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On the significance of the watershed management approach in studying highland-lowland interactive systems
Review of current research on agriculture in the highlands of northern Thailand
A watershed as a complex natural ecosystem provides one of the best means to study the behaviour of a natural ecosystem. especially from the point of view of the interaction of its key components. Minimizing the fluctuating of water debit, which is most widely interrelated to the other objectives of area based development, can be used as a key indicator of the state of natural resource utilization in a given watershed. In the development process the spatial divisions are upland, lowland, and coastal subsystems. Interfacial aspects between development subsystems may be described using a cross impact matrix.
There are two schools of thought in area-based research or development: (1 ) the administrative approach, and (2) the watershed approach. The only advantage in using the administrative approach (province, district, or county) lies in the fact that it is already operational It is familiar both to the planners and to the executives. However, this approach does not fit natural resource development in which the three basic components are land, water, and biological resources. In policy analysis and implementation, both approaches can be synthesized. Interest in watershed analysis stems from the evidence that (1 ) water resource utilization is best optimized through basin-wide management, (2) as the water resource component is analogous to the blood systems in animal bodies, it provides the best method to diagnose the state of natural resources utilization in a given watershed, and (3) fluctuation of water debit is most widely interrelated to the other objectives of area-based development as is shown in the following compatibility matrix (see Table 1).
TABLE 1. Compatibility Matrix of Objectives
|Z1 Water yield||1|
|Z2 Water debit fluctuation||-||2|
|Z3 Water quality||+||-||3|
|Z4 Erosion level||-||+||-||4|
|Z5 Soil fertility||+||-||+||-||5|
|Z6 Food production||+||-||+||-||+||6|
|Z7 Electric power and fuel||+||-||-||-||+||+||7|
|Z8 Building material||+||-||-||0||+||0/-||+||8|
|Z10 Industry and mining||+||-||-||-||0||+||+||+||+||10|
|Z11 Income equity||0||-||0||0||0||+||+||+||0||+||11|
|Z17 Natural beauty||0||-||+||-||+||0/-||-||-||0/+||-||0/+||0/+||0||0/+||0||0/-||17|
|Z18 Historical, cultural, and archaeological considerations||0||0||0||0||0||0||0||0||+||0||0/-||+||0||0||0||0||+||18|
|Z19 Minimum waste||+||-||+||+||+||+||+||-||0||-||0||0||0||0||0||0||+||0||19|
Z2 = f (Z1. Z3, Z4. Z5, Z6, Z7, Z8 Z9 Z10 Z11, Z12, Z13. Z14.
717. Z19). and since
Z15 = n (Z4, Z5, Z6 Z7 Z9 Z10 711 Z12. Z14), and
Z16 = g (74 Z5 Z7 Z8 Z9, Z10 Z14. Z17), then
Z2 (fluctuation of water debit) interrelates with other objectives except Z18 (historical, cultural, and archaelogical aspects) and Z20 (uniqueness). This means that Z18 and Z20 can be managed separately while Z2 can be used as a measure of performance of watershed management. In other words fluctuation of water debit can be considered as a state variable which should be attained in each time span in the whole planning horizon (see Fig. 1).
One obvious advantage of using fluctuation of water debit as an indicator is that it is easily measured. With proper management strategies, fluctuation of water debit could be minimized (or minimize DZ2/Dt)
The ideal condition is when DZ2/dt = 0 Since this kind of condition is only theoretical, our effort is to achieve a certain permissible level of fluctuation, in which dZ2/dt = m. The value of m should be the target from one time span to the other time spans. Using multi-criterion optimization models, Z2 is the most important one to be minimized. The remaining 17 objectives are then treated as constraints in the subsequent optimization process by specifying a minimum level of attainment for each of these secondary objectives.
As a system, a watershed may be divided into three subsystems: upland, lowland, and coastal subsystems (see Fig. 2). The boundary between upland and lowland subsystems is a line connecting potential sites of reservoir construction, while the boundary between lowland and coastal subsystems is a line connecting the points in which marine influences are significantly detectable, through cation distribution or electrical conductivity. The idea to divide the watershed ecosystems into those three subsystems is based on the consideration that each subsystem has its own function and characteristics:
Referring to Fig. 2, what is to be transferred is water. However, it can be expressed in terms of energy or nutrient flow. For each subsystem the components are vegetation, land, and channel networks.
The cross impact matrix of Table 2 depicts the closed loop interactions between subsystems, in which each element of the matrix tells the effect of a row subsystem on a column subsystem. The upland subsystem supplies water regularly all year around to be used efficiently in the lowland and coastal subsystem. The lowland subsystem should be developed into efficient agriculture and industrial estates to generate employment opportunities. Mangrove forest in the coastal subsystem is a protection belt against marine influences. A more detailed closed loop of interactions between variables should be scrutinized further in the form of a causal diagram loop.
