"Jang, W. S., Yoo, D. S., Chung, I. M., Kim, N. W., Jun, M. S., Park, Y. S., Kim,
J. G. and Lim, K. J. (2009). “Development of SWAT SD-HRU pre-processor module for
accurate estimation of slope and slope length of each HRU considering spatial topographic
characteristics in SWAT.” Journal of Korean Society on Water Quality, Vol. 25, No.
3, pp. 351-362."