Python -> Virtually Create Dams on GSI Japan DEM

 Before I will explain the codes and consdertion, I show one of the results that are analysised my codes. The below image is the result that I run the virtual dam creation code near Yamatosaka Dam, 山鳥坂ダム, construction site which is under construction by MILT, Japan at Kawabegawa Branch River Hiji River Ehime Pref. 

By Shikoku Regional Development Bureau, MLIT, Yamatosaka Dam's specification is below.(URL: https://www.skr.mlit.go.jp/yamatosa/pamphlet/pdf/yamadam_jigyou.pdf)

 the comparing between Yamatosaka Dam basic design(first value) and the calculation result(second value) are like below.

• Dam Height: Approximately 96m, 82m (I think that this difference is caused  including surface soft soil thickness on the dam site under calculation.)
• Dam Top Length: Approximately 275m, 206m
• Dam Top Elevation: EL161m, EL161m (I try to mutch this values)
• Storage Area: 0.7km2, 669754m2=0.67km2
• Total Storage Volume: 22million cubic meter, 20million cubic meter

 It's allowable range for me as rough calculation.

 I seem that these conseptis  useful to to guess the seservoire volumes which will be made embankment( or natural dams) on river caused by land slide's and the others natural disaster like it. I think that  Apps like this have existed in the world. 

That aside, I introduce my codes besed on this concept.

 At first, we need to import some libraries which are needed our codes.

!pip install geopandas

import folium

from folium import plugins

import sys

from folium.plugins import MarkerCluster

import geopandas as gpd

from shapely.geometry import Point, LineString, MultiPoint, MultiLineString, Polygon

import pandas as pd

 At second step, I write the code which have previously introduced the code for downloading  Digital Elevation Model of an area from Geospetial Information Authority in Japan. 

 We need to describe the download map area with north-west corner coordinate as longitude and latitude and necessary number of tiles for direction to south( coodination y) and east(coordination x) like below.

   

###################################

##### 使用するタイルデータ入力箇所 #####

##### Code No.1 use this data #####

###################################

# Yamatosaka Dam Point

zoom = 13 #zoomを入力

north_west_x = 7114 #北西端tileのx座標を入力

north_west_y = 3283 #北西端tileのy座標を入力

tile_num_x = 6 #東西方向のtile数を入力

tile_num_y = 7 #南北方向のtile数を入力

 I explain before now about zoom and tile there(URL: https://shikuuk.blogspot.com/2024/10/catchment-area-calculator-with-python.html)(I'm sorry If I mistake the link setting)