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Land Use
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Land Use Planning to Avert the Migration Oriented Watershed Degradation
5.2 The Result of simulating Land Use/Cover:
Change in land use pattern has resulted lower rate of soil erosion than existing one in all of the scenarios, but the variation differs considerably (Table 2). The 2nd Scenario is the worst as it has
Reduced less than one t/ha/yr. Soil erosion rate even after converting 8.90% of degraded forest to forest. All other scenarios gave, more or less, considerably reduced rate of soil erosion . It we consider the higher rate of soil erosion from agriculture land, which is matter or concern is at impact is immediate, 4 th and 5 th scenarios are desirable.
The 5th seems more reasonable and feasible considering that agriculture includes crop cultivation along with livestock rearing. Over-utilization/overgrazing of Forestland, by the farming community, results in to Degraded Forest first and then in Shrubs. Thus, once agriculture of the area is removed, conversion of Shrubs and Degraded Forest Land in to Forest land in to forestland is easier. It also limits the agriculture land below 20 percentage slope. If this option is adapted, 5.23 percent of total land area should be re-planned. This work will include plantation of forest trees in the part of shrub land, degraded forest and agricultural land along with conversion of around 0.67 percentage degraded forest in to agricultural land. The distribution of land use and soil erosion rate of land use simulation with 5 th scenario is shown in Map 3 and 4 respectively.
Table 2: The Land Use/Cover Simulation and Soil Erosion Rate
Land
use/cover |
Area (%) in Different Scenario |
Ave. Soil Erosion Rate t/ha/yr.) |
| |
S1 |
S2 |
S3 |
S4 |
S5 |
S1 |
S2 |
S3 |
S4 |
S5 |
| Shrubs |
0.00 |
3.45 |
1.90 |
3.45 |
1.90 |
0.00 |
180.29 |
81.28 |
180.29 |
81.28 |
Degraded
forest |
8.90 |
0.00 |
6.57 |
8.22 |
5.89 |
10.53 |
0.00 |
5.13 |
10.53 |
5.13 |
| Forest |
61.32 |
66.77 |
61.74 |
58.54 |
62.42 |
2.05 |
2.07 |
2.28 |
1.94 |
2.35 |
| Agriculture |
23.65 |
23.65 |
23.65 |
23.65 |
23.65 |
41.23 |
41.23 |
41.23 |
27.05 |
27.05 |
| River |
6.14 |
6.14 |
6.14 |
6.14 |
6.14 |
0.00 |
0.00 |
0.00 |
0.00 |
0.00 |
| Total |
100 |
100 |
100 |
100 |
100 |
11.9 |
17.36 |
13.04 |
14.51 |
9.56 |
| S1,S2,S3,S4 and S5 are the Scenario 1,2,3,4 and 5 respectively |
6. The Land Use Planning and Recommendations:
The 5 th scenario should be adapted and recommended for immediate action while considering the sustainable utilization of watershed resources. This option is most convincing, as almost 50 percent reduction in soil erosion rate will be achieved by readjusting just 5.23 percent of total land area. The institutional support for enforcement of land use criteria and restriction are the most crucial factors here.
6.1 Relocation of Agricultural Land and Its Owner (Household):
The area of agricultural land above 20 percent of slope is 4.94 square km. (0.67 % of total land area). This land should be planted with forest tree and substituted with equivalent land area from degraded forest of below 5 percent slope.
The total household (HH) of the study area is 18004 (CBS, 1994b). Average land holding per HH of the study area is 1.27 ha, while it is just 0.86 ha in the hilly area (Sah, 1996). Agriculture land which is supposed to be replaced with forest tree, lies in hilly area. Thus number of household which should be relocated, can be calculated as:
No. of HH (Considered for relocation)= 4.94 sq. km/0.86 ha. = 575
Thus, percent of HH to be relocated = 575/18004 = 3.20 percent
As 48 percent of HH of the study area were in-migrated from outside watershed area, internal migration of 575 HH (3.20%) is very small and manageable.
