Experts say drying underground water currents, or changes in soil drainage, could be to blame.

专家称，地下水干燥或者水土流失可能是事故发生原因。

Beyond the vernacular terms, grasslands vary more technically in the height of grass, and in the absence of grazing animals, this relationship is determined by the amount of rainfall and soil drainage.

除了俗语外， 草原在草的高度上有更严格的差异，在没有食草动物的情况下，这种关系是由降雨量和土壤排水量决定的。