Spatial Landuse and Farming System Analyses of Reclaimed Tidal Lowland in South

Abstract: This study aims to analyze spatial landuse and farming system of reclamated tidal lowland in South Sumatra, Indonesia by using remote sensing technology and GIS in knowing the distribution of landuse change of tidal lowland. From these conditions, it can see cropping patterns on each of the secondary block and its relation to the condition of the water system network. The study was carried out in Delta Saleh areas. The used methodology was field survey and remote sensing technique. It was combined with GIS technology for spatial analysis. Over the last 11 years (1992-2002), a decline in the paddy field area is from 23,619.4 ha to 18,518.40 ha(27.65%). A decrease of river acreage (water body) occurred from 6,643.53 ha to 6,559.83 ha. In 1992 it has not detected any coconut plantation, while in 2001 it showed an area of coconut plantation 3,422.84 ha and 3,822.84 ha in 2011. Significant changes are also presented in primary mangrove forest, widespread declining around 1,940.88 ha (147.20%). Most of the mangrove forest was converted into secondary mangrove forest and scrub. Linkage with topography type showed that the land with topography Type A was majority for paddy fields 250.28-262.80 ha (62.72%-65.59%). Mixed crop fields were in second place with acreage of 90.66-107.36 ha(22.72%-26.80%). The land with topography Type B showed the widest paddy fields (283.14-314.20 ha or 70.70%-78.48%), followed by upland crops. The land with topography Type C showed that paddy fields were 283.03-300.41 ha (70.66%-75.02 %), followed by upland crops 94.85-102.78 ha (23.69%-25.66%), and coconut was the smallest 0.09-0.27 ha. Generally, the cropping index was 100 on PS-1 (planting season 1) for BL-1 (business land 1) and BL-2 planted with paddy fields, while the PS-2 are generally not cultivated land (fallow).

Key words: Landuse, farming system, analyses, reclamated tidal lowland, South Sumatra, Indonesia.

1. Introduction

Swampy land in Indonesia is estimated to 39.4 million ha, comprising 24.7 million ha of tidal lowland and 14.7 million ha of lowland swamp. Around 33.7 million ha of swamp land is located in the Islands of Sumatra, Kalimantan, Sulawesi and Papua. From these acreages, 9.65 million ha have the potential to become agricultural land, but only about 13.5 % of which was utilized [1].

Land clearing of tidal lowland in Delta Saleh was purposed for transmigration program. The tidal lowland was given to the transmigration farmers an area of 2.25 ha per household. It consisted of business land 1 (BL-1, 1 ha), business land 2 (BL-2, 1 ha) and 0.25 ha for garden [1]. After some years occupied, some lands were converted to others purposes, not cultivated or becoming fallow. It was also built infrastructure to support community activities [2]. For the cultivated land, cropping patterns are generally not the same applied in a tertiary plot with other tertiary plots. Delta Saleh area was not all used for business, but there is a conservation area, green lines, residential areas, location of economic activity.

Based on topography (overflow type), the land reclamation was done by doing drainage channels which is likely to change according to environmental conditions. There are no available time series data to see a change in landuse patterns, park, conditions of existing infrastructure, so it often leads to make mistakes in decision-making development of the tidal area [3].

Changes in landuse, topography, conditions as well as cropping patterns in the field can be more easily interpreted by the help of remote sensing technology without having to survey the entire region. The infrastructure and other land conditions can be recorded through field observations and interviews with the community [4-6]. Remote sensing technology in this case using Landsat TM image is able to detect various types of landuse, vegetation and infrastructure. With such capabilities, the potential image is used as a means of identification of landuse, cropping patterns and hydrotopography of tidal lowland [7].

Problems in the Delta Saleh since reclaimed for transmigration program till today are follows, changes in landuse patterns are difficult to be estimated and its distribution in detail from year to year was calculated with conventional methods. Application of cropping patterns is not uniform and not suitable with the land condition especially in each secondary plots, thus it is causing low production. The infrastructure condition in each block varied, so it affected landuse patterns, land productivity and local community welfare. Conditions and design of various drainage networks are resulting in the availability of water in different fields and ultimately cropping patterns and landuse vary also [8, 9]. Currently not available time series data of land development of tidal lowland is the main problem in developing land management plans and land improvement. This study aims to analyze spatial landuse and farming system of reclaimedted tidal lowland in south Sumatra, Indonesia by using remote sensing technology and GIS in knowing the distribution of landuse change of tidal lowland. From these conditions, it can see cropping patterns on each of the secondary block and its relation to the condition of the water system network.

