Valley Water Level Management Plan (WLMP)
concept of Water Level Management Plans was introduced in 1991 by MAFF
(now Defra) and requires that plans should be produced for areas where
water levels are
Priority is given to Sites of Special Scientific Interest (SSSIs) with
the main requirement that "ideally, plans should be prepared for all
areas which have a conservation interest where the control of water
levels is important to the maintenance or rehabilitation of that
The Defra WLMP database
currently identifies 476 SSSIs as requiring Water Level Management Plans, one of which is the
Bourne Valley SSSI.
A pre-plan study was funded by Defra. To
produce the Bourne Valley WLMP the
Partnership's Project Officer worked with English Nature, local
botanist & consulting scientist Robin M Walls, and environmental quality consultant
Spreadsheet Model of the
Bourne Stream in the Bourne Valley SSSI
An in-depth study into the
sources and hydrology of the Bourne Stream has been carried
out for the WLMP by Robin Walls.
One output of that is a spreadsheet
model of the stream into which a flood pulse measured at the
Branksome Wood Road gauging weir (October 2003) was input to
test the dynamic response (excel
The results are discussed in
Appendix III of the WLMP.
The model is interactive; the
effect of adding new information or changing the value of a
feature (the width of a weir, for instance) can quickly and
easily be seen in the graphic representation(s).
The model is not fully tested, not all
assumptions are necessarily valid, and it is for
illustrative purposes only; neither BSP nor Robin Walls accepts
responsibility for its use outside of the Partnership.
Constructive comments and suggested improvements welcome!
In August 2005
Robert Aquilina carried out an ecological survey of the stream in the
Bourne Valley SSSI.
He found that the
biological assessment graded the Bourne Stream as High with a RIVPACS
band B (Good). The environmental quality has improved over the last ten
years compared with two previous surveys. Three Nationally Notable
species of beetle were found in the valley.