Steps and Methods for the Identification of Potential Land-Use Units

In the San Patong Land Reform Area, Chiang Mai Province, Northern Thailand

Dr. Harald Kirsch1, German Development Service (DED), Phnom Penh Abstract Within a joint project carried out by three academic institutions from Germany, Netherlands and Thailand in 1992 - 1995 potential land-use units were defined for a land reform area in Northern Thailand. After a stepwise integration of physical and socio-economic data all land use potentials and con-strains were analysed to explain land use changes occurred during the project period, and to sug-gest potential future types of land utilization. Besides economical constrains, the soil quality and access to water proved to be the main factors. Since the physical conditions defining the land suitability in the study area are very similar to the flat to slightly undulating lowland areas of Cambodia, conclusions for a process leading from land resource assessment (LRA) to a land suitability evaluation in this country can be drawn. Land suit-ability evaluation is supposed to support Participatory Land Use Planning (PLUP) in Cambodia. This paper summarizes the content and main points of the corresponding presentation given by the author during the LRA Forum in Phnom Penh, Cambodia in Sept. 20042. 1. Introduction The project reported here, with the title Improvement of Crop Yields and Simultaneous Environ-mental Impact Assessment in Conjunction with Intensification and Diversification of Agroforestry on Marginal Land in Northern Thailand was carried out between May 1992 and April 1995. It was sup-ported by the European Commission under the program "Life Sciences and Technologies for De-veloping Countries #3 (STD3). The project's main objectives were (RAKARIYATHAM & KIRSCH 1995): Improvement of crop yields by analyzing their key parameters together with an inventory of

natural resources, followed by a classification of potential land-use units. Assessment of the impact of agricultural land-use on the environment. Assessment of the sustainability of agroforestry on marginal land. Training of Thai scientists in the fields of ecological research and GIS. Improving agricultural technology and making it available to the farmers. Providing data as a base for further development.

Institutions from three countries were involved in the project. These were: Institute for Physical Geography, Frankfurt University, Germany ITC Enschede, The Netherlands Dept. of Geography, Faculty of Social Sciences, Chiang Mai University; Dept. of Sociology and Political Science, Faculty of Social Sciences, Chiang Mai University Dept. of Chemistry, Faculty of Science, Chiang Mai University Multiple Cropping Centre, Faculty of Agriculture, Chiang Mai University

1 Dr. Harald Kirsch, PLUP Adviser, c/o DED, P.O. Box 628, Phnom Penh, Cambodia; HaraldCM@hotmail.com 2 BELL et al. (2006)

Harald Kirsch: Steps and Methods for the Identification of Potential Land-Use Units

2

The Dept. of Geography of Chiang Mai University (CMU) was responsible for the co-ordination and management of the multidisciplinary project, supported by a visiting scientist from Frankfurt University. Students from Chiang Mai and Frankfurt had the chance to do research in the study area for their M.Sc. or Diploma thesis. 2. The study area: location, relief, history and background The project area is located in the upper Mae Nam Ping basin about 35 km southwest of Changwat Chiang Mai, between Amphoe San Patong, Changwat Lamphun, Amphoe Chom Thong and the Doi Inthanon mountain range (fig. 1). It comprises 26 km2, and elevations range from 300 to 370 m above sea level. The relief is in general flat to undulating (photo1), with escarpments separating the upper terrace from the lower lying relief units (photo 2, fig. 2). The area is under the land allo-cation program (Chom Thong Land Reform Area) of the Land Reform Department (LRD); its larg-est part of it is located on the topographical map sheet named Amphoe San Patong. The rain shadow effect of the Doi Inthanon mountain range is quite significant. The average annual precipitation of 690 mm amounts about 60 % of the rainfall in Chiang Mai 35 km to the north. In the study area a very pronounced dry spell occurs in July.

Since 1986 at total number of 2400 plots of land were distributed by LRD to 1960 poor, landless farmers and their families. Most of the farmers (85%) have a plot of 5 rai (8000 m2), while the early settlers who cleared the land received 10 rai (15%). Previously the land was covered by degraded dry deciduous forest and grassland (mainly Dipterocarpus spp. and Imperata cylindrica). The deg-radation was a result of the extension of farmland for soybean and tobacco cultivation, but also of extensive firewood and charcoal production since 1952.