2. Materials and Methods

The research was conducted in the Delta Saleh, South Sumatra, Indonesia. Maps used are maps of reclamation network, topography maps, Landsat TM image Path/Row 124/62 in June 1992 and June 2002 record packaged in a CD-media ROM, and questioner for data collection of reclamation network conditions, cropping patterns and tracking network. The research was done by using maps with 1:100,000 scales. Field survey was done in July 2011 where soils were intensively described and classified according to Soil Taxonomy [10]. Composite soil samples were taken after completing soil profile descriptions and then analyzed in the laboratory for physical and chemical soil analyses. Agricultural production was recorded by using field square method (25 m × 25 m size) and combined with the questionnaire results and interview to the farmers.

3. Results and Discussion

3.1 Overview of the Delta Saleh

Delta Saleh is geographically located at latitudes 105°02’31" to 105°33′66′E and longitudes 2°20′10′to 3°07′43′S (Fig. 1).

Delta Saleh is a tidal lowland that is reclaimed and occupied by transmigration in 1981. Based on the topography type of land reclamation in Delta Saleh, the overflow Type B has 1,856 ha area, Type C is 5,630 ha and Type D is covering 2,944 ha. The dominant land(Type A) is a potential land area of 9,438 ha, and acid sulfate soil is 992 ha.

3.2 Spatial Analyses of Landuse Change

Delta Saleh was opened since in 1970s designed for transmigration program based on agricultural businesses. Since its opening till now, Delta Saleh has undergone many changes in landuse. Landuse change mainly is because of the pressure of population increases in order to fulfill the need for increased food. Based on the results of Landsat image interpretation

in 1992, 2002 and field survey of 2011 in Delta Saleh, the landuse types are summarized in Table 1.

From the results of interpretation of Landsat images in 1992 and field survey of 2011, there were changes in the type of significant landuse from 1992 to 2011. Changes in landuse are even up to more than 100%, either increase or reduction (Fig. 2). Large decrease in the river or water body was from 6,643.53 ha to 6,539.18 ha or 1.60% down. This is expected because the narrowing of the body due to sedimentation of the river, and land in 1992 was still under water, because of the making of the channel by the Bugis tribe, so the land can be cultivated for paddy fields or coconut plantation. There are significant changes in the primary mangrove forest, widespread decline around 1,940.08 ha (147.20%).

Direct interpretation resulted that most of the mangrove forest was converted into a secondary mangrove forest and scrub. This is presumably because the reducing of mangrove forests is becoming the shrubs. On the other hand an increase in secondary mangrove forest area of 345.64 ha (11.81%) is probably derived from primary mangrove forest.

1992 the extent of 7,889.40 ha, in 2002 the area of 8,756.48 ha, while in 2011 to 9,345.78 ha. During the twenty years, it had an increase of 1,456.36 ha (18.46%) in area. This happens because the mangrove forest was cut down and then left as the shrubs. Shrubs land also comes from fields that are not cultivated, which is because of inadequate drainage infrastructure and lack of manpower and technology to work on these fields.

In 1992, the land area or an upland mixed crops was 7,410.87 ha area, it increased to 9,924.89 ha in 2002 and 9,206.24 ha in 2011. From 1992 to 2002 it was an increase of 2,514.02 ha (33.92%), whereas in 2011, a decline number was 718.65 ha (7.24%) compared with those in 2002 This field was caused by that a lot of lands are not cultivated and becoming shrubs.

During the last ten years a decline in the paddy fields field was from 23,619.4 ha in 1992 to 18,518.40 ha in 2002. It was around 5,101.0 ha or 21.59%. This was due to conversion of paddy field to coconut plantation, besides that, because the inadequate drainage facilities cause the water available in the fields, so that fields cannot be cultivated.

