I am interested to find soil hydrological group of my catchment area that is TYPE A, B, C or D, for which I need soil classification of my project area.
How can I find the soil texture of my desired area, which are 598 Sq Km. Is there any published charts or data, and how can I access it?
You should download the HWSD Viewer and install it. Add your soil layer polygon in shapefile format clipped based on your basin.
For each polygon read its SMU table data and copy and paste them in excel.
Each polygon usually consists of 1 to 7 different soils. Their number and share are shown in the first and second rows of the SMU table, respectively.
Then, roll down to Top Soil (30cm) section. Just in the forth row of this section, the soil texture in USDA system is given.
For each soil texture, from soil or hydrology text books, you may find the average saturated hydraulic conductivity. if you want to be more accurate, you may consider the minimum and maximum saturated hydraulic conductivity for each soil texture.
Then, make a weighted average of these saturated hydraulic conductivity values based on the share of the soil texture in the soil polygon (second row of the SMU table) which you will gain the mean saturated hydraulic conductivity for that polygon. Based on this mean saturated hydraulic conductivity, you may identify the hydrologic soil group of that polygon.
Hi, if you cannot find any data/map specific for your area of interest, you may use data from HWSD (FAO, 2012). You will find polygons containing a mix of several soil textures. For each soil texture you may know your average saturated hydraulic conductivity (which is equal to your maximum soil infiltration rate). You will make a weighted mean to come to a mean saturated hydraulic conductivity for each polygon. Based on this mean saturated hydraulic conductivity you will know their hydrologic soil group.
when i use that data and processed i come to the following conclusion i.e
area code for my catchment is 3673. but i dont understand its result.please if u kindly provide me email address. so that i can share my results with you sir
The best source for soil grouping and hydrologic classification for runoff characteristics is The National Engineering Handbook, Chapter 7. That should help you match soil type to A, B, C, and D classifications.