FIG. 1. Decreasing Fluctuation of Water Debit over Tirne. (t = time span; T = planning horizon; Z2 = fluctuation of water debit.)
FIG. 2. The Structure of a Watershed Ecosystem. (V = vegetation; S = soil; C = channel network.)
TABLE 2. Interfacial Aspects of a Watershed Development
|Change in||Upland subsystem||Lowland subsystem||Coastal subsystem|
networks dev More efficient use of water. Labour
intensive dev. to accommodate migrants from the upland
( 1 ) Agric. Intensification and diversification.
(2) Agro-based industries. and
(3) Dev. of transportation
|Lowland subsystem||Minimizing fluctuation of water debit through land treatment, vegetation cover, and management of channel systems. Selective and protective agricultural technology. To relieve population pressure on agricultural land||Dev. of mangrove forest belt to minimize salt in trusion. prevent marine erosion. as wind breaker. Spawning and nursery ground of commercially important aquatic species, supporting land accretion processes.|
|Coastal subsystem||Minimizing fluctuation of water debit through land treatment, vegetation cover and management of channel systems. Selective agric -technology. To relieve population pressure on agric land.||Irrigation networks dev. Special irrigation for brackish water ponds. Aquatic weed control. Proper use of pesticides industrial pollution abatement.|
Chow, V.T., ed. 1964 Handbook of Applied Hydrology. New York: McGraw-Hill Book Company
Knop. H, ed. 1975. Proceedings of the UNEP/IIASA Meeting of Experts on Environmental Management.
Reichle, D E 1970 Analysis of Temperate Forest Ecosystems. New York: Springer-Verlag.
Sharif. N., and P. Adulbhan. ed. 1978. Systems Models for Decision Making. Bangkok: Asian Institute of Technology
White, F.G . ed. 1977 Environmental Effects of Complex River Development. Boulder, Colo: Westview Press
Review of current research on agriculture in the highlands of northern Thailand
The Faculty of Agriculture of Kasetsart University is the pioneer in research in the field of applied agricultural science in the highlands. This work was initiated in 1970. Nevertheless, forestry research began long before this by the Faculty of Forestry of the same university. Since research work carried out in only one institute. knowledge concerning the highlands was therefore limited.
The lack of knowledge of highland agriculture may have been an obstacle to the study of agro-forestry systems during the past three years. However, in the last five years agricultural research in the highlands has spread more rapidly and various institutes have become involved in addition to the staff of Kasetsart University, for instance, the staff of Chiang Mai University, the Institute of Applied Scientific Research Corporation of Thailand, the Department of Agriculture, and the Royal Forestry Department.
The results of pooling ideas and the ability to carry them out enable agriculturists to arrive at definite conclusions about suitable methods of plant cultivation and raising certain kinds of animals. These results were sufficient to start work on agroforestry in the highlands.
No fewer than 20 research projects on agriculture in the highlands are being carried out.
1. Deciduous Fruit
The studies were carried out both on the varieties which had long been introduced into the highlands and are generally grown by the hill peoples and also on 87 varieties of newly introduced ones.
Many aspects of peaches which were on varietal trial and different cultural practices, for seed germination. pruning, thinning, grafting. and finally, rootstock selection were examined.
Furthermore, the project produced the new product of canned local peaches in syrup.
From the studies it was possible to successfully select those varieties which were suitable for growing in the highlands.
Besides peaches, several kinds of stone fruits had also been introduced, including 20 varieties of nectarines and 2 varieties of Japanese apricots. Both of these stone fruits showed very promising results. In addition, 23 varieties of plums, 17 varieties of almonds, 19 varieties of common apricots and 13 varieties of sweet cherries had also been introduced into the highlands.
Two kinds of pome fruits were introduced. These were 45 varieties of apples and 31 varieties of pears. A study on their growth performance was conducted.
A study concerning apple rootstock was also undertaken.
Forty-eight varieties of Chinese persimmon were introduced for both varietal and for rootstock studies. The results obtained indicated that some varieties of persimmon tried were suitable for cultivation in the highlands.
The first step of this project was to grow Pyrethrum var. Shirayuki from Japan and for the study of flower and pyrethrin production. After the possibility of pyrethrin production was established. investigations were then made on cultural practices regarding time of planting, spacing. fertilization, and the effects of nutrients on flower yield.
