COPING WITH EXTREMESTHE IMPACT OF WATER SUPPLY INFRASTRUCTURE ON FLOODSAND DROUGHT AND THE IMPLICATIONS FOR FOOD SECURITYTarek Ketelsen, Simon Tilleard, Arun Parameswaran, Mai Ky Vinh
Assessing variability in the Angkor hydroclimate • 1250-1450 extreme fluctuations in drought & storm conditions: mega-drought 1330s -1360s more severe but shorter drought 1400s -1420s Interspersed by high magnitude monsoon years • Two severe droughts punctuated by heavy monsoon rain weakened the kingdom by: – shrinking water supplies for drinking and agriculture – damaging Angkors vast irrigation system which was central to it’s economySource: Buckley et al (2010) Source: Day et al (2011)
“…the Khmer water management system is a vivid example of a sophisticated human technology that failed in the face of extreme (threshold) environmental conditions.” Day et al, 2011
WSI expansion in the Mekong BasinBy 2030• Hydropower => quadruple• Irrigation command area => double• How will the Mekong’s current WSI handle extremes in hydroclimate?
Key research questions1. Do WSI modulate the frequency and severity of droughts and floods?2. How do descriptions of droughts and floods vary between the various stakeholders and genders upstream and downstream of WSI infrastructure?3. Have impacts of drought and floods diminished with dams and other WSI?4. Through their effects on flood and drought, have WSI enhanced food security?5. How can WSI design and management be improved to enhance their contribution to food security?
Main components of the study 1. Assessment of the Mekong flood & drought regime 2. GIS database of Mekong WSI and their capacity to regulate extremes 3. Regulating effects of WSI during hydroclimate extremes 4. Documentation of d/s community coping strategies during hydroclimate extremes 5. Implications for food security
Basin wide assessment• focus will be hydropower• regional review of floods and droughts and food security in the Mekong Basin – Definitions of extreme hydro-climate conditions in the Mekong – Characterisation of their role in Mekong productivity• develop a consolidated inventory of WSI in the basin. – Dam characteristics – Catchment characteristics – Downstream user characteristics.
Case study assessment• with Institute of Water Resource Planning (IWRP) and Enterprise Development Institute (EDI)• selection based on preliminary findings of the basin-wide review & consultations with key government agencies• select one WSI in Cambodia and one in Vietnam and conduct computational modelling, community surveys and participatory consultations to understand how the downstream communities experience of floods and droughts have changed due to the introduction of WSI.• develop an understanding of how WSI have impacted food security (both positive and negative) and scope implications of improvements to management.
Typical Reservoir Management for Electricity Generation: flood management considerations1. Dry Season Low rainfall and plant operation begins to lower storage level Dry Season Wet Season2. End of the Dry Season Storms Storage level continues to drop towards Low Supply Level 1 43. Start of the Wet Season High rainfall causes storage level to rise4. Dam at full capacity Early wet season, Full Supply Level reached and 2 maintained. Allowance forFull Supply Level Flood Storage?? 3 Live Storage Source: Räsänen et al, under publicationLow Supply Level Dead Storage
Storms and peak events Average maximum daily precipitation (1985-2005) Source: MRC, 2010
Towards a flood control index…. 1. Reservoir characteristics 2. Sub-catchment characteristics 3. Downstream considerations - Management and operational rules - Response time to storm events - Population Density - Regulating Capacity (storage/MAF) - Precipitation dynamics - Land use characteristics - Spillway and plant discharge capacities - Storm frequency and intensity - Infrastructure assets - Freeboard capacity - River flow and networks Flood Control IndexLow capacity to High capacity toregulate floods regulate floods