Applying seasonal climate forecasts and satellite information for improving decisions in the agricultural sector:

the 1999-2000 drought in Uruguay.

Walter E. BaethgenResearch and Development Division

International Soil Fertility and Agricultural Development CenterIFDC – Uruguay Officebaethgen@undp.org.uy

and

Agustín GiménezGRAS - Climate, Environment and Remote Sensing team

Instituto Nacional de Investigación AgropecuariaINIA - Uruguay

agimenez@inia.org.uy

Uruguayan economy is largely dependent, directly or indirectly, on agriculture (crops and livestock). Production in Uruguay is based on the highly fertile soils of the Pampas, an ecosystem in which native temperate and subtropical grasslands are used for livestock production or have been converted to improved pastures (grasses/legumes) and to croplands. Interannual and interseasonal climatic fluctuations in Uruguay result in high variability in crop and pasture production with frequent negative consequences on the economy.

The first published studies conducted on the impact of ENSO phases on rainfall and temperature in Southeastern South America were those by Ropelewski and Halpert (1987 and 1989). These authors concluded that precipitation during November-February in this region tended to be above normal during years with warm ENSO events (Ropelewski and Halpert, 1987). They also found that years with high values of the Southern Oscillation Index (typically, La Niña years) presented negative rainfall anomalies during June-December (Ropelewski and Halpert, 1989).

More recent studies conducted in Southeastern South America revealed the existence of a near symmetry between impacts of El Niño and La Niña on precipitation as well as on crop productivity. Positive rainfall anomalies prevail in El Niño years, and negative rainfall anomalies prevail in La Niña years, during the austral spring and/or summer months. Some research results also suggest that the impacts of La Niña are stronger and/or less variable in both, rainfall and crop yields than the impacts of El Niño (Baethgen, 1998). Regarding the impact of ENSO phases on temperature, the very few studies conducted in Uruguay suggest that the temperature amplitude in northern Uruguay is reduced in El Niño years. The studies also suggest that mean temperatures in the whole country tend to be lower in La Niña years in all months but a few exceptions during the summer (Bidegain and Krecl, 1998; Pisciottano et al., 1994; Grimm et al., 1998; Grondona et al., 1998; Díaz et al., 1998; Baethgen, 1997; Podestá et al., 1998; Myneni et al, 1996).

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Two recent La Niña-related droughts in Uruguay: 1988/1989 and 1999/2000

The last two strong La Niña episodes (1988/1989 and 1999/2000) had strong negative impacts on the Uruguayan economy. Both episodes were characterized by extended periods with reduced rainfall that strongly affected the agricultural sector (Figures 1 and 2).

One of the most critical rainfall period for agriculture in Uruguay is late spring and summer (October - February). Average rainfall conditions during the summer months (90-130 mm/month, depending on location) is typically not sufficient to compensate for evapotranspiration losses. Therefore, pasture and crop growth greatly depends on the soil ability to store water. Natural grasslands in Uruguay occupy more than 70% of the total land area and are mostly located in the northern and central regions of the country. Soils in these regions are typically shallow (less than 30cm depth), and therefore possess low water storing capacity. Pasture production in these regions is thus highly dependent on the rainfall during the late spring and summer months.

On the other hand, annual summer crops (e.g. maize) require large water quantities during the critical flowering growth stage. Maize in Uruguay is grown in deep soils with relatively large water holding capacity. However, the amount of stored water in these soils is typically insufficient to satisfy the crop water demand, and yields of non-irrigated crops strongly depend on rainfall during the flowering months (late December and January).

In summary, good years in Uruguay for natural grasslands in shallow soils and for annual summer crops in deeper soils are characterized by larger than normal rainfall during late spring and summer. The results presented in figures 1 and 2 show that in the two most recent La Niña episodes (1988/1989 and 1999/2000), rainfall during these critical periods was considerably below average.

Although Uruguay total land area is relatively small (approximately 190,000 km2), large spatial variability is typically found in the spring and summer rainfall across the country’s regions. For example in both, 1988/89 and 1999/2000 seasons, rainfall in spring and summer was much lower in the NW region than in the SW or central regions (Fig. 1 and 2). Also, the negative rainfall anomalies in 1999/2000 started earlier and lasted longer than in 1988/89.

