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5.0. WATER  QUANTITY  

         

AIMS: Increase  water  attenuation,  slow  run-­‐off,  improve  resilience  to  low  flows  and  increase   aquifer  re-­‐charge.    

5.1. What  are  the  issues?     Abstraction  and  low  flows   The  Test  &  Itchen  supply  much  of  Hampshire’s  public  water  needs,  including  a  large  proportion  of   the   Isle   of   Wight’s   requirements.   There   are   a   number   of   significant   surface   water   abstractions   as   well   as   groundwater   abstractions   from   the   chalk.   The   catchment   also   supports   a   large   number   of   commercial  fish  farms  and  watercress  growers  who  are  dependant  on  reliable  and  abundant  water   supplies.   Although   the   majority   of   abstraction   is   non-­‐consumptive   and   returns   water   locally   the   overall   impact   of   abstraction   puts   pressure   on   flows   and   can   potentially   lead   to   rivers   not   having   enough  water  to  support  a  healthy  ecosystems.   Flooding   With   changes   in   climate   affecting   rainfall   patterns   and   larger   areas   of   land   being   covered   for   development   and   thus   loosing   their   natural   ability   to   drain   water,   flooding   has   become   an   increasingly  apparent  issue  in  recent  years.  Groundwater  flooding  is  a  particular  problem  for  many   parts  of  the  catchment  and  following  heavy  rainfall  events  it  is  often  exacerbated  by  surface  water   flooding.      5.2.  Where  are  the  pressures?   There   are   a   number   of   locations   in   the   catchment   landscape   where   a   reduced   ability   to   maintain   base   flows   during   periods   of   low   rainfall   will   exert   a   negative   impact.   Water   quantity   has   a   direct   bearing   on   the   effluent   volumes   that   can   be   discharged   from   point   sources   of   pollution,   where   sufficient  flows  are  needed  to  ensure  the  effluent  is  diluted  appropriately  downstream.  Abstraction   licenses   for   drinking   water   supplies   also   depend   on   maintenance   of   sufficient   base   flows   and   similarly,  rivers  and  streams  require  sufficient  flow  during  dry  periods  to  remain  in  good  ecological   condition.   At   the   other   end   of   the   spectrum,   there   are   many   locations   where   the   unregulated   release   of   water   from   the   land   and   into   our   rivers   can   pose   a   threat   to   people   living   in   the   catchment   and   cause   community   disruption.   In   addition   to   residential   properties   there   may   also   be   locations   where   important   buildings   and   other   critical   infrastructure   are   at   risk   of   flooding.   The   properties   and   infrastructure   at   risk   of   being   flooded   are   shown   in   Figure   26   which   cross-­‐references   settlements   against  flood  risk  zones  and  surface  water  flood  risk  areas  to  identify  where  there  is  a  risk  of  flooding   and  damage  to  property  or  threatening  human  health  and  safety.      

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Profile for TICP

TICP Catchment Action Plan (low res)  

TICP Catchment Action Plan (low res)  

Profile for ticp
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