1986 Volume 42 Issue 2 Pages 103-112
The method to obtain the detailed map of the maximum snow depth is developed on the basis of the mesh-square technique. It is applied to planning and design for fruit-tree cultivation in the Hokuriku District, where heavy snowfall occurs in winter. Results are summarized as follows:
1) Statistical relationships were established between the maximum snow depths and topographical land features for selected 58-point locations in the Hokuriku District. The third degree orographic mesh data was used to determine the topographical parameters which, in turn, were related to the maximum snow depth on average (Sh, m, cm), on five-year return periods (Sh, 5, cm), on ten-year return periods (Sh, 10, cm) and on twenty-year return periods (Sh, 20, cm). They were respectively given by following relations:
Sh, m=119+2.060Hm+0.182K+2.05√Mh, r15+0.021Ks, r1+1.729Re, r10-2.548Rd, r5-3.056√P10, r15, (r=0.94) (3)
Sh, 5=211+13.36 ln (Hm)+11.59ln(P20, r5)+0.060Ks, r1+0.222K-2.37Rd, r5-7.03√P60, r13-2.67√Rd, r10-5.86√Sr15, (r=0.93) (4)
Sh, 10=224+0.299K+6.21√Mh, r15+3.53Ha, r1-0.215Hm-2.63Rd, r5-5.30√P10, r15-0.191 (S100, r2)2 (r=0.94) (5)
Sh, 20=260+0.301I+11.15√Mh, r15+1.34Ha, r1+0.051Ks, r1+10.15 ln (P20, r5)-4.03Rd, r5-8.17√P10, r15-7.59√Mh, r11 (r=0.93) (6)
where each predictor variable is defined in Table 1.
2) Relatively large errors of estimate, around 20% of the observed values, were obtained for several stations. The regressions used here overestimated the maximum snow depths for the adjacent regions of isolated mountains in the coastal plain, the Noto Peninsula and most inland areas of the Hokuriku District. On the other hand, underestimates of them were obtained for those stations in inland hilly countries. Such deficiency suggests that the accuracy of estimate is not satisfactory if different climates are included in a given area of interest.
3) The detailed geographical distribution of the maximum snow depth was then estimated from these multiple regression equations with the orographic mesh data as inputs. An example of the distribution as mapped using all the points of about 1km2 grid in the basal part of the Noto Peninsula is illustrated in Fig. 4.
4) Agroclimatic classification criteria for fruit-tree cultivation planning based on the maximum snow depths were made from the survey data on physical snow damages reported for the Hokuriku District (Table 2). This result was superimposed on the mesh distribution of the maximum snow depth to construct the land use planning for fruit-tree cultivation (Fig. 6).
The map thus obtained indicates not only the design criteria for a normal climatological period but also the probability of occurrence of snow damage on fruit trees.