Responses in the agricultural sector to the 1988/1989 and 1999/2000 droughts

1988/1989

In 1988 Uruguay had no institutional structures nor special policies or programs in place to respond to droughts. At that time droughts were viewed as very low frequency phenomena which did not justify the development of special structures or programs. Consequently, governments had typically reacted to previous droughts with crisis management responses such as special aid programs to affected regions.

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In August 1989 when the drought was already showing important negative effects on agriculture, water resources and hydroelectric dams, the government of Uruguay and UNDP hired a consultant to assist in the development of reactive strategies to confront the drought. The consultant (Dr Donald A. Wilhite, International Drought Information Center, University of Nebraska) prepared a report to the government with a large list of recommendations for future droughts including the following:

1. Create a National Drought Commission to assist the government in the assessment, planning, management and response activities.

2. Create a National Water Availability and Outlook Committee (NWAOC) to develop a National drought plan in order to systematically prepare for the next major episodes. Among many other responsibilities, the NWAOC should: (a) continuously monitor water availability, (b) distribute monthly summaries of National water availability, (c) develop climatological techniques (e.g., probability tables, indices, etc.), (d) explore the potential use of AVHRR data to provide a country-wide assessment of biomass activity.

In 1988 research on teleconnections and impacts of ENSO on rainfall in Uruguay was incipient. Ropelewski and Halpert (1987) had just published the first article that showed the correlation between ENSO anomalies and rainfall patterns in southeastern South America. Climate scientists from the University of Uruguay and the National Weather Service were starting the first research studies on ENSO impacts. Still, Dr. Wilhite’s report to the government emphasized the need to consider ENSO in the climatic research National programs.

In summary, the 1988/89 drought found Uruguay with no institutional structures, with no capabilities to assess or monitor water availability, and with incipient research on the ENSO impacts on rainfall. Consequently, the government and the private sector could only respond to the drought with a crisis management approach. Only in the livestock sector the direct losses due to animal death attributed to the drought were 300 million US dollars. However, the losses were much larger since the reduction in the population of breeding animals was felt for several years after 1988/89. Other very important losses were found in the forestry sector due to frequent fires and in the summer crops where National yields were reduced by more than 40%.

1999/2000

Several changes had occurred in Uruguay during the period between both droughts. Firstly, the government had created two institutions, the National Emergency System (NES) and the National Commission for Drought (NCD). The NES is appointed directly by the office of the President of Uruguay, and had played a key role in crisis management activities during the 1997/98 (El Niño) floods in Uruguay. On the other hand the NCD was created under the leadership of the Ministry of Agriculture and included representatives of the research community (agriculture and climate), a few governmental offices, and several organizations from the private sector.

Also, the National Institute for Agricultural Research (INIA) had formed a Climate, Environment and Satellite Agriculture interdisciplinary team (GRAS), which started collaborative research

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with the International Institute for Soil Fertility Management (IFDC-Uruguay Regional Office). The collaboration included research projects in the following areas: (a) applications of seasonal climate forecasts in the agricultural sector (with climate scientists

from the University of Uruguay), and (b) development of an information and decision support system (IDSS) for the agricultural sector

of Uruguay (with NASA's Goddard Institute for Space Studies, with the Soils Department of Uruguay, and with INTA, the National Agricultural Research Institute of Argentina).

These research projects started activities during the period when the first negative impacts of the 1999/2000 drought were starting to be felt in the Uruguayan agriculture and proved to have major impacts on the government response.

The INIA/IFDC collaborative projects included the creation of a Technical Working Group (TWG) for improving the dissemination and applications of seasonal climate forecasts. The TWG was composed by researchers (agriculture and climate) working in the projects and by representatives of the major farmer organizations, agribusiness and governmental offices. The TWG met every three months immediately after the South East South America Regional Climate Outlook Fora (RCOF). During the TWG meetings the climate scientists presented the regional outlook produced in the RCOF and the results of their own climate research conducted at the National level. The agricultural scientists presented advances on the tools to apply this climate information, and the stakeholders from the public and private sector discussed the results and limitations of the information they received. In addition to creating the adequate environment to improve the applications of climate information, these meetings were also crucial for the dissemination of the climate outlooks in the agricultural sector (Figure 9).