In 1992, it has not detected any coconut plantation, while in 2002 it showed an area of coconut plantation 3,422.84 ha and 3,822.84 ha in 2011. This land had been a paddy field or shrubs, most of these are found in the North of Delta Saleh. This is because of the activities of the Bugis tribe making channel to open the land into coconut plantations or paddy fields. 3.3 Relationship of Topography and Landuse

The determination the effect of topography, landuse

patterns and farming systems was carried out using detailed observations on several blocks that have secondary topography or different type of overflow. The observation in the village of Srimulyo, primary and secondary block 10 South 2 (P10-2S), P10-2N, and Category III (Type C overflow) showed that this land is not flooded by high tide and low tide, but ground water is less than 50 cm. This information shows that this land could be used for paddy field, but need good water management. This land can also be used for plantation crops.

The observation in the village of secondary block of Sidoharjo P8 and P8-6S-7S showed that most of it consists of Category II (Type B overflow) or periodically inundated by the high tide, the surface soil above the water level below the lowest tide). This land could be used for paddy fields.

Results showed that Damarwulan village in the secondary block P6-P6-7S and 7N, mostly consisted of Category I (Type a overflow) or periodically inundated by the high tide and low tide). This land is suitable for paddy fields. Landuse of each topography type is summarized in Table 2 and the landuse maps in each type of topography in 1992 and 2002 are presented in Fig. 3. From the image interpretation results of 2002 and filed survey in 2011 showed that the Type A of topography (Damarwulan Village Primary Secondary 6 Block 7 South (P6-7S) and (P6-7N), most of the landuse were paddy fields of 250.28-262.80 ha of these secondary block area. Upland crops or mixed crops were in the second place 90.66-10.74 ha.

In the Type B topography in the village of Sidohardjo (P8 and P8-6S-7S), it showed that the largest fields were under paddy (283.14-314.20 ha) and the upland crops are in the second place. On this site, channel or water body was not interpreted because the channel was covered with grass. At this location is not found in coconut plantations, because its location is far away from the river, so the coconut is less suitable.

Land that has topography of Type C in the village

of Srimulyo (P10-2N and P10-2S) was identified as paddy fields around 283.03-300.41 ha. Dry field area was in second place (94.85-102.78 ha). Coconut occupied the smallest area of 0.09-0.27 ha and mostly it was found in home garden only.

Using spatial analysis, it is indicated that the uncultivated land or shrubs was in the largest Type A of topography (10.80 ha) and the smallest in topography Type C was 2.97 ha. From these data it is shown that although Type A is still a lot of land is not utilized due to lack of appropriated drainage network conditions, so there is land that is flooded, and there is a drought.

Image analysis showed the greatest changes in landuse occurred in the Type A topography was 123.31 ha in the Secondary Block P6-7S and 130.31 ha in the Secondary Block P6-7N. The biggest change in the paddy field reached 48.64%, decreased area changes, the paddy field of 1992 reached 80.29% of the secondary block, whereas in 2011 the area was decreased 65.59%. Widespread decline of this field is due to the drainage channels that are not equipped with proper infrastructure to support so that land can no longer be used as paddy fields. Beside that lack of technology of land cultivation causes farmers could not work on all the land he owned.

From the results of imagery landsat interpretation and field observation for ten years, the landuse in this field changed into the shrubs land, upland crops or a mixed crops and coconut trees. This is reflected by an increase in the shrubs area in 1992 covering 15.23 ha to 37.53 in 2011 for a secondary block, and the addition of coconut was 11.16 ha in 2011.

Wide-enhancing land also occurred in the field or mixed crop. In 1992 its extent was 52.58 ha and 62.73 ha in 2001 while in 2011 it reached 90.66 ha. Changes occurred for 22.65% and 44.06%. This increase occurred because the water is not sufficient that a mix plants do not require so much water.

On topography Type B in Sidoharjo Village (P8 and P8-6S-7S), it occurred reduction of the shrubs area 25.00 ha and 48.71 ha in 1992 to 18.58 ha and 12.78 ha in 2011. This caused a lot of shrubs land in many open fields or crops to be mixed crops. This is reflected in the increasing expansion of the mixed crops in 1992, covering 55.17 ha and 70.12 ha and increased to 104.57 ha and 102.78 ha in 2011, in other words an increase in area of 12.42 ha and 34.45 ha.

The topography Type C is represented by the village of Srimulyo (P10-P10-2S and 2N), paddy fields declined fields of 59.37 ha and 57.35 ha. The same thing happened in the shrubs decrease of 6.21 ha and 15.40 ha. Results from field observations and images showed changes landuse of paddy fields, shrubs and mix crop. Results also showed that upland crops increased to 61.98 ha and mixed crops increased to 73.42 ha. This is because of lack of water and the dry land can only be planted with these crops.

