하수처리수의 농업용수 재이용을 위한 관개수량 산정방법에 관한 연구

A Study on the Estimation of Irrigation Water for Sewage Treated Water Reuse for Agriculture

Abstract

The purpose of this study was to establish the estimation method of irrigation water amount for sewage treated water reuse for agricultural purpose. To calculate the irrigation water amount, we adopted Penman-Monteith for potential evapotranspiration estimation and applied crop coefficient and irrigation efficiency factor. We developed the irrigation water amount calculation program using C language in Xcode environment. The target district for calculation is having 259 ha of agricultural land located near the Jinyeong Clear Water Circulation Center in Hanrim-myeon, Gimhae city. The meteorological data of the study area were obtained from Changwon weather station from 1986 to 2017. Calculated average and maximum of annual mean potential evapotranspiration were 2.72 mm/day and 6.22 mm/day, respectively. We used K-S (Kolmogorov-Smirnov) for goodness-of-fit test to find optimal probability distribution of annual mean and maximum evapotranspiration. As a result, the normal distribution was selected for the appropriate distribution. The annual mean and maximum potential evapotranspiration for 10-year return period by applying normal distribution were 2.88 mm/day and 6.76 mm/day, respectively. Assuming that the irrigation efficiency is 80%, the irrigation water requirement was calculated as $36.05m^3/day/ha$ and $84.45m^3/day/ha$, respectively, when annual mean and maximum potential evapotranspiration were applied. The actual irrigation water amount can be calculated by applying the crop coefficient and cropping days for the study area based on the developed irrigation water amount estimation program in this study.

Fig. 1 Overview of study area

Fig. 2 Procedure of calculating irrigation amount using Penman-Monteith evapotranspiration, K-S goodness-of-fit test, and frequency analysis

Fig. 3 Daily potential evapotranspiration for study area (1986-2017)

Fig. 4 Annual mean and annual maximum potential evapotranspiration for study area (1986-2017)

Fig. 5 Frequency distributions and probability distributions of annual mean potential evapotranspiration (1986-2017)

Fig. 6 Frequency distributions and probability distributions of annual maximum potential evapotranspiration (1986-2017)

Table 1 Cultivated area of greenhouse crops and paddy fields area by section

Table 2 Probability distribution type goodness-of-fit test for annual mean potential evapotranspiration

Table 3 Annual mean and maximum potential evapotranspiration by return period

Table 4 Estimation of irrigation water requirement according to the scenario of change in greenhouse crop area