Furthermore, the INIA/IFDC project for developing the Information and Decision Support System (IDSS) included two activities that were also extensively used by the public and private sectors responding to the 1999/2000 drought. Firstly, the IDSS included calibrated and tested crop simulation models that were used to identify agronomic practices better adapted to the drought conditions. Also, the INIA/IFDC Research Group included two types of satellite data: AVHRR and Landsat images. The AVHRR images (1km) were used to monitor the vegetation status (NDVI) throughout the season for the entire country. Maximum monthly NDVI values were expressed in absolute terms and as deviations from long-term (1982-1995) mean values ("Normal" = mean 1 standard deviation, "Low" = less than mean 1 standard deviation, "High" = greater than mean 1 standard deviation, "Very Low" = less than minimum value of the long-term series, "Very High" = larger than maximum value of the long-term series) (Figure 3 and Figure 4). Landsat 5 and 7 images were used for more detailed studies at the farm level.

All the information produced in these collaborative projects was published and continuously updated in the GRAS-INIA's web page (www.inia.org.uy/disciplinas/agroclima), which is visited by farmers, agribusiness representatives, agronomists and government officers. In addition, IFDC and GRAS-INIA staff gave several live presentations and teleconferences in collaboration with the Ministry of Agriculture and Fisheries that reached all the major regions of the country. Researchers also appeared in several TV and radio programs and prepared several articles for the major newspapers. In these communications, the researchers presented the results of the latest

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climate forecasts, as well as the evolution of the monitored vegetation status, and the results of the crop and pasture simulation models.

This continuous communication of researchers with the public and private agricultural sectors had major impact in providing stakeholders with the most updated, objective and sound information on the status and evolution of the drought. Emergency situations are often characterized by the existence of an overflow of information from many different sources (National, International, and Regional), and with varying level of objectivity and scientific soundness. This information overflow often causes confusion and hamper stakeholders from taking effective responsive actions. In such scenarios identifying trustworthy sources of clear, relevant and applicable information is crucial for making decisions at any level.

Two documented actions are included in this article that exemplify how the government of Uruguay used the information provided by the INIA/IFDC Research Group during the 1999/2000 drought. Several other similar examples are very likely to exist in the country (public sector, agribusiness and individual farmers). An INIA/IFDC planned activity for the near future consists in documenting such cases. Two other examples are also included in the present article that illustrate the type of applications of satellite-based information that INIA/IFDC are developing for the agricultural sector of Uruguay.

Case 1: Ministry of Agriculture and Fisheries

During the early months of 2000 the impacts of the drought were already very evident. Cattle herds were clearly suffering due to the lack of adequate forage and water availability. The Ministry of Agriculture needed to establish an emergency plan and set priorities for distributing aid to the different regions of the country. In the past, the definition of such priorities had mainly been based on reports prepared by the Ministry's staff working in the field. Since resources are always scarce, the Ministry field staff was not able to cover the entire country and consequently, several regions were left behind in the distribution of aid, even though they might have been in a critical situation. Also, similarly to what happens in the rest of the world, some regions in Uruguay can have more political influence than others. Confronted with the lack of objective and technically sound information, governmental decision-makers were often persuaded to prioritize such regions in the distribution of emergency aid.

Regarding this situation, the then Minister of Agriculture and Fisheries (Mr. Juan E. Notaro) sent a letter to the INIA/IFDC Research Group coordinators and wrote: "(...) The results of your work during the recent drought were useful for making both, operational and political decisions. From the operational standpoint, your work allowed us to concentrate our efforts in the regions highlighted as being the ones with the worst and longest water deficit (1). We prioritized those identified regions for concentrating the use of our resources, both financial aid and machines for dams, water reservoirs, etc. We also established plans that were more flexible than usual (relaxing sanitary and commercial controls) to mobilize cattle from the most affected regions.

(1) The Minister refers to the AVHRR images processed by the INIA/IFDC Research Group (both, absolute and relative values). The data was presented in several public meetings and was published in INIA's WEB page.

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(...) From the strictly political standpoint, your work provided us with objective information to defend our prioritization of regions, in a moment in which every governor, politician and farmer in the country was asking for aid. We received no complaints in this respect. In the same line, your work also allowed to mitigate pressures since we provided the press and the general public with transparent, technically sound and precise information.