Figure 1: Location of the study area

Location of the study area (Topographic Map 1:250 000, Sheet NE 47-6, Changwat Chiang Mai)

Harald Kirsch: Steps and Methods for the Identification of Potential Land-Use Units

3

Photo1: Gently sloping relief of the project area Photo 2: Edge of the upper terrace

The land reform program is supported by the Multiple Cropping Centre (MCC) of Chiang Mai Uni-versity in the fields of crop research, extension and technical advisory service. MCC is also running a test and demonstration plot in the LRD area

3. Basic data: collection, processing and presentation The data sources used were field survey results, aerial photos, satellite images, and topographical maps of various scales. Additional information came from laboratory analysis of soil and water samples, socio-economic studies conducted by students of CMU, and participation of local farmers. All field data and mapped information were processed with the GIS ILWIS, provided by ITC Enschede. These were the major steps:

Figure 2: Overview map of the major relief units of the upper Ping Basin

Harald Kirsch: Steps and Methods for the Identification of Potential Land-Use Units

4

To get an overview on the landscape and its characteristics, the relief units of the upper Mae

Ping basin were classified according to interpretation of aerial photographs (1:50 000). A draft was made with the topographical map (1:250 000) as a base map, and then digitized.

Through field survey it was found that the flood plain / lower terrace, middle terrace and upper

terrace (photo 2) as well as the eastern part of the hilly and mountainous area are composed of loose Pleistocene sediments. Tectonic uplift and lowering, and related sedimentation and de-nudation caused the different relief units and elevation levels (fig. 2 & 43).

A LandSat 5 TM interpretation provided information on different ground cover and moisture

conditions in the study area and its surrounding landscape. Based on a topographical map (1:10 000) with 1-meter contour interval (provided by the LRD)

elevation and slope maps were produced. Elevations range from 305 m on the lower terrace to 368 m in the hills. About 80% oft the area has a level to gently sloping (undulating) relief with a slope of 0 – 3.5% (photo1).

Zones of geomorphological structures (faults and joints, drainage systems, escarpments) were

identified by interpretation of aerial photographs (1:15 000), then transferred on the base map (topo map 1:10 000) and later digitized (fig. 4).

Land use and vegetation data were collected by ground survey conducted by Geography stu-

dents of CMU in 1992 and 1994. The surveys showed that the number of fallow land plots and orchards increased during that period, while the number of plots with annual crops declined (fig. 5).

Geologically the whole project area is build up by 4 types of loose sediments. Point data gained from field survey (ca. 70 soil survey sites) were extrapolated and then correlated with relief units and land use. In more than 70% of the area the pinkish white sand forms the topsoil. Five different soil profile types could be distinguished according to the sequence of the geological material (fig. 3).

It was found that the 5 major profile types form different soil types - mainly varieties of Alisols, Ac-risols, Plinthosols and Arenosols - related to relief, tectonics, and hydromorphic influence (fig. 6, photo 3). Like in other parts of Thailand, alternating sedimentation and erosion processes and also 3 Figures 4 - 7 see annex

Figure 3: The five major soil profile types of the study area distinguished according to geology and strati-graphic sequences (CL1: pinkish white sandy layer, CL2: orange/red clayey layer, GR: gravel layer in sandy clayey matrix, Other material (hillwash or suspended load).

Harald Kirsch: Steps and Methods for the Identification of Potential Land-Use Units

