Dear all

          I have two data elevation sources which are DEM grid file and
river cross-section surveyed data. DEM data is grid file covering the whole
watershed area. Surveying data is 500-m interval cross sections along a
river reach in the watershed area. However, these are much difference in
elevation value at the same coordinate points. I want to generate a new
grid file from surveyed data along the river reach to be input of
hydrodynamic model.  Can I solve this problem with any R packages?  or  Can
I use R to  interpolate river cross section between upstream and downstream
river cross sections?

The example of 2 cross section data are as following :

Cross section No- 1
chainage,x,y,z
0,537545.1,2219340,452.11
4,537541.1,2219340,452.05
12,537533.2,2219339,451.54
14,537531.2,2219338,451.6
16,537529.2,2219338,451.39
24,537521.3,2219337,450.13
34,537511.4,2219336,450.32
39,537506.5,2219335,448.55
44,537501.5,2219334,447.05
49,537496.6,2219333,446.15
54,537491.6,2219333,445.58
59,537486.7,2219332,445.11
64,537481.7,2219331,445
69,537476.8,2219331,444.83
74,537471.8,2219330,444.94
79,537466.9,2219329,444.69
84,537461.9,2219329,444.76
89,537456.9,2219328,444.8
94,537452,2219327,444.94
99,537447,2219326,445.04
104,537442.1,2219326,445.94
110,537436.2,2219325,446.89
114,537432.2,2219324,450.51
124,537422.3,2219323,457.19
134,537412.4,2219322,464.5
144,537402.5,2219320,471.79
154,537392.6,2219319,478.5

Cross section No- 2

chainage,x,y,z
0,537545.1,2219340,452.11
4,537541.1,2219340,452.05
12,537533.2,2219339,451.54
14,537531.2,2219338,451.6
16,537529.2,2219338,451.39
24,537521.3,2219337,450.13
34,537511.4,2219336,450.32
39,537506.5,2219335,448.55
44,537501.5,2219334,447.05
49,537496.6,2219333,446.15
54,537491.6,2219333,445.58
59,537486.7,2219332,445.11
64,537481.7,2219331,445
69,537476.8,2219331,444.83
74,537471.8,2219330,444.94
79,537466.9,2219329,444.69
84,537461.9,2219329,444.76
89,537456.9,2219328,444.8
94,537452,2219327,444.94
99,537447,2219326,445.04
104,537442.1,2219326,445.94
110,537436.2,2219325,446.89
114,537432.2,2219324,450.51
124,537422.3,2219323,457.19
134,537412.4,2219322,464.5
144,537402.5,2219320,471.79
154,537392.6,2219319,478.5

    Thank you for your help.

-- 
Wongwatana Sombunying

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