In summary, the most important issue is that the celerity and precision of the information you provided, allowed us to be effective in our decision-making and at the same time to publicly defend those decisions with technical solvency. We did not get complaints about politicizing our actions: in the contrary our actions were complimented. And most importantly, the most feared threat of significant cattle deaths due to the drought never occurred thanks to the celerity of the actions taken, which would have been impossible without the information you provided to us."

Case 2: National Emergency System

One of the most dramatic effects of drought in the Uruguayan agricultural sector is the reduction of drinkable water for the cattle herds. An important function of the National Emergency System during a drought consists of working with the other governmental offices to move machinery to the affected areas for constructing new water reservoirs and/or improving the existing ones. Similarly to the situation reported by the Minister of Agriculture, the NES has to make decisions in this respect confronting several different types of pressures. In January 2000 the Director of NES asked the INIA/IFDC Research Group to provide him with information that would assist him in the definition of an operational plan to mobilize the required machinery.

The INIA/IFDC Research Group worked with INTA-Castelar (Argentina) staff members analyzing the water resource availability for cattle in January 2000 compared to the corresponding to March 2000. The objective of this study was to identify regions in Uruguay with the largest water resources reduction. Researchers used Landsat images to identify water reservoirs in different regions of the country and to measure their areas in January 2000 and in March 2000 and determine the percent reduction. The study identified which of the regions showed the largest free-water area reduction (Figure 5).

The Uruguayan National Emergency System (NES) used the results of this study to establish regional priorities and to implement an operational plan for mobilizing the machinery required to improve the water availability situation. The Director of NES (Cnel. Haris de Mello) also wrote a letter to the INIA/IFDC Research Group coordinators stating: (...) "the information you provided was very useful for our Operative Working Group to plan, execute and coordinate the activities for mitigating the drought effects, specially with respect to the animal water consumption."

Case 3: Water Contamination in an Irrigated Basin

The Río de la Plata estuary located between Uruguay and Argentina is formed where the Parana and Uruguay rivers meet the Atlantic Ocean. Therefore, the composition of the estuary varies from pure freshwater from the mouth of the Uruguay River and the Parana delta to salty seawater

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about 350km to the east where the Atlantic Ocean starts. The seawater front is normally located in front of Montevideo City (approximately 200 km to the east of the Uruguay River mouth), but its location varies throughout the year depending on winds and the Uruguay and Parana rivers' discharge. In years with high rainfall in the Rio de la Plata basin, the Parana and Uruguay river flows is reduced and the seawater front moves toward the east, while in years with low rainfall in the Rio de la Plata basin the front moves to the west.

During the summer 1999/2000 rainfall in the Rio de la Plata basin had been much lower than average (e.g., Figures 1 and 2). Consequently, the seawater front moved to an unusual location to the west of Montevideo City, and reached the Santa Lucía River mouth. This river was also affected by the drought and the flow was very low which allowed the incoming of seawater to the river displacing its normally freshwater. Several farms take water for irrigation from the Santa Lucía River, and in January 2000 important damage to irrigation equipment and fields were observed. The INIA/IFDC Research Group used Landsat images and showed the evolution of the seawater front by monitoring the sediment concentration of water that is typical of the Uruguay and Parana rivers. This study demonstrated that the incoming and spread of the salty water (Figure 6) caused the field and equipment damage observed in January 2000.

Case 4: Assessment of the spatial variability in farmer fields

One of the objectives of the INIA/IFDC research activities is to use satellite data for assessing the within-field variability of crop and pasture production. Early detection of spatial variability in the crop fields can help farmers to identify, and eventually adjust, agronomic factors that may be limiting yields (e.g., nutrients, water, diseases). Figures 7 and Figure 8 show two examples of this application during the 1999/2000 drought in Uruguay.

In the first case (Fig. 7), a maize grower measured grain yield variability at harvest with a device that is connected to the combine (commonly called "yield monitor"). His data indicated strong spatial variability: although the mean grain yield for the entire field was 5.5 ton/ha, values ranged from 1.5 to almost 10 ton/ha. Likely causes for this high variability were water and/or nutrient deficiency (associated with soil type, topographic position, etc.). INIA/IFDC researchers determined NDVI values for that same field at the maize flowering growth stage (January, i.e. than 2 months before harvest). The patterns found in the January NDVI values were very similar to the corresponding to grain yields measured by the farmer in March (Fig. 7a and 7b). In certain situations, early detection of this spatial variability can be used to identify factors that are limiting productivity (e.g., uneven water distribution, nutrient deficiencies, diseases) and adjust the crop management practices to overcome them (e.g., adjusting water distribution, adding plant nutrients, using pesticides, etc.).