6.2 Forest Plantation and Development Works:
All together 4.56 percent area should be planted with forest species. Breakdown of the plantation area is given in Table 3. For settlement of the migrated (relocated HH) people, from higher to lower slope land, 0.67 percent (4.94 sq. km. Area) of the secondary forest should be cleared for cultivation purpose.
Table 3: Sustainable Land Use Plan
| Land use/cover |
Area (Percent) |
| Present (1991) |
Scenario5 (S5) |
Difference |
| Shrubs |
3.45 |
1.90 |
-1.55 |
| Degraded forest |
8.90 |
5.89 |
-3.01 |
| Forest |
57.86 |
62.42 |
4.56 |
| Agriculture |
23.65 |
23.65 |
0.00 |
| River |
6.14 |
6.14 |
0.00 |
| Total |
100.00 |
100.00 |
0.00 |
Suitable activities for agricultural (Crop and Livestock) production enhancement, socioeconomic and demographic factor improvement and awareness should be lunched. Additional soil and forest conservation measures are also desirable.
7. Conclusion
The methodology presented here is simple, but it is more appropriate to control watershed degradation. Forest plantation is required only in 4.56 percent of total area to reduce soil erosion rate by 50 percent that is from 17.98 to 9.56 t/ha/yr. This will require the reallocation of 0.67 percent agricultural land and 575 Household, that is 3.2 percent of total Household. The relocation of such as small household number is feasible while considering the 48 percent of in-migration in the watershed area during last 15 years.
8. Reference:
-
Central Bureau of Statistics, CBS 91994a), Population of Nepal by District & Village Development Committee/Municipalities (Population Census, 1991), National Planning commission Secretariat, HMG, Nepal
- Central Bureau of Statistics, CBS *1994b), Statistical year book of Nepal, National Planning commission Secretariat, HMG, Nepal
- DSCWM 91983), Watershed conditions of the Districts of Nepal, Department of Soil Conservation and Watershed Management, Kathmandu
- DSCWM/HMG, Nepal, (1992), Soil conservation and Watershed management Operation Plan for Subwatersheds of Palpa District, DSCWM/HMG, Nepal.
- FAO (1995), tropical Forestry Action Plan, Committee on Forest Developmnet in the Tropics, FAO, UN, Rome
- Huang, C.T. and C.C.Wu 91995), Farmland Planning: A Practical Approach, Report of an APO Seminar on Soil Conservation and Watershed Protection in Asia and The pacific: 1993, Asian Productivity Organization, Tokyo.
- Sah, B.P. 91996), Assessment of Watershed Degradation and its Socioeconomic Impacts Using Remore Sensing and GIS : A Case Study of Trijuga Watershed, Nepal, AIT Thesis No. SR-96-20.
- Sah, B.P. Honda, K and S. Murai (1997), Land Degradation and Socioeconmic Modeling by Using Remote Sensing and GIS for Watershed management, Asian-Pacific Remote Sensing Journal, Vol. 9,No.2.
- Schertz, D.L. (1993), The Basis for Soil Loss Tolerances, Journal of Soil & Water Conservation, Vol.38, No.1.
- Schwab, G.O., Fangmeier, D.D. Elliot, W.J. and R.K. Frevert 91993), Soil and Water Conservation Engineering, 4th Edition, John wiley & sons, Inc., NY
- Sharma, C.K. (1981), Landslide and soil erosion in Nepal 2nd Edition, Navana printing works private Ltd., Calcutta
- WEC (1982), Hydrological Studies of Nepal, Vol 1 & WEC, Water and Energy Commission, Ministry of water Resource, HMG, Nepal
- Williams, J.R., Renard, K.G. and P.T. Dyke 91993), EPIC A New Method for Assessing Erosion's Effect on Soil Productivity, Journal of Soil & Water Conservation, Vol. 38, No.5.
Map 1: Land Use/Cover Map of Trijuga Watershed, Nepal (Derived from Landsat TM, Dec., 1991)
Map 2: Soil Erosion Map of Trijuga Watershed, Nepal: 1991
Map 3: Simulated (Scenario-5) Land Use/Cover Map of Trijuga Watershed, Nepal
Map 4: Simulated (Scenario-5) Soil Erosion Map of Trijuga Watershed, Nepal
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