Updating and application of DTM on Violent Hill-Slope Land Development
Result Analysis and Discussion
1.Change of Elevation
By overlaying, we can compare the change of elevation of DTM before and after the development. The statistics file of elevation change chart can signify The maximum, minimum, average , and standard deviation of elevation change.
Table 2 shown:
| Min | Max | Aver. | Standard deviation |
| -71.991 | 104.583 | -0.007 | 2.421 |
Table 2 Elevation change statistics of the full
If only is the developed site put into calculation, as table 3 shown:
| Min | Max | Aver. | Standard deviatIon |
| -71.991 | 104.583 | -0.007 | 2.421 |
Unit: meters
Table 3 Elevation change statistics of the Developed area
As table 2 and 3 shows, negative signifies (blue) cut, positive (red) fill and (white) cut-and-fill balance. Table 2 shows the cut depth reaches 71.991 meters, fill height 104.583 meters. It shows clearly the violent situation of cut-and-fill,-the average, -0.393 is that of the total developed site. Negative signifies that cut and fill is not balance, that cut volume is greater than the fill volume.
Table 4 shows the elevation change of the different developed sites. The result is similar to the reality. The total cut depth reaches 32008.1 meters. With a resolution of 40 meters, we can get the total cut volume, that is 51,210,000 cubic meter. And the total fill height is 30060.6 meters. In the same way, we can get the total fill volume,48,090,000 cubic meter. We can conclude that the total soil loss is 3,120,000 cubic meter. From above, the situation of the development in different developed sites and the disturbance site is known easily and quickly.
| | Minimum | Maximum | Average | Standard dev. |
| Full developed area | -71.991 | 104.583 | -0.393 | 17.775 |
| Full watershed | -71.991 | 104.583 | -0.007 | 2.421 |
| Yu-san Lau-yea golf course | -71.991 | 104.583 | 10.488 | 27.258 |
| Pau-Fu golf course | -60.877 | 42.428 | -2.107 | 19.858 |
| Li-Yi goal course | -68 | 44 | -3.449 | 20.280 |
| San-In golf course | -47.309 | 26.057 | 0.015 | 10.495 |
| Lan-In golf course | 3.523 | 28.121 | 16.953 | 5.000 |
| Liou-Fu village recreation site | -20.967 | 11 | -6.564 | 5.355 |
| Siang-Tsoon golf course | -44.866 | 22.751 | -3.492 | 12.099 |
| Free way | -43.042 | 22.162 | -5.635 | 9.889 |
Table 4 The statistics of cutting filling depth in every developed sits
2. Comparison of the physiographic parameter :
(1) Slope
Divide the slope before and after the development into six grades, and Compare the percentages of the gardes.
Table 5 shown:
| Slope | Before Development | After Development | Difference % |
| Areas(ha) | % | Area(ha) | % |
| 0~5% | 3100.96 | 14.53 | 309.56 | 14.50 | -0.03 |
| 5-15% | 3506.40 | 16.43 | 3673.76 | 17.22 | 0.79 |
| 15-30% | 5816.00 | 27.26 | 5847.20 | 27.41 | 0.15 |
| 30-40% | 3485.44 | 16.33 | 3388.00 | 15.88 | -0.45 |
| 40-55% | 3234.40 | 15.16 | 3138.88 | 14.71 | -0.45 |
| Over 55% | 2195.04 | 10.29 | 2192.48 | 10.28 | -0.01 |
Table 5 Difference of slope Grade Before and After Development
The table demonstrates there is a striking slope increase in Grade 2 and a lesser increase in grade 3.There two grades increase 19.3%, and Grade 4 and grade 5 reduce to 9.24%. There is striking reduction in them. But the changes in Grade 1 and Grade 6 are slight. This demonstrates that the cut-and-fill turn steep slopes into flat plain with connect to mining field, playground and highway and the construction of numerous golf courses. especially, the result is greatly influenced by the regulation that the golf course slope is limited to 15%.
Figure 2. Developed area boundary overlaying DTM
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Figure.3 Developed area boundary overlaying updated DTM
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Figure.4 Shaded DTM before development
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Figure.5 Shaded DTM after development
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Figure.6 Cut and fill location of full area
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Figure.7 The detailed Cut and fill of Pau-fu Golf Course
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