The impacts of climate change on irrigation water requirement for spring season paddy in Ha Noi city, Ha Nam, Hung Yen and Nam Dinh provinces

Abstract

    In this paper, irrigation water requirement of spring season paddy with the meteorological data at Lang, Ha Nam, Hung Yen, and Nam Dinh rain gauge stations of Vietnam are forecasted, based on the projected meteorological data of 6 global climate models under A1B climate change scenario after using the bias correction and spatial downscaling to increase the horizontal resolution. The irrigation water requirements are simulated by CROPWAT model version 8.0. The calculation results show an increasing trend under the climate change in the most models when compared with present result, except the results of the CCCMA_CGCM3_1 model. The results of MIROC3_2_MEDRES, and MRI_CGCM2_3_2a models gives the highest increasing values. In Ha Nam province, the irrigation water requirement increases significantly to over 360 mm compared with 260 mm of referent period. Next increase value is in Ha Noi and Nam Dinh provinces, around 300 mm in 5 models. The irrigation water requirement would continue increasing trend in the far future from 2080-2099 when compared with the year 2050-2069 and reference period (1980-1999) in all models. It means that the increment/decrement of irrigation requirement has a strong relationship with the climate variable such as temperature and rainfall under the impacts of climate change.