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National Workshop on Water Resources and Livelihoods in the Dry Areas Considering Climate Uncertainty Hammamet, Tunisia, 25 -26 September 2014 INTEGRATED TECHNICAL AND ECONOMIC ASSESSMENT OF WATER HARVESTING INTERVENTIONS IN PERSPECTIVE FOR CC MITIGATION (Case of Oum Zessar Watershed)
Introduction & general approach Review of conducted works WLI and CRP-DS findings Conclusions & prospects
Climate Soil Rainfed dominated Socioeconomic mutations CC
Biophysical Environmental CC WH Social Economic
Catchment 400 Croppin g Area 100 Jessour Dike
Oum Zess ar Area (km 2) 350 Annual rainfall (mm) 180 Mean annual temperature (°C) 20 Altitude (m) 0 -715 Population (inhabitants) 24000
Water balance on the terrace Hyd. Year Wet Dry Very dry ETrel (2/1) ETrel (3/2) 1. 1 2. 3 2. 5 1. 1 12. 0 15. 6 1. 3 Hyd. Year: type of the hydrological year ETrel: relative ETa 1: ETa with only rainfall on the terrace 2: ETa with rainfall and runoff on the terrace 3: ETa with rainfall, runoff and supplemental irrigation
Recharge structures Capacity loss of the gabion structures Wadi Location Sediment (cm) Loss (%) Oum Zessar Down 5 5 Koutine Down 50 14 Koutine Mid 20 18 Koutine Mid 20 21 Nkim Mid 50 56 Hallouf Up 150 88
Recharge well filter transmission capacity Runs 1 5 6 7 13 K (cm/h) 193. 5 52. 7 40. 2 33. 0 7. 0 Loss (%) 0. 0 72. 8 79. 2 82. 9 96. 4
Piézométrie et exploitation de la nappe de ZK Effets des aménagements Chute de la PZ quelque soit la pluviométrie Exploitation accrue !!! 14
SC 0 SC 1 SC 2 SC 3 mm % Rainfall 183. 9 - 183. 9 - ET 107. 0 a 58. 2 147. 2 b 80. 1 150. 9 b 82. 0 Outflow 34. 3 a 18. 7 4. 0 b 2. 2 Perco 14. 5 a 7. 9 24. 3 b 13. 2 TLOSS 28. 0 a 15. 2 8. 2 b 4. 4 3. 1 c Seepage 0 a 0. 0 1. 1 b 0. 1 c 0. 0 28. 2 b 15. 4 28. 3 b 15. 4 1. 7 3. 2 c 1. 7 0. 6 0. 9 b 0. 5
SC 0 SC 2 VD D N W VW
Chabeat Anez Site
Oued Moussa Site
INTEGRATED IMPACT ASSESSMENT OF LIVELIHOOD & WATER MANAGEMENT PRACTICES IN OUM ZESSAR WATERSHED
Methodology Extended cost-benefit analysis (ECBA) to environmental externalities : It was carried out in order to assess the costs and benefits of WHT works implemented by the WLI project in the selected farms. External economic and environmental phenomena, tangible as well as intangible effects have been integrated in the analysis. Evaluation criteria used were the Net Present Value (NPV) and the Internal Rate of Return (IRR). Data for CBA come from a survey conducted during 2013. An appropriate time horizon was set at 30 years Sustainable Livelihoods Approach (SLA): this approach is carried out in order to assess patterns and drivers impacts on livelihood condition. SLA is an analytical framework that helps to understand the factors that influence the ability of people to achieve sustainable development in a particular circumstance. The livelihood framework is based on five capital assets; social, human, physical and financial capital. To evaluate the five livelihood assets in the up-stream, mid-stream and down-stream of Oum Zessar watershed, data has been gathered using socio economic survey (139 surveys) conducted in 2013. LADA approach was adapted in order to select indicators and carry out the scoring for each asset.
Sustainable Livelihoods Approach (SLA) List of indicators by type of livelihood capital Natural capital Financial capital Physical capital Human capital Social capital Livestock Farm size Land quality Water quality Olive trees Agriculture income Livestock income Off-farm income Jessour Ownership of plowing means Education, Household size Age Households expenditure Member of association, Distance to nearest hospital , Certificate of Ownership, SONEDE network
Social capital is the most dominating capital in the three locations followed by physical capital mainly in Beni khdeche and Sidi Makhlouf. Financial capital seems to be not representative in the different location due to the low agriculture and livestock incomes. Projections indicate that the livelihood assets will be changed during 2013 -2030 period. Physical, human and social capital will be improved with very little increment in financial capital. Natural capital will slowly decrease. Factors that contributed to the decline of natural capital were agricultural intensification and poor land management.
Trends of different livelihood capitals over time
IRR and sensitivity analysis (WHT investment at farm level) IRR % Observed Costs + 10 % Benefits - 20 % Financial CBA 24% 27% 21% Economic CBA 27% 29% 23% Extended CBA 23% 27% 20% Net Present Value , WHT investment Discount rate NPV (DT) Costs + 10 Benefits - 20 % % 12% 10% 8% Finacial CBA 2491 3615 5231 2340 1691 Economic CBA 3023 4283 6092 2884 2140 Extended CBA 2073 3027 4402 1910 1333
The CBA shows that the WHT works are profitable at the private level with an IRR of 24 % and an NPV (at 12 % discount rate) of 2491 DT. The inclusion in the analysis of the off-site benefits improves the economic profitability considerably, with an NPV (at 12% discount rate) of 3023 DT DT and an IRR of 27 %. The incorporation of other external and indirect effects with no market prices (failure of jessour) resulted in a decrease NPV (at 12 % discount rate) of 2073 DT and IRR of 23 %. The sensitivity analysis confirm the basic analysis. The WHT works are apparently beneficial at private and social levels for local population within the watershed. Conclusion Integrated impact assessment can be a useful tool for community inclusion and livelihood strategy assessment. Sustainable land water management practices and livelihood strategies improve rural livelihoods of farmers in dry area. The presented results are under finalization, the next steps consist of hypothesis verification and scenario building.
q Water harvesting techniques have been developed since antiquity to cope with climate variability in the dry areas. q. They played major role in the development of rainfed agriculture and others (recharge, flood control, etc. ) q. With the prospect of CC, those systems/techniques would be more useful.
q. However: o Economic profitability is becoming increasingly low and variable o Migration (due to cities attractions) and competition of other sectors would favor abandonment q Need for new paradigm (water productivity, local products value chain, etc. ) q Technical adaptation and adoption (SI, etc. ) q Other functions (ecosystem services, etc. )