Cropping system optimization for drought prevention and disaster reduction with a risk assessment model in Sichuan Province

It is very important that making full use of the regional precipitation resources, evaluating the comprehensive risks overall and choosing drought-resisting and disaster-avoiding cropping system reasonably. Based on the meteorological data from 1961 to 2017 and crop growth period data from 1981 to 2017 in Sichuan Province, Sichuan Province was divided into seven agro-ecological zones and one non-agricultural zone according to their interregional differences and regional similarities in aspects of nature, social economy and current agricultural infrastructures. Besides, the representative station and cropping system in each region were selected. This paper evaluated the current cropping systems and cropping patterns in different agro-ecological zones of Sichuan Province by calculating the ensure index of precipitation, the yield variation coefficient, the ratio of sown area to cultivated area and the disaster resistance capability coefficient of agricultural planting areas in Sichuan Province under the background of droughts. Moreover, taking representative stations as an example, the evaluation index of cropping system optimization was put forward based on four factors, namely risk, vulnerability, exposure and the capacity of drought prevention and disaster reduction, from the perspective of the natural disaster formation mechanism. Then, a risk assessment model was established to evaluate the cropping system optimization in different agro-ecological zones of Sichuan Province. The results showed that winter wheat-maize-sweet potato (soybean) triple cropping pattern in upland is the best cropping system for the wide valley area of Southwest Sichuan (such as Panzhihua), the mountain area of Southwest Sichuan (such as Xichang), the basin-edged mountain area (such as Guangyuan) and the parallel ridge-valley area of eastern basin (such as Dazhou). Winter wheat (rape)-maize-soybean triple cropping pattern in upland is the best cropping system for the hilly area in southern basin (such as Yibin). Winter wheat (rape)-maize-soybean (sweet potato) triple cropping pattern in upland is the best cropping system for the summer-drought-prone hilly area of central basin (such as Suining). Paddy potato-upland rice rotation double cropping pattern is optimal for the Chengdu Plain under the moist climate.