Two other aspects of this study are investigation of the management of this crop concerning the intercropping system and also a study on slope effect.
The results of these studies showed clearly that pyrethrum can be grown in the highlands of the northern part of Thailand.
Seventeen varieties of strawberry were introduced and grown to find out their yielding ability, the possibility of producing strawberry 'off season', and its daughter plant production.
4. Coffee Arabica
The coffee varieties employed in the project came from two sources: those introduced into Thailand about twenty years ago and 30 varieties of both pure lines and hybrids which were introduced more recently. The plant materials introduced were first used in a study of plant selection for rust-resistance.
It was found that the variety introduced twenty years ago was most promising. Moreover, it was also found that those pure lines from India were rust-resistant. A study was also carried out to solve the problem of crooked root systems and to find shady plants (trees) or crops which would provide suitable shade for coffee trees. In addition, studies were also conducted on mineral nutrition and the pathology and entomology of coffee plants.
5. Vegetables for Seed Production
A study has been carried out on varietal trial of cabbage. Chinese cabbage. broccoli, and cauliflower. The study was done on their growth in terms of fresh weight and seed production of Chinese cabbage, broccoli. cauliflower, lettuce, and Chinese radish.
Fifteen varieties of onions were introduced for varietal trial and also for the study of the effects of nitrogen, phosphorus, and potassium on their yields and quality.
7. Legumes for the Highlands
The work in this project dealt with plant introduction, evaluation. and yield trial of 82 varieties of soya bean; 133 varieties of mung bean; 38 varieties of groundnut; 538 entries of common bean (Phaseolus vulgaris); 169 cultivars of lentil (Lens esculenta); 79 cultivars of chick pea (Cicer arietinum); 123 cultivars of cowpea (Vigna unguiculata); 11 varieties of pigeon pea (Cajanua cajan); and more than 200 cultivars of broad bean (Vicia faba). Moreover, these studies also included experimentation on nutrients of N, P, K, and also trace elements in order to understand their effects on the yield of several kinds of the tested legumes.
The studies of crop management. e.g.. planting date and cultural practices, were also undertaken.
One hundred and eighty-three varieties of highland castor bean and sunflower were employed for the studies of their growth in general and also on the planting date as well as yield.
These studies on mushroom were undertaken under both laboratory conditions and field conditions. concerning spawn composition and cultural practices on Shiitake mushroom (Lentinus edodes) and button mushroom (Agaricus bisporus).
10. Essential Oil
These experiments were conducted on agronomic study and varietal trial of Chrysanthemum morifolium. Cymbopogon nardus. Mentha spp. Eucalyptus spp., Pelargonium spp. and Rosa damascena.
11. Insecticidal Plants
Plants suspected to be insecticidal were collected for toxicity tests. The most promising plants were grown in the highlands for growth study. It was found that 20 species grew well. The next steps of research will be on the testing of cultural practices of the plants.
12. Crops and Plants for Dye Production
The research in this project involves six kinds of plants for dye, i.e.. marigold, curcuma, red beet, carrot. safflower, and dahlia.
13. Medicinal Plants
In this project. the aim of the study was to find those plants which have a potentiality to yield medicine. The plants studied were of nine kinds: Curcuma (two species), Zingiber (two species), Alpina. Gloriosa. Kaempferia Piper and Plumbago.
14. Tea Project
Studies on cultural practices for tea production have been undertaken.
15. Nut Project
Several kinds of nuts-almonds, macadamia nuts, Chinese chestnuts. filberts, walnuts, pecans, araucarias. and Malabar chestnuts-were introduced for both growth and cultural practices studies.
16. Multiple Cropping
Eight systems of multiple cropping have been investigated in order to find out the return of each system as well as the ecological problems.
17. Wild Silkworm
Tests were carried out of the effects of different kinds of food plants, i.e. wild apple. apple, peach, and parchard, on the growth and development of the Eri silkworm. The study was, moreover. concerned with the conditions suitable for wild silkworm culture.
The studies emphasized various methods and various plants which would be suitable for honey production. Simultaneously, the bees were beneficial agents for pollination.
The pasture project was aimed at the improvement of Imperata grassland for grazing. Not only grass but also legumes were introduced to test for the response of fertilizers on dry matter and also the grazing of these tested crops. The studies in this project also included pasture in relation to forestry and were also extended to feeding swine.
20. Flower and Ornamental Plants
More than 50 kinds of both flower and ornamental plants have been employed in this project for the studies of seed, flower. plant, and/or bulb production.
As can be seen from all the agricultural researches undertaken in the highlands which are being carried out at present, it is believed that the results obtained will subtantially support the work in agro-forestry.
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