Graham Jewitt School of Bioresources Engineering and Environmental Hydrology University of KwaZulu-Natal
A massive land- grabbing scramble in Africa as foreign companies - some with foreign aid money support - rapidly establish enormous monoculture fields in tropical countries. Prof Seif Madoffe SUA 'climate colonialism' Sugar Cane Kilombera Basin, Tanzania
African agriculture Vital role for feeding Africa Africa s potential to provide food, fuel, fibre and fodder for future global food and energy security CAADP Comprehensive Africa Agriculture Development Programme NEPAD s Water Flagship Scientific Assessment of Africa's Water Resources and Systems - Not simplistic Water Footprinting Research and Technologies to Assess and Monitor Water-related Disasters Knowledge and Technologies to Improve Water Quality and Quantity Capacity building
Source: WWF-UK and SABMillar: Water Footprinting BUT this is Hydrology in 1-D only!
As crop consumes water, less moves downward and downslope to groundwater and rivers and streams. Soil moisture deficits increase Low flows are impacted Springs may dry up After Lorentz, 2008
Land Use Wet Season Recharge Onset of wet season flows Impact on onset of dry season flows Long term impact on groundwater Reserves Commercial Forest Moderate-High High High Moderate-High Dryland Agric (Sugar Cane) Moderate Moderate Low Low Runoff Harvesting Low Moderate Low Low Streamflow (m 3.s -1) 25 20 15 10 5 Basic Human Needs October January September
SADC Map Proposed as NEPAD CoE project Hydrological modelling Daily time step Quarternary or Quinary catchment Model parameterisation and enhancement Hydrological process studies Model verification Green water flows Crop yields Soil Moisture Not only streamflow guages! Linked to capacity building Masters degree in EO and RS for Water Resources Management (Waternet)
PRECIPITATION INTERCEPTION SURFACE LAYER TOPSOIL SUBSOIL INTERMEDIATE STORE GROUNDWATER STORE Daily streamflow Sediments NPS OPERATIONAL MODES South African Agro- Hydrological Atlas (digital) Many other SADC and global datasets Well established research Afforestation Sugar Cane Various food and biofuel crops Ongoing field studies in SADC Climate Change Downscaled GCMS linked to hydrological l model SIMULATION OPTIONS / COMBINATIONS Daily OUT- Monthly Annual PUT Risk Analyses QUICKFLOW RUNOFF ACRU MODEL Stormflow Baseflow SPECIFIC Peak Discharge Hydrograph : OBJECTIVES / - generation COMPONENTS - routing EV analyses Outflows: overflow normal flow seepage - abstractions Interbasin transfers Off-channel storage Sediment - generation Reservoir - siltation Crop Demand Application: - on demand - fixed cycle - fixed amount - deficit From : - reservoir - river - river and reservoir - off channel storage Return flows Gradual change Abrupt change Total evaporation Tillage practices Wetlands CO 2 T E P Maize Winter Wheat Sugarcane Primary productivity - dryland - irrigated - profit / loss
South African Atlas of Climatology and Agrohydrology (Schulze et al., 2007)
Agricultural Planning & Decisions Hydrological Planning & Decisions
Climate Data Solar Radiation (Section 5) Precipitation (Section 6) Temperature (Section 7) Heat Units (Section 8) Frost (Section 9) Chill Units (Section 10) Vapour Pressure (Section 11) Relative Humidity (Section 12) Potential Evaporation (Section 13)
Examples of available information
Examples of available information
SA Atlas of Climatology & Agrohydrology EXAMPLES OF SOIL HYDROLOGICAL ATTRIBUTES Examples of available information
SA Atlas of Climatology & Agrohydrology EXAMPLES OF PRECIPITATION MAPS 3 Examples of available information
SA Atlas of Climatology & Agrohydrology EXAMPLES OF POTENTIAL EVAPORATION MAPS BY THE PENMAN MONTEITH APPROACH 1 Examples of available information
SA Atlas of Climatology & Agrohydrology Examples of available information
Water Use = change in streamflow relative e to baseline e vegetation Importance of Baseline
Quinary catchment scale Daily hydrology -Forestry - Sugar Cane -Biofuels crops -
Seasonal Differences Crop uses more water than baseline in summer, especially inland areas. Seasonal Differences Crop uses less water than baseline in winter, especially coastal areas.
