2 A timeframe for agricultural recovery
Immediate activities: 0–6 months
Restoring public health and safety is the top priority in the aftermath of a major disaster (Waste Management World 2013). Sustainable management of disaster debris involves:
- collecting debris
- determining the constituents of the debris
- determining the potential toxicity of the debris and waste
- sorting the debris
- disposing of residual wastes.
Large amounts of debris similar to construction and demolition waste are generated in disaster events in urban areas; in rural areas, debris is more likely to contain natural materials and organic matter.
In Aceh, the bulk of the waste on agricultural land (Figure 6) consisted of sediments of various origin (see Section 3), organic matter and, on fields closer to urban centres, building debris.
In Japan, the three prefectures most affected by the tsunami on 11 March 2011 accumulated 22.5 million tonnes of tsunami waste (Jakarta Post 2013). Japanese authorities established temporary storage sites before separating the waste and incinerating combustible material.
Survey land levels
When a local earthquake triggers a tsunami, land levels can be altered. Surveys may be needed to establish the land levels, and direct the rehabilitation of drainage lines and irrigation channels. Some coastal areas may no longer be suitable for agriculture as a result of subsidence and increased frequency of tidal inundation.
The earthquake that produced the Aceh tsunami had a significant effect on the topography of the Aceh coast—land levels dropped 1–2 m in some coastal areas (FAO 2005c). Areas that were previously inhabited became permanently flooded, and drainage patterns and river flows changed, particularly in estuarine areas. In West Aceh, farmers reported that sand dunes disappeared, the river mouth clogged up and drainage channels changed, making land unsuitable for dryland crops. Restoring agriculture in such areas without adapting to these changes can lead to inappropriate management and wasted resources, and can be dispiriting for farmers who are already traumatised by the tsunami. Indonesia’s Soils Research Institute mapped tsunami-affected land on Aceh’s west coast using the Food and Agriculture Organization of the United Nations classification system (see Section 1), and GIS-referenced data and mapping software. This enabled assessment of the suitability of land for certain crops in tsunami-affected areas.
Topographic changes were not a problem in tsunami-affected countries such as Sri Lanka, India and Thailand, which were further from the earthquake zone. The combination of earthquake-induced changes in topography and the high inundation force of the tsunami led to more complex impacts in Indonesia than in other countries.
Assess soils, and train agricultural staff and farmers
The degree of soil salinity resulting from seawater inundation will depend on the soil conditions at the site, the duration of inundation and subsequent rainfall. Tsunami-affected agricultural soils need to be tested for salinity, physical condition and nutrient levels to ensure that farmers avoid sowing crops in unproductive soils. Farmers should be closely involved in these soil assessment processes to improve their understanding of soil conditions in the area and build their soil management capacity.
Details about how to assess soil salinity, water salinity and soil nutrient status are provided in Section 3.