SARF 2014_Simon Maddrell & Benson Masila.pptx

0 downloads 0 Views 3MB Size Report
A recently converted culvert bridge in Makueni County, Kenya. The river crossings in Makueni County provide an Interes ng case study: • Recognising the poten ...

Title slide

1  

The importance of rural roads Physical, social and political isolation are core features of the poverty trap. The concepts of access, services, and participation are at the centre of the development debate. Without reliable roads infrastructure, rural communities struggle to access health and education services or take advantage of markets or employment opportunities. In 2011, one billion people, or 31% of the world's rural population, live isolated from markets and services – defined as living more than 2km from an "all season road" (one that is drivable at all times of the year and within, at most, six hours after rain) by the prevailing means of transport.* Well managed rural roads are a tool for social inclusion, economic development and environmental sustainability. *http://www.worldhighways.com/sections/world-reports/features/rural-roadsimportant-to-global-development/  

2  

In Niger, harvesting rainwater from roads is done as a matter of policy.* In Kenya it is done sporadically. Investment in roads much greater than that in agriculture *Source: Meta Meta  

3  

*Source: Kenya Rural Roads Authority, Makueni region   Swaziland  has  an  area  of  17,363km2    

4  

•  Drainage  is  key  to  roads  design.   •  This  is  especially  true  of  low  volume  rural  roads,  as  the  weather  causes  more   damage  than  the  traffic.   •  Given  the  financial  constraints  many  low-­‐income  countries  operate  under,  the   challenge  is  to  design  roads,  and  especially  river  crossings,  that  are  less  prone  to   flood  damage  and  require  less  rouIne  maintenance.  

5  

Current  designs  don’t  work:     Culverts  are  the  most  common  design  for  road  crossing  on  LVRRs.       However,  they  are  oPen  insufficient  to  cope  with  peak  floods  and  require  significant   investments  in  maintenance.       Because  in  rural  areas  of  developing  countries  maintenance  is  oPen  inadequate,   erosion  and  fractured  road  systems  result.     80% of roads maintenance costs are spent on emergency repair or reconstruction, often of culvert bridges which wash away.       Some  common  causes  of  damage  to  culvert  river  crossings:     1.  Poor  construcIon/headwall   2.  Culverts  get  blocked   3.  The  paved  secIon  does  not  accommodate  the  peak  flood  and  the  river  spreads   and  is  diverted    

6  

Erosion    

7  

Erosion  

8  

Widening  of  the  river  

9  

Blockages  

10  

A  washed  then  extended  culvert  bridge  

11  

Source:  InternaIonal  Labour  OrganisaIon  

12  

Makueni  County  example:     •       In  Makueni  County  there  are  7,640  km  of  unpaved  roads  with  483  culvert  or  driP   crossings  –  an  esImated  total  construcIon  cost  of  $225M.     •       The  InternaIonal  Labour  Office  (ILO)  recommends  a  maintenance  budget  of  6%  to   maintain  rural  road  crossings.     •       The  total  budget  for  Makueni  County  is  only  $1.1M  –  meaning  that  a  significantly   more  sustainable  and  cost-­‐effecIve  road  infrastructure  is  required  to  maintain  access   to  services  and  markets  for  the  rural  poor.     •       This  is  exemplified  by  the  fact  that  out  of  the  483  culvert  or  driP  crossings  that  121   (25%)  are  currently  in  need  of  reconstrucIon  aPer  being  washed  away,  and  362   (75%)  are  in  need  of  rouIne  maintenance.     •       This  proves  the  inherent  weakness  of  the  design  in  terms  of  robustness  and  its   high  on-­‐going  maintenance  costs.  

13  

Why  sand  dams  are  an  improvement     Sand  dams  are  specifically  designed  to  cope  with  seasonal  river  flows,  while  at  the   same  Ime  storing  water  (rather  than  channelling  it  downstream)  –making  it  available   for  local  use.     They  address  four  key  barriers  to  food  security  in  drylands:     1.  The  lack  of  Ime  –  driven  by  the  need  to  collect  water  from  distant  sources.   2.  The  lack  of  water  for  small-­‐scale  irrigaIon  and  livestock.   3.  Poor  access  to  markets  and  services.   4.  The  diminished  investment  in  agriculture.     Building  san  dam  road  crossings  at  the  same  height  as  current  road  bridges  would   cost  about  the  same.     But  –  repairs  would  be  minimal  and  therefore  maintenance  costs  would  be  much   lower  –  so  the  lifeIme  costs  would  be  much  less.     Building  the  san  dam  road  crossing  higher  would  have  about  the  same  lifeIme  cost   as  current  road  bridges  –  but  with  the  significant  advantages  of  supplying  year  round    

14  

A  sand  dam  is  a  reinforced  rubble  cement  wall  built  across  a  seasonal  sandy  river.      

15  

•  During  the  rainy  season,  a  seasonal  river  forms  that  carries  soil  downstream.     •  The  heavier  sand  accumulates  behind  the  dam,  while  the  lighter  silt  is  carried   downstream.      

