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International Congress on Water 2011 Integrated Water Resources Management in Tropical and Subtropical Drylands  Mekelle, ...
The  problem   <ul><li>Many African highland rivers discharge in drylands </li></ul><ul><li>(naturally closed basins)  </l...
The Ewaso Ng’iro catchment  Lorian Swamp To Nairobi Archer’s Post Mt. Kenya Upstream agriculture Merti
Purpose of the study  <ul><li>Assess water users’ downstream vulnerability to upstream abstractions  </li></ul><ul><ul><li...
Permitted abstractions  <ul><li>Since 2000 2.4 m 3 .s -1 </li></ul><ul><li>Increasing over time  </li></ul><ul><li>Underes...
Demand for water  <ul><li>Estimated demand for water 2000  (Mutiga et al. 2010)  </li></ul><ul><ul><li>200 million m 3 .ye...
River discharge Archer’s Post  <ul><li>Highly variable </li></ul><ul><li>Low discharge events more frequent since 1980’s  ...
Number of days per year when discharge does not reach the Lorian Swamp 1950  Year  2010
Impact on Merti aquifer  <ul><li>Sustains more than 500,000 people </li></ul><ul><li>Aquifer recharges during peak water f...
Monthly NDVI maps 1998 - 2010 2010  Year  1998 January  Month  December
Impact on vegetation biomass <ul><li>NDVI fluctuates over time  </li></ul><ul><li>Swamp has higher NDVI than surrounding a...
Impact on vegetation biomass  <ul><li>Significant relation water inflow and difference NDVI swamp and surroundings </li></...
Ewaso Ng’iro discharge and ecosystem services Lorian swamp
Vulnerability to abstractions of the benefits from river water  <ul><li>Blue surface water – highly vulnerable  </li></ul>...
Conclusions  <ul><li>Abstractions upstream significant, particularly in dry season  </li></ul><ul><li>Significant impact w...
Recommendations  <ul><li>Stimulate information exchange and dialogue between up and downstream water users  </li></ul><ul>...
After thought <ul><li>Similar eco-hydrological processes underpinning upstream-downstream linkages: </li></ul><ul><ul><li>...
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Impact of abstractions upstream on the benefits of riverine water discharge into the Lorian swamps, Kenya

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Presented by Jan de Leeuw, Shem Kifugo, Zipporah Msiyuni, Mohamed Said and Don Peden at the International Congress on Water 2011 Integrated Water Resources Management in Tropical and Subtropical Drylands, Mekelle, Ethiopia, 19-26 September 2011.

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Impact of abstractions upstream on the benefits of riverine water discharge into the Lorian swamps, Kenya

  1. 1. International Congress on Water 2011 Integrated Water Resources Management in Tropical and Subtropical Drylands Mekelle, Ethiopia, 19-26 September 2011 Impact of abstractions upstream on the benefits of riverine water discharge into the Lorian swamps, Kenya Jan de Leeuw, Shem Kifugo, Zipporah Msiyuni, Mohamed Said and Don Peden
  2. 2. The problem <ul><li>Many African highland rivers discharge in drylands </li></ul><ul><li>(naturally closed basins) </li></ul><ul><li>Discharge important to downstream users </li></ul><ul><ul><li>Secure surface water and forage during dry periods </li></ul></ul><ul><ul><li>Recharge of aquifers and wetlands </li></ul></ul><ul><ul><li>Opportunities for development </li></ul></ul><ul><li>Retention of agricultural water upstream deprives downstream communities from rivers’ benefits </li></ul>
  3. 3. The Ewaso Ng’iro catchment Lorian Swamp To Nairobi Archer’s Post Mt. Kenya Upstream agriculture Merti
  4. 4. Purpose of the study <ul><li>Assess water users’ downstream vulnerability to upstream abstractions </li></ul><ul><ul><li>Magnitude of upstream abstractions </li></ul></ul><ul><ul><li>Upstream and downstream linkages </li></ul></ul><ul><ul><li>Describe downstream water uses </li></ul></ul>
  5. 5. Permitted abstractions <ul><li>Since 2000 2.4 m 3 .s -1 </li></ul><ul><li>Increasing over time </li></ul><ul><li>Underestimate </li></ul><ul><ul><li>Illegal abstractions </li></ul></ul><ul><ul><li>Higher in dry periods </li></ul></ul>Percent of the Total Annual Discharge at Archer's Post 1960 1985 2010
  6. 6. Demand for water <ul><li>Estimated demand for water 2000 (Mutiga et al. 2010) </li></ul><ul><ul><li>200 million m 3 .year -1 or 3.6 m 3 .s -1 </li></ul></ul><ul><ul><li>≈ 10-15% of annual discharge at Archer’s Post </li></ul></ul><ul><ul><li>50% higher than permitted </li></ul></ul><ul><ul><li>Sesaonally variable </li></ul></ul><ul><ul><ul><li>Low during rainy season </li></ul></ul></ul><ul><ul><ul><li>Escalate in dry season when river discharge is low </li></ul></ul></ul>
  7. 7. River discharge Archer’s Post <ul><li>Highly variable </li></ul><ul><li>Low discharge events more frequent since 1980’s </li></ul>
  8. 8. Number of days per year when discharge does not reach the Lorian Swamp 1950 Year 2010
  9. 9. Impact on Merti aquifer <ul><li>Sustains more than 500,000 people </li></ul><ul><li>Aquifer recharges during peak water flow </li></ul><ul><li>Current abstractions appear to have little impact on aquifer </li></ul>Recharge (km 3 /year)
  10. 10. Monthly NDVI maps 1998 - 2010 2010 Year 1998 January Month December
  11. 11. Impact on vegetation biomass <ul><li>NDVI fluctuates over time </li></ul><ul><li>Swamp has higher NDVI than surrounding area </li></ul>
  12. 12. Impact on vegetation biomass <ul><li>Significant relation water inflow and difference NDVI swamp and surroundings </li></ul><ul><li>Outliers reflect local rains </li></ul>Lorian Swamp NDVI
  13. 13. Ewaso Ng’iro discharge and ecosystem services Lorian swamp
  14. 14. Vulnerability to abstractions of the benefits from river water <ul><li>Blue surface water – highly vulnerable </li></ul><ul><li>Green water – highly vulnerable </li></ul><ul><li>Groundwater recharge – low vulnerability </li></ul>
  15. 15. Conclusions <ul><li>Abstractions upstream significant, particularly in dry season </li></ul><ul><li>Significant impact water security downstream </li></ul><ul><li>Benefits from surface water (green and blue) vulnerable to abstractions </li></ul><ul><li>Benefits from groundwater less vulnerable to abstractions </li></ul><ul><li>Basin level water productivity depends on upstream-downsream linkages </li></ul>
  16. 16. Recommendations <ul><li>Stimulate information exchange and dialogue between up and downstream water users </li></ul><ul><li>Quantify demands for water in down- and upstream areas with emphasis on dry periods </li></ul><ul><li>Consider mechanisms to secure access to water at both ends of basin </li></ul>
  17. 17. After thought <ul><li>Similar eco-hydrological processes underpinning upstream-downstream linkages: </li></ul><ul><ul><li>Naturally closed basins </li></ul></ul><ul><ul><li>Closing basins </li></ul></ul><ul><ul><li>Rahabiltated streams and springs caused by upslope restoration of land productivity. </li></ul></ul><ul><li>Potential for shared learning for management </li></ul><ul><ul><li>Thank you! </li></ul></ul>

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