نویسندگان
1 کارشناس طرحهای توسعه منابع آب شرکت سهامی آب منطقهای گیلان
2 استادیار پژوهش موسسه تحقیقات خاک و آب
3 استادیار پژوهش موسسه تحقیقات برنج کشور
4 دانشیار گروه مهندسی آب دانشگاه تبریز
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
In the recent years, frequent droughts and construction and operation of different dams in the Sepidroud River watershed have markedly decreased water quality (increase salinity) and quantity of the river which is the most important water supply resources in Guilan province. It is predicted that in the next years, due to increasing intervals between irrigations, crack development will be inevitable due to the type of clay and its high content in Guilan paddy soils. Therefore, the loss of water in cracking soils is going to be considered as one of the most important problems. Besides, increase in irrigation water salinity affects soil physical properties associated with the soil shrinkage and crack developments. In this study, shrinkage cracking processes were investigated in laboratory using paddy soils, in the absence of rice plants, with 2, 3, 4 and 5 dSm-1salinity levels using shrinkage characteristic curve. The results showed that change in soil volume started with vertical subsidence and crack initiated at a moisture content almost close to saturation (50% to 55% gravimetric water). Also, the shape of aggregated was orthogonal. At higher soil salinity levels, the mean width and depth of cracks increased. At the end of the experiment, average width and depth of 5 dSm-1treatment were 4.9 and 16.6 cm, respectively, . In desiccation period, the trend of crack index changes showed that 2 dSm-1treatment had the lowest crack development and this factor increased by increasing soil salinity.
کلیدواژهها [English]
)