and Linford Bottom. After the perambulation boundary it passesthrough farmland and between gravel pits to the north of Ringwood before entering theRiver Avon at SU147058.
Smaller un-named tributaries drain Foulford Bottom and Cranesmoor to the south of theA31.
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Table 3-7: Principal Watercourses & Tributaries
Principal Length Named Guaging/MonitoringWatercourse (km) Tributaries Stations
Avon Water 18.5 ✓ (Flexford)
Lymington River 15.0 Bagshot Gutter
Warwickslade Cutting
Longbrook
Highland Water ✓ (Highland Water 1 & 2, Brockenhurst
Bratley Water
Blackensford Brook ✓ (Blackensford Brook, Blackwater 1)
Blackwater ✓ (Blackwater 2)
Fletchers Water ✓ (Blackwater 3)
Silver Stream
Mill Lawn Brook
Ober Water ✓ (Ober Water 1)
Etherise Gutter
Passford Water
Beaulieu River 26.0 Worts Gutter Hartford Bridge (ultrasonic)
Shepton Water Beaulieu Gates
Penerley Water Penerley Farm
Bartley Water 12 Millstream Ashurst Bridge
Fleet Water Totton (Tidal)
Cadham River -
Hampshire Avon Millersford Bottom
Black Gutter
Ditchend Brook
Latchmoor Brook
Huckles Brook
Dockens Water ✓ (Dockens Water)
Linford Brook
3.4.3 Channel & Floodplain geomorphology
Channel and floodplain form is a result of the processes of erosion, deposition and sediment transport over
time. The processes are naturally constrained by the geology and topography of the catchment and the way
in which the river responds to changes in climate and hydrology.
The natural form of many New Forest streams is a sinuous meandering channel of variable width and depth
that is laterally, relatively stable and contains pools, riffles and debris dams (except in flood). However, a num-
ber of streams throughout the Forest catchments have been modified by straightening, deepening and
removal of debris dams.
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The gradient of most of the streams is relatively low ranging from 1% - 0.6%. The majorityof channels are less than 5m wide with shallow flows. Channels wider than 7m and morethan 1m deep are limited to the lowest reaches of the Lymington & Beaulieu rivers. Thestreams with the steepest gradients are generally the Hampshire Avon tributaries whichdrain down from the highest areas of the Forest. Debris dams (discussed further in section3.4.7) can have a significant influence on channel width resulting in a greater variation inwidths than might be found on a non-forested stream.
Distinct areas of floodplain border the natural channels of the Forest streams and display atypical range of floodplain features such as
◆ ephemeral channels - (sinuous , linear scour features around 50cm wide and 5-50cm deep)◆ pools and hollows ◆ wake deposits - material deposited behind obstacles such as trees, tussocks and woody debris◆ abandoned channels – old river channels left one part of the floodplain when the river
moved laterally elsewhere◆ woody debris, trees & vegetation◆ shallow man made drainage channel lawns
Even where the channels have been over deepened and flooding is less frequent remnantfeatures can often be discerned.
3.4.4 Flow
The New Forest streams are fed by a combination of mires, bogs and surface water run offand through flow. Many of the streams typically have a mean daily flow rate of less than0.5 m3s-1 during dry weather (Langford, 1996) and flows can be considerable lower duringperiods of summer drought. Flows measured at the gauging stations on the Dockens Waterand the Lymington River are shown in Table 3-8 which give values for two contrastingstreams. Further flow data for the Hampshire Avon Tributaries is given in Appendix D. Therivers and streams are characterised by their flashy nature and can rise rapidly in responseto heavy or prolonged rainfall as shown in the hydrographs for the Lymington River andDockens Water (Figure 8 & 9). Flood peaks tend to pass through quickly and during out ofbank events the total magnitude of the flow cannot always be recorded.
During the summer months those streams fed by well developed seepage steps or mirescontinue to flow although at a much reduced level with only a few centimetres depth ofwater. However a number of streams, particularly the Hampshire Avon Tributaries areseasonally dry or reduced to a series of small pools separated by dry gravel bars or smalltrickles under the surface gravel (Plate I). Often only the deeper pools scoured out behinddebris dams or on the inside of meanders contain any water.
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Figure 8Sample Hydrograph of Gauged Daily Flows of Lymington River at Brockenhurst
Figure 9Sample Hydrograph of Gauged Daily Flows – Dockens Water at Moyles Court
Source: Centre of Ecology & Hydrology
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