16  

•  Within  one  to  four  rainy  seasons  the  dam  completely  fills  with  sand.  But,  up  to   40%  of  the  volume  behind  the  dam  is  water,  trapped  in  the  pores  between  sand   parIcles.   •  Sand  dams  are  the  most  cost-­‐effecIve  method  of  rainwater  harvesIng  in  drylands.   A  mature  sand  dam  stores  up  to  40  million  litres  of  water  -­‐  recharging   groundwater  and  providing  people  with  a  safe,  reliable  and  local  source  of  water   all  year  round.     •  They  have  virtually  zero  operaIon  and  maintenance  costs  and  last  for  over  50   years.  They  are  widely  suited  to  dryland  regions  of  the  world.    

17  

•  A  typical  infiltraIon  gallery,  shallow  well  and  hand  pump.   •  On  large  dams  a  shallow  well  can  serve  3,000  people.   •  Water  can  also  be  abstracted  from  scoop  holes  or  from  pipes  or  taps  in  the  dam   wall.  

18  

More  reliable  rural  roads  infrastructure  and  therefore  improved  access  to  markets   and  services.     While  the  iniIal  investment  is  similar  to  that  of  culverts,    the  long  term  costs  is   significantly  lower  due  to  low  maintenance  requirements.  Sand  dams  last  up  over  50   years.     The  Kenya  Rural  Roads  Authority  (KERRA)  in  Makueni  County  has  built  50  sand  dam   road  crossings  since  2007.      

19  

The  cross  secIon  of  a  sand  dam  road  crossing  

20  

A  suspended  sand  dam  road  crossing,  innovated  by  Benson  Masila  in  Makueni   County,  Kenya.  

21  

This  sand  dam  road  bridge  is  near  Kako  village  in  Makueni  County,  Kenya.       It  is  80m  wide  and  3m  above  the  bedrock.  This  dam  was  built  solely  to  support  the   rural  roads  infrastructure.  However,  following  construcIon  the  increased  water   storage  capacity  was  recognized  and  an  infiltraIon  gallery  installed  to  create  a   municipal  water  supply  that  feeds  seven  village  kiosks.       Water  is  pumped  at  a  rate  of  50m3/day.  Independent  evaluaIons  found  that  the   significantly  improved  water  access  impacts  the  ability  of  smallholder  family  farmers   to  invest  in  agriculture,  as  well  as  improving  health  and  educaIon.     A  similar  sand  dam  road  bridge  (Thwake)  in  Makueni  County,  Kenya  supports  three   nearby  farms  to  produce  Maize,  Bananas  and  Mangoes  -­‐    even  out  of  season.         These  examples,  and  the  48  other  sand  dam  road  crossings  built  in  Makueni  County,   demonstrate  the  technical  feasibility  of  the  innovaIon.  However,  they  were  not   planned  and  built  for  the  purpose  of  water  abstracIon,  and  so  infiltraIon  galleries   and  abstracIon  methods  were  not  integrated  in  the  design.  They  were  also  built   more  like  sand  dam  driPs  (with  a  maximum  height  of  1.5m  above  the  river  bed).    

22  

A  recently  converted  culvert  bridge  in  Makueni  County,  Kenya.       The  river  crossings  in  Makueni  County  provide  an  InteresIng  case  study:     •  Recognising  the  potenIal  to  capture  water  for  people  and  agriculture,   there  has  been  a  conscious  deviaIon  from  building  culverts  to  building   driPs.   •  These  driPs  are  essenIally  acIng  as  sand  dams  –  providing  reliable  access   to  markets  and  services  for  isolated  communiIes,  at  reduced  maintenance   cost  to  the  managing  authority,  as  well  as  improving  access  to  water  for   people  and  agriculture.  

23  

24  

(i) 

Asset investment:

Ø  Culvert bridge cost vs. sand dam cost broadly equal. Ø  Opportunity to build higher bridges to maximise other benefits. (ii) Maintenance or repair costs: Our experience of 415 dams shown a 2% failure rate (requiring significant repair). Ø  Only 5% sand dams require maintenance and last at least 25 years. Ø  Sand dam road crossings would be higher maintenance but 10-20% of culverts.   (iii) Environmental and livelihood benefits:   Ø  Year round water supply averaging 20M litres (20,000m3) yield per year. Supporting people, livestock and irrigation. Ø  Reduced soil erosion and land degradation. Ø  Natural regeneration of vegetation. Ø  Time for farmers to invest in SLM (averaging 2.5 to 5.5 hours a day).   Ø 

25  

There  are  many  opportuniIes  for  uIlising  roads  to  harvest  water  and  prevent  land   degradaIon  –  in  parIcular  through  improved  road  crossings.     In  semi-­‐arid  drylands,  sand  dam  road  crossings  are  a  viable  and  cost-­‐effecIve   approach  for  addressing  water  insecurity  and  land  degradaIon.     Key  challenges  to  take  this  forward  include:     1.  CollaboraIon  between  sectors  (roads,  water  and  agriculture)  and  government   ministries.     OpportuniIes  are:     1.  Climate  proofing  rural  roads  infrastructure,  enhancing  aquifer  recharge  and   creaIng  dry  season  water  storage  builds  community  based  resilience  to  climate   change  and  are  effecIve  disaster  risk  reducIon  strategies  in  dryland  regions   prone  to  flood,  drought  and  severe  weather  events.    

26  

Final  slide  

27  
Nachhilfe | AMC Security download full | Curver prullenbakken