Desk study Resilient WASH systems in Drought prone areas CARE Nederland © CARE International In collaboration with The Netherlands Red Cross Techniques to improve the resilience of community WASH systems in drought- prone areas Commissioned by: CARE Nederland In collaboration with: The Netherlands Red Cross With support of: PSO October 2010 This study has been commissioned by CARE Nederland, to explore the current body of knowledge with regards to resilient techniques in water supply where water availability is limited – in particular drought-prone areas – and to prepare the technical basis for the evaluation of WASH projects developed in areas that are (potentially) exposed to drought Drafted by: Eric Fewster 2 Table of Contents: With support of:................................................................................................................................................................................................2 Impact of drought on WASH systems ...............................................................................................................................................................4 Definitions of drought ......................................................................................................................................................................................11 Drought & resilient WASH resources overview..............................................................................................................................................14 Drought actors overview..................................................................................................................................................................................22 Drought scenarios & links to other disasters.................................................................................................................................................26 Overview of drought-resilient WASH techniques: focus on water supply & non-motorized irrigation.......................................................27 Introduction ....................................................................................................................................................................................................27 Techniques to increase resilience and reduce vulnerability ............................................................................................................................29 Overall issues to consider..........................................................................................................................................................................29 Concrete techniques..................................................................................................................................................................................34 Saline water quality....................................................................................................................................................................................36 Mechanical water extraction - handpumps .................................................................................................................................................39 Surface water: Managed Aquifer Recharge (MAR) ....................................................................................................................................40 Infiltration ponds.......................................................................................................................................................................................45 Contour trenches .....................................................................................................................................................................................46 Bunds ......................................................................................................................................................................................................48 Gully plugs / check-dams .........................................................................................................................................................................50 Leaky dams .............................................................................................................................................................................................51 Controlled flooding / irrigation...................................................................................................................................................................52 Drip irrigation ...........................................................................................................................................................................................54 Well shafts & boreholes ...........................................................................................................................................................................56 Surface water: ground catchment & storage ..............................................................................................................................................58 Natural rock catchment & open water reservoir........................................................................................................................................62 Natural or artificial ground catchment & lined sub-surface tanks...............................................................................................................64 Natural ground catchment & open water reservoir....................................................................................................................................69 Surface water: roof catchment & storage ...................................................................................................................................................74 Surface water: fog collection & storage ......................................................................................................................................................78 Surface water: dew collection & storage ....................................................................................................................................................81 Shallow groundwater: hand-dug, jetted & driven wells ...............................................................................................................................83 Traditional hand-dug wells .......................................................................................................................................................................87 Riverbed hand-dug wells..........................................................................................................................................................................89 Riverbed infiltration galleries ....................................................................................................................................................................90 Riverbed jetted & driven wells ..................................................................................................................................................................91 Infiltration wells ........................................................................................................................................................................................93 Shallow groundwater: groundwater dams ..................................................................................................................................................94 Shallow groundwater: spring protections..................................................................................................................................................101 Shallow to deep groundwater: boreholes .................................................................................................................................................103 Water trucking & water vendors ...............................................................................................................................................................107 Criteria of applicability of drought-resilient WASH techniques...................................................................................................................108 Framework for evaluation of WASH projects in drought-prone areas ........................................................................................................109 Annex 1: Water stress in relation to population ...........................................................................................................................................111 Annex 2: Water scarcity in relation to population demand..........................................................................................................................112 Annex 3: Drought Cycle Management...........................................................................................................................................................113 3 Impact of drought on WASH systems There are uncertainties with projected impacts of climate change, but reliability of projection depends on the area. For some regions projections of future precipitation change are more robust, while outside of these areas the predictions vary between models. Predictions also become less consistent between models as scale decreases.1