Water Use = MAR base MAR crop in mm. Hence, MAR crop > MAR base Crop uses less water than natural vegetation by an average of 54 mm
KZN Midlands Eucalyptus
Potential Environmental Potential Environmental Flow Problem
Available EO information Malawi Land Use Swaziland Land Use Daily Temp and ET South Africa
Directly hydrologically relevant information! Daily and Monthly Soil Moisture www.ukzn.ac.za/sahg
Data and Information Many sources Rainfall! Model verification and validation Streamflow Soil Moisture Crop Yield Total Evaporation at o Process studies Jatropha (SA) Sugar Cane (SA, Swaziland and Tanzania) Miombo (Tanzania and Mocambique) Teak (Tanzania) a a) Biofuels (SA)
BEEH Hydrological Process Studies Rainfall Monitoring Field sites in SA, Tanzania, Mozambique Cell Phone network Remote Sensing
HEAT PULSE/SAP FLOW Estimates stand transpiration p Spatially explicit and species specific info on transpiration within a forest stand/orchard. Allows for continuous and automated direct measure of plant response to atmospheric and soil conditions.
Gush et al, in press
The Large Aperture Scintillometer (LAS) in Potshini Rn E H G
Date Oct-04 Nov-04 Dec-04 Jan-05 Feb-05 Mar-05 Apr-05 May-05 Jun-05 Jul-05 Aug-05 Sep-05 Equipment Net Radiometer Scintillometer Hobo Soil Thermocouples MCS Soil Thermometers 1 MCS Soil Thermometers 2 TDR Moisture Sensor Rainfall Reliable Total Evaporation Energy and water balance studies Sugar Cane 400 m N
900 800 700 Energy Balance (4-8 Mar 2005) 3.4mm 5.6mm 6.5mm 2.7mm 4.7mm Net Radiation Sensible heat flux Soil Heat Flux Latent Heat Flux He eat FLux (w/m2) 600 500 400 300 200 100 0-100 0 24 48 72 96 120 Time (Hours) 800 700 600 Energy Balance for 18-22 July 2005 1.34mm 1.12mm 0.8mm 0.87mm 0.82mm 500 W.m-2 400 300 200 100 0-100 0 24 48 72 96 120 Time (Hours) Net Radiation Sensible Heat Soil Heat Latent Heat
ET Estimates The Surface Energy Balance Approach (SEBAL and SEBS) Pixel based estimates of ET from Remote Sensing In Africa a much bigger flux than streamflow Kongo & Jewitt, 2005
Landsat: 2003/08/31 MODIS: 2003/08/31 Landsat Spatial res. 30m 8 or 16 days Resolution MODIS Allenet et al, (2005) Spatial res. 250, 500 & 1000m Daily coverage BUT does not provide useable images daily!!
Major challenges Cloud free images Summer season; cloudy Satellite overpass time and frequency
SEBAL Estimates Dry winter season SEBAL Estimates Wet summer season
Cult. temp.comm. irrigated Monthly evaporative water use SEBAL June, 2005 120 Actual ET ETo Rain 100 80 60 40 20 0 Residential (informal township) Bare rock & soil Wetlands Degraded Grassland Cultiv. Temp. subs. dryland Urban - residential Unimproved Grassland Improved Grassland Waterbodies Woodland Thicket, Bushland Indigenous forest Other / mixed spp Eucalyptus spp Shrubland and Low Fynbos Pine spp Month ly ET (mm /m)
Initial phases of a large project (NEPAD CoE) Research and training New tools Beyond SADC Seeking collaboration Other aspects Climate Change scenarios Crop yield forecasting Soil health Water quality etc