The basis of drought contingency planning

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Drought planning and water crisis management needs to be proactive, ^is is largely because overall policy, legislation, and specific mitigation strategies should be in place before a drought or water crisis affects the use of the country's water resources. Bruins (2001) provided the basic elements involved in the development of proactive drought contingency planning and their respective relationships, ^ese basic elements (Figure 24.1) involve drought risk analysis, drought impact assessment, and drought scenarios. Assessments have to be made of the impact of drought on the various water resources, economic sectors, population centres, and the environment. Different types of drought should be considered in the impact assessment studies. Drought scenarios have to be calculated on the basis of available information, including development of a frequency and severity index. From this, drought risk assessment can be investigated, primarily on the basis of meteorological data but may also include paleoclimatic information and other historical data in relation to climatic variation, ^e latter may be important as the time scale of recurrence of severe drought may well exceed the average human lifespan. Finally, proactive drought contingency planning needs to be developed (Bruins 2001).

To aid in drought assessment remarkably comprehensive meteorological and climatological information and advice is now starting to appear as output prod

Fig. 24.1. Basicelements involved in proactive drought contingency planning (Bruins, 2001)

Tracking Tracing

Fig. 24.1. Basicelements involved in proactive drought contingency planning (Bruins, 2001)

ucts emanating from meteorological and agricultural departments of governments worldwide, ttese can have fundamental value to those organizations that need to assess information related to the potential likelihood for drought and exceptional drought conditions in a region. Examples include those under tte World Agrome-teorological Information Service (WAMIS) of WMO in which products, (e.g. output from Germany) include monthly agro-weather bulletins, soil temperature information, actual and potential evaporation, grain dampness, forest and grass fire indices, and animal thermal load (

Policy makers, analysts, and farmers in regions prone to drought requiring access to the most recent climate, drought status, and crop prospects are able to use information on specialised drought exceptional circumstance information on sites such as the Australian National Agricultural Monitoring System (NAMS) (http:// However, major stakeholder groups involved in preparedness planning (policy makers, regulators and large agribusinesses, including financial institutions) and those involved directly in crop production (farmers, farm managers, rural businesses and consultants) may require widely varying different information. ttis means that information sources need to be continually re-evaluated and assessed as to their appropriateness in provision of most appropriate information for key users. Tactical as well as strategic preparedness decisions need to be made continuously and some climate forecast-related information outputs might onlybe relevant for some of these decisions.

Another approach in drought assessment is to apply crop or pasture simulation models that contain over 100 years of historical daily weather data to construct time series of modeled crop yield or pasture growth and so provide frequency data on occurrence of the likelihood of extremely low yields. In an Australian example for assessing exceptionally poor wheat yields the APSIM model (Keating et al. 2003) has been applied to over 100 years of historical data to provide simulated wheat yields for each of the 100 years in the study. From these data an assessment of the relative severity of the current or recent drought was made (Fig. 24.2) and the results provided to authorities responsible for exceptional drought circumstance payments (Keating and Meinke 1998; dejager et al. 1998). For grazing industry needs the Aussie GRASS modelling framework (Carter et al. 2000) has been adapted to provide alerts of impending drought for Australian shires, ttis approach combines calculations of pasture utilization by livestock and other animals. Additionally, the Aussie GRASS system has been modified to provide pasture condition alerts. Figure 24.3 provides an illustration of the structure of this drought alert system. Figure 24.4 provides an example of routine forecast of simulated pasture growth values using known soil moisture levels, recent and forecast temperature and rainfall values, tte pasture condition alert takes into account the fact that high pasture utilization under conditions of relatively high pasture growth can have different impacts (e.g. woody weed increase) than that under low pasture growth (e.g. loss of perennial grasses and pasture cover), tte development of an associated 'drought alert' system in 1991 produced interpolated percentile maps of pasture growth (as well as rainfall) and similar products that were particularly instrumental in convincing policy agencies as to the severity and spatial extent of drought. At the end of the drought period, indices such as pasture growth can be used in the drought assessment process to provide additional evidence that, although rainfall

Fig. 24.2. Estimation of drought severity using simulated wheat yield analysis from 1890 to 1997 at Wentworth, Australia (Keating and Meinke 1998).

Current Conditions ulAjùxiâiijuit by Spjlijl Simuhii'ji

Systems Operation

J Climate forecasts + 120 days \

• Analogue years • gcm output • Statistical Methods


WARNINGS - on potential for land degradation by species change, erosion & loss of animal production

Fig. 24.3. Flow diagram depicting Aussie GRASS system for drought and land degradation warning (Dayet al,2003).

patterns had returned to 'normal', the outputs from the pasture growth model indicated drought conditions were continuing as the rainfall received was still insufficient to produce growth in major grass species in Queensland (Day et al. 2003).

It has been suggested that more recent interest in, and development of, contingency planning programs to aid agrometeorological coping strategies may be due to important shifts in underlying climatic systems that have had a large influence

Pani Jesie

Fig. 24.4. Example of forecast output from Aussie GRASS depicting pasture growth likelihood for subsequent three month period (September to November 2006) using climate forecast system integrated into pasture growth simulation model for 5 degree pixel regions.

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