Effect of Precipitation Timescale Selection on Tempo-spatial Assessment of Paddy Water Demand in Chikugo-Saga Plain, Japan

For the purpose of fully understanding tempo-spatial water circulation in the rice growing region of Chikugo-Saga, Japan, an assessment model of paddy water demand at daily/monthly time and one-kilometer space scales was established by using agro-statistic data, land use and meteorological data under GIS environment. Then, the daily and monthly precipitation data were, respectively, imported into the model to assess the tempo-spatial distribution of paddy water demand. Through the comparison between the two estimated results, it is shown that the selection of precipitation timescale has significant influence on the assessment of paddy water requirements during non-drought seasons while hardly effects the paddy water demand estimated for drought seasons. Furthermore, the daily-time-series analysis of the paddy water demand assessment was performed. It is found that the timescale-induced difference in the paddy water demand has a direct relation to the frequency and the amount of the concentrated heavy rainfall. From the investigation, it can be concluded that the proposed GIS-based model is suitable to be used to quantitatively carry out the tempo-spatial assessment of paddy water demand, and the daily precipitation data are more reasonably adopted to estimate paddy water requirements in non-drought seasons than the monthly precipitation data are done. Copyright Springer Science+Business Media B.V. 2012