that stains their waters brown. 水变得很浑浊

100. As the land flattens out
     由于地势平坦
101. rivers slow down and lose their destructive power.
     河水流速变慢 没有了原来的破坏力
102. Now they are carrying heavy loads of sediment
     河流中带着大量的泥沙
103. that stains their waters brown.
     水变得很浑浊
104. Lines of wildebeest are on their march.
     一队队的角马正在迁徙途中
105. Each year nearly two million animals migrate across the Serengeti plains
     每年都会有将近200万只角马 横越塞伦盖蒂平原
106. in search of fresh green pastures.
     去寻找新鲜草场

来自《行星地球 第一季 第三集 Planet Earth S01E03 淡水》第 103 行