3.4 Farming System

Farmers in Delta Saleh come mostly from Java Island. The allocated land for transmigration area is 2 ha per household, consisting of BL-1 (business land 1) 1 ha and BL-2 (business land 2) 1 ha. The cropping pattern conditions depended on the land, the overflow type and completeness of existing drainage network system. Generally there are two planting seasons, i.e. PS-1(planting season 1) in month of November to March and PS-2 (planting season 2) in the month of May to August. Existing cropping patterns in each block of secondary observations are presented in Table 2.

In the Damarwulan Village represented by Type A topography in Block Secondary (P6-7N) showed in Planting Season 1 (PS-1) and BL-1, mostly cultivated for paddy (84.37%) and 9.38% planted with coconut along boundaries of paddy fields to increase farmer’s income. BL-2 was still dominated by paddy fields 71.8%, but the BL-2 in PS-1 still have fallow of 15.7%. Whereas on the PS-2 (both BL-1 and BL-2), most of area was not cultivated (fallow) 84.37% on the BL-1 and 87.5% on the BL-2. On the PS-2, the land was fallowed due to lack of irrigation infrastructure causing

flood on the land.

In the secondary block (P6-7S) on the PS-1, BL-1 and PS-2, mostly paddy fields were cultivated (85.93%) in the BL-1 and (88.2%) in the BL-2, while on the PS-2 generally, it was not cultivated (fallow) by farmers. In the Village Sidoharjo (P8-6S) and (P8-7S), it was Type B. In both PS-1, BL-1 and BL-2 were dominated by paddy fields (more than 80%). Results showed that in village BL-1 was not only cultivated monocrop, but also intercropping vegetables between paddy fields which were 12.5% in the BL-1 and 10.16% in the BL-2. On the PS-2, most of land was fallowed mainly in the BL-2 (100%), whereas in the BS-1, it was still planted with vegetables (12.50%). This is because the land is relatively dry and its drainage infrastructure does not work; farmers can still grow vegetables only just to meet the needs of their own households.

In the overflow Type C in Srimulyo village (P10-2N) of PS-1, BL-1 and BL-2, all lands were planted with paddy fields, although there is intercropping with coconut trees. While on the PS-2, the land was fallowed because the drainage network is not functioning and not equipped with water gates and plants were suffering water shortage problems.

In the secondary block (P10-2S), on the PS-1, around 93.75-100% of lands were cultivated with paddy fields, while on the PS-2, the BL-1 was cultivated with corn 15.63% and 6.40% for soybean. In the PS-2, the lands can still cultivate both grain and cash crop, because it was equipped with facilities of adequate drainage network, but it was well maintained channels because the drainage systems are equipped with water gate. Only socio-economic problems cause farmers cannot plant twice of paddy fields.

4. Conclusions

Over the last ten years (1992-2001), a decline in the paddy field area is from 23,619.4 ha to 18,518.40 ha(27.65%). A decrease of river acreage (water body) occurred from 6,643.53 ha to 6,559.83 ha. In 1992, it has not detected any coconut plantation, while in 2002 it showed an area of coconut plantation 3,422.84 ha and 3,822.84 ha in 2011. Significant changes are also presented in primary mangrove forest, widespread decline around 1,940.88 ha (147.20%).

Most of the mangrove forest was converted into secondary mangrove forest and scrub. Linkage with topography type showed that the land with topography Type A was majority for paddy fields 250.28-262.80 ha(62.72%-65.59%). Mixed crop fields were in second place with acreage of 90.66-106.36 ha(22.72%-26.80%). The land with topography Type B showed the widest paddy fields (283.14-314.20 ha or 70.70%-78.48%), followed by upland crops. The land with topography Type C showed that paddy fields was 283.03-300.41 ha (70.66%-75.02%), followed by upland crops 94.85-102.78 ha (23.69%-25.66%), and coconut was the smallest 0.09-0.27 ha. Generally the cropping index was 100 (it is planted one time per year) on PS-1 for BL-1 and BL-2 planted with paddy fields, while the PS-2 are generally not cultivated land(fallow).

References

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