INDONESIA

8 October 2005 - 30 May 2006

UniConsult International Ltd (UCIL)

DESALINISATION & SOIL IMPROVEMENT SPECIALIST

Earthquake & Tsunami Emergency Support Project (ETESP)

ADB (Asian Development Bank) and BRR (Badan Reclamasi dan Rekonstruktsi)

 

Ship in Middle of Banda Aceh City Damaged Drain Northern Sumatera Dead Crops on Saline Fields Dead Rice & Saline Flood-water

Background: The Tsunami of 26 December 2004 inundated northern Sumatra and dumped vast amounts of sea-water plus sediments and debris on the land as well as virtually totally destroying a large proportion of the infrastructure - social and agricultural.  Under ADB the Earthquake and Tsunami Emergency Support Project (ETESP) was set-up to assess the situation and propose remedial measures to assist the area recover from this natural disaster.  The Desalinisation and Soil Improvement Specialist mobilised in October 2005 and was tasked with assessing the situation with respect to soil damage and designing remedial interventions to enable the reclamation of the soil and farmland to allow agriculture to resume as quickly as possible.

What was available: At the time the ETESP Inception Report was prepared very little data had been located about the soils, salinity and sediment problems brought about by the tsunami. However, there was limited information available relating to the extent and degree of damages – most of this data being available in the ADB GIS Mapframe system  Other data were made available through BPTP (Balai Pengkajian Teknologi Pertanian), including the raw data for a salinity survey done using an EM38 salinity probe.  These data were studied, analysed and manipulated to produce salinity values for the soils to enable reporting and pinpoint missing data items.  The sites were then visited to collect additional data to allow completion of the assessment.

What was found: The data collected from the salinity survey had not been fully assessed or used and that no or very few interventions to improve the condition of the land had been put in place or designed, apart from supplying the farmers with standard inputs of seed, fertiliser and other agricultural materials.  Any of these inputs of seed and fertilisers that were applied to salt damaged land were totally wasted as no crops grew where salinity existed.

What had been done: People saved, assisted and housed plus fed, houses built, roads re-habilitated and basic infrastructure built-up

What had not been done: There had been no attempt to spatially locate and map the variously damaged areas.  There were tables of data for districts and villages which were damaged and to what degree but the the lack of a rapidly compiled map showing what was damaged, to what degree where just did not exist. As of the end of 2005 no map had been produced so planning rehabilitation activities was well nigh impossible

Salinity and Drainage: At some point “someone” said – “there is NO SALINITY problem” in Aceh and people / experts / advisers stopped thinking. However, there was, and still is in places, is a “chronic”, low grade problem and it does involve salinity.  Generally, soil EC values are less than 4dS/m and this falls in Salinity Class SC1, which is usually an easy problem to overcome – often without a reclamation leaching programme.  However, something that virtually everyone missed, or ignored, was the WATER TABLE levels which were horrendously high in many places. High water tables mean any soil drainage has to be “lateral” in nature and, as the Tsunami affected area is virtually flat and drainage lines and channels were blocked, damaged and not operating – often through long-term neglect and not just due to tsunami damage – land drainage was NOT operating.

Salinity in Low Lying Places: Very few locations had been badly salinised and usually those that were badly effected are very low lying, close to the sea or coastline and adjacent to fish ponds. In some cases there is now active sea-water intrusion to these low lying sites. Such soils may not be reclaimable for agriculture but income generation can be restored via land use change with the development of, for example, fish ponds.

Sediments: The perceived large problems caused by depths of sediment appeared to be unfounded in most cases.  Many sites were seen where farming has been restored following desalinisation after the sediments were thoroughly mixed in with the native soil, often with the addition of copious amounts of organic matter in the form of FYM or compost and sometimes  mineral fertilisers.  Most of the fine textured sediments would not have come from the sea but would have been topsoil material picked up by the tsunami wave as it crossed the land, they would have been saline but only from the sea water that carried them. 

 Sandy, or coarse textured, sediments, which were found mainly close to the coast line, would most probably have originated from the sea-bed, would have been saline but, being sandy in nature, could not contain vast amounts of salt and  salts are easily removed from sand by leaching. However, there is a problem in places by the depth of sand that has been deposited since sands have low water holding capacity, low inherent fertility and low fertility potential.  Where there are deep deposits of sand these deposits may have to be manually removed and trucked away.  Shallow sand deposits should be ploughed in just like other deposits and incorporated with the native soil.

Input: The Soil scientist mobilised October 2005 and completed tour on 21st December when he departed from BA on leave returning in February 2006 until May 2006

 Activities: Using raw data supplied by Government partnership agency (BPTP) of salinity survey of 20 sites in Banda Aceh, Aceh Besar, Pidie and Bireuen; studied, analysed and manipulated these data to get soil salinity values for the sites in question.  All sites then visited to collect additional data to allow full assessment plus compile scenario descriptions with required intervention activities and recommendations.

 Manipulated semi processed soil laboratory data supplied by NSIASP (Northern Sumatera Irrigated Agricultural Sector Project) to allow assessment by ETESP Agriculture and Irrigation Components.  System and spreadsheet designed to allow improved processing and data presentation – assessment completed for areas on North Coast with data.

Attended and participated in FAO – BRR Workshop session on soil and land reclamation, compiling the output report for the session and passing to FAO Banda Aceh.

 Participated in inter-component meetings between Agriculture, Irrigation and Fisheries to respond to soil points arising.

 Visited salinity survey sites in Aceh Besar (Nusa, Blang Kreung and Suleue) with BPTP staff,  FAO field staff from Bangkok, ETESP Agriculture staff and ETESP Spatial Planning civil engineering and GIS staff to describe findings and conditions.  At these same sites held discussions with farmers and other local people explaining soils and drainage problems and suggesting self-help interventions, plus advised that all drains required rehabilitation.

Outputs:

  1. Compiled full reports for Banda Aceh and Kabupatens Aceh Besar, Pidie and Bireuen covering the salinity survey with all data collated, problems described and interventions suggested

  2. Compiled Executive Summary report for the above areas

  3. Compiled “Site Visit” report describing Lhoong area with possible soil survey requirements

  4. Compiled and used MS Excel spreadsheets as tools covering:

  • Calculation of salinity levels from EM38 salinity probe data

  • Calculation of “leaching water” requirements based on data extracted from above reports

  • Calculation of “leaching progress” and volumes of water required to reclaim any specific site

  • Calculation of “ratings” for various soil fertility and other data based on laboratory data

Obtained and processed topographical maps for much of the Northern Sumatera Area from an FAO source and geo-registered these maps in the GPS software Ozi Explorer for use by project.

 

Austin Hutcheon January 2006