The second example (Figure 8) shows the typical pattern found in crop biomass production in irrigated (central pivot) fields with problems in the water distribution. The NDVI values at the maize flowering growth stage evidenced that the field presented radius-shaped areas with lower biomass, which indicates problems with the irrigation distribution. Early detection of this type of problem can also lead to adjust the irrigation resulting in higher and more uniform crop yields.

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The high correlation found in these studies between NDVI values at maize flowering and the final grain yield obtained by farmers, also indicate a good potential to use remotely sensed data to develop crop yield forecasts. Being able to predict crop yields is crucial for government planning activities. In poor countries crop yield forecasts are needed for famine early warning systems (FEWS). In more developed countries crop production forecasts allow governments to be prepared for possible grain import needs and/or export grain surplus.

INIA/IFDC researchers are using NDVI information at critical crop growth stages to adjust regression functions for predicting grain yields. Work has begun with maize, wheat and pastures with excellent results. The NDVI values are being used jointly with crop/pasture simulation model runs to issue and update crop yield forecasts.

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References

Baethgen, W.E. 1998. El Niño and La Niña Impacts in Southeastern South America. Review on the causes and consequences of cold events: A la Niña Summit. Proceedings. M. Glantz (ed.) NCAR, Boulder, CO (http://www.dir.ucar.edu/esig/lanina/).

Baethgen, W.E. 1997. Relaciones entre la temperatura superficial del Pacífico tropical y los rendimientos de cultivos en Uruguay. Workshop and Conference on the 1997-98 El Niño: Impacts and Potential Applications of Climate Prediction in Southeast South America. December 1997. Montevideo, Uruguay.

Bidegain, M. and P. Krecl. 1998. Comportamiento de la temperatura en el sudeste de Sudamerica (Uruguay) asociado al fenómeno ENSO. Congreso Iberico - Latinoamericano de Meteorologia. Brasilia, Brazil. September 1998.

Díaz, A.; C.D. Studzinski and C.R. Mechoso. 1998. Relationships between precipitation anomalies in Uruguay and southern Brazil and sea surface temperature in the Pacific and Atlantic oceans. J. Climate, 11:251-271

Grimm, A.M.; S.E.T. Ferraz and J. Gomes. 1998. Precipitation anomalies in southern Brazil associated with El Niño and La Niña events. J. Climate:11:2863–2880.

Grondona, M.O.; G.O. Magrin; M.I. Travasso; R.C. Moschini; G.R. Rodriguez; C. Messina; D.R. Boullon; G. Podesta and J.Jones. Impacto del fenomeno "El Nino" sobre la produccion de trigo y maiz en la region Pampeana Argentina. Workshop and Conference on the 1997-98 El Niño: Impacts and Potential Applications of Climate Prediction in Southeast South America. December 1997. Montevideo, Uruguay.

Myneni, R.B.; S.O. Los and C.J. Tucker. 1996. Satellite-based identification of linked vegetation index and sea surface temperature anomaly areas from 1982-1990 for Africa, Australia and South America. Geophys. Res. Letters. 23:729-732.

Pisciottano, G.J; A.F. Díaz and C.R. Mechoso. 1994. El Niño-Southern Oscillation impact on rainfall in Uruguay. J. Climate, 7:1286-1302.

Podestá, G.P., C. D. Messina, M.O. Grondona and G.O. Magrin. 1998. Associations between grain crop yields in central-eastern Argentina and El Niño-Southern Oscillation. Journal of Applied Meteorology 38: 1488-1498.

Ropelewski, C.F. and M.S. Halpert. 1987. Global and regional scale precipitation patterns associated with El Niño/Southern Oscillation. Mon. Wea. Rev. 115:1606-1626.

Ropelewski, C.F. and M.S. Halpert. 1989. Precipitation patterns associated with high index phase of Southern Oscillation. J. Climate, 2:268-284.

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