Remote sensing and census data water productivity analysis for limpopo basin
1. Remote Sensing and Census Data Based Water Productivity Analysis for Limpopo Basin – a preliminary report for discussion Xueliang Cai and Poolad Karimi Project Meeting, Pretoria 01 July 2009
2. Structure of the presentation ETa 1 – Actual Evapotranspiration Introd. Data ETa Introduction SGVP Data collection Simplified Surface Energy Balance model to calculate ETa 1 Standardized Gross Value of Production Results The water productivity mapping results Discuss. Discussion and plan
8. Land use and land cover map Synthesized by combining the basin LULC map and South Africa Limpopo province map Source: Created by IWMI using data from the basin LULC map and South Africa Limpopo province map Introd. Data ETa SGVP Results Discuss.
9. Actual ET estimation - SSEB ET a – the actual Evapotranspiration , mm. E T f – the evaporative fraction , 0-1, unitless. ET 0 – Potential ET, mm. T x – the Land Surface Temperature (LST) of pixel x from thermal data. T H /T C – the LST of hottest/coldest pixels . Simplified surface energy balance (SSEB) is a ET estimate model proposed by Senay (2007). It combines remotely sensed thermal imagery with ground measured climate data, providing quick ET estimate for large scale areas. Introd. Data ETa SGVP Results Discuss.
11. Actual ET estimation - SSEB Step 2. Actual ET calculation by Simplified Surface Energy Balance (SSEB) approach Actual ET map (2005 Apr 23 - 30) ET fraction map DEM corrected MODIS LST potential ET map Source: IWMI Introd. Data ETa SGVP Results Discuss.
12. Standardized gross value of production SGVP: is an index which helps to compare the economical value of different crops regardless in which country or region they are. Maize is the major crop in the basin and it is taken as base crop. Source: Molden, 2001 Introd. Data ETa SGVP Results Discuss.
14. Evapotranspiration Average ETa is less than half of ETo, indicating significant water stress Source: IWMI Introd. Data ETa SGVP Results Discuss. ETa: 779 mm ETo: 1676 mm Histogram ET (mm)
16. SGVP SGVP calculate based on FAO data While SGVP calculated using countries major crops production value at Source: IWMI Country Total Cropped are a (ha) Total SGVP (Million US$) Average SGVP (US$/ha) Major cultivated crops Crop Yield (kg/ha) Percentage of cropped area Contribution to total SGVP South Africa 6,043,944 8,216.4 1,360 Maize 3,635 53% 17% Wheat 2,366 13% 5% Sunflower 1,348 8% 2% Mozambique 4,525,760 1,068.3 286 Maize 1,141 27% 16% Cassava 5,882 24% 55% Sorghum 629 11% 3% Zimbabwe 2,975,330 1,724.7 580 Maize 529 58% 7% cotton 668 10% 8% Groundnuts 288 7% 1% Botswana 142,525 Introd. Data ETa SGVP Results Discuss.
17. SGVP The SGVP figures estimated through country statistic for the part fall in the basin boundary: - South Africa; 450 US$/ha ; from 442 to 453 US$/ha - Mozambique; 80 US$/ha ; from 47 to 126 US$/ha Which much are lower than the one calculated by FAO data. Within the Mozambique districts Beline, Chibuto and Xai xai Districts in south east part of the basin have higher SGVP Whereas, Chicualacuala has the lowest Source: IWMI Introd. Data ETa SGVP Results Discuss.