5

Photo 3: Lateritic gravel underlying a sandy cover layer

bioturbations - mainly by termites - seem to be a main cause for the development of multi-layered soil profiles (KIRSCH 1998). 4. Data interpretation To identify significant land use changes between 1992 and 1994, the results of both surveys were overlaid. Fallow land and mango orchards have been mainly unchanged in that period. Most of the land that was mapped as fallow plots in 1994 was normally used for annual crops two years before. Orchards were newly established on most formerly fallow land plots that came under cultivation in 1994 (fig. 5). Land plots that have been allocated by the Land Reform Department (LRD) and were not used (fal-low) during the 1994-95 cropping season were overlaid with the soil map to identify the respective soil types. To determine the reasons why the respective farmers did not use their land, the dis-tances to the reservoirs (photo 4) were also taken into consideration: Table 1: Soil types and land use limitations in the study area FAO Soil Unit4 Area km2 Area % Possible obstacles for land use Haplic Alisol/Acrisol 2.21 29.66 Distance to reservoir; economical Gleyic Alisol/Acrisol 0.53 7.11 Flooding during the rainy season Stagnic Ali./Acrisol 0.38 5.10 Distance to reservoir; economical Dystric Plinthosol 0.57 7.65 Gravel and laterite at the surface, soil poorly developed Albic Plinthosol 1.53 20.54 Distance to reservoir; low fertility, shallow soil development Calceric Regosol 0.03 0.40 Coarse-textured soil; soil poorly developed Ferralic Cambisols 0.15 2.01 Distance to reservoir; economical Albic Arenosols 0.95 12.75 Low fertility, distance to reservoir Gleyic Arenosols 1.09 14.63 Low fertility, distance to reservoir Gleysols 0.0 0.13 Flooding during the rainy season To determine the potential erodibility of bare soil by water, the slope map and the spatial data of the composition of the upper soil layer were overlaid. The erodibility by water (EfW classes 0-5) was classified (AG BODENKUNDE 1992: 172-175; rain factor = 80, slope length = 100m) accord-ing to slope and texture of the topsoil: Table 2: Potential Erodibility of the Topsoil by Water Efw Class Classification Assumed Ero-

sion [t/ha/y] Protective Measures Area [km2] Area [%]

0 None < 1 Not required 0.43 1.651 Very low 1 - 5 Required according to land use 2.17 8.342 Low 5 - 10 Required according to land use 8.22 31.583 Medium 10 - 15 Required according to land use 6.18 23.744 High 15 - 30 Strongly recommended 5.59 21.485 Very high > 30 Strongly recommended 2.28 1.00 Considering the fact, that 400 m is the maximum reasonable distance the farmers can carry water in buckets (VEERAYANO 1994), a 400 m buffer line from the edges of the reservoirs was drawn.

4 FAO-UNESCO (1988)

Harald Kirsch: Steps and Methods for the Identification of Potential Land-Use Units

6

Photo 4: Reservoir on upper terrace

Only reservoirs which contain a sufficient amount of water throughout the year have been taken into account. The water demand of fruit trees reaches the maximum in April and May, the end of the dry season. A water deficiency during that time will result in a loss of the harvest. Only 21% of the land plots are located within a 400 m dis-tance from a reservoir. Relatively high ground-water levels were ob-served in certain areas during fieldwork. These areas are strongly related to the geo-morphologic development of the relief. As there is an urgent need for additional water supply in the LRD area, a map identifying these areas with high groundwater level pro-vides information about potential locations for wells. In contrast to reservoirs, wells can be dug by the farmers without great cash invest-ment. Another advantage of wells is the very low evaporation compared with the open water sur-face of a reservoir. Three classes can be distinguished: 1. High potential: a ground water table of 2-6 m below surface (in the dry season) can be expected in de-

pressions without outlet, and in positions located up to about 150 m away from intermittent drainage (pe-riodical streamlets) on the middle terrace and lower parts of the upper terrace [Area = 5.48 km2, 21.07%].

2. Medium potential: a ground water table of 8-15m below surface (in the dry season) on the middle terrace. [Area = 2.17 km2, 8.34%].

3. Unsuitable: the rest of the area is unsuitable because of hard laterite in the soil profile, deep ground-water levels (>20 m), or because reservoirs have been built there already. [Area = 18.38 km2, 70.59%]

5. Results of data interpretation By combining all relevant information from the previous maps the research team identified thematic mapping units for potential land use. Figure 7 (see annex) indicates these potential land-use areas (or TMUs) and their attributes. The classification of the TMUs was done using information on pre-vious land use, soil properties, and the availability of water (distances from a reservoir). It has to be noted that the TMUs (tab. 3) reflect the conditions during the time of the research pro-ject and might have a different appearance today, since conditions and opportunities have changed and new agricultural technologies have been developed. By adapting the input parame-ters of the model - e.g. after improving water supply - the effected plots can be reclassified into other units. Table 3: TMUs for Potential Land Use TMU No. Name Description Limitations Area

1 Forest Already forested areas located out-side the LRD plots 2.47 km2,

9.50%

2 Unsuitable for agriculture

Previously fallow land on Dystric Plinthosols

Poor soil quality makes this area unsuitable for field crops as well as for fruit-trees

0.68 km2, 2.61%

3.1 Animal farm (live-stock)

Already established pig and cow farms < 400 m from reservoir 0.01 km2,

0.03% 3.2 Animal farm (lim-

ited suitable) Already established pig and cow farms > 400 m from reservoir 0.09 km2,

0.36%

Harald Kirsch: Steps and Methods for the Identification of Potential Land-Use Units

7

TMU No. Name Description Limitations Area

4.1 Undemanding5 field crops with shallow root sys-tems

Previous fallow and field crop ar-eas. Albic Plinthosols with low soil-moisture capacities and fertility rates; < 400 m from reservoir

Laterite in 40-60 cm depth can limit the root develop-ment

0.87 km2, 3.34%

4.2 Undemanding5 field crops with shallow root sys-tems

Previous fallow and field crop ar-eas. Albic Plinthosols with low soil-moisture capacities and fertility rates.

Laterite in 40-60 cm depth can limit the root develop-ment; > 400 m from reser-voir; unsuitable for reservoirs or wells

1.68 km2, 6.47%

5.1 Orchard

Already established orchards or intercropping systems (mango and longan mixed with field crops, e.g. soya) on various soil types; < 400 m from reservoir

1.17 km2, 4.49%]

5.2 Orchard (limited suitable)

Already established orchards or intercropping systems (mango and longan mixed with field crops, e.g. soya) on various soil types

> 400 m from reservoir 6.03 km2, 23.15%

6.1 Field crops, or-chards (inter-cropping), agro-forestry

Previously fallow, field crop and intercropping areas on Haplic or Stagnic Alisols and Acrisols < 400m from reservoir; most suitable crop-ping area.

0.75 km2, 2.87%]

6.2

Field crops, or-chards (inter-cropping), agro-forestry (limited suitable)

Previously fallow, field crop and intercropping areas on Haplic or Stagnic Alisols and Acrisols

> 400 m from reservoir 4.24 km2, 16.29%

6.3

Field crops, or-chards (inter-cropping), agro-forestry (perched ground water)

Previously fallow and field crop ar-eas on Gleyic Alisols and Acrisols

Frequent flooding during the rainy season can damage crops

1.02 km2, 3.91%

7.1 Field crops, or-chards (inter-cropping)

Previously fallow and field crop ar-eas on Arenosols < 400 m from reservoir

Sandy soil 0.22 km2, 0.86%

7.2 Field crops, or-chards (inter-cropping), limited suitable

Previously fallow and field crop ar-eas on Arenosols

Sandy soil, > 400 m from reservoir

2.97 km2, 11.41

8 Public and resi-dential areas

Already established public and residential areas 0.79 km2.

3.02%

9 Reservoir or pond Already established reservoirs and ponds

Water-holding capacities could be improved by cover-ing the bottom with plastic sheets

0.49 km2, 1.88%

In thematic units defined suitable for agriculture, protective measures against soil erosion might be required in certain areas. Soil-improvement measures, like mulching and application of lime and fertilizers, are absolutely necessary on all soil types.

5 Related to nutrients supply

Harald Kirsch: Steps and Methods for the Identification of Potential Land-Use Units

8

6. Lessons learned -> Implications for Cambodia Since the physical conditions defining the land suitability in the study area in Thailand are very similar to the flat to slightly undulating lowland areas in Cambodia, conclusions for a process lead-ing from land resource assessment (LRA) to a land suitability evaluation in this country can be drawn. Land suitability evaluation is supposed to support Participatory Land Use Planning (PLUP) in Cambodia (ROCK 2001, MIN et al. 2003, KIRSCH 2005). Any land use planning should strongly consider suitability aspects based on bio-physical and so-cioeconomic conditions. Improvement of soil fertility and water supply can increase the suitability. Simple technologies have to be preferred. A clear legal situation with respect to land tenure and the rule of law are preconditions for every successful planning process. Survey tools should be used according to the objective. The use of remote sensing needs confir-mation by ground check. Depending on the scale, ground survey is sometimes cheaper and more accurate. Cooperation between independent academic institutions, government departments, and the rural population can be very fruitful for both sides, e.g. in the sector of agricultural extension and diversi-fication of crops. However, success depends on the capacity of universities, etc. and the coopera-tive attitude of government officials. To set up demonstration plots in villages can inform and motivate farmers. Integrated decentralized projects need to be initiated. Government institutions should eventually acquire the attitude of a service provider and enable ac-cess to information products and data without bureaucratic hurdles. 7. References AG BODENKUNDE (1992): Bodenkundliche Kartieranleitung. - 3rd ed.: 331 pp., 19 fig., 98 tab.; Hannover. BELL, R., COUGHLAN, K., HUNTER, G., McNAUGHTON, R., & SENG, V. [Eds.] (2006): Proceedings Land

Resource Assessment Forum for Cambodia. September 14-17, 2004. – CARDI; Phnom Penh. BROGE, N.H., ISAGER, L., UPARASIT, U., SANGAWONGSE, S. & KIRSCH, H. (2000): The use of remote

sensing and anthropological tools to define multifunctional landscapes in Thailand. - In: BRANDT, J., TRESS, B. and TRESS, G. [Eds.] Multifunctional Landscapes: Interdisciplinary Approaches to Land-scape Research and Management. - Conference material for the conference on "multifunctional landscapes", Center for Landscape Research, Roskilde, 18-21 October 2000.

FAO-UNESCO (1988): Soil Map of the World, Revised Legend. - World Soil Resources Report, 60: 79 pp.;

Rome KIRSCH, H. (1998): Untersuchungen zur jungquartären Boden- und Reliefentwicklung im Bergland

Nordthailands am Beispiel des Einzugsgebiets des Nam Mae Chan in der Provinz Chiang Rai. – (Quaternary Soil and Relief Development in Northern Thailand, German with English and Thai sum-mary) Frankfurter Geowiss. Arb., Ser. D, 23, 307 pp.; Frankfurt a.M.

KIRSCH, H. (2005): The Use of Geo-Information Tools and Products in Participatory Land Use Planning

(PLUP) in Rural Cambodia. – Pacific News 23: 23 – 26; Göttingen. MIN BUNNARA, KIRSCH, H., & DÜMMER, I. (2003): Participatory Land Use Planning in Cambodia: Concept

and Experiences after the first year. – KEN, S.R., CARSON, T., RIEBE, K., COX, S. & KASCHKE, E. VAN [Eds.] (2005): The Development of Community Based Natural Resources Management

Harald Kirsch: Steps and Methods for the Identification of Potential Land-Use Units

9

(CBNRM) in Cambodia. – WWF Cambodia, CBNRM Learning Institute; Phnom Penh. RAKARIYATHAM, P. & KIRSCH, H. [Ed.] (1995): Improvement of Crop Yields and Simultaneous Environ-

mental Impact Assessment in Conjunction with Intensification and Diversification of Agroforestry on Marginal Land in Northern Thailand. - Final Report to EC; Vol. 1 [General Reports and Summaries]: 73 pp.; Vol. 2 [The Database]: 91 pp., 1 micro disk; Vol. 3 [Maps of the Chom Thong Land Reform Area]: 34 pp., 17 maps; Chiang Mai (Faculty of Social Sciences, CMU).

ROCK, F, [Ed.] (2001): Participatory Land Use Planning PLUP in Rural Cambodia. Manual for Government

Staff and Development Workers. - (English and Khmer Version) Ministry of Land Management, Ur-ban Planning and Construction; Phnom Penh.

VEERAYANO, V. (1994): Land use and Land Suitability in the Land Reform Project Area, Amphoe Chom

Thong, Changwat Chiang Mai. - B.Sc. thesis in Thai, Chiang Mai University; Chiang Mai. 8. Annex Four out of 17 maps produced for the map volume of RAKARITATHAM & KIRSCH (1995) are pre-sented on the following pages (figures 4 – 7).

Harald Kirsch: Steps and Methods for the Identification of Potential Land-Use Units

10

Figure 4: Map of Relief Units and Geomorphological Structures Figure 5: Map of Land Use Changes between 1992 and 1994

Harald Kirsch: Steps and Methods for the Identification of Potential Land-Use Units

11

Figure 6: Soil Map

Figure 7: